diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index d354c062b..7b97a1c22 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -15,19 +15,31 @@ jobs:
               with:
                   node-version: 24
                   cache: npm
-                  cache-dependency-path: |
-                      gpx/package-lock.json
-                      website/package-lock.json
+                  cache-dependency-path: website/package-lock.json
 
-            - name: Install dependencies for gpx
-              run: npm install --prefix gpx
+            - name: Install Rust
+              uses: dtolnay/rust-toolchain@stable
+              with:
+                  targets: wasm32-unknown-unknown
 
-            - name: Build gpx
-              run: npm run build --prefix gpx
+            - name: Install wasm-pack
+              uses: taiki-e/install-action@v2
+              with:
+                  tool: wasm-pack
+
+            - name: Test gpx-rs
+              run: cargo test
+
+            - name: Build wasm
+              run: wasm-pack build --target bundler
+              working-directory: wasm
 
             - name: Install dependencies for website
               run: npm install --prefix website
 
+            - name: Test website
+              run: npm test --prefix website
+
             - name: Create env file
               run: |
                   touch website/.env
diff --git a/.gitignore b/.gitignore
index 496ee2ca6..f2564bc44 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
-.DS_Store
\ No newline at end of file
+.DS_Store
+target/
diff --git a/tauri/Cargo.lock b/Cargo.lock
similarity index 95%
rename from tauri/Cargo.lock
rename to Cargo.lock
index 26240fd50..04b7f2155 100644
--- a/tauri/Cargo.lock
+++ b/Cargo.lock
@@ -47,6 +47,17 @@ version = "1.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"
 
+[[package]]
+name = "async-trait"
+version = "0.1.92"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "82f6aeea286b8eb4dd3431a1be1b59d290ace00f5bfd8e2a159bc2a05e2c1667"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.6",
+]
+
 [[package]]
 name = "atk"
 version = "0.18.2"
@@ -283,10 +294,16 @@ dependencies = [
 ]
 
 [[package]]
-name = "cc"
-version = "1.8.0"
+name = "cast"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6651c9ed80effdc7db0ff72512157f901af5e3549e341e24b1dd4887d836d838"
+checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
+
+[[package]]
+name = "cc"
+version = "1.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3eb0f42d6c360dc3f8a821f6bf2fdea7f72bfd36b3076eb0e6d1e9e0752fff4"
 dependencies = [
  "find-msvc-tools",
  "shlex",
@@ -321,9 +338,9 @@ dependencies = [
 
 [[package]]
 name = "cfg-if"
-version = "1.0.5"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e7648175b45a9a48536d676f68d918270699102aa8dab5496df06904c914600"
+checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "chrono"
@@ -358,6 +375,16 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "console_error_panic_hook"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a06aeb73f470f66dcdbf7223caeebb85984942f22f1adb2a088cf9668146bbbc"
+dependencies = [
+ "cfg-if",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "cookie"
 version = "0.18.2"
@@ -477,7 +504,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d045de693cb712d0b22c6a64be5b953f67b3ce00ab5ad3dd5d8b441886ab8e1a"
 dependencies = [
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -506,7 +533,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "strsim",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -517,7 +544,7 @@ checksum = "2ac7135c3ef02b2f7833bbeb1be5ba7f966dcde8a87c6b87f65a778d71a02785"
 dependencies = [
  "darling_core",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -550,7 +577,7 @@ dependencies = [
  "defmt-parser",
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -589,7 +616,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "rustc_version",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -643,7 +670,7 @@ checksum = "c6232dd377dcc64799954cbd3a9bb882e9cdc1308ccd87b1c098f1fb2eaf82a8"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -666,7 +693,7 @@ checksum = "0fbbb781877580993a8707ec48672673ec7b81eeba04cfd2310bd28c08e47c8f"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -754,9 +781,9 @@ checksum = "edd0f118536f44f5ccd48bcb8b111bdc3de888b58c74639dfb034a357d0f206d"
 
 [[package]]
 name = "equivalent"
-version = "1.0.3"
+version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "00d174d5400e5e8fd687ad1049e2f578285fa914201b1af7e8b112a4546bd826"
+checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
 [[package]]
 name = "erased-serde"
@@ -796,9 +823,9 @@ dependencies = [
 
 [[package]]
 name = "find-msvc-tools"
-version = "0.1.14"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aedcfb3409746eddb02b9e19ebda1c3394f759a152e48ee875a0844d1b955484"
+checksum = "3e0f1c7c3a72c66fd80abe965175f7523475c0489a87d3ff9d6e8c87d87a9d2d"
 
 [[package]]
 name = "flate2"
@@ -841,7 +868,7 @@ checksum = "ea5190182e6915eb873ddbc16e23b711b6eb1f9c00a0d0a3a91b5f6228475225"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -899,7 +926,7 @@ checksum = "9fb9654ba8355388abeb8dcb4fc62f511300867002afc858860463bdd9fe0c44"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -1128,7 +1155,7 @@ dependencies = [
  "proc-macro-error",
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -1181,6 +1208,22 @@ dependencies = [
  "uuid",
 ]
 
+[[package]]
+name = "gpx-wasm"
+version = "0.1.0"
+dependencies = [
+ "console_error_panic_hook",
+ "gpx-engine",
+ "idb",
+ "js-sys",
+ "serde",
+ "serde-wasm-bindgen",
+ "uuid",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "wasm-bindgen-test",
+]
+
 [[package]]
 name = "gtk"
 version = "0.18.2"
@@ -1230,7 +1273,7 @@ dependencies = [
  "proc-macro-error",
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -1495,6 +1538,21 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "idb"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6554f394e990a1af530a528a7fdcad6e01b29cb1b990f89df3ffd62cf15f7828"
+dependencies = [
+ "indexmap 2.14.2",
+ "js-sys",
+ "num-traits",
+ "thiserror 2.0.21",
+ "tokio",
+ "wasm-bindgen",
+ "web-sys",
+]
+
 [[package]]
 name = "ident_case"
 version = "1.0.1"
@@ -1625,7 +1683,7 @@ dependencies = [
  "jiff-core",
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -1684,7 +1742,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "38c0b942f458fe50cdac086d2f946512305e5631e720728f2a61aabcd47a6264"
 dependencies = [
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -1756,9 +1814,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.190"
+version = "0.2.189"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ce5d3ddc6d3fa000eb1536d85e147bfe31aacaba692ed6a876f95cb7c855be78"
+checksum = "3eaf3ede3fee6db1a4c2ee091bf8a8b4dccdc6d17f656fb07896ee72867612f2"
 
 [[package]]
 name = "libdbus-sys"
@@ -1779,6 +1837,12 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "libm"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6d2cec3eae94f9f509c767b45932f1ada8350c4bdb85af2fcab4a3c14807981"
+
 [[package]]
 name = "libredox"
 version = "0.1.25"
@@ -1841,6 +1905,16 @@ version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
 
+[[package]]
+name = "minicov"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4869b6a491569605d66d3952bcdf03df789e5b536e5f0cf7758a7f08a55ae24d"
+dependencies = [
+ "cc",
+ "walkdir",
+]
+
 [[package]]
 name = "miniz_oxide"
 version = "0.8.9"
@@ -1929,6 +2003,15 @@ version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "650eef8c711430f1a879fdd01d4745a7deea475becfb90269c06775983bbf086"
 
+[[package]]
+name = "nu-ansi-term"
+version = "0.50.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
+dependencies = [
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "num-conv"
 version = "0.2.2"
@@ -1942,6 +2025,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
 dependencies = [
  "autocfg",
+ "libm",
 ]
 
 [[package]]
@@ -1963,7 +2047,7 @@ dependencies = [
  "proc-macro-crate 3.5.0",
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -2168,6 +2252,12 @@ version = "1.21.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 
+[[package]]
+name = "oorandom"
+version = "11.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6790f58c7ff633d8771f42965289203411a5e5c68388703c06e14f24770b41e"
+
 [[package]]
 name = "option-ext"
 version = "0.2.0"
@@ -2269,7 +2359,7 @@ dependencies = [
  "phf_shared",
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -2436,9 +2526,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.107"
+version = "1.0.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
+checksum = "8fd00f0bb2e90d81d1044c2b32617f68fcb9fa3bb7640c23e9c748e53fb30934"
 dependencies = [
  "unicode-ident",
 ]
@@ -2454,9 +2544,9 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.47"
+version = "1.0.46"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
+checksum = "dfbc457d0c7a0759a614551b11a6409e5951f6c7537be1f1b7682b9ae9230368"
 dependencies = [
  "proc-macro2",
 ]
@@ -2515,7 +2605,7 @@ checksum = "92ecd8964f8453721699a1ed72037b0db49ce2f5a5138486ee89bed6f67cdf3a"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -2659,7 +2749,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "serde_derive_internals",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -2719,6 +2809,17 @@ dependencies = [
  "typeid",
 ]
 
+[[package]]
+name = "serde-wasm-bindgen"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8302e169f0eddcc139c70f139d19d6467353af16f9fce27e8c30158036a1e16b"
+dependencies = [
+ "js-sys",
+ "serde",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "serde_core"
 version = "1.0.229"
@@ -2736,7 +2837,7 @@ checksum = "e7a5d71263a5a7d47b41f6b3f06ba276f10cc18b0931f1799f710578e2309348"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -2747,14 +2848,14 @@ checksum = "18d26a20a969b9e3fdf2fc2d9f21eda6c40e2de84c9408bb5d3b05d499aae711"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
 name = "serde_json"
-version = "1.0.154"
+version = "1.0.151"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e7e9cc8b1b85264074fbcc02a88680c4096b1e47df8f739dceb03bf482f04bd6"
+checksum = "c841b55ecdae098c80dcae9cf767f6f8a0c2cdb3416bbef72181df4d0fe73f14"
 dependencies = [
  "itoa",
  "memchr",
@@ -2771,7 +2872,7 @@ checksum = "8d3b1629de253c70a0508c3899572da79ca359fdab27c7920ff00406df418906"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -2822,7 +2923,7 @@ dependencies = [
  "darling",
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -2844,7 +2945,7 @@ checksum = "772ee033c0916d670af7860b6e1ef7d658a4629a6d0b4c8c3e67f09b3765b75d"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -3023,9 +3124,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.119"
+version = "2.0.118"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "872831b642d1a07999a962a351ed35b955ea2cfc8f3862091e2a240a84f17297"
+checksum = "1b9ae57f904213ebb649ce6895b8a66c66f0203b9319718f69a5612a065b1422"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3034,9 +3135,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "3.0.9"
+version = "3.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d78c8dee4c7bf0e14673097256fed6142ce9d3b85a408189d07482442145823b"
+checksum = "8593e8e72159ed2257d083c7a454a85cbf854f37a0966d8d483aff8c8a3ebcee"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3060,7 +3161,7 @@ checksum = "901704edd0dfe137f1987838ee4f259e4e063c31371bdb423f7ae38ec6f77f02"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -3124,7 +3225,7 @@ checksum = "5f7eeb6d99155545da6150a1795945f16ac9c178deb2a5f2e74d776107bd5849"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -3223,7 +3324,7 @@ dependencies = [
  "serde",
  "serde_json",
  "sha2",
- "syn 2.0.119",
+ "syn 2.0.118",
  "tauri-utils",
  "thiserror 2.0.21",
  "time",
@@ -3241,7 +3342,7 @@ dependencies = [
  "heck 0.5.0",
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
  "tauri-codegen",
  "tauri-utils",
 ]
@@ -3381,7 +3482,7 @@ checksum = "4fee6c4efc90059e10f81e6d42c60a18f76588c3d74cb83a0b242a2b6c7504c1"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -3392,7 +3493,7 @@ checksum = "fe5197923287db20a58125f0bc85c062f7f2c892de97b18c356f9efb14b28524"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
@@ -3443,9 +3544,9 @@ checksum = "fd3ca314f692efd6c868f8408f53fe444634a845f96c028b97d35f6a1f79f0ee"
 
 [[package]]
 name = "tokio"
-version = "1.53.3"
+version = "1.53.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ce3335fa71841cda333a58d7615b03901380ecf09d59b3296d21f8bbac0dde4e"
+checksum = "e95f91fcc7a621e8b030f6aa23c71fe9838ae2fb4d8118b75602a328f5144044"
 dependencies = [
  "bytes",
  "libc",
@@ -3670,9 +3771,9 @@ checksum = "b6f5e870be6c3b371b77fe0ee0bafb859fa4964b4404c27de1d380043c4dda20"
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.27"
+version = "1.0.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2c754d6c33795a1c324727428e5a7dedb5b06195f9890bdbcba760d3e246563"
+checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
 
 [[package]]
 name = "unicode-segmentation"
@@ -3713,9 +3814,9 @@ checksum = "b6c140620e7ffbb22c2dee59cafe6084a59b5ffc27a8859a5f0d494b5d52b6be"
 
 [[package]]
 name = "uuid"
-version = "1.28.0"
+version = "1.26.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7cc1186384beb7dd8eedea376413fd654937285ea6c9cfbb928dc3043ea4b606"
+checksum = "2ef6dac1e96601b4fb3acccccff2139741fcb757cb9a36089bf5be91cfb285ce"
 dependencies = [
  "getrandom 0.4.3",
  "js-sys",
@@ -3832,7 +3933,7 @@ dependencies = [
  "bumpalo",
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
  "wasm-bindgen-shared",
 ]
 
@@ -3845,6 +3946,45 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "wasm-bindgen-test"
+version = "0.3.79"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae7499dfd45780a0a91d7ee6bb9ac51970a4479a41a89da443fdda5a39547d42"
+dependencies = [
+ "async-trait",
+ "cast",
+ "js-sys",
+ "libm",
+ "minicov",
+ "nu-ansi-term",
+ "num-traits",
+ "oorandom",
+ "serde",
+ "serde_json",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "wasm-bindgen-test-macro",
+ "wasm-bindgen-test-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-test-macro"
+version = "0.3.79"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b84b5ac638bfb168196a1a461fcc8f46a294a18b1b6be52133b4e0db122cc9f"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.6",
+]
+
+[[package]]
+name = "wasm-bindgen-test-shared"
+version = "0.2.129"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4f692aa943ccd88363733b77063f32cfed5bc6cbea8e6e8b251b302f881606fe"
+
 [[package]]
 name = "wasm-streams"
 version = "0.5.0"
@@ -3954,7 +4094,7 @@ checksum = "67a921c1b6914c367b2b823cd4cde6f96beec77d30a939c8199bb377cf9b9b54"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -4068,7 +4208,7 @@ checksum = "053e2e040ab57b9dc951b72c264860db7eb3b0200ba345b4e4c3b14f67855ddf"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -4079,7 +4219,7 @@ checksum = "3f316c4a2570ba26bbec722032c4099d8c8bc095efccdc15688708623367e358"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.119",
+ "syn 2.0.118",
 ]
 
 [[package]]
@@ -4333,7 +4473,7 @@ checksum = "ec8ebde2db3681e8c9980cc27822030e68752690ddfa9473e739aeb4dbde6d71"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
  "synstructure",
 ]
 
@@ -4354,7 +4494,7 @@ checksum = "f75b4683f6c7f45248d4d64056a24298c6281e0993356d7d1b4a1a962ef10d4a"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
  "synstructure",
 ]
 
@@ -4388,7 +4528,7 @@ checksum = "34df6fc39dbd26ddc9c10e6a2984476e13acce22e64e4487636ef494369225da"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 3.0.9",
+ "syn 3.0.6",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 000000000..43d8f2060
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,5 @@
+[workspace]
+members = ["gpx-rs", "wasm", "tauri"]
+# `cargo test` at the root only tests the engine: the others need their own tooling
+default-members = ["gpx-rs"]
+resolver = "3"
\ No newline at end of file
diff --git a/README.md b/README.md
index a6af9c34f..4a8f5f895 100644
--- a/README.md
+++ b/README.md
@@ -25,18 +25,20 @@ Any help is greatly appreciated!
 
 ## Development
 
-The code is split into two parts:
+The code is split into four parts:
 
-- `gpx-rs`: a Rust library, compiled to WebAssembly, for parsing and manipulating GPX files,
-- `website`: the website itself, which is a [SvelteKit](https://kit.svelte.dev/) application.
+- `gpx-rs`: a Rust library for parsing and manipulating GPX files (the engine), and the interface to it that the next two share (`gpx_engine::api`),
+- `wasm`: the engine for the browser, compiled to WebAssembly,
+- `tauri`: the desktop app, which runs the engine natively,
+- `website`: the website itself, which is a [SvelteKit](https://kit.svelte.dev/) application. It also is the UI of the desktop app.
 
-You will need [Node.js](https://nodejs.org/), [Rust](https://rustup.rs/) and [wasm-pack](https://rustwasm.github.io/wasm-pack/) to build and run these two parts.
+You will need [Node.js](https://nodejs.org/), [Rust](https://rustup.rs/) and [wasm-pack](https://rustwasm.github.io/wasm-pack/) to build and run the website. See [`tauri`](tauri/README.md) for the desktop app.
 
-### Building the `gpx-rs` library
+### Building the WebAssembly engine
 
 ```bash
-cd gpx-rs
-wasm-pack build wasm --target bundler --out-dir ../pkg
+cd wasm
+wasm-pack build --target bundler
 ```
 
 ### Running the website
diff --git a/gpx-rs/.gitignore b/gpx-rs/.gitignore
deleted file mode 100644
index 38adc0efd..000000000
--- a/gpx-rs/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-target/
-pkg/
\ No newline at end of file
diff --git a/gpx-rs/Cargo.lock b/gpx-rs/Cargo.lock
deleted file mode 100644
index 62ebb9ec0..000000000
--- a/gpx-rs/Cargo.lock
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diff --git a/gpx-rs/Cargo.toml b/gpx-rs/Cargo.toml
index 7ff8215fa..f6e72066f 100644
--- a/gpx-rs/Cargo.toml
+++ b/gpx-rs/Cargo.toml
@@ -1,6 +1,11 @@
-[workspace]
-members = ["engine", "wasm"]
-resolver = "3"
+[package]
+name = "gpx-engine"
+version = "0.1.0"
+edition = "2024"
 
-[profile.release]
-debug = true
+[dependencies]
+chrono = "0.4.45"
+postcard = { version = "1.1.3", features = ["use-std"] }
+quick-xml = "0.42.0"
+serde = { version = "1.0.229", features = ["derive"] }
+uuid = { version = "1.26.1", features = ["serde", "v4"] }
diff --git a/gpx-rs/README.md b/gpx-rs/README.md
index 7645015bd..9473ae43b 100644
--- a/gpx-rs/README.md
+++ b/gpx-rs/README.md
@@ -1,14 +1,10 @@
 # gpx-rs
 
-- `engine`: the GPX engine, plain Rust. Tested natively: `cargo test`.
-- `wasm`: the interface to the web page, compiled to WebAssembly.
+The GPX engine: plain Rust, no knowledge of who uses it. Tested natively with `cargo test` (from
+here or from the root).
 
-```
-wasm-pack build wasm --target bundler --out-dir ../pkg
-```
-
-The interface is tested in Node (it needs `wasm-pack`, which fetches the test runner the first time):
-
-```
-wasm-pack test --node wasm
-```
+- `src/core`, `src/engine`, `src/storage`: the engine itself.
+- `src/api`: the interface to the engine that the frontends (`../wasm`, `../tauri`) share. Each
+  function takes the engine and typed arguments, and gives plain data (`api::dto`, serde types, or
+  slices for the numeric buffers). A frontend only converts what crosses: ids from strings or
+  bytes, results to JS objects or JSON, slices to typed arrays or raw bytes.
diff --git a/gpx-rs/engine/data/self_closing_points.gpx b/gpx-rs/data/self_closing_points.gpx
similarity index 100%
rename from gpx-rs/engine/data/self_closing_points.gpx
rename to gpx-rs/data/self_closing_points.gpx
diff --git a/gpx-rs/engine/data/simple.gpx b/gpx-rs/data/simple.gpx
similarity index 100%
rename from gpx-rs/engine/data/simple.gpx
rename to gpx-rs/data/simple.gpx
diff --git a/gpx-rs/engine/data/with_cad.gpx b/gpx-rs/data/with_cad.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_cad.gpx
rename to gpx-rs/data/with_cad.gpx
diff --git a/gpx-rs/engine/data/with_highway.gpx b/gpx-rs/data/with_highway.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_highway.gpx
rename to gpx-rs/data/with_highway.gpx
diff --git a/gpx-rs/engine/data/with_hr.gpx b/gpx-rs/data/with_hr.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_hr.gpx
rename to gpx-rs/data/with_hr.gpx
diff --git a/gpx-rs/engine/data/with_links.gpx b/gpx-rs/data/with_links.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_links.gpx
rename to gpx-rs/data/with_links.gpx
diff --git a/gpx-rs/engine/data/with_power_1.gpx b/gpx-rs/data/with_power_1.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_power_1.gpx
rename to gpx-rs/data/with_power_1.gpx
diff --git a/gpx-rs/engine/data/with_power_2.gpx b/gpx-rs/data/with_power_2.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_power_2.gpx
rename to gpx-rs/data/with_power_2.gpx
diff --git a/gpx-rs/engine/data/with_route_extensions.gpx b/gpx-rs/data/with_route_extensions.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_route_extensions.gpx
rename to gpx-rs/data/with_route_extensions.gpx
diff --git a/gpx-rs/engine/data/with_route_points.gpx b/gpx-rs/data/with_route_points.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_route_points.gpx
rename to gpx-rs/data/with_route_points.gpx
diff --git a/gpx-rs/engine/data/with_routes.gpx b/gpx-rs/data/with_routes.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_routes.gpx
rename to gpx-rs/data/with_routes.gpx
diff --git a/gpx-rs/engine/data/with_segments.gpx b/gpx-rs/data/with_segments.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_segments.gpx
rename to gpx-rs/data/with_segments.gpx
diff --git a/gpx-rs/engine/data/with_style.gpx b/gpx-rs/data/with_style.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_style.gpx
rename to gpx-rs/data/with_style.gpx
diff --git a/gpx-rs/engine/data/with_surface.gpx b/gpx-rs/data/with_surface.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_surface.gpx
rename to gpx-rs/data/with_surface.gpx
diff --git a/gpx-rs/engine/data/with_temp.gpx b/gpx-rs/data/with_temp.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_temp.gpx
rename to gpx-rs/data/with_temp.gpx
diff --git a/gpx-rs/engine/data/with_time.gpx b/gpx-rs/data/with_time.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_time.gpx
rename to gpx-rs/data/with_time.gpx
diff --git a/gpx-rs/engine/data/with_tracks.gpx b/gpx-rs/data/with_tracks.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_tracks.gpx
rename to gpx-rs/data/with_tracks.gpx
diff --git a/gpx-rs/engine/data/with_tracks_and_segments.gpx b/gpx-rs/data/with_tracks_and_segments.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_tracks_and_segments.gpx
rename to gpx-rs/data/with_tracks_and_segments.gpx
diff --git a/gpx-rs/engine/data/with_waypoint.gpx b/gpx-rs/data/with_waypoint.gpx
similarity index 100%
rename from gpx-rs/engine/data/with_waypoint.gpx
rename to gpx-rs/data/with_waypoint.gpx
diff --git a/gpx-rs/engine/Cargo.toml b/gpx-rs/engine/Cargo.toml
deleted file mode 100644
index f6e72066f..000000000
--- a/gpx-rs/engine/Cargo.toml
+++ /dev/null
@@ -1,11 +0,0 @@
-[package]
-name = "gpx-engine"
-version = "0.1.0"
-edition = "2024"
-
-[dependencies]
-chrono = "0.4.45"
-postcard = { version = "1.1.3", features = ["use-std"] }
-quick-xml = "0.42.0"
-serde = { version = "1.0.229", features = ["derive"] }
-uuid = { version = "1.26.1", features = ["serde", "v4"] }
diff --git a/gpx-rs/engine/src/lib.rs b/gpx-rs/engine/src/lib.rs
deleted file mode 100644
index 8fef69875..000000000
--- a/gpx-rs/engine/src/lib.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-mod core;
-mod engine;
-mod storage;
-
-pub use core::*;
-pub use engine::*;
-pub use storage::*;
diff --git a/gpx-rs/src/api/commands.rs b/gpx-rs/src/api/commands.rs
new file mode 100644
index 000000000..aeb29e8db
--- /dev/null
+++ b/gpx-rs/src/api/commands.rs
@@ -0,0 +1,554 @@
+//! The functions that edit the files or change the selection.
+
+use uuid::Uuid;
+
+use super::dto::*;
+use crate::{self as engine, Action, Command, Engine, LngLat, LngLatBounds};
+
+/// Executes an action and tells what it did.
+pub fn execute(engine: &mut Engine, action: Action) -> Outcome {
+    match engine.execute(action) {
+        Ok(outcome) => Outcome::new(&outcome, None),
+        Err(error) => Outcome::failed(error.to_string()),
+    }
+}
+
+pub fn edit(engine: &mut Engine, command: Command) -> Outcome {
+    execute(engine, Action::Edit(command))
+}
+
+fn file_ids(ids: &[Uuid]) -> Vec<engine::FileId> {
+    ids.iter().copied().map(engine::FileId).collect()
+}
+
+// Selection
+
+/// Selects files. Unknown files are ignored, and selecting nothing deselects everything.
+pub fn select(engine: &mut Engine, file_ids_: &[Uuid], mode: engine::SelectMode) -> Outcome {
+    select_elements(
+        engine,
+        engine::Selection::File {
+            file_ids: file_ids(file_ids_).into_iter().collect(),
+        },
+        mode,
+    )
+}
+
+/// Selects elements: they are merged with the selection when it holds elements of the same kind in
+/// the same place (same file, same track for segments), otherwise they replace it.
+pub fn select_elements(
+    engine: &mut Engine,
+    selection: engine::Selection,
+    mode: engine::SelectMode,
+) -> Outcome {
+    execute(engine, Action::Select { selection, mode })
+}
+
+/// Selects all the elements of the same kind as the selected ones, in the same place: all the
+/// files, the tracks of the file, the segments of the track, the waypoints of the file. All the
+/// files when nothing is selected.
+pub fn select_all(engine: &mut Engine) -> Outcome {
+    execute(engine, Action::SelectAll)
+}
+
+/// Moves the selection to the next (`down`) or previous element of the same kind, like the arrow
+/// keys do in the file list. With `add` (shift + arrow), the element is added to the selection,
+/// otherwise it replaces it.
+pub fn arrow_select(engine: &mut Engine, down: bool, add: bool) -> Outcome {
+    execute(engine, Action::ArrowSelect { down, add })
+}
+
+pub fn select_tracks(
+    engine: &mut Engine,
+    file_id: Uuid,
+    track_ids: &[Uuid],
+    mode: engine::SelectMode,
+) -> Outcome {
+    let selection = engine::Selection::Track {
+        file_id: engine::FileId(file_id),
+        trk_ids: track_ids.iter().copied().map(engine::TrackId).collect(),
+    };
+    select_elements(engine, selection, mode)
+}
+
+pub fn select_segments(
+    engine: &mut Engine,
+    file_id: Uuid,
+    track_id: Uuid,
+    segment_ids: &[Uuid],
+    mode: engine::SelectMode,
+) -> Outcome {
+    let selection = engine::Selection::TrackSegment {
+        file_id: engine::FileId(file_id),
+        trk_id: engine::TrackId(track_id),
+        trkseg_ids: segment_ids
+            .iter()
+            .copied()
+            .map(engine::TrackSegmentId)
+            .collect(),
+    };
+    select_elements(engine, selection, mode)
+}
+
+/// Selects the node standing for all the waypoints of a file.
+pub fn select_waypoint_group(
+    engine: &mut Engine,
+    file_id: Uuid,
+    mode: engine::SelectMode,
+) -> Outcome {
+    let selection = engine::Selection::Waypoints {
+        file_id: engine::FileId(file_id),
+    };
+    select_elements(engine, selection, mode)
+}
+
+pub fn select_waypoints(
+    engine: &mut Engine,
+    file_id: Uuid,
+    waypoint_ids: &[Uuid],
+    mode: engine::SelectMode,
+) -> Outcome {
+    let selection = engine::Selection::Waypoint {
+        file_id: engine::FileId(file_id),
+        wpt_ids: waypoint_ids
+            .iter()
+            .copied()
+            .map(engine::WaypointId)
+            .collect(),
+    };
+    select_elements(engine, selection, mode)
+}
+
+// History
+
+pub fn undo(engine: &mut Engine) -> Outcome {
+    execute(engine, Action::Undo)
+}
+
+pub fn redo(engine: &mut Engine) -> Outcome {
+    execute(engine, Action::Redo)
+}
+
+// Files
+
+/// Creates a file and selects it. With `lng` and `lat`, it starts with a track and a segment that
+/// hold that trackpoint (at `ele`, 0 by default).
+pub fn new_file(
+    engine: &mut Engine,
+    name: &str,
+    lng: Option<f64>,
+    lat: Option<f64>,
+    ele: Option<f64>,
+) -> Outcome {
+    let trackpoint = lng.zip(lat).map(|(lng, lat)| engine::NewTrackpoint {
+        lng,
+        lat,
+        ele: ele.unwrap_or_default(),
+    });
+    edit(engine, Command::New(engine::New { name, trackpoint }))
+}
+
+/// Loads files as a single command (one undo step). The files are in `data`, one after the other,
+/// `lengths` being the number of bytes of each one. `names`: the name of each file when its data
+/// has none (the name on disk, without extension). The files that cannot be read are skipped, the
+/// first one that was read is selected.
+pub fn load_files(
+    engine: &mut Engine,
+    data: &[u8],
+    lengths: &[usize],
+    names: &[String],
+) -> Outcome {
+    if lengths.len() != names.len() {
+        return Outcome::failed(format!(
+            "{} lengths for {} names",
+            lengths.len(),
+            names.len()
+        ));
+    }
+    let mut files = Vec::with_capacity(names.len());
+    let mut offset = 0;
+    for (length, name) in lengths.iter().zip(names) {
+        let end = offset + *length;
+        let Some(data) = data.get(offset..end) else {
+            return Outcome::failed(format!("the data of {name} is shorter than its length"));
+        };
+        files.push(engine::Load { data, name });
+        offset = end;
+    }
+    edit(engine, Command::LoadFiles(engine::LoadFiles { files }))
+}
+
+pub fn duplicate(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::Duplicate(engine::Duplicate))
+}
+
+/// Deletes the selected elements. With `whole_files`, the files holding the selected elements are
+/// deleted instead, even if only a track or a waypoint is selected.
+pub fn delete(engine: &mut Engine, whole_files: bool) -> Outcome {
+    edit(engine, Command::Delete(engine::Delete { whole_files }))
+}
+
+pub fn delete_all(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::DeleteAll(engine::DeleteAll))
+}
+
+/// Moves the files to `index` among the other files, in the given order (not undoable).
+pub fn reorder(engine: &mut Engine, file_ids_: &[Uuid], index: usize) -> Outcome {
+    execute(
+        engine,
+        Action::Reorder {
+            file_ids: file_ids(file_ids_),
+            index,
+        },
+    )
+}
+
+/// Puts the selected elements in the clipboard. Nothing happens when nothing is selected.
+pub fn copy(engine: &mut Engine) -> Outcome {
+    execute(engine, Action::Copy)
+}
+
+/// Like `copy`, but the elements are moved when they are pasted.
+pub fn cut(engine: &mut Engine) -> Outcome {
+    execute(engine, Action::Cut)
+}
+
+/// Pastes the clipboard according to the selection (see `can_paste`). What is pasted is always the
+/// elements as they were when they were copied or cut, even if they were changed or deleted since.
+/// It can be pasted several times: what was copied is copied again, what was cut is moved the first
+/// time (and the clipboard is not cut after that), then it is copied.
+pub fn paste(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::Paste(engine::Paste))
+}
+
+/// Moves elements to a place of the file tree, keeping their ids, like dragging and dropping them
+/// does. The moved elements are selected.
+///
+/// Files can only go among the files; tracks among the files (each becomes a file) or the tracks
+/// of a file; segments among the files (each becomes a file), the tracks of a file (each becomes
+/// a track) or the segments of a track; waypoints, or all the waypoints of a file, among the
+/// waypoints of a file.
+pub fn move_elements(engine: &mut Engine, what: Selection, to: MoveTarget) -> Outcome {
+    edit(
+        engine,
+        Command::Move(engine::Move {
+            what: what.into(),
+            to: to.into(),
+        }),
+    )
+}
+
+pub fn metadata(engine: &mut Engine, name: &str, desc: &str) -> Outcome {
+    edit(engine, Command::Metadata(engine::Metadata { name, desc }))
+}
+
+/// Only the given fields are changed.
+pub fn style(
+    engine: &mut Engine,
+    color: Option<&str>,
+    opacity: Option<f64>,
+    width: Option<f64>,
+) -> Outcome {
+    edit(
+        engine,
+        Command::Style(engine::Style {
+            color,
+            opacity,
+            width,
+        }),
+    )
+}
+
+pub fn new_track(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::NewTrack(engine::NewTrack))
+}
+
+pub fn new_track_segment(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::NewTrackSegment(engine::NewTrackSegment))
+}
+
+// Waypoints. The strings that are empty are the fields that the waypoint does not have.
+
+/// Adds a waypoint to each selected file (or to the file of the selected elements).
+#[allow(clippy::too_many_arguments)]
+pub fn new_waypoint(
+    engine: &mut Engine,
+    lng: f64,
+    lat: f64,
+    ele: f64,
+    name: &str,
+    desc: &str,
+    icon: &str,
+    link: &str,
+) -> Outcome {
+    edit(
+        engine,
+        Command::NewWaypoint(engine::NewWaypoint {
+            lng,
+            lat,
+            ele,
+            name,
+            desc,
+            icon,
+            link,
+        }),
+    )
+}
+
+/// Moves a waypoint of a file, whatever is selected.
+pub fn move_waypoint(
+    engine: &mut Engine,
+    file_id: Uuid,
+    waypoint_id: Uuid,
+    lng: f64,
+    lat: f64,
+    ele: f64,
+) -> Outcome {
+    edit(
+        engine,
+        Command::MoveWaypoint(engine::MoveWaypoint {
+            file_id: engine::FileId(file_id),
+            waypoint_id: engine::WaypointId(waypoint_id),
+            lng,
+            lat,
+            ele,
+        }),
+    )
+}
+
+/// Deletes a waypoint of a file, whatever is selected.
+pub fn delete_waypoint(engine: &mut Engine, file_id: Uuid, waypoint_id: Uuid) -> Outcome {
+    edit(
+        engine,
+        Command::DeleteWaypoint(engine::DeleteWaypoint {
+            file_id: engine::FileId(file_id),
+            waypoint_id: engine::WaypointId(waypoint_id),
+        }),
+    )
+}
+
+/// Changes a waypoint of a file, whatever is selected: its name, description, icon, link,
+/// position and elevation.
+#[allow(clippy::too_many_arguments)]
+pub fn update_waypoint(
+    engine: &mut Engine,
+    file_id: Uuid,
+    waypoint_id: Uuid,
+    lng: f64,
+    lat: f64,
+    ele: f64,
+    name: &str,
+    desc: &str,
+    icon: &str,
+    link: &str,
+) -> Outcome {
+    edit(
+        engine,
+        Command::EditWaypoint(engine::EditWaypoint {
+            file_id: engine::FileId(file_id),
+            waypoint_id: engine::WaypointId(waypoint_id),
+            lng,
+            lat,
+            ele,
+            name,
+            desc,
+            icon,
+            link,
+        }),
+    )
+}
+
+// Tools
+
+pub fn reverse(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::Reverse(engine::Reverse))
+}
+
+/// Adds to each selected segment a reversed copy of itself (without repeating its last point), so
+/// that it goes back to where it started.
+pub fn round_trip(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::RoundTrip(engine::RoundTrip))
+}
+
+/// Keeps the trackpoints `start` to `end` (both included) of the selection, counted over its
+/// segments one after the other, and removes the others (and what is left empty).
+pub fn crop(engine: &mut Engine, start: u32, end: u32) -> Outcome {
+    if start > end {
+        return Outcome::failed(format!("the range {start}..{end} is reversed"));
+    }
+    edit(engine, Command::Crop(engine::Crop { start, end }))
+}
+
+/// Removes the trackpoints of the selection that are less than `tolerance` meters away from the
+/// line of their neighbours, except the ends of the segments.
+pub fn reduce(engine: &mut Engine, tolerance: f64) -> Outcome {
+    edit(engine, Command::Reduce(engine::Reduce { tolerance }))
+}
+
+/// Sets the timestamps of the selection, which starts at `start_time` (ms since the epoch): the
+/// trackpoints that have some keep their durations multiplied by `ratio`, the others follow the
+/// previous one at `speed` (km/h).
+pub fn change_timestamps(engine: &mut Engine, start_time: f64, speed: f64, ratio: f64) -> Outcome {
+    edit(
+        engine,
+        Command::Time(engine::Time {
+            start_time: start_time as i64,
+            kind: engine::TimeKind::Change { speed, ratio },
+        }),
+    )
+}
+
+/// Makes up timestamps for the selection, which starts at `start_time` (ms since the epoch) and
+/// lasts `total_time` seconds.
+pub fn create_artificial_timestamps(
+    engine: &mut Engine,
+    start_time: f64,
+    total_time: f64,
+) -> Outcome {
+    edit(
+        engine,
+        Command::Time(engine::Time {
+            start_time: start_time as i64,
+            kind: engine::TimeKind::Artificial { total_time },
+        }),
+    )
+}
+
+/// Merges the selection into its first element. `remove_gaps` brings the parts that are connected
+/// closer in time, if they have timestamps.
+pub fn merge(engine: &mut Engine, type_: engine::MergeType, remove_gaps: bool) -> Outcome {
+    edit(engine, Command::Merge(engine::Merge { type_, remove_gaps }))
+}
+
+pub fn extract(engine: &mut Engine) -> Outcome {
+    edit(engine, Command::Extract(engine::Extract))
+}
+
+/// Sets the elevation of the trackpoints of the selection, one elevation per trackpoint.
+pub fn elevation(engine: &mut Engine, ele: &[f64]) -> Outcome {
+    edit(engine, Command::Elevation(engine::Elevation { ele }))
+}
+
+/// Removes the trackpoints and/or waypoints of the selection inside (or outside) a rectangle.
+#[allow(clippy::too_many_arguments)]
+pub fn clean(
+    engine: &mut Engine,
+    west: f64,
+    south: f64,
+    east: f64,
+    north: f64,
+    type_: engine::CleanType,
+    trkpt: bool,
+    wpt: bool,
+) -> Outcome {
+    edit(
+        engine,
+        Command::Clean(engine::Clean {
+            bounds: LngLatBounds {
+                sw: LngLat {
+                    lng: west,
+                    lat: south,
+                },
+                ne: LngLat {
+                    lng: east,
+                    lat: north,
+                },
+            },
+            type_,
+            trkpt,
+            wpt,
+        }),
+    )
+}
+
+// Routing
+//
+// The indices of the trackpoints and of the anchors are the ones of the routing buffers: they only
+// mean something for the `revision` they were read with (`routing_revision`), and the commands
+// that use them do nothing if the selection is not the one of that revision anymore.
+
+/// Makes the call `f`, unless the selection is not the one of the revision anymore.
+fn at_revision(
+    engine: &mut Engine,
+    revision: u32,
+    f: impl FnOnce(&mut Engine) -> Outcome,
+) -> Outcome {
+    if engine.routing().revision == revision {
+        f(engine)
+    } else {
+        Outcome::failed("the selection changed since the routing buffers were read")
+    }
+}
+
+/// Replaces the trackpoints `start..end` of the selection by the given ones, in a single segment
+/// (a pure insertion if `start == end`, a pure removal without new points). `attributes` holds the
+/// surface, highway, SAC scale and MTB scale of the new points, as intervals, and `anchors` the
+/// indices among the new points of the ones that become anchors.
+#[allow(clippy::too_many_arguments)]
+pub fn route(
+    engine: &mut Engine,
+    revision: u32,
+    start: u32,
+    end: u32,
+    lng: &[f64],
+    lat: &[f64],
+    ele: &[f64],
+    attributes: &RouteAttributes,
+    anchors: &[u32],
+) -> Outcome {
+    if lng.len() != lat.len() || lat.len() != ele.len() {
+        return Outcome::failed("lng, lat and ele differ in length");
+    }
+    at_revision(engine, revision, |engine| {
+        edit(
+            engine,
+            Command::Route(engine::Route {
+                start,
+                end,
+                lng,
+                lat,
+                ele,
+                surface: attributes.surface.view(),
+                highway: attributes.highway.view(),
+                sac_scale: attributes.sac_scale.view(),
+                mtb_scale: attributes.mtb_scale.view(),
+                anchors,
+            }),
+        )
+    })
+}
+
+/// Makes an anchor of the point of the selected segments that is the closest to the coordinates,
+/// inserting a trackpoint on the path if none is there.
+pub fn insert_anchor(engine: &mut Engine, revision: u32, lng: f64, lat: f64) -> Outcome {
+    at_revision(engine, revision, |engine| {
+        edit(
+            engine,
+            Command::InsertAnchor(engine::InsertAnchor { lng, lat }),
+        )
+    })
+}
+
+/// Makes the trackpoint `index` of the selection the start of its segment, which is a loop (the
+/// trackpoints before it go to the end, and the loop closes on it).
+pub fn change_loop_start(engine: &mut Engine, revision: u32, index: u32) -> Outcome {
+    at_revision(engine, revision, |engine| {
+        edit(
+            engine,
+            Command::ChangeLoopStart(engine::ChangeLoopStart { index }),
+        )
+    })
+}
+
+/// Cuts the file, the track or the segment (see `SplitType`) of the trackpoint `at` of the
+/// selection in two, there: the trackpoint ends the first part and starts the second one.
+pub fn split(
+    engine: &mut Engine,
+    revision: u32,
+    at: u32,
+    split_type: engine::SplitType,
+) -> Outcome {
+    at_revision(engine, revision, |engine| {
+        edit(engine, Command::Split(engine::Split { at, split_type }))
+    })
+}
diff --git a/tauri/src/dto.rs b/gpx-rs/src/api/dto.rs
similarity index 85%
rename from tauri/src/dto.rs
rename to gpx-rs/src/api/dto.rs
index f05671fc3..b922fe6ad 100644
--- a/tauri/src/dto.rs
+++ b/gpx-rs/src/api/dto.rs
@@ -1,32 +1,12 @@
-//! What crosses to the frontend, as JSON: the same shapes as the objects of the WASM interface
-//! (`gpx-rs/wasm/src/ts.rs` holds their TypeScript types).
+//! What crosses to the frontend, as plain data (serde): the shapes of the objects that the frontend
+//! reads, which `wasm/src/ts.rs` declares in TypeScript. Ids are hyphenated UUID strings, times
+//! are numbers (ms since the epoch), absent fields are skipped.
 
-use gpx_engine::{self as engine, FileId};
+use crate as engine;
+use engine::FileId;
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
 
-/// Bytes that cross as they are: typed arrays (little-endian), GPX files.
-pub type Bytes = tauri::ipc::Response;
-
-pub fn f64s(values: &[f64]) -> Vec<u8> {
-    values.iter().flat_map(|v| v.to_le_bytes()).collect()
-}
-
-pub fn i64s(values: &[i64]) -> Vec<u8> {
-    values.iter().flat_map(|v| v.to_le_bytes()).collect()
-}
-
-pub fn u32s(values: &[u32]) -> Vec<u8> {
-    values.iter().flat_map(|v| v.to_le_bytes()).collect()
-}
-
-/// An array that can be absent: the first byte tells whether it is there, the array follows.
-pub fn optional(array: Option<Vec<u8>>) -> Bytes {
-    let mut bytes = vec![u8::from(array.is_some())];
-    bytes.extend(array.unwrap_or_default());
-    Bytes::new(bytes)
-}
-
 pub fn ids(items: &[FileId]) -> Vec<String> {
     items.iter().map(|id| id.0.to_string()).collect()
 }
@@ -46,6 +26,9 @@ pub struct Outcome {
     removed: Vec<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     error: Option<String>,
+    /// Whether the files changed in a way that has to be saved (not sent).
+    #[serde(skip)]
+    pub saves: bool,
 }
 
 impl Outcome {
@@ -60,6 +43,7 @@ impl Outcome {
             modified: ids(&diff.modified),
             removed: ids(&diff.removed),
             error,
+            saves: outcome.changed && (outcome.diff.is_some() || outcome.order_changed),
         }
     }
 
@@ -478,76 +462,6 @@ impl TrackpointDetails {
     }
 }
 
-// Enumerations
-
-#[derive(Clone, Copy, Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub enum SelectMode {
-    Replace,
-    Add,
-    Toggle,
-}
-
-impl From<SelectMode> for engine::SelectMode {
-    fn from(m: SelectMode) -> Self {
-        match m {
-            SelectMode::Replace => Self::Replace,
-            SelectMode::Add => Self::Add,
-            SelectMode::Toggle => Self::Toggle,
-        }
-    }
-}
-
-#[derive(Clone, Copy, Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub enum MergeType {
-    Connect,
-    Group,
-}
-
-impl From<MergeType> for engine::MergeType {
-    fn from(t: MergeType) -> Self {
-        match t {
-            MergeType::Connect => Self::Connect,
-            MergeType::Group => Self::Group,
-        }
-    }
-}
-
-#[derive(Clone, Copy, Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub enum SplitType {
-    Files,
-    Tracks,
-    Segments,
-}
-
-impl From<SplitType> for engine::SplitType {
-    fn from(t: SplitType) -> Self {
-        match t {
-            SplitType::Files => Self::Files,
-            SplitType::Tracks => Self::Tracks,
-            SplitType::Segments => Self::Segments,
-        }
-    }
-}
-
-#[derive(Clone, Copy, Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub enum CleanType {
-    Inside,
-    Outside,
-}
-
-impl From<CleanType> for engine::CleanType {
-    fn from(t: CleanType) -> Self {
-        match t {
-            CleanType::Inside => Self::Inside,
-            CleanType::Outside => Self::Outside,
-        }
-    }
-}
-
 // Routing
 
 /// A category of the trackpoints of a route, as in `RouteCategory` of the engine.
diff --git a/gpx-rs/src/api/mod.rs b/gpx-rs/src/api/mod.rs
new file mode 100644
index 000000000..41ac8b906
--- /dev/null
+++ b/gpx-rs/src/api/mod.rs
@@ -0,0 +1,21 @@
+//! The interface to the engine, which the interfaces to the frontend share: the web page
+//! (`wasm`) and the desktop app (`tauri`) each expose these functions, and only convert what
+//! crosses to their own way of passing data.
+//!
+//! - `commands`: the functions that edit the files or change the selection. Each returns an
+//!   `Outcome`: whether anything changed, what changed (to update what the frontend keeps), and why
+//!   nothing was done when that is so (the command had nothing to do, the data is invalid, an
+//!   argument is wrong).
+//! - `queries`: the functions that read the state of the engine.
+//! - `dto`: the data that crosses, as serde types.
+//!
+//! Ids are `Uuid`s: how the frontend sends them (strings, bytes) is for the interfaces to parse.
+//! Coordinates and statistics are slices of numbers, which the interfaces copy to typed arrays.
+
+pub mod commands;
+pub mod dto;
+pub mod queries;
+
+pub use commands::*;
+pub use dto::*;
+pub use queries::*;
diff --git a/gpx-rs/src/api/queries.rs b/gpx-rs/src/api/queries.rs
new file mode 100644
index 000000000..fd05ed0f0
--- /dev/null
+++ b/gpx-rs/src/api/queries.rs
@@ -0,0 +1,234 @@
+//! The functions that read the state of the engine.
+//!
+//! The files are described by one ordered list of ids and one structure per file, so that the UI
+//! can react to what changed only: after each command, its `Outcome` tells which structures to
+//! (re)read or drop and whether the order changed. The trackpoints of a segment and the waypoints
+//! of a file are in the same order as the coordinates of their buffers.
+
+use uuid::Uuid;
+
+use super::dto::*;
+use crate::{self as engine, Engine, FileId};
+
+/// Ids of the files in display order.
+pub fn file_order(engine: &Engine) -> Vec<String> {
+    ids(engine.order())
+}
+
+/// Structure of a file, `None` if the id is unknown.
+pub fn file_structure(engine: &Engine, file_id: Uuid) -> Option<FileStructure> {
+    engine
+        .file_structure(&FileId(file_id))
+        .map(FileStructure::new)
+}
+
+/// Global statistics of a file, `None` if the id is unknown.
+pub fn file_statistics(engine: &Engine, file_id: Uuid) -> Option<GlobalStatistics> {
+    engine
+        .file_statistics(&FileId(file_id))
+        .map(|stats| GlobalStatistics::new(&stats))
+}
+
+/// The current selection.
+pub fn selection(engine: &Engine) -> Selection {
+    engine.selection().into()
+}
+
+/// What was copied or cut and is waiting to be pasted.
+pub fn clipboard(engine: &Engine) -> Option<Clipboard> {
+    engine.clipboard().map(Clipboard::new)
+}
+
+pub fn can_undo(engine: &Engine) -> bool {
+    engine.can_undo()
+}
+
+pub fn can_redo(engine: &Engine) -> bool {
+    engine.can_redo()
+}
+
+/// Whether the clipboard can be pasted with the current selection.
+pub fn can_paste(engine: &Engine) -> bool {
+    engine.can_paste()
+}
+
+/// All the data of a waypoint of a file, `None` if it does not exist.
+pub fn waypoint(engine: &Engine, file_id: Uuid, waypoint_id: Uuid) -> Option<WaypointDetails> {
+    engine
+        .waypoint(&FileId(file_id), &engine::WaypointId(waypoint_id))
+        .map(WaypointDetails::new)
+}
+
+/// A trackpoint of a segment of a file, `None` if it does not exist.
+pub fn trackpoint(
+    engine: &Engine,
+    file_id: Uuid,
+    segment_id: Uuid,
+    index: usize,
+) -> Option<TrackpointDetails> {
+    engine
+        .trackpoint(&FileId(file_id), &engine::TrackSegmentId(segment_id), index)
+        .map(TrackpointDetails::new)
+}
+
+/// A file as GPX (UTF-8 bytes), `None` if it does not exist. The options say which data of the
+/// trackpoints to keep, and with `as_route` that the segments are written as routes (`rte`)
+/// instead of tracks: the anchors are the route points, and the trackpoints between them the
+/// points of their path.
+pub fn export_file(
+    engine: &Engine,
+    file_id: Uuid,
+    options: engine::ExportOptions,
+) -> Option<Vec<u8>> {
+    engine.export(&FileId(file_id), options)
+}
+
+/// The data that some files have, so that the ones that none has are not offered when exporting
+/// them: a bit for the time (1), heart rate (2), cadence (4), temperature (8), power (16) and the
+/// OpenStreetMap data (32).
+pub fn exportable_data(engine: &Engine, file_ids: &[Uuid]) -> u8 {
+    let ids: Vec<FileId> = file_ids.iter().copied().map(FileId).collect();
+    let data = engine.exportable_data(&ids);
+    [
+        data.time, data.hr, data.cad, data.atemp, data.power, data.osm,
+    ]
+    .iter()
+    .enumerate()
+    .fold(0, |bits, (i, on)| bits | (u8::from(*on) << i))
+}
+
+/// For each trackpoint of the selection (numbered as in the statistics), the highest tolerance
+/// (m) of `reduce` that keeps it: infinite for the ends of the segments.
+pub fn reduction_distances(engine: &Engine) -> Vec<f64> {
+    engine.reduction_distances()
+}
+
+// Coordinates, as flat `[lng, lat, ...]` slices. Compare `rev` / `waypointsRev` of the file
+// structures with the previous ones to know which ones actually changed.
+
+/// Coordinates of the trackpoints of a segment (empty if the id is unknown).
+pub fn segment_coordinates(engine: &Engine, segment_id: Uuid) -> &[f64] {
+    engine.segment_coordinates(&engine::TrackSegmentId(segment_id))
+}
+
+/// Coordinates of the waypoints of a file (empty if the id is unknown).
+pub fn waypoint_coordinates(engine: &Engine, file_id: Uuid) -> &[f64] {
+    engine.waypoint_coordinates(&FileId(file_id))
+}
+
+// Statistics of the selection
+
+/// Global statistics of the whole selection (the buffers below cover it).
+pub fn selection_statistics(engine: &Engine) -> GlobalStatistics {
+    GlobalStatistics::new(&engine.statistics().global)
+}
+
+/// Global statistics of the trackpoints from `start` to `end` (both included) of the selection,
+/// as indexed by the buffers. `None` when the range is not in the selection.
+pub fn slice_statistics(engine: &Engine, start: usize, end: usize) -> Option<GlobalStatistics> {
+    engine
+        .statistics()
+        .slice(start, end)
+        .map(|stats| GlobalStatistics::new(&stats))
+}
+
+macro_rules! buffers {
+    ($($name:ident),*) => {$(
+        pub fn $name(engine: &Engine) -> &[f64] {
+            &engine.statistics().$name
+        }
+    )*};
+}
+
+// One entry per trackpoint of the selection.
+buffers!(
+    total_distance,
+    elevation_gain,
+    elevation_loss,
+    slope,
+    slope_segment_slope,
+    slope_segment_distance,
+    lng,
+    lat,
+    ele
+);
+
+macro_rules! optional_buffers {
+    ($($name:ident: $type:ty),*) => {$(
+        /// `None` when no trackpoint of the selection has the value, else an entry per trackpoint,
+        /// the missing ones being NaN (`NO_TIME` for the timestamps, 0 before the first trackpoint
+        /// that has them for the cumulative distances and durations).
+        pub fn $name(engine: &Engine) -> Option<&[$type]> {
+            engine.statistics().$name.as_deref()
+        }
+    )*};
+}
+
+optional_buffers!(moving_distance: f64, speed: f64, hr: f64, cad: f64, atemp: f64, power: f64);
+optional_buffers!(total_time: i64, moving_time: i64);
+
+/// Timestamps in milliseconds since the epoch (`NO_TIME` when missing), see `optional_buffers`.
+pub fn timestamps(engine: &Engine) -> Option<&[i64]> {
+    engine.statistics().time.as_deref()
+}
+
+// Surface, highway, SAC scale and MTB scale of the trackpoints, as intervals of trackpoints that
+// have the same value: `<name>_starts` holds the index of the first trackpoint of each interval,
+// and `<name>_values` its value (0 when unknown, else 1 + the index in the names of the category).
+// A value that is unknown for every trackpoint is a single interval.
+macro_rules! categories {
+    ($starts:ident, $values:ident, $names:ident, $field:ident) => {
+        pub fn $starts(engine: &Engine) -> &[u32] {
+            &engine.statistics().$field.starts
+        }
+
+        pub fn $values(engine: &Engine) -> &[u8] {
+            &engine.statistics().$field.values
+        }
+
+        /// The names of the category, in the order of their codes. The list only grows: a name
+        /// keeps its index.
+        pub fn $names(engine: &Engine) -> &[String] {
+            engine.categories().$field.names()
+        }
+    };
+}
+
+categories!(surface_starts, surface_values, surfaces, surface);
+categories!(highway_starts, highway_values, highways, highway);
+categories!(sac_scale_starts, sac_scale_values, sac_scales, sac_scale);
+categories!(mtb_scale_starts, mtb_scale_values, mtb_scales, mtb_scale);
+
+// The anchors of the routing tool among the trackpoints of the selection (numbered as in the
+// statistics). The ends of the segments are always anchors.
+
+/// The index in the selection of each anchor.
+pub fn anchor_indices(engine: &Engine) -> &[u32] {
+    &engine.routing().anchor_indices
+}
+
+/// The lowest map zoom level at which each anchor is shown.
+pub fn anchor_zooms(engine: &Engine) -> &[u8] {
+    &engine.routing().anchor_zooms
+}
+
+/// Index in the selection of the first trackpoint of each selected segment that has some.
+pub fn segment_starts(engine: &Engine) -> &[u32] {
+    &engine.routing().segment_starts
+}
+
+/// The id of each selected segment that has trackpoints, as `segment_starts`.
+pub fn segment_ids(engine: &Engine) -> Vec<String> {
+    engine
+        .routing()
+        .segment_ids
+        .iter()
+        .map(|id| id.0.to_string())
+        .collect()
+}
+
+/// Changes when the selected segments or their trackpoints change: the indices in the selection
+/// are only valid while it stays the same.
+pub fn routing_revision(engine: &Engine) -> u32 {
+    engine.routing().revision
+}
diff --git a/gpx-rs/engine/src/core/algorithm/anchors.rs b/gpx-rs/src/core/algorithm/anchors.rs
similarity index 100%
rename from gpx-rs/engine/src/core/algorithm/anchors.rs
rename to gpx-rs/src/core/algorithm/anchors.rs
diff --git a/gpx-rs/engine/src/core/algorithm/mod.rs b/gpx-rs/src/core/algorithm/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/core/algorithm/mod.rs
rename to gpx-rs/src/core/algorithm/mod.rs
diff --git a/gpx-rs/engine/src/core/algorithm/reverse.rs b/gpx-rs/src/core/algorithm/reverse.rs
similarity index 100%
rename from gpx-rs/engine/src/core/algorithm/reverse.rs
rename to gpx-rs/src/core/algorithm/reverse.rs
diff --git a/gpx-rs/engine/src/core/algorithm/simplify.rs b/gpx-rs/src/core/algorithm/simplify.rs
similarity index 100%
rename from gpx-rs/engine/src/core/algorithm/simplify.rs
rename to gpx-rs/src/core/algorithm/simplify.rs
diff --git a/gpx-rs/engine/src/core/algorithm/smooth.rs b/gpx-rs/src/core/algorithm/smooth.rs
similarity index 100%
rename from gpx-rs/engine/src/core/algorithm/smooth.rs
rename to gpx-rs/src/core/algorithm/smooth.rs
diff --git a/gpx-rs/engine/src/core/algorithm/timestamps.rs b/gpx-rs/src/core/algorithm/timestamps.rs
similarity index 100%
rename from gpx-rs/engine/src/core/algorithm/timestamps.rs
rename to gpx-rs/src/core/algorithm/timestamps.rs
diff --git a/gpx-rs/engine/src/core/gpx/categories.rs b/gpx-rs/src/core/gpx/categories.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/categories.rs
rename to gpx-rs/src/core/gpx/categories.rs
diff --git a/gpx-rs/engine/src/core/gpx/chunk.rs b/gpx-rs/src/core/gpx/chunk.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/chunk.rs
rename to gpx-rs/src/core/gpx/chunk.rs
diff --git a/gpx-rs/engine/src/core/gpx/chunked.rs b/gpx-rs/src/core/gpx/chunked.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/chunked.rs
rename to gpx-rs/src/core/gpx/chunked.rs
diff --git a/gpx-rs/engine/src/core/gpx/common.rs b/gpx-rs/src/core/gpx/common.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/common.rs
rename to gpx-rs/src/core/gpx/common.rs
diff --git a/gpx-rs/engine/src/core/gpx/file.rs b/gpx-rs/src/core/gpx/file.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/file.rs
rename to gpx-rs/src/core/gpx/file.rs
diff --git a/gpx-rs/engine/src/core/gpx/mod.rs b/gpx-rs/src/core/gpx/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/mod.rs
rename to gpx-rs/src/core/gpx/mod.rs
diff --git a/gpx-rs/engine/src/core/gpx/segment.rs b/gpx-rs/src/core/gpx/segment.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/segment.rs
rename to gpx-rs/src/core/gpx/segment.rs
diff --git a/gpx-rs/engine/src/core/gpx/track.rs b/gpx-rs/src/core/gpx/track.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/track.rs
rename to gpx-rs/src/core/gpx/track.rs
diff --git a/gpx-rs/engine/src/core/gpx/trackpoint.rs b/gpx-rs/src/core/gpx/trackpoint.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/trackpoint.rs
rename to gpx-rs/src/core/gpx/trackpoint.rs
diff --git a/gpx-rs/engine/src/core/gpx/waypoint.rs b/gpx-rs/src/core/gpx/waypoint.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/waypoint.rs
rename to gpx-rs/src/core/gpx/waypoint.rs
diff --git a/gpx-rs/engine/src/core/gpx/waypoints.rs b/gpx-rs/src/core/gpx/waypoints.rs
similarity index 100%
rename from gpx-rs/engine/src/core/gpx/waypoints.rs
rename to gpx-rs/src/core/gpx/waypoints.rs
diff --git a/gpx-rs/engine/src/core/io/mod.rs b/gpx-rs/src/core/io/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/core/io/mod.rs
rename to gpx-rs/src/core/io/mod.rs
diff --git a/gpx-rs/engine/src/core/io/parse.rs b/gpx-rs/src/core/io/parse.rs
similarity index 100%
rename from gpx-rs/engine/src/core/io/parse.rs
rename to gpx-rs/src/core/io/parse.rs
diff --git a/gpx-rs/engine/src/core/io/write.rs b/gpx-rs/src/core/io/write.rs
similarity index 100%
rename from gpx-rs/engine/src/core/io/write.rs
rename to gpx-rs/src/core/io/write.rs
diff --git a/gpx-rs/engine/src/core/mod.rs b/gpx-rs/src/core/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/core/mod.rs
rename to gpx-rs/src/core/mod.rs
diff --git a/gpx-rs/engine/src/core/statistics/compute.rs b/gpx-rs/src/core/statistics/compute.rs
similarity index 100%
rename from gpx-rs/engine/src/core/statistics/compute.rs
rename to gpx-rs/src/core/statistics/compute.rs
diff --git a/gpx-rs/engine/src/core/statistics/mod.rs b/gpx-rs/src/core/statistics/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/core/statistics/mod.rs
rename to gpx-rs/src/core/statistics/mod.rs
diff --git a/gpx-rs/engine/src/core/statistics/utils.rs b/gpx-rs/src/core/statistics/utils.rs
similarity index 100%
rename from gpx-rs/engine/src/core/statistics/utils.rs
rename to gpx-rs/src/core/statistics/utils.rs
diff --git a/gpx-rs/engine/src/core/utils.rs b/gpx-rs/src/core/utils.rs
similarity index 100%
rename from gpx-rs/engine/src/core/utils.rs
rename to gpx-rs/src/core/utils.rs
diff --git a/gpx-rs/engine/src/engine/action.rs b/gpx-rs/src/engine/action.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/action.rs
rename to gpx-rs/src/engine/action.rs
diff --git a/gpx-rs/engine/src/engine/command/apply.rs b/gpx-rs/src/engine/command/apply.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/apply.rs
rename to gpx-rs/src/engine/command/apply.rs
diff --git a/gpx-rs/engine/src/engine/command/edit/metadata.rs b/gpx-rs/src/engine/command/edit/metadata.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/edit/metadata.rs
rename to gpx-rs/src/engine/command/edit/metadata.rs
diff --git a/gpx-rs/engine/src/engine/command/edit/mod.rs b/gpx-rs/src/engine/command/edit/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/edit/mod.rs
rename to gpx-rs/src/engine/command/edit/mod.rs
diff --git a/gpx-rs/engine/src/engine/command/edit/new_track.rs b/gpx-rs/src/engine/command/edit/new_track.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/edit/new_track.rs
rename to gpx-rs/src/engine/command/edit/new_track.rs
diff --git a/gpx-rs/engine/src/engine/command/edit/new_track_segment.rs b/gpx-rs/src/engine/command/edit/new_track_segment.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/edit/new_track_segment.rs
rename to gpx-rs/src/engine/command/edit/new_track_segment.rs
diff --git a/gpx-rs/engine/src/engine/command/edit/style.rs b/gpx-rs/src/engine/command/edit/style.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/edit/style.rs
rename to gpx-rs/src/engine/command/edit/style.rs
diff --git a/gpx-rs/engine/src/engine/command/file/delete.rs b/gpx-rs/src/engine/command/file/delete.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/delete.rs
rename to gpx-rs/src/engine/command/file/delete.rs
diff --git a/gpx-rs/engine/src/engine/command/file/delete_all.rs b/gpx-rs/src/engine/command/file/delete_all.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/delete_all.rs
rename to gpx-rs/src/engine/command/file/delete_all.rs
diff --git a/gpx-rs/engine/src/engine/command/file/delete_waypoint.rs b/gpx-rs/src/engine/command/file/delete_waypoint.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/delete_waypoint.rs
rename to gpx-rs/src/engine/command/file/delete_waypoint.rs
diff --git a/gpx-rs/engine/src/engine/command/file/duplicate.rs b/gpx-rs/src/engine/command/file/duplicate.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/duplicate.rs
rename to gpx-rs/src/engine/command/file/duplicate.rs
diff --git a/gpx-rs/engine/src/engine/command/file/load.rs b/gpx-rs/src/engine/command/file/load.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/load.rs
rename to gpx-rs/src/engine/command/file/load.rs
diff --git a/gpx-rs/engine/src/engine/command/file/mod.rs b/gpx-rs/src/engine/command/file/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/mod.rs
rename to gpx-rs/src/engine/command/file/mod.rs
diff --git a/gpx-rs/engine/src/engine/command/file/move_elements.rs b/gpx-rs/src/engine/command/file/move_elements.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/move_elements.rs
rename to gpx-rs/src/engine/command/file/move_elements.rs
diff --git a/gpx-rs/engine/src/engine/command/file/new.rs b/gpx-rs/src/engine/command/file/new.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/new.rs
rename to gpx-rs/src/engine/command/file/new.rs
diff --git a/gpx-rs/engine/src/engine/command/file/paste.rs b/gpx-rs/src/engine/command/file/paste.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/paste.rs
rename to gpx-rs/src/engine/command/file/paste.rs
diff --git a/gpx-rs/engine/src/engine/command/file/transfer.rs b/gpx-rs/src/engine/command/file/transfer.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/file/transfer.rs
rename to gpx-rs/src/engine/command/file/transfer.rs
diff --git a/gpx-rs/engine/src/engine/command/fixture.rs b/gpx-rs/src/engine/command/fixture.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/fixture.rs
rename to gpx-rs/src/engine/command/fixture.rs
diff --git a/gpx-rs/engine/src/engine/command/mod.rs b/gpx-rs/src/engine/command/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/mod.rs
rename to gpx-rs/src/engine/command/mod.rs
diff --git a/gpx-rs/engine/src/engine/command/pattern/copy.rs b/gpx-rs/src/engine/command/pattern/copy.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/pattern/copy.rs
rename to gpx-rs/src/engine/command/pattern/copy.rs
diff --git a/gpx-rs/engine/src/engine/command/pattern/mod.rs b/gpx-rs/src/engine/command/pattern/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/pattern/mod.rs
rename to gpx-rs/src/engine/command/pattern/mod.rs
diff --git a/gpx-rs/engine/src/engine/command/pattern/produce.rs b/gpx-rs/src/engine/command/pattern/produce.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/pattern/produce.rs
rename to gpx-rs/src/engine/command/pattern/produce.rs
diff --git a/gpx-rs/engine/src/engine/command/pattern/update_segments.rs b/gpx-rs/src/engine/command/pattern/update_segments.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/pattern/update_segments.rs
rename to gpx-rs/src/engine/command/pattern/update_segments.rs
diff --git a/gpx-rs/engine/src/engine/command/pattern/update_selected.rs b/gpx-rs/src/engine/command/pattern/update_selected.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/pattern/update_selected.rs
rename to gpx-rs/src/engine/command/pattern/update_selected.rs
diff --git a/gpx-rs/engine/src/engine/command/pattern/update_waypoint.rs b/gpx-rs/src/engine/command/pattern/update_waypoint.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/pattern/update_waypoint.rs
rename to gpx-rs/src/engine/command/pattern/update_waypoint.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/change_loop_start.rs b/gpx-rs/src/engine/command/tools/change_loop_start.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/change_loop_start.rs
rename to gpx-rs/src/engine/command/tools/change_loop_start.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/clean.rs b/gpx-rs/src/engine/command/tools/clean.rs
similarity index 99%
rename from gpx-rs/engine/src/engine/command/tools/clean.rs
rename to gpx-rs/src/engine/command/tools/clean.rs
index c543d6ebb..3cf3715c7 100644
--- a/gpx-rs/engine/src/engine/command/tools/clean.rs
+++ b/gpx-rs/src/engine/command/tools/clean.rs
@@ -5,7 +5,8 @@ use crate::{
     TrackSegment, TrackSegmentId, Trackpoint, Waypoint, delete_waypoints, update_selected,
 };
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Deserialize)]
+#[serde(rename_all = "camelCase")]
 pub enum CleanType {
     Inside,
     Outside,
diff --git a/gpx-rs/engine/src/engine/command/tools/crop.rs b/gpx-rs/src/engine/command/tools/crop.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/crop.rs
rename to gpx-rs/src/engine/command/tools/crop.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/edit_waypoint.rs b/gpx-rs/src/engine/command/tools/edit_waypoint.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/edit_waypoint.rs
rename to gpx-rs/src/engine/command/tools/edit_waypoint.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/elevation.rs b/gpx-rs/src/engine/command/tools/elevation.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/elevation.rs
rename to gpx-rs/src/engine/command/tools/elevation.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/extract.rs b/gpx-rs/src/engine/command/tools/extract.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/extract.rs
rename to gpx-rs/src/engine/command/tools/extract.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/insert_anchor.rs b/gpx-rs/src/engine/command/tools/insert_anchor.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/insert_anchor.rs
rename to gpx-rs/src/engine/command/tools/insert_anchor.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/merge.rs b/gpx-rs/src/engine/command/tools/merge.rs
similarity index 99%
rename from gpx-rs/engine/src/engine/command/tools/merge.rs
rename to gpx-rs/src/engine/command/tools/merge.rs
index 130ce5a68..9916ee929 100644
--- a/gpx-rs/engine/src/engine/command/tools/merge.rs
+++ b/gpx-rs/src/engine/command/tools/merge.rs
@@ -5,7 +5,8 @@ use crate::{
     TrackSegment, TrackSegmentId, Waypoint, Waypoints, replace_trackpoints,
 };
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Deserialize)]
+#[serde(rename_all = "camelCase")]
 pub enum MergeType {
     /// The trackpoints of the elements are connected in a single segment.
     Connect,
diff --git a/gpx-rs/engine/src/engine/command/tools/mod.rs b/gpx-rs/src/engine/command/tools/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/mod.rs
rename to gpx-rs/src/engine/command/tools/mod.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/move_waypoint.rs b/gpx-rs/src/engine/command/tools/move_waypoint.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/move_waypoint.rs
rename to gpx-rs/src/engine/command/tools/move_waypoint.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/new_waypoint.rs b/gpx-rs/src/engine/command/tools/new_waypoint.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/new_waypoint.rs
rename to gpx-rs/src/engine/command/tools/new_waypoint.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/reduce.rs b/gpx-rs/src/engine/command/tools/reduce.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/reduce.rs
rename to gpx-rs/src/engine/command/tools/reduce.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/reverse.rs b/gpx-rs/src/engine/command/tools/reverse.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/reverse.rs
rename to gpx-rs/src/engine/command/tools/reverse.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/round_trip.rs b/gpx-rs/src/engine/command/tools/round_trip.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/round_trip.rs
rename to gpx-rs/src/engine/command/tools/round_trip.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/route.rs b/gpx-rs/src/engine/command/tools/route.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/route.rs
rename to gpx-rs/src/engine/command/tools/route.rs
diff --git a/gpx-rs/engine/src/engine/command/tools/split.rs b/gpx-rs/src/engine/command/tools/split.rs
similarity index 99%
rename from gpx-rs/engine/src/engine/command/tools/split.rs
rename to gpx-rs/src/engine/command/tools/split.rs
index 73f7e93bb..2130b073f 100644
--- a/gpx-rs/engine/src/engine/command/tools/split.rs
+++ b/gpx-rs/src/engine/command/tools/split.rs
@@ -8,7 +8,8 @@ use crate::{
 use super::route::find_target;
 
 /// What is cut in two where the trackpoint is.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Deserialize)]
+#[serde(rename_all = "camelCase")]
 pub enum SplitType {
     /// The file becomes two files, which both have the waypoints (copies, in the second one).
     Files,
diff --git a/gpx-rs/engine/src/engine/command/tools/time.rs b/gpx-rs/src/engine/command/tools/time.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/command/tools/time.rs
rename to gpx-rs/src/engine/command/tools/time.rs
diff --git a/gpx-rs/engine/src/engine/derived/coordinates_cache.rs b/gpx-rs/src/engine/derived/coordinates_cache.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/derived/coordinates_cache.rs
rename to gpx-rs/src/engine/derived/coordinates_cache.rs
diff --git a/gpx-rs/engine/src/engine/derived/file_structure.rs b/gpx-rs/src/engine/derived/file_structure.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/derived/file_structure.rs
rename to gpx-rs/src/engine/derived/file_structure.rs
diff --git a/gpx-rs/engine/src/engine/derived/file_structure_cache.rs b/gpx-rs/src/engine/derived/file_structure_cache.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/derived/file_structure_cache.rs
rename to gpx-rs/src/engine/derived/file_structure_cache.rs
diff --git a/gpx-rs/engine/src/engine/derived/mod.rs b/gpx-rs/src/engine/derived/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/derived/mod.rs
rename to gpx-rs/src/engine/derived/mod.rs
diff --git a/gpx-rs/engine/src/engine/derived/routing_buffer.rs b/gpx-rs/src/engine/derived/routing_buffer.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/derived/routing_buffer.rs
rename to gpx-rs/src/engine/derived/routing_buffer.rs
diff --git a/gpx-rs/engine/src/engine/derived/statistics_buffer.rs b/gpx-rs/src/engine/derived/statistics_buffer.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/derived/statistics_buffer.rs
rename to gpx-rs/src/engine/derived/statistics_buffer.rs
diff --git a/gpx-rs/engine/src/engine/derived/statistics_cache.rs b/gpx-rs/src/engine/derived/statistics_cache.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/derived/statistics_cache.rs
rename to gpx-rs/src/engine/derived/statistics_cache.rs
diff --git a/gpx-rs/engine/src/engine/mod.rs b/gpx-rs/src/engine/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/mod.rs
rename to gpx-rs/src/engine/mod.rs
diff --git a/gpx-rs/engine/src/engine/outcome.rs b/gpx-rs/src/engine/outcome.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/outcome.rs
rename to gpx-rs/src/engine/outcome.rs
diff --git a/gpx-rs/engine/src/engine/state/clipboard.rs b/gpx-rs/src/engine/state/clipboard.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/state/clipboard.rs
rename to gpx-rs/src/engine/state/clipboard.rs
diff --git a/gpx-rs/engine/src/engine/state/history.rs b/gpx-rs/src/engine/state/history.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/state/history.rs
rename to gpx-rs/src/engine/state/history.rs
diff --git a/gpx-rs/engine/src/engine/state/mod.rs b/gpx-rs/src/engine/state/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/state/mod.rs
rename to gpx-rs/src/engine/state/mod.rs
diff --git a/gpx-rs/engine/src/engine/state/order.rs b/gpx-rs/src/engine/state/order.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/state/order.rs
rename to gpx-rs/src/engine/state/order.rs
diff --git a/gpx-rs/engine/src/engine/state/selection.rs b/gpx-rs/src/engine/state/selection.rs
similarity index 99%
rename from gpx-rs/engine/src/engine/state/selection.rs
rename to gpx-rs/src/engine/state/selection.rs
index 15baa6e9c..bbd7cc108 100644
--- a/gpx-rs/engine/src/engine/state/selection.rs
+++ b/gpx-rs/src/engine/state/selection.rs
@@ -3,7 +3,8 @@ use std::collections::HashSet;
 use crate::{FileId, Files, TrackId, TrackSegmentId, WaypointId};
 
 /// How a new selection combines with the current one.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Deserialize)]
+#[serde(rename_all = "camelCase")]
 pub enum SelectMode {
     /// The new selection replaces the current one.
     Replace,
diff --git a/gpx-rs/engine/src/engine/tests.rs b/gpx-rs/src/engine/tests.rs
similarity index 100%
rename from gpx-rs/engine/src/engine/tests.rs
rename to gpx-rs/src/engine/tests.rs
diff --git a/gpx-rs/src/lib.rs b/gpx-rs/src/lib.rs
new file mode 100644
index 000000000..3cd415c8c
--- /dev/null
+++ b/gpx-rs/src/lib.rs
@@ -0,0 +1,10 @@
+//! The GPX engine, and `api`, what the interfaces to it (the web page, the desktop app) share.
+
+pub mod api;
+mod core;
+mod engine;
+mod storage;
+
+pub use core::*;
+pub use engine::*;
+pub use storage::*;
diff --git a/gpx-rs/engine/src/storage/codec/mod.rs b/gpx-rs/src/storage/codec/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/storage/codec/mod.rs
rename to gpx-rs/src/storage/codec/mod.rs
diff --git a/gpx-rs/engine/src/storage/codec/v1.rs b/gpx-rs/src/storage/codec/v1.rs
similarity index 100%
rename from gpx-rs/engine/src/storage/codec/v1.rs
rename to gpx-rs/src/storage/codec/v1.rs
diff --git a/gpx-rs/engine/src/storage/memory.rs b/gpx-rs/src/storage/memory.rs
similarity index 100%
rename from gpx-rs/engine/src/storage/memory.rs
rename to gpx-rs/src/storage/memory.rs
diff --git a/gpx-rs/engine/src/storage/mod.rs b/gpx-rs/src/storage/mod.rs
similarity index 100%
rename from gpx-rs/engine/src/storage/mod.rs
rename to gpx-rs/src/storage/mod.rs
diff --git a/gpx-rs/engine/src/storage/persister.rs b/gpx-rs/src/storage/persister.rs
similarity index 100%
rename from gpx-rs/engine/src/storage/persister.rs
rename to gpx-rs/src/storage/persister.rs
diff --git a/gpx-rs/wasm/src/command/routing.rs b/gpx-rs/wasm/src/command/routing.rs
deleted file mode 100644
index 6fa5e1d76..000000000
--- a/gpx-rs/wasm/src/command/routing.rs
+++ /dev/null
@@ -1,144 +0,0 @@
-//! The commands that refer to trackpoints by their index in the routing buffers.
-
-use gpx_engine::{self as engine, Command};
-use js_sys::{Array, Uint8Array, Uint32Array};
-use wasm_bindgen::prelude::*;
-
-use crate::convert::*;
-use crate::ids::*;
-use crate::queries::routing::with_routing;
-use crate::session::*;
-use crate::ts::*;
-use crate::types::*;
-
-// Routing
-//
-// The indices of the trackpoints and of the anchors are the ones of the routing buffers: they only
-// mean something for the `revision` they were read with (`routing_revision`), and the commands
-// that use them do nothing if the selection is not the one of that revision anymore.
-
-/// Makes the call `f`, unless the selection is not the one of the revision anymore.
-pub(crate) fn at_revision(revision: u32, f: impl FnOnce() -> Outcome) -> Outcome {
-    if with_routing(|r| r.revision == revision).unwrap_or(false) {
-        f()
-    } else {
-        fail("the selection changed since the routing buffers were read")
-    }
-}
-
-/// A category of the trackpoints of a route: see `RouteCategory` in `engine`.
-pub(crate) struct ParsedCategory {
-    starts: Vec<u32>,
-    values: Vec<u8>,
-    names: Vec<String>,
-}
-
-impl ParsedCategory {
-    fn parse(attributes: &JsValue, key: &str) -> Option<Self> {
-        let Some(category) = property(attributes, key) else {
-            return Some(Self {
-                starts: vec![],
-                values: vec![],
-                names: vec![],
-            });
-        };
-        Some(Self {
-            starts: property(&category, "starts")?
-                .unchecked_into::<Uint32Array>()
-                .to_vec(),
-            values: property(&category, "values")?
-                .unchecked_into::<Uint8Array>()
-                .to_vec(),
-            names: Array::from(&property(&category, "names")?)
-                .iter()
-                .map(|name| name.as_string())
-                .collect::<Option<_>>()?,
-        })
-    }
-
-    fn view(&self) -> engine::RouteCategory<'_> {
-        engine::RouteCategory {
-            starts: &self.starts,
-            values: &self.values,
-            names: &self.names,
-        }
-    }
-}
-
-/// Replaces the trackpoints `start..end` of the selection by the given ones, in a single segment
-/// (see `RoutingBuffer`). A pure insertion if `start == end`, a pure removal without new points.
-/// `attributes` holds the surface, highway, SAC scale and MTB scale of the new points, as
-/// intervals, and `anchors` the indices among the new points of the ones that become anchors.
-/// Does nothing, and says why, if the revision of the routing buffers is not the given one.
-#[wasm_bindgen]
-#[allow(clippy::too_many_arguments)]
-pub fn route(
-    revision: u32,
-    start: u32,
-    end: u32,
-    lng: &[f64],
-    lat: &[f64],
-    ele: &[f64],
-    attributes: RouteAttributes,
-    anchors: &[u32],
-) -> Outcome {
-    let parse = |key| ParsedCategory::parse(&attributes, key);
-    let (Some(surface), Some(highway), Some(sac_scale), Some(mtb_scale)) = (
-        parse("surface"),
-        parse("highway"),
-        parse("sacScale"),
-        parse("mtbScale"),
-    ) else {
-        return fail("the attributes of the route are not valid");
-    };
-    if !same_len(lng, lat, ele) {
-        return fail("lng, lat and ele differ in length");
-    }
-    at_revision(revision, || {
-        edit(Command::Route(engine::Route {
-            start,
-            end,
-            lng,
-            lat,
-            ele,
-            surface: surface.view(),
-            highway: highway.view(),
-            sac_scale: sac_scale.view(),
-            mtb_scale: mtb_scale.view(),
-            anchors,
-        }))
-    })
-}
-
-/// Makes an anchor of the point of the selected segments that is the closest to the coordinates,
-/// inserting a trackpoint on the path if none is there. Does nothing, and says why, if the
-/// revision of the routing buffers is not the given one.
-#[wasm_bindgen]
-pub fn insert_anchor(revision: u32, lng: f64, lat: f64) -> Outcome {
-    at_revision(revision, || {
-        edit(Command::InsertAnchor(engine::InsertAnchor { lng, lat }))
-    })
-}
-
-/// Makes the trackpoint `index` of the selection the start of its segment, which is a loop (the
-/// trackpoints before it go to the end, and the loop closes on it). Does nothing, and says why, if the revision of the
-/// routing buffers is not the given one.
-#[wasm_bindgen]
-pub fn change_loop_start(revision: u32, index: u32) -> Outcome {
-    at_revision(revision, || {
-        edit(Command::ChangeLoopStart(engine::ChangeLoopStart { index }))
-    })
-}
-
-/// Cuts the file, the track or the segment (see `SplitType`) of the trackpoint `at` of the
-/// selection in two, there: the trackpoint ends the first part and starts the second one. Does
-/// nothing, and returns false, if the revision of the routing buffers is not the given one.
-#[wasm_bindgen]
-pub fn split(revision: u32, at: u32, split_type: SplitType) -> Outcome {
-    at_revision(revision, || {
-        edit(Command::Split(engine::Split {
-            at,
-            split_type: split_type.into(),
-        }))
-    })
-}
diff --git a/gpx-rs/wasm/src/command/waypoints.rs b/gpx-rs/wasm/src/command/waypoints.rs
deleted file mode 100644
index b6058d0bc..000000000
--- a/gpx-rs/wasm/src/command/waypoints.rs
+++ /dev/null
@@ -1,90 +0,0 @@
-//! Creating, editing, moving and deleting waypoints.
-
-use gpx_engine::{self as engine, Command};
-use wasm_bindgen::prelude::*;
-
-use crate::ts::Outcome;
-
-use crate::ids::*;
-use crate::session::*;
-
-#[wasm_bindgen]
-pub fn new_waypoint(
-    lng: f64,
-    lat: f64,
-    ele: f64,
-    name: &str,
-    desc: &str,
-    icon: &str,
-    link: &str,
-) -> Outcome {
-    edit(Command::NewWaypoint(engine::NewWaypoint {
-        lng,
-        lat,
-        ele,
-        name,
-        desc,
-        icon,
-        link,
-    }))
-}
-
-/// Moves a waypoint of a file, whatever is selected.
-#[wasm_bindgen]
-pub fn move_waypoint(file_id: &str, waypoint_id: &str, lng: f64, lat: f64, ele: f64) -> Outcome {
-    match (parse_file_id(file_id), parse_waypoint_id(waypoint_id)) {
-        (Some(file_id), Some(waypoint_id)) => edit(Command::MoveWaypoint(engine::MoveWaypoint {
-            file_id,
-            waypoint_id,
-            lng,
-            lat,
-            ele,
-        })),
-        _ => fail("the file or waypoint id is not a UUID"),
-    }
-}
-
-/// Deletes a waypoint of a file, whatever is selected.
-#[wasm_bindgen]
-pub fn delete_waypoint(file_id: &str, waypoint_id: &str) -> Outcome {
-    match (parse_file_id(file_id), parse_waypoint_id(waypoint_id)) {
-        (Some(file_id), Some(waypoint_id)) => {
-            edit(Command::DeleteWaypoint(engine::DeleteWaypoint {
-                file_id,
-                waypoint_id,
-            }))
-        }
-        _ => fail("the file or waypoint id is not a UUID"),
-    }
-}
-
-/// Changes a waypoint of a file, whatever is selected: its name, description, icon, link, position
-/// and elevation. The strings that are empty remove the field.
-#[wasm_bindgen]
-#[allow(clippy::too_many_arguments)]
-pub fn update_waypoint(
-    file_id: &str,
-    waypoint_id: &str,
-    lng: f64,
-    lat: f64,
-    ele: f64,
-    name: &str,
-    desc: &str,
-    icon: &str,
-    link: &str,
-) -> Outcome {
-    match (parse_file_id(file_id), parse_waypoint_id(waypoint_id)) {
-        (Some(file_id), Some(waypoint_id)) => edit(Command::EditWaypoint(engine::EditWaypoint {
-            file_id,
-            waypoint_id,
-            lng,
-            lat,
-            ele,
-            name,
-            desc,
-            icon,
-            link,
-        })),
-        _ => fail("the file or waypoint id is not a UUID"),
-    }
-}
diff --git a/gpx-rs/wasm/src/convert.rs b/gpx-rs/wasm/src/convert.rs
deleted file mode 100644
index 0c98d65d7..000000000
--- a/gpx-rs/wasm/src/convert.rs
+++ /dev/null
@@ -1,254 +0,0 @@
-//! Turning engine types into JS objects and back.
-
-use gpx_engine::{self as engine, FileId};
-use js_sys::{Array, Object, Reflect};
-use wasm_bindgen::prelude::*;
-
-use crate::ts::*;
-
-pub(crate) fn property(object: &JsValue, key: &str) -> Option<JsValue> {
-    Reflect::get(object, &key.into())
-        .ok()
-        .filter(|value| !value.is_undefined())
-}
-
-pub(crate) fn uuid_property(object: &JsValue, key: &str) -> Option<uuid::Uuid> {
-    uuid::Uuid::parse_str(&property(object, key)?.as_string()?).ok()
-}
-
-pub(crate) fn uuids_property(object: &JsValue, key: &str) -> Option<Vec<uuid::Uuid>> {
-    Array::from(&property(object, key)?)
-        .iter()
-        .map(|id| uuid::Uuid::parse_str(&id.as_string()?).ok())
-        .collect()
-}
-
-/// The inverse of `selection_object`.
-pub(crate) fn parse_selection(value: &JsValue) -> Option<engine::Selection> {
-    use engine::Selection as S;
-    let file_id = || uuid_property(value, "fileId").map(FileId);
-    Some(match property(value, "type")?.as_string()?.as_str() {
-        "empty" => S::Empty,
-        "file" => S::File {
-            file_ids: uuids_property(value, "fileIds")?
-                .into_iter()
-                .map(FileId)
-                .collect(),
-        },
-        "track" => S::Track {
-            file_id: file_id()?,
-            trk_ids: uuids_property(value, "trackIds")?
-                .into_iter()
-                .map(engine::TrackId)
-                .collect(),
-        },
-        "segment" => S::TrackSegment {
-            file_id: file_id()?,
-            trk_id: engine::TrackId(uuid_property(value, "trackId")?),
-            trkseg_ids: uuids_property(value, "segmentIds")?
-                .into_iter()
-                .map(engine::TrackSegmentId)
-                .collect(),
-        },
-        "waypoints" => S::Waypoints {
-            file_id: file_id()?,
-        },
-        "waypoint" => S::Waypoint {
-            file_id: file_id()?,
-            wpt_ids: uuids_property(value, "waypointIds")?
-                .into_iter()
-                .map(engine::WaypointId)
-                .collect(),
-        },
-        _ => return None,
-    })
-}
-
-pub(crate) fn parse_move_target(value: &JsValue) -> Option<engine::MoveTarget> {
-    use engine::MoveTarget as T;
-    // a negative index is the start, an infinite one is the end
-    let index = property(value, "index")?.as_f64()?.max(0.0) as usize;
-    let file_id = || uuid_property(value, "fileId").map(FileId);
-    Some(match property(value, "type")?.as_string()?.as_str() {
-        "files" => T::Files { index },
-        "tracks" => T::Tracks {
-            file_id: file_id()?,
-            index,
-        },
-        "segments" => T::Segments {
-            file_id: file_id()?,
-            trk_id: engine::TrackId(uuid_property(value, "trackId")?),
-            index,
-        },
-        "waypoints" => T::Waypoints {
-            file_id: file_id()?,
-            index,
-        },
-        _ => return None,
-    })
-}
-
-pub(crate) fn set(object: &Object, key: &str, value: impl Into<JsValue>) {
-    Reflect::set(object, &key.into(), &value.into()).unwrap();
-}
-
-pub(crate) fn array<T>(items: &[T], f: impl Fn(&T) -> JsValue) -> Array {
-    items.iter().map(f).collect()
-}
-
-pub(crate) fn ids(items: &[FileId]) -> Array {
-    array(items, |id| id.0.to_string().into())
-}
-
-pub(crate) fn named_node(id: uuid::Uuid, name: Option<&str>) -> Object {
-    let node = Object::new();
-    set(&node, "id", id.to_string());
-    if let Some(name) = name {
-        set(&node, "name", name);
-    }
-    node
-}
-
-pub(crate) fn structure_object(file: &engine::FileStructure) -> Object {
-    let node = named_node(file.id.0, Some(&file.name));
-    if let Some(desc) = &file.desc {
-        set(&node, "desc", desc.as_str());
-    }
-    set(
-        &node,
-        "tracks",
-        array(&file.tracks, |trk| {
-            let node = named_node(trk.id.0, trk.name.as_deref());
-            if let Some(desc) = &trk.desc {
-                set(&node, "desc", desc.as_str());
-            }
-            if let Some(color) = &trk.color {
-                set(&node, "color", color.as_str());
-            }
-            if let Some(opacity) = trk.opacity {
-                set(&node, "opacity", opacity);
-            }
-            if let Some(width) = trk.width {
-                set(&node, "width", width);
-            }
-            set(
-                &node,
-                "segments",
-                array(&trk.segments, |seg| {
-                    let node = named_node(seg.id.0, None);
-                    set(&node, "rev", seg.rev_id.0.to_string());
-                    set(&node, "length", seg.len as f64);
-                    node.into()
-                }),
-            );
-            node.into()
-        }),
-    );
-    set(
-        &node,
-        "waypoints",
-        array(&file.waypoints, |wpt| {
-            let node = named_node(wpt.id.0, wpt.name.as_deref());
-            if let Some(sym) = &wpt.sym {
-                set(&node, "sym", sym.as_str());
-            }
-            node.into()
-        }),
-    );
-    set(&node, "waypointsRev", file.wpt_rev_id.0.to_string());
-    node
-}
-
-pub(crate) fn statistics_object(stats: &engine::GlobalStatistics) -> GlobalStatistics {
-    let object = Object::new();
-    let optional = |key: &str, value: Option<f64>| {
-        if let Some(value) = value {
-            set(&object, key, value);
-        }
-    };
-    let seconds = |ms: Option<i64>| ms.map(|ms| ms as f64 / 1000.0);
-    set(&object, "totalDistance", stats.total_distance);
-    optional("movingDistance", stats.moving_distance);
-    optional("totalTime", seconds(stats.total_time));
-    optional("movingTime", seconds(stats.moving_time));
-    set(&object, "elevationGain", stats.elevation_gain);
-    set(&object, "elevationLoss", stats.elevation_loss);
-    optional("startTime", stats.start_time.map(|t| t as f64));
-    optional("endTime", stats.end_time.map(|t| t as f64));
-    optional("totalSpeed", stats.total_speed());
-    optional("movingSpeed", stats.moving_speed());
-    let (sw, ne) = (&stats.bounds.sw, &stats.bounds.ne);
-    if sw.lng <= ne.lng && sw.lat <= ne.lat {
-        let bounds = Object::new();
-        set(&bounds, "west", sw.lng);
-        set(&bounds, "south", sw.lat);
-        set(&bounds, "east", ne.lng);
-        set(&bounds, "north", ne.lat);
-        set(&object, "bounds", bounds);
-    }
-    object.unchecked_into()
-}
-
-pub(crate) fn uuids<T>(
-    items: impl IntoIterator<Item = T>,
-    uuid: impl Fn(T) -> uuid::Uuid,
-) -> Array {
-    items
-        .into_iter()
-        .map(|item| JsValue::from(uuid(item).to_string()))
-        .collect()
-}
-
-pub(crate) fn selection_object(selection: &engine::Selection) -> Object {
-    use engine::Selection as S;
-    let object = Object::new();
-    match selection {
-        S::Empty => set(&object, "type", "empty"),
-        S::File { file_ids } => {
-            set(&object, "type", "file");
-            set(&object, "fileIds", uuids(file_ids, |id| id.0));
-        }
-        S::Track { file_id, trk_ids } => {
-            set(&object, "type", "track");
-            set(&object, "fileId", file_id.0.to_string());
-            set(&object, "trackIds", uuids(trk_ids, |id| id.0));
-        }
-        S::TrackSegment {
-            file_id,
-            trk_id,
-            trkseg_ids,
-        } => {
-            set(&object, "type", "segment");
-            set(&object, "fileId", file_id.0.to_string());
-            set(&object, "trackId", trk_id.0.to_string());
-            set(&object, "segmentIds", uuids(trkseg_ids, |id| id.0));
-        }
-        S::Waypoints { file_id } => {
-            set(&object, "type", "waypoints");
-            set(&object, "fileId", file_id.0.to_string());
-        }
-        S::Waypoint { file_id, wpt_ids } => {
-            set(&object, "type", "waypoint");
-            set(&object, "fileId", file_id.0.to_string());
-            set(&object, "waypointIds", uuids(wpt_ids, |id| id.0));
-        }
-    }
-    object
-}
-
-/// The outcome of a call. `error` is what it says about why nothing was done, if that is so.
-pub(crate) fn outcome_object(outcome: &engine::Outcome, error: Option<&str>) -> Outcome {
-    let object = Object::new();
-    let diff = outcome.diff.clone().unwrap_or_default();
-    set(&object, "changed", outcome.changed);
-    set(&object, "orderChanged", outcome.order_changed);
-    set(&object, "selectionChanged", outcome.selection_changed);
-    set(&object, "clipboardChanged", outcome.clipboard_changed);
-    set(&object, "added", ids(&diff.added));
-    set(&object, "modified", ids(&diff.modified));
-    set(&object, "removed", ids(&diff.removed));
-    if let Some(error) = error {
-        set(&object, "error", error);
-    }
-    object.unchecked_into()
-}
diff --git a/gpx-rs/wasm/src/ids.rs b/gpx-rs/wasm/src/ids.rs
deleted file mode 100644
index 2f48e8d01..000000000
--- a/gpx-rs/wasm/src/ids.rs
+++ /dev/null
@@ -1,25 +0,0 @@
-//! Ids, which cross as strings (one id) or as concatenated 16-byte UUIDs (several).
-
-use gpx_engine::{self as engine, FileId};
-
-pub(crate) fn uuid_list(bytes: &[u8]) -> Option<Vec<uuid::Uuid>> {
-    let (chunks, rest) = bytes.as_chunks::<16>();
-    rest.is_empty()
-        .then(|| chunks.iter().map(|c| uuid::Uuid::from_bytes(*c)).collect())
-}
-
-pub(crate) fn file_ids(bytes: &[u8]) -> Option<Vec<FileId>> {
-    uuid_list(bytes).map(|ids| ids.into_iter().map(FileId).collect())
-}
-
-pub(crate) fn parse_file_id(id: &str) -> Option<FileId> {
-    uuid::Uuid::parse_str(id).ok().map(FileId)
-}
-
-pub(crate) fn same_len(a: &[f64], b: &[f64], c: &[f64]) -> bool {
-    a.len() == b.len() && b.len() == c.len()
-}
-
-pub(crate) fn parse_waypoint_id(id: &str) -> Option<engine::WaypointId> {
-    uuid::Uuid::parse_str(id).ok().map(engine::WaypointId)
-}
diff --git a/gpx-rs/wasm/src/queries/coordinates.rs b/gpx-rs/wasm/src/queries/coordinates.rs
deleted file mode 100644
index 5448b7122..000000000
--- a/gpx-rs/wasm/src/queries/coordinates.rs
+++ /dev/null
@@ -1,37 +0,0 @@
-//! The coordinates of the trackpoints and waypoints, as flat typed arrays.
-
-use gpx_engine::{self as engine, Engine, FileId};
-use js_sys::Float64Array;
-use wasm_bindgen::prelude::*;
-
-use crate::session::*;
-
-// Coordinates buffers
-//
-// Like the statistics buffers, these are copies. They are flat `[lng, lat, ...]` arrays. Compare `rev` / `waypointsRev` of the file structures with the previous ones to know which
-// buffers actually changed.
-
-pub(crate) fn coordinates_array(f: impl FnOnce(&Engine) -> Option<&[f64]>) -> Float64Array {
-    ENGINE.with(|engine| match engine.borrow().as_ref().and_then(f) {
-        Some(coordinates) => Float64Array::from(coordinates),
-        None => Float64Array::new_with_length(0),
-    })
-}
-
-/// Coordinates of the trackpoints of a segment (empty if the id is unknown).
-#[wasm_bindgen]
-pub fn segment_coordinates(segment_id: &str) -> Float64Array {
-    match uuid::Uuid::parse_str(segment_id) {
-        Ok(id) => coordinates_array(|e| Some(e.segment_coordinates(&engine::TrackSegmentId(id)))),
-        Err(_) => Float64Array::new_with_length(0),
-    }
-}
-
-/// Coordinates of the waypoints of a file (empty if the id is unknown).
-#[wasm_bindgen]
-pub fn waypoint_coordinates(file_id: &str) -> Float64Array {
-    match uuid::Uuid::parse_str(file_id) {
-        Ok(id) => coordinates_array(|e| Some(e.waypoint_coordinates(&FileId(id)))),
-        Err(_) => Float64Array::new_with_length(0),
-    }
-}
diff --git a/gpx-rs/wasm/src/queries/files.rs b/gpx-rs/wasm/src/queries/files.rs
deleted file mode 100644
index 400f06061..000000000
--- a/gpx-rs/wasm/src/queries/files.rs
+++ /dev/null
@@ -1,219 +0,0 @@
-//! The files, their structure and statistics, the selection and the clipboard.
-
-// File order and structures
-//
-// The files are described by one ordered list of ids and one structure object per file, so that
-// the UI can react to what changed only: after each action, `last_update` tells which
-// structures to (re)read or drop and whether the order changed. Ids are UUID strings. The
-// trackpoints of a segment and the waypoints of a file are in the same order as the coordinates
-// of their buffers (see below).
-
-use gpx_engine::{self as engine, FileId};
-use js_sys::Object;
-use wasm_bindgen::prelude::*;
-
-use crate::convert::*;
-use crate::ids::*;
-use crate::queries::statistics::with_stats;
-use crate::session::*;
-use crate::ts::*;
-
-/// Ids of the files in display order.
-#[wasm_bindgen]
-pub fn file_order() -> FileOrder {
-    let order = with_engine(|e| ids(e.order())).unwrap_or_default();
-    order.unchecked_into()
-}
-
-/// Structure of a file, `undefined` if the id is unknown.
-#[wasm_bindgen]
-pub fn file_structure(file_id: &str) -> FileStructure {
-    let structure = uuid::Uuid::parse_str(file_id)
-        .ok()
-        .and_then(|id| {
-            with_engine(|e| e.file_structure(&FileId(id)).map(structure_object)).flatten()
-        })
-        .map_or(JsValue::UNDEFINED, JsValue::from);
-    structure.unchecked_into()
-}
-
-/// Global statistics of a file, `undefined` if the id is unknown.
-#[wasm_bindgen]
-pub fn file_statistics(file_id: &str) -> GlobalStatistics {
-    uuid::Uuid::parse_str(file_id)
-        .ok()
-        .and_then(|id| with_engine(|e| e.file_statistics(&FileId(id))).flatten())
-        .map_or(JsValue::UNDEFINED.unchecked_into(), |stats| {
-            statistics_object(&stats)
-        })
-}
-
-/// Global statistics of the whole selection (the arrays of the statistics buffers cover it).
-#[wasm_bindgen]
-pub fn selection_statistics() -> GlobalStatistics {
-    with_stats(|buffer| statistics_object(&buffer.global))
-        .unwrap_or_else(|| JsValue::UNDEFINED.unchecked_into())
-}
-
-/// A file as GPX (UTF-8 bytes), `undefined` if it does not exist. The options say which data of the trackpoints
-/// to keep, and with `as_route` that the segments are written as routes (`rte`) instead of tracks:
-/// the anchors are the route points, and the trackpoints between them the points of their path.
-#[wasm_bindgen]
-#[allow(clippy::too_many_arguments)]
-pub fn export_file(
-    file_id: &str,
-    time: bool,
-    hr: bool,
-    cad: bool,
-    atemp: bool,
-    power: bool,
-    osm: bool,
-    as_route: bool,
-) -> Option<Vec<u8>> {
-    let id = parse_file_id(file_id)?;
-    let options = engine::ExportOptions {
-        time,
-        hr,
-        cad,
-        atemp,
-        power,
-        osm,
-        as_route,
-    };
-    with_engine(|e| e.export(&id, options)).flatten()
-}
-
-/// The data that some files have, so that the ones that none has are not offered when exporting
-/// them: a bit for the time (1), heart rate (2), cadence (4), temperature (8), power (16) and the
-/// OpenStreetMap data (32). `file_ids` are concatenated UUIDs.
-#[wasm_bindgen]
-pub fn exportable_data(file_ids: &[u8]) -> u8 {
-    let Some(ids) = self::file_ids(file_ids) else {
-        return 0;
-    };
-    let data = with_engine(|e| e.exportable_data(&ids)).unwrap_or(engine::ExportOptions::NONE);
-    [
-        data.time, data.hr, data.cad, data.atemp, data.power, data.osm,
-    ]
-    .iter()
-    .enumerate()
-    .fold(0, |bits, (i, on)| bits | (u8::from(*on) << i))
-}
-
-/// Global statistics of the trackpoints from `start` to `end` (both included) of the selection,
-/// as indexed by the statistics buffers. `undefined` when the range is not in the selection.
-#[wasm_bindgen]
-pub fn slice_statistics(start: usize, end: usize) -> GlobalStatistics {
-    with_stats(|buffer| buffer.slice(start, end))
-        .flatten()
-        .map_or(JsValue::UNDEFINED.unchecked_into(), |stats| {
-            statistics_object(&stats)
-        })
-}
-
-/// The current selection (ids are UUID strings).
-#[wasm_bindgen]
-pub fn selection() -> Selection {
-    with_engine(|e| selection_object(e.selection()))
-        .unwrap_or_default()
-        .unchecked_into()
-}
-
-/// All the data of a waypoint of a file, `undefined` if it does not exist.
-#[wasm_bindgen]
-pub fn waypoint(file_id: &str, waypoint_id: &str) -> WaypointDetails {
-    uuid::Uuid::parse_str(file_id)
-        .ok()
-        .zip(uuid::Uuid::parse_str(waypoint_id).ok())
-        .and_then(|(file_id, id)| {
-            with_engine(|e| {
-                e.waypoint(&FileId(file_id), &engine::WaypointId(id))
-                    .map(|wpt| {
-                        let object = Object::new();
-                        set(&object, "id", wpt.id.0.to_string());
-                        set(&object, "lng", wpt.coordinates.lng);
-                        set(&object, "lat", wpt.coordinates.lat);
-                        set(&object, "ele", wpt.ele);
-                        if let Some(time) = wpt.time {
-                            set(&object, "time", time as f64);
-                        }
-                        for (key, value) in [
-                            ("name", &wpt.name),
-                            ("desc", &wpt.desc),
-                            ("cmt", &wpt.cmt),
-                            ("sym", &wpt.sym),
-                        ] {
-                            if let Some(value) = value {
-                                set(&object, key, value.as_str());
-                            }
-                        }
-                        if !wpt.links.is_empty() {
-                            set(
-                                &object,
-                                "links",
-                                array(&wpt.links, |link| {
-                                    let link_object = Object::new();
-                                    set(&link_object, "href", link.href.as_str());
-                                    if let Some(text) = &link.text {
-                                        set(&link_object, "text", text.as_str());
-                                    }
-                                    link_object.into()
-                                }),
-                            );
-                        }
-                        JsValue::from(object)
-                    })
-            })
-            .flatten()
-        })
-        .unwrap_or(JsValue::UNDEFINED)
-        .unchecked_into()
-}
-
-/// A trackpoint of a segment of a file, `undefined` if it does not exist.
-#[wasm_bindgen]
-pub fn trackpoint(file_id: &str, segment_id: &str, index: usize) -> TrackpointDetails {
-    parse_file_id(file_id)
-        .zip(uuid::Uuid::parse_str(segment_id).ok())
-        .and_then(|(file_id, segment_id)| {
-            with_engine(|e| {
-                e.trackpoint(&file_id, &engine::TrackSegmentId(segment_id), index)
-                    .map(|pt| {
-                        let object = Object::new();
-                        set(&object, "lng", pt.coordinates.lng);
-                        set(&object, "lat", pt.coordinates.lat);
-                        set(&object, "ele", pt.ele);
-                        if let Some(time) = pt.time {
-                            set(&object, "time", time as f64);
-                        }
-                        JsValue::from(object)
-                    })
-            })
-            .flatten()
-        })
-        .unwrap_or(JsValue::UNDEFINED)
-        .unchecked_into()
-}
-
-/// What was copied or cut and is waiting to be pasted, `undefined` if nothing: the kind of the
-/// elements and their ids (UUID strings).
-#[wasm_bindgen]
-pub fn clipboard() -> Clipboard {
-    with_engine(|e| {
-        e.clipboard().map_or(JsValue::UNDEFINED, |clipboard| {
-            let object = Object::new();
-            let (kind, ids) = match clipboard.content.ids() {
-                engine::ClipboardIds::Files(ids) => ("files", uuids(ids, |id| id.0)),
-                engine::ClipboardIds::Tracks(ids) => ("tracks", uuids(ids, |id| id.0)),
-                engine::ClipboardIds::Segments(ids) => ("segments", uuids(ids, |id| id.0)),
-                engine::ClipboardIds::Waypoints(ids) => ("waypoints", uuids(ids, |id| id.0)),
-            };
-            set(&object, "type", kind);
-            set(&object, "ids", ids);
-            set(&object, "cut", clipboard.cut);
-            object.into()
-        })
-    })
-    .unwrap_or(JsValue::UNDEFINED)
-    .unchecked_into()
-}
diff --git a/gpx-rs/wasm/src/queries/statistics.rs b/gpx-rs/wasm/src/queries/statistics.rs
deleted file mode 100644
index 76a645dba..000000000
--- a/gpx-rs/wasm/src/queries/statistics.rs
+++ /dev/null
@@ -1,142 +0,0 @@
-//! The statistics of the selection, as typed arrays, and the categories they refer to.
-
-use gpx_engine as engine;
-use js_sys::{BigInt64Array, Float64Array, Uint8Array, Uint32Array};
-use wasm_bindgen::prelude::*;
-
-use crate::convert::*;
-use crate::session::*;
-use crate::ts::*;
-
-// Statistics buffers
-//
-// Each getter returns a copy of the buffer, as a new JS typed array.
-
-pub(crate) fn with_stats<T>(f: impl FnOnce(&engine::StatisticsBuffer) -> T) -> Option<T> {
-    ENGINE.with(|engine| engine.borrow().as_ref().map(|e| f(e.statistics())))
-}
-
-macro_rules! stats_getter {
-    ($name:ident, $array:ident) => {
-        #[wasm_bindgen]
-        pub fn $name() -> $array {
-            with_stats(|s| $array::from(&s.$name[..])).unwrap_or_else(|| $array::new_with_length(0))
-        }
-    };
-}
-
-stats_getter!(total_distance, Float64Array);
-stats_getter!(elevation_gain, Float64Array);
-stats_getter!(elevation_loss, Float64Array);
-stats_getter!(slope, Float64Array);
-stats_getter!(slope_segment_slope, Float64Array);
-stats_getter!(slope_segment_distance, Float64Array);
-stats_getter!(lng, Float64Array);
-stats_getter!(lat, Float64Array);
-stats_getter!(ele, Float64Array);
-
-// The optional values are `undefined` when no trackpoint of the selection has one, else they have
-// an entry per trackpoint, the missing ones being NaN (`NO_TIME` for the timestamps, 0 before the
-// first trackpoint that has them for the cumulative distances and durations).
-macro_rules! optional_stats_getter {
-    ($name:ident, $field:ident, $array:ident) => {
-        #[wasm_bindgen]
-        pub fn $name() -> Option<$array> {
-            with_stats(|s| s.$field.as_deref().map($array::from)).flatten()
-        }
-    };
-}
-
-optional_stats_getter!(moving_distance, moving_distance, Float64Array);
-// Durations since the start of the selection, in milliseconds.
-optional_stats_getter!(total_time, total_time, BigInt64Array);
-optional_stats_getter!(moving_time, moving_time, BigInt64Array);
-optional_stats_getter!(speed, speed, Float64Array);
-// Timestamps in milliseconds since the epoch (`NO_TIME`, the smallest i64, when missing).
-optional_stats_getter!(timestamps, time, BigInt64Array);
-
-/// Value of the timestamps of the trackpoints that have none.
-#[wasm_bindgen]
-pub fn no_time() -> i64 {
-    engine::NO_TIME
-}
-
-optional_stats_getter!(hr, hr, Float64Array);
-optional_stats_getter!(cad, cad, Float64Array);
-optional_stats_getter!(atemp, atemp, Float64Array);
-optional_stats_getter!(power, power, Float64Array);
-
-// Surface, highway, SAC scale and MTB scale of the trackpoints, as intervals of trackpoints that
-// have the same value: `<name>_starts` holds the index of the first trackpoint of each interval,
-// and `<name>_values` its value (0 when unknown, else 1 + the index in `surfaces()`,
-// `highways()`, `sac_scales()` or `mtb_scales()`). A value that is unknown for every trackpoint is
-// a single interval.
-macro_rules! intervals_getters {
-    ($starts:ident, $values:ident, $field:ident) => {
-        #[wasm_bindgen]
-        pub fn $starts() -> Uint32Array {
-            with_stats(|s| Uint32Array::from(&s.$field.starts[..]))
-                .unwrap_or_else(|| Uint32Array::new_with_length(0))
-        }
-
-        #[wasm_bindgen]
-        pub fn $values() -> Uint8Array {
-            with_stats(|s| Uint8Array::from(&s.$field.values[..]))
-                .unwrap_or_else(|| Uint8Array::new_with_length(0))
-        }
-    };
-}
-
-intervals_getters!(surface_starts, surface_values, surface);
-intervals_getters!(highway_starts, highway_values, highway);
-intervals_getters!(sac_scale_starts, sac_scale_values, sac_scale);
-intervals_getters!(mtb_scale_starts, mtb_scale_values, mtb_scale);
-
-/// The names of the surfaces, in the order of their codes (see `surface_values`). The list only grows:
-/// a name keeps its index.
-#[wasm_bindgen]
-pub fn surfaces() -> StringList {
-    with_engine(|e| array(e.categories().surface.names(), |name| name.as_str().into()))
-        .unwrap_or_default()
-        .unchecked_into()
-}
-
-/// The names of the highways, in the order of their codes (see `highway_values`).
-#[wasm_bindgen]
-pub fn highways() -> StringList {
-    with_engine(|e| array(e.categories().highway.names(), |name| name.as_str().into()))
-        .unwrap_or_default()
-        .unchecked_into()
-}
-
-/// The names of the SAC scales, in the order of their codes (see `sac_scale_values`).
-#[wasm_bindgen]
-pub fn sac_scales() -> StringList {
-    with_engine(|e| {
-        array(e.categories().sac_scale.names(), |name| {
-            name.as_str().into()
-        })
-    })
-    .unwrap_or_default()
-    .unchecked_into()
-}
-
-/// The names of the MTB scales, in the order of their codes (see `mtb_scale_values`).
-#[wasm_bindgen]
-pub fn mtb_scales() -> StringList {
-    with_engine(|e| {
-        array(e.categories().mtb_scale.names(), |name| {
-            name.as_str().into()
-        })
-    })
-    .unwrap_or_default()
-    .unchecked_into()
-}
-
-/// For each trackpoint of the selection (numbered as in the statistics), the highest tolerance
-/// (m) of `reduce` that keeps it: infinite for the ends of the segments.
-#[wasm_bindgen]
-pub fn reduction_distances() -> Float64Array {
-    with_engine(|e| Float64Array::from(&e.reduction_distances()[..]))
-        .unwrap_or_else(|| Float64Array::new_with_length(0))
-}
diff --git a/tauri/Cargo.toml b/tauri/Cargo.toml
index 39013bcc2..e8395fa8d 100644
--- a/tauri/Cargo.toml
+++ b/tauri/Cargo.toml
@@ -19,6 +19,5 @@ tauri = { version = "2", features = [] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 uuid = { version = "1", features = ["serde"] }
-gpx-engine = { path = "../gpx-rs/engine" }
+gpx-engine = { path = "../gpx-rs" }
 
-[workspace]
diff --git a/tauri/src/bytes.rs b/tauri/src/bytes.rs
new file mode 100644
index 000000000..0bd9d45e6
--- /dev/null
+++ b/tauri/src/bytes.rs
@@ -0,0 +1,40 @@
+//! Typed arrays and files cross as raw bytes (little-endian), not as JSON.
+
+pub type Bytes = tauri::ipc::Response;
+
+pub fn f64s(values: &[f64]) -> Bytes {
+    Bytes::new(
+        values
+            .iter()
+            .flat_map(|v| v.to_le_bytes())
+            .collect::<Vec<u8>>(),
+    )
+}
+
+pub fn u32s(values: &[u32]) -> Bytes {
+    Bytes::new(
+        values
+            .iter()
+            .flat_map(|v| v.to_le_bytes())
+            .collect::<Vec<u8>>(),
+    )
+}
+
+pub fn u8s(values: &[u8]) -> Bytes {
+    Bytes::new(values.to_vec())
+}
+
+/// An array that can be absent: the first byte tells whether it is there, the array follows.
+pub fn optional(array: Option<Vec<u8>>) -> Bytes {
+    let mut bytes = vec![u8::from(array.is_some())];
+    bytes.extend(array.unwrap_or_default());
+    Bytes::new(bytes)
+}
+
+pub fn f64_bytes(values: &[f64]) -> Vec<u8> {
+    values.iter().flat_map(|v| v.to_le_bytes()).collect()
+}
+
+pub fn i64_bytes(values: &[i64]) -> Vec<u8> {
+    values.iter().flat_map(|v| v.to_le_bytes()).collect()
+}
diff --git a/tauri/src/commands/edit.rs b/tauri/src/commands/edit.rs
index c02397403..dd30604fd 100644
--- a/tauri/src/commands/edit.rs
+++ b/tauri/src/commands/edit.rs
@@ -1,22 +1,15 @@
 //! Editing the metadata, the style, the structure and the waypoints of the files, and the tools:
 //! reversing, cropping, reducing, timestamps, merging, cleaning...
 
-use gpx_engine::{self as engine, Command, LngLat, LngLatBounds};
+use gpx_engine::{api, CleanType, MergeType, SplitType};
 use tauri::State;
 use uuid::Uuid;
 
-use crate::dto::*;
-use crate::state::{act, edit, AppState};
+use crate::state::AppState;
 
 #[tauri::command(async)]
-pub fn metadata(state: State<AppState>, name: String, desc: String) -> Outcome {
-    edit!(
-        state,
-        Command::Metadata(engine::Metadata {
-            name: &name,
-            desc: &desc,
-        })
-    )
+pub fn metadata(state: State<AppState>, name: String, desc: String) -> api::Outcome {
+    state.run(move |e| api::metadata(e, &name, &desc))
 }
 
 #[tauri::command(async)]
@@ -25,25 +18,18 @@ pub fn style(
     color: Option<String>,
     opacity: Option<f64>,
     width: Option<f64>,
-) -> Outcome {
-    edit!(
-        state,
-        Command::Style(engine::Style {
-            color: color.as_deref(),
-            opacity,
-            width,
-        })
-    )
+) -> api::Outcome {
+    state.run(move |e| api::style(e, color.as_deref(), opacity, width))
 }
 
 #[tauri::command(async)]
-pub fn new_track(state: State<AppState>) -> Outcome {
-    edit!(state, Command::NewTrack(engine::NewTrack))
+pub fn new_track(state: State<AppState>) -> api::Outcome {
+    state.run(api::new_track)
 }
 
 #[tauri::command(async)]
-pub fn new_track_segment(state: State<AppState>) -> Outcome {
-    edit!(state, Command::NewTrackSegment(engine::NewTrackSegment))
+pub fn new_track_segment(state: State<AppState>) -> api::Outcome {
+    state.run(api::new_track_segment)
 }
 
 // Waypoints
@@ -59,19 +45,8 @@ pub fn new_waypoint(
     desc: String,
     icon: String,
     link: String,
-) -> Outcome {
-    edit!(
-        state,
-        Command::NewWaypoint(engine::NewWaypoint {
-            lng,
-            lat,
-            ele,
-            name: &name,
-            desc: &desc,
-            icon: &icon,
-            link: &link,
-        })
-    )
+) -> api::Outcome {
+    state.run(move |e| api::new_waypoint(e, lng, lat, ele, &name, &desc, &icon, &link))
 }
 
 #[tauri::command(async)]
@@ -82,28 +57,13 @@ pub fn move_waypoint(
     lng: f64,
     lat: f64,
     ele: f64,
-) -> Outcome {
-    edit!(
-        state,
-        Command::MoveWaypoint(engine::MoveWaypoint {
-            file_id: engine::FileId(file_id),
-            waypoint_id: engine::WaypointId(waypoint_id),
-            lng,
-            lat,
-            ele,
-        })
-    )
+) -> api::Outcome {
+    state.run(move |e| api::move_waypoint(e, file_id, waypoint_id, lng, lat, ele))
 }
 
 #[tauri::command(async)]
-pub fn delete_waypoint(state: State<AppState>, file_id: Uuid, waypoint_id: Uuid) -> Outcome {
-    edit!(
-        state,
-        Command::DeleteWaypoint(engine::DeleteWaypoint {
-            file_id: engine::FileId(file_id),
-            waypoint_id: engine::WaypointId(waypoint_id),
-        })
-    )
+pub fn delete_waypoint(state: State<AppState>, file_id: Uuid, waypoint_id: Uuid) -> api::Outcome {
+    state.run(move |e| api::delete_waypoint(e, file_id, waypoint_id))
 }
 
 #[tauri::command(async)]
@@ -119,46 +79,43 @@ pub fn update_waypoint(
     desc: String,
     icon: String,
     link: String,
-) -> Outcome {
-    edit!(
-        state,
-        Command::EditWaypoint(engine::EditWaypoint {
-            file_id: engine::FileId(file_id),
-            waypoint_id: engine::WaypointId(waypoint_id),
+) -> api::Outcome {
+    state.run(move |e| {
+        api::update_waypoint(
+            e,
+            file_id,
+            waypoint_id,
             lng,
             lat,
             ele,
-            name: &name,
-            desc: &desc,
-            icon: &icon,
-            link: &link,
-        })
-    )
+            &name,
+            &desc,
+            &icon,
+            &link,
+        )
+    })
 }
 
 // Tools
 
 #[tauri::command(async)]
-pub fn reverse(state: State<AppState>) -> Outcome {
-    edit!(state, Command::Reverse(engine::Reverse))
+pub fn reverse(state: State<AppState>) -> api::Outcome {
+    state.run(api::reverse)
 }
 
 #[tauri::command(async)]
-pub fn round_trip(state: State<AppState>) -> Outcome {
-    edit!(state, Command::RoundTrip(engine::RoundTrip))
+pub fn round_trip(state: State<AppState>) -> api::Outcome {
+    state.run(api::round_trip)
 }
 
 #[tauri::command(async)]
-pub fn crop(state: State<AppState>, start: u32, end: u32) -> Outcome {
-    if start > end {
-        return Outcome::failed(format!("the range {start}..{end} is reversed"));
-    }
-    edit!(state, Command::Crop(engine::Crop { start, end }))
+pub fn crop(state: State<AppState>, start: u32, end: u32) -> api::Outcome {
+    state.run(move |e| api::crop(e, start, end))
 }
 
 #[tauri::command(async)]
-pub fn reduce(state: State<AppState>, tolerance: f64) -> Outcome {
-    edit!(state, Command::Reduce(engine::Reduce { tolerance }))
+pub fn reduce(state: State<AppState>, tolerance: f64) -> api::Outcome {
+    state.run(move |e| api::reduce(e, tolerance))
 }
 
 #[tauri::command(async)]
@@ -167,14 +124,8 @@ pub fn change_timestamps(
     start_time: f64,
     speed: f64,
     ratio: f64,
-) -> Outcome {
-    edit!(
-        state,
-        Command::Time(engine::Time {
-            start_time: start_time as i64,
-            kind: engine::TimeKind::Change { speed, ratio },
-        })
-    )
+) -> api::Outcome {
+    state.run(move |e| api::change_timestamps(e, start_time, speed, ratio))
 }
 
 #[tauri::command(async)]
@@ -182,35 +133,23 @@ pub fn create_artificial_timestamps(
     state: State<AppState>,
     start_time: f64,
     total_time: f64,
-) -> Outcome {
-    edit!(
-        state,
-        Command::Time(engine::Time {
-            start_time: start_time as i64,
-            kind: engine::TimeKind::Artificial { total_time },
-        })
-    )
+) -> api::Outcome {
+    state.run(move |e| api::create_artificial_timestamps(e, start_time, total_time))
 }
 
 #[tauri::command(async)]
-pub fn merge(state: State<AppState>, merge_type: MergeType, remove_gaps: bool) -> Outcome {
-    edit!(
-        state,
-        Command::Merge(engine::Merge {
-            type_: merge_type.into(),
-            remove_gaps,
-        })
-    )
+pub fn merge(state: State<AppState>, merge_type: MergeType, remove_gaps: bool) -> api::Outcome {
+    state.run(move |e| api::merge(e, merge_type, remove_gaps))
 }
 
 #[tauri::command(async)]
-pub fn extract(state: State<AppState>) -> Outcome {
-    edit!(state, Command::Extract(engine::Extract))
+pub fn extract(state: State<AppState>) -> api::Outcome {
+    state.run(api::extract)
 }
 
 #[tauri::command(async)]
-pub fn elevation(state: State<AppState>, ele: Vec<f64>) -> Outcome {
-    edit!(state, Command::Elevation(engine::Elevation { ele: &ele }))
+pub fn elevation(state: State<AppState>, ele: Vec<f64>) -> api::Outcome {
+    state.run(move |e| api::elevation(e, &ele))
 }
 
 #[tauri::command(async)]
@@ -224,23 +163,56 @@ pub fn clean(
     clean_type: CleanType,
     trkpt: bool,
     wpt: bool,
-) -> Outcome {
-    edit!(
-        state,
-        Command::Clean(engine::Clean {
-            bounds: LngLatBounds {
-                sw: LngLat {
-                    lng: west,
-                    lat: south,
-                },
-                ne: LngLat {
-                    lng: east,
-                    lat: north,
-                },
-            },
-            type_: clean_type.into(),
-            trkpt,
-            wpt,
-        })
-    )
+) -> api::Outcome {
+    state.run(move |e| api::clean(e, west, south, east, north, clean_type, trkpt, wpt))
+}
+
+// Routing
+
+#[tauri::command(async)]
+#[allow(clippy::too_many_arguments)]
+pub fn route(
+    state: State<AppState>,
+    revision: u32,
+    start: u32,
+    end: u32,
+    lng: Vec<f64>,
+    lat: Vec<f64>,
+    ele: Vec<f64>,
+    attributes: api::RouteAttributes,
+    anchors: Vec<u32>,
+) -> api::Outcome {
+    state.run(move |e| {
+        api::route(
+            e,
+            revision,
+            start,
+            end,
+            &lng,
+            &lat,
+            &ele,
+            &attributes,
+            &anchors,
+        )
+    })
+}
+
+#[tauri::command(async)]
+pub fn insert_anchor(state: State<AppState>, revision: u32, lng: f64, lat: f64) -> api::Outcome {
+    state.run(move |e| api::insert_anchor(e, revision, lng, lat))
+}
+
+#[tauri::command(async)]
+pub fn change_loop_start(state: State<AppState>, revision: u32, index: u32) -> api::Outcome {
+    state.run(move |e| api::change_loop_start(e, revision, index))
+}
+
+#[tauri::command(async)]
+pub fn split(
+    state: State<AppState>,
+    revision: u32,
+    at: u32,
+    split_type: SplitType,
+) -> api::Outcome {
+    state.run(move |e| api::split(e, revision, at, split_type))
 }
diff --git a/tauri/src/commands/files.rs b/tauri/src/commands/files.rs
index b35c96755..01572f8f9 100644
--- a/tauri/src/commands/files.rs
+++ b/tauri/src/commands/files.rs
@@ -1,12 +1,11 @@
 //! Creating, loading, deleting, moving, copying and pasting files and their elements, and undoing.
 
-use gpx_engine::{self as engine, Action, Command};
+use gpx_engine::api;
 use tauri::ipc::{InvokeBody, Request};
 use tauri::State;
 use uuid::Uuid;
 
-use crate::dto::*;
-use crate::state::{act, edit, AppState};
+use crate::state::AppState;
 
 #[tauri::command(async)]
 pub fn new_file(
@@ -15,73 +14,35 @@ pub fn new_file(
     lng: Option<f64>,
     lat: Option<f64>,
     ele: Option<f64>,
-) -> Outcome {
-    let trackpoint = lng.zip(lat).map(|(lng, lat)| engine::NewTrackpoint {
-        lng,
-        lat,
-        ele: ele.unwrap_or_default(),
-    });
-    edit!(
-        state,
-        Command::New(engine::New {
-            name: &name,
-            trackpoint,
-        })
-    )
+) -> api::Outcome {
+    state.run(move |e| api::new_file(e, &name, lng, lat, ele))
 }
 
-/// The files are in the body, one after the other, the headers `lengths` and `names` (JSON) telling
-/// the number of bytes and the name of each one.
+/// The files are in the body, one after the other, the headers `lengths` and `names` (JSON,
+/// percent-encoded) telling the number of bytes and the name of each one.
 #[tauri::command(async)]
-pub fn load_files(state: State<AppState>, request: Request<'_>) -> Outcome {
+pub fn load_files(state: State<AppState>, request: Request<'_>) -> api::Outcome {
     let InvokeBody::Raw(data) = request.body() else {
-        return Outcome::failed("the files are missing");
+        return api::Outcome::failed("the files are missing");
     };
     let header = |key: &str| {
         request
             .headers()
             .get(key)
             .and_then(|value| value.to_str().ok())
-            .and_then(urlencoding_decode)
+            .and_then(percent_decode)
     };
     let (Some(lengths), Some(names)) = (
         header("lengths").and_then(|json| serde_json::from_str::<Vec<usize>>(&json).ok()),
         header("names").and_then(|json| serde_json::from_str::<Vec<String>>(&json).ok()),
     ) else {
-        return Outcome::failed("the lengths or the names of the files are not valid");
+        return api::Outcome::failed("the lengths or the names of the files are not valid");
     };
-    if lengths.len() != names.len() {
-        return Outcome::failed(format!(
-            "{} lengths for {} names",
-            lengths.len(),
-            names.len()
-        ));
-    }
-    let (data, mut offset) = (data.clone(), 0);
-    let mut ranges = Vec::with_capacity(names.len());
-    for (length, name) in lengths.iter().zip(&names) {
-        let end = offset + length;
-        if end > data.len() {
-            return Outcome::failed(format!("the data of {name} is shorter than its length"));
-        }
-        ranges.push(offset..end);
-        offset = end;
-    }
-    edit!(state, {
-        let files = ranges
-            .into_iter()
-            .zip(&names)
-            .map(|(range, name)| engine::Load {
-                data: &data[range],
-                name,
-            })
-            .collect();
-        Command::LoadFiles(engine::LoadFiles { files })
-    })
+    let data = data.clone();
+    state.run(move |e| api::load_files(e, &data, &lengths, &names))
 }
 
-/// Headers are ASCII: the frontend percent-encodes the JSON.
-fn urlencoding_decode(value: &str) -> Option<String> {
+fn percent_decode(value: &str) -> Option<String> {
     let bytes = value.as_bytes();
     let mut decoded = Vec::with_capacity(bytes.len());
     let mut i = 0;
@@ -99,63 +60,55 @@ fn urlencoding_decode(value: &str) -> Option<String> {
 }
 
 #[tauri::command(async)]
-pub fn duplicate(state: State<AppState>) -> Outcome {
-    edit!(state, Command::Duplicate(engine::Duplicate))
+pub fn duplicate(state: State<AppState>) -> api::Outcome {
+    state.run(api::duplicate)
 }
 
 #[tauri::command(async)]
-pub fn delete(state: State<AppState>, whole_files: bool) -> Outcome {
-    edit!(state, Command::Delete(engine::Delete { whole_files }))
+pub fn delete(state: State<AppState>, whole_files: bool) -> api::Outcome {
+    state.run(move |e| api::delete(e, whole_files))
 }
 
 #[tauri::command(async)]
-pub fn delete_all(state: State<AppState>) -> Outcome {
-    edit!(state, Command::DeleteAll(engine::DeleteAll))
+pub fn delete_all(state: State<AppState>) -> api::Outcome {
+    state.run(api::delete_all)
 }
 
 #[tauri::command(async)]
-pub fn reorder(state: State<AppState>, file_ids: Vec<Uuid>, index: usize) -> Outcome {
-    act!(
-        state,
-        Action::Reorder {
-            file_ids: file_ids.into_iter().map(engine::FileId).collect(),
-            index,
-        }
-    )
+pub fn reorder(state: State<AppState>, file_ids: Vec<Uuid>, index: usize) -> api::Outcome {
+    state.run(move |e| api::reorder(e, &file_ids, index))
 }
 
 #[tauri::command(async)]
-pub fn copy(state: State<AppState>) -> Outcome {
-    act!(state, Action::Copy)
+pub fn copy(state: State<AppState>) -> api::Outcome {
+    state.run(api::copy)
 }
 
 #[tauri::command(async)]
-pub fn cut(state: State<AppState>) -> Outcome {
-    act!(state, Action::Cut)
+pub fn cut(state: State<AppState>) -> api::Outcome {
+    state.run(api::cut)
 }
 
 #[tauri::command(async)]
-pub fn paste(state: State<AppState>) -> Outcome {
-    edit!(state, Command::Paste(engine::Paste))
+pub fn paste(state: State<AppState>) -> api::Outcome {
+    state.run(api::paste)
 }
 
 #[tauri::command(async)]
-pub fn move_elements(state: State<AppState>, what: Selection, to: MoveTarget) -> Outcome {
-    edit!(
-        state,
-        Command::Move(engine::Move {
-            what: what.into(),
-            to: to.into(),
-        })
-    )
+pub fn move_elements(
+    state: State<AppState>,
+    what: api::Selection,
+    to: api::MoveTarget,
+) -> api::Outcome {
+    state.run(move |e| api::move_elements(e, what, to))
 }
 
 #[tauri::command(async)]
-pub fn undo(state: State<AppState>) -> Outcome {
-    act!(state, Action::Undo)
+pub fn undo(state: State<AppState>) -> api::Outcome {
+    state.run(api::undo)
 }
 
 #[tauri::command(async)]
-pub fn redo(state: State<AppState>) -> Outcome {
-    act!(state, Action::Redo)
+pub fn redo(state: State<AppState>) -> api::Outcome {
+    state.run(api::redo)
 }
diff --git a/tauri/src/commands/mod.rs b/tauri/src/commands/mod.rs
index 9e4936727..ad227c01b 100644
--- a/tauri/src/commands/mod.rs
+++ b/tauri/src/commands/mod.rs
@@ -8,7 +8,6 @@
 pub mod edit;
 pub mod files;
 pub mod queries;
-pub mod routing;
 pub mod selection;
 pub mod statistics;
 pub mod storage;
diff --git a/tauri/src/commands/queries.rs b/tauri/src/commands/queries.rs
index 93d246e48..f58922583 100644
--- a/tauri/src/commands/queries.rs
+++ b/tauri/src/commands/queries.rs
@@ -1,54 +1,51 @@
 //! The files, their structure and statistics, the selection, the clipboard, and the coordinates of
 //! the trackpoints and waypoints (flat `[lng, lat, ...]` little-endian `f64` arrays).
 
-use gpx_engine::{self as engine, FileId};
+use gpx_engine::{api, ExportOptions};
 use tauri::State;
 use uuid::Uuid;
 
-use crate::dto::*;
+use crate::bytes::*;
 use crate::state::AppState;
 
 #[tauri::command(async)]
 pub fn file_order(state: State<AppState>) -> Vec<String> {
-    state.read(|e| ids(e.order()))
+    state.read(api::file_order)
 }
 
 #[tauri::command(async)]
-pub fn file_structure(state: State<AppState>, file_id: Uuid) -> Option<FileStructure> {
-    state.read(move |e| e.file_structure(&FileId(file_id)).map(FileStructure::new))
+pub fn file_structure(state: State<AppState>, file_id: Uuid) -> Option<api::FileStructure> {
+    state.read(move |e| api::file_structure(e, file_id))
 }
 
 #[tauri::command(async)]
-pub fn file_statistics(state: State<AppState>, file_id: Uuid) -> Option<GlobalStatistics> {
-    state.read(move |e| {
-        e.file_statistics(&FileId(file_id))
-            .map(|s| GlobalStatistics::new(&s))
-    })
+pub fn file_statistics(state: State<AppState>, file_id: Uuid) -> Option<api::GlobalStatistics> {
+    state.read(move |e| api::file_statistics(e, file_id))
 }
 
 #[tauri::command(async)]
-pub fn selection(state: State<AppState>) -> Selection {
-    state.read(|e| e.selection().into())
+pub fn selection(state: State<AppState>) -> api::Selection {
+    state.read(api::selection)
 }
 
 #[tauri::command(async)]
-pub fn clipboard(state: State<AppState>) -> Option<Clipboard> {
-    state.read(|e| e.clipboard().map(Clipboard::new))
+pub fn clipboard(state: State<AppState>) -> Option<api::Clipboard> {
+    state.read(api::clipboard)
 }
 
 #[tauri::command(async)]
 pub fn can_undo(state: State<AppState>) -> bool {
-    state.read(|e| e.can_undo())
+    state.read(api::can_undo)
 }
 
 #[tauri::command(async)]
 pub fn can_redo(state: State<AppState>) -> bool {
-    state.read(|e| e.can_redo())
+    state.read(api::can_redo)
 }
 
 #[tauri::command(async)]
 pub fn can_paste(state: State<AppState>) -> bool {
-    state.read(|e| e.can_paste())
+    state.read(api::can_paste)
 }
 
 #[tauri::command(async)]
@@ -56,11 +53,8 @@ pub fn waypoint(
     state: State<AppState>,
     file_id: Uuid,
     waypoint_id: Uuid,
-) -> Option<WaypointDetails> {
-    state.read(move |e| {
-        e.waypoint(&FileId(file_id), &engine::WaypointId(waypoint_id))
-            .map(WaypointDetails::new)
-    })
+) -> Option<api::WaypointDetails> {
+    state.read(move |e| api::waypoint(e, file_id, waypoint_id))
 }
 
 #[tauri::command(async)]
@@ -69,11 +63,8 @@ pub fn trackpoint(
     file_id: Uuid,
     segment_id: Uuid,
     index: usize,
-) -> Option<TrackpointDetails> {
-    state.read(move |e| {
-        e.trackpoint(&FileId(file_id), &engine::TrackSegmentId(segment_id), index)
-            .map(TrackpointDetails::new)
-    })
+) -> Option<api::TrackpointDetails> {
+    state.read(move |e| api::trackpoint(e, file_id, segment_id, index))
 }
 
 /// A file as GPX (UTF-8 bytes), the first byte telling whether the file exists.
@@ -90,7 +81,7 @@ pub fn export_file(
     osm: bool,
     as_route: bool,
 ) -> Bytes {
-    let options = engine::ExportOptions {
+    let options = ExportOptions {
         time,
         hr,
         cad,
@@ -99,38 +90,25 @@ pub fn export_file(
         osm,
         as_route,
     };
-    optional(state.read(move |e| e.export(&FileId(file_id), options)))
+    optional(state.read(move |e| api::export_file(e, file_id, options)))
 }
 
-/// The data that some files have: a bit for the time (1), heart rate (2), cadence (4), temperature
-/// (8), power (16) and the OpenStreetMap data (32).
 #[tauri::command(async)]
 pub fn exportable_data(state: State<AppState>, file_ids: Vec<Uuid>) -> u8 {
-    state.read(move |e| {
-        let ids: Vec<FileId> = file_ids.into_iter().map(FileId).collect();
-        let data = e.exportable_data(&ids);
-        [
-            data.time, data.hr, data.cad, data.atemp, data.power, data.osm,
-        ]
-        .iter()
-        .enumerate()
-        .fold(0, |bits, (i, on)| bits | (u8::from(*on) << i))
-    })
+    state.read(move |e| api::exportable_data(e, &file_ids))
 }
 
 #[tauri::command(async)]
 pub fn reduction_distances(state: State<AppState>) -> Bytes {
-    Bytes::new(state.read(|e| f64s(&e.reduction_distances())))
+    f64s(&state.read(api::reduction_distances))
 }
 
 #[tauri::command(async)]
 pub fn segment_coordinates(state: State<AppState>, segment_id: Uuid) -> Bytes {
-    Bytes::new(
-        state.read(move |e| f64s(e.segment_coordinates(&engine::TrackSegmentId(segment_id)))),
-    )
+    f64s(&state.read(move |e| api::segment_coordinates(e, segment_id).to_vec()))
 }
 
 #[tauri::command(async)]
 pub fn waypoint_coordinates(state: State<AppState>, file_id: Uuid) -> Bytes {
-    Bytes::new(state.read(move |e| f64s(e.waypoint_coordinates(&FileId(file_id)))))
+    f64s(&state.read(move |e| api::waypoint_coordinates(e, file_id).to_vec()))
 }
diff --git a/tauri/src/commands/routing.rs b/tauri/src/commands/routing.rs
deleted file mode 100644
index 56fd9770f..000000000
--- a/tauri/src/commands/routing.rs
+++ /dev/null
@@ -1,73 +0,0 @@
-//! The commands that refer to trackpoints by their index in the routing buffers, which only mean
-//! something for the `revision` they were read with: the commands do nothing if the selection is
-//! not the one of that revision anymore.
-
-use gpx_engine::{self as engine, Command};
-use tauri::State;
-
-use crate::dto::*;
-use crate::state::{edit_at, AppState};
-
-#[tauri::command(async)]
-#[allow(clippy::too_many_arguments)]
-pub fn route(
-    state: State<AppState>,
-    revision: u32,
-    start: u32,
-    end: u32,
-    lng: Vec<f64>,
-    lat: Vec<f64>,
-    ele: Vec<f64>,
-    attributes: RouteAttributes,
-    anchors: Vec<u32>,
-) -> Outcome {
-    if lng.len() != lat.len() || lat.len() != ele.len() {
-        return Outcome::failed("lng, lat and ele differ in length");
-    }
-    edit_at!(
-        state,
-        revision,
-        Command::Route(engine::Route {
-            start,
-            end,
-            lng: &lng,
-            lat: &lat,
-            ele: &ele,
-            surface: attributes.surface.view(),
-            highway: attributes.highway.view(),
-            sac_scale: attributes.sac_scale.view(),
-            mtb_scale: attributes.mtb_scale.view(),
-            anchors: &anchors,
-        })
-    )
-}
-
-#[tauri::command(async)]
-pub fn insert_anchor(state: State<AppState>, revision: u32, lng: f64, lat: f64) -> Outcome {
-    edit_at!(
-        state,
-        revision,
-        Command::InsertAnchor(engine::InsertAnchor { lng, lat })
-    )
-}
-
-#[tauri::command(async)]
-pub fn change_loop_start(state: State<AppState>, revision: u32, index: u32) -> Outcome {
-    edit_at!(
-        state,
-        revision,
-        Command::ChangeLoopStart(engine::ChangeLoopStart { index })
-    )
-}
-
-#[tauri::command(async)]
-pub fn split(state: State<AppState>, revision: u32, at: u32, split_type: SplitType) -> Outcome {
-    edit_at!(
-        state,
-        revision,
-        Command::Split(engine::Split {
-            at,
-            split_type: split_type.into(),
-        })
-    )
-}
diff --git a/tauri/src/commands/selection.rs b/tauri/src/commands/selection.rs
index 6f7658952..8555e6dd8 100644
--- a/tauri/src/commands/selection.rs
+++ b/tauri/src/commands/selection.rs
@@ -1,49 +1,24 @@
 //! Changing what is selected.
 
-use gpx_engine::{self as engine, Action};
+use gpx_engine::{api, SelectMode};
 use tauri::State;
 use uuid::Uuid;
 
-use crate::dto::*;
-use crate::state::{act, AppState};
+use crate::state::AppState;
 
-fn select_elements(
-    state: &AppState,
-    selection: Option<engine::Selection>,
-    mode: SelectMode,
-) -> Outcome {
-    match selection {
-        Some(selection) => act!(
-            state,
-            Action::Select {
-                selection,
-                mode: mode.into(),
-            }
-        ),
-        None => Outcome::failed("the ids are not UUIDs"),
-    }
-}
-
-fn to_file_ids(ids: Vec<Uuid>) -> Vec<engine::FileId> {
-    ids.into_iter().map(engine::FileId).collect()
+#[tauri::command(async)]
+pub fn select(state: State<AppState>, file_ids: Vec<Uuid>, mode: SelectMode) -> api::Outcome {
+    state.run(move |e| api::select(e, &file_ids, mode))
 }
 
 #[tauri::command(async)]
-pub fn select(state: State<AppState>, file_ids: Vec<Uuid>, mode: SelectMode) -> Outcome {
-    let selection = engine::Selection::File {
-        file_ids: to_file_ids(file_ids).into_iter().collect(),
-    };
-    select_elements(&state, Some(selection), mode)
+pub fn select_all(state: State<AppState>) -> api::Outcome {
+    state.run(api::select_all)
 }
 
 #[tauri::command(async)]
-pub fn select_all(state: State<AppState>) -> Outcome {
-    act!(state, Action::SelectAll)
-}
-
-#[tauri::command(async)]
-pub fn arrow_select(state: State<AppState>, down: bool, add: bool) -> Outcome {
-    act!(state, Action::ArrowSelect { down, add })
+pub fn arrow_select(state: State<AppState>, down: bool, add: bool) -> api::Outcome {
+    state.run(move |e| api::arrow_select(e, down, add))
 }
 
 #[tauri::command(async)]
@@ -52,12 +27,8 @@ pub fn select_tracks(
     file_id: Uuid,
     track_ids: Vec<Uuid>,
     mode: SelectMode,
-) -> Outcome {
-    let selection = engine::Selection::Track {
-        file_id: engine::FileId(file_id),
-        trk_ids: track_ids.into_iter().map(engine::TrackId).collect(),
-    };
-    select_elements(&state, Some(selection), mode)
+) -> api::Outcome {
+    state.run(move |e| api::select_tracks(e, file_id, &track_ids, mode))
 }
 
 #[tauri::command(async)]
@@ -67,24 +38,17 @@ pub fn select_segments(
     track_id: Uuid,
     segment_ids: Vec<Uuid>,
     mode: SelectMode,
-) -> Outcome {
-    let selection = engine::Selection::TrackSegment {
-        file_id: engine::FileId(file_id),
-        trk_id: engine::TrackId(track_id),
-        trkseg_ids: segment_ids
-            .into_iter()
-            .map(engine::TrackSegmentId)
-            .collect(),
-    };
-    select_elements(&state, Some(selection), mode)
+) -> api::Outcome {
+    state.run(move |e| api::select_segments(e, file_id, track_id, &segment_ids, mode))
 }
 
 #[tauri::command(async)]
-pub fn select_waypoint_group(state: State<AppState>, file_id: Uuid, mode: SelectMode) -> Outcome {
-    let selection = engine::Selection::Waypoints {
-        file_id: engine::FileId(file_id),
-    };
-    select_elements(&state, Some(selection), mode)
+pub fn select_waypoint_group(
+    state: State<AppState>,
+    file_id: Uuid,
+    mode: SelectMode,
+) -> api::Outcome {
+    state.run(move |e| api::select_waypoint_group(e, file_id, mode))
 }
 
 #[tauri::command(async)]
@@ -93,10 +57,6 @@ pub fn select_waypoints(
     file_id: Uuid,
     waypoint_ids: Vec<Uuid>,
     mode: SelectMode,
-) -> Outcome {
-    let selection = engine::Selection::Waypoint {
-        file_id: engine::FileId(file_id),
-        wpt_ids: waypoint_ids.into_iter().map(engine::WaypointId).collect(),
-    };
-    select_elements(&state, Some(selection), mode)
+) -> api::Outcome {
+    state.run(move |e| api::select_waypoints(e, file_id, &waypoint_ids, mode))
 }
diff --git a/tauri/src/commands/statistics.rs b/tauri/src/commands/statistics.rs
index f5af50774..a20f5991e 100644
--- a/tauri/src/commands/statistics.rs
+++ b/tauri/src/commands/statistics.rs
@@ -2,16 +2,17 @@
 //! (one per call, copies of the buffers of the engine). Optional ones start with a byte telling
 //! whether they are there.
 
+use gpx_engine::api;
 use tauri::State;
 
-use crate::dto::*;
+use crate::bytes::*;
 use crate::state::AppState;
 
 macro_rules! f64_getters {
     ($($name:ident),*) => {$(
         #[tauri::command(async)]
         pub fn $name(state: State<AppState>) -> Bytes {
-            Bytes::new(state.read(|e| f64s(&e.statistics().$name)))
+            f64s(&state.read(|e| api::$name(e).to_vec()))
         }
     )*};
 }
@@ -30,7 +31,7 @@ macro_rules! optional_f64_getters {
     ($($name:ident),*) => {$(
         #[tauri::command(async)]
         pub fn $name(state: State<AppState>) -> Bytes {
-            optional(state.read(|e| e.statistics().$name.as_deref().map(f64s)))
+            optional(state.read(|e| api::$name(e).map(f64_bytes)))
         }
     )*};
 }
@@ -40,12 +41,12 @@ optional_f64_getters!(speed, hr, cad, atemp, power);
 /// Timestamps in milliseconds since the epoch (`NO_TIME` when missing), as `i64`.
 #[tauri::command(async)]
 pub fn timestamps(state: State<AppState>) -> Bytes {
-    optional(state.read(|e| e.statistics().time.as_deref().map(i64s)))
+    optional(state.read(|e| api::timestamps(e).map(i64_bytes)))
 }
 
 #[tauri::command(async)]
-pub fn selection_statistics(state: State<AppState>) -> GlobalStatistics {
-    state.read(|e| GlobalStatistics::new(&e.statistics().global))
+pub fn selection_statistics(state: State<AppState>) -> api::GlobalStatistics {
+    state.read(api::selection_statistics)
 }
 
 #[tauri::command(async)]
@@ -53,83 +54,55 @@ pub fn slice_statistics(
     state: State<AppState>,
     start: usize,
     end: usize,
-) -> Option<GlobalStatistics> {
-    state.read(move |e| {
-        e.statistics()
-            .slice(start, end)
-            .map(|s| GlobalStatistics::new(&s))
-    })
+) -> Option<api::GlobalStatistics> {
+    state.read(move |e| api::slice_statistics(e, start, end))
 }
 
-macro_rules! intervals_getters {
-    ($starts:ident, $values:ident, $field:ident) => {
+macro_rules! category_getters {
+    ($starts:ident, $values:ident, $names:ident) => {
         #[tauri::command(async)]
         pub fn $starts(state: State<AppState>) -> Bytes {
-            Bytes::new(state.read(|e| u32s(&e.statistics().$field.starts)))
+            u32s(&state.read(|e| api::$starts(e).to_vec()))
         }
 
         #[tauri::command(async)]
         pub fn $values(state: State<AppState>) -> Bytes {
-            Bytes::new(state.read(|e| e.statistics().$field.values.clone()))
+            u8s(&state.read(|e| api::$values(e).to_vec()))
+        }
+
+        #[tauri::command(async)]
+        pub fn $names(state: State<AppState>) -> Vec<String> {
+            state.read(|e| api::$names(e).to_vec())
         }
     };
 }
 
-intervals_getters!(surface_starts, surface_values, surface);
-intervals_getters!(highway_starts, highway_values, highway);
-intervals_getters!(sac_scale_starts, sac_scale_values, sac_scale);
-intervals_getters!(mtb_scale_starts, mtb_scale_values, mtb_scale);
-
-/// The names of the categories, in the order of their codes. The lists only grow.
-#[tauri::command(async)]
-pub fn surfaces(state: State<AppState>) -> Vec<String> {
-    state.read(|e| e.categories().surface.names().to_vec())
-}
-
-#[tauri::command(async)]
-pub fn highways(state: State<AppState>) -> Vec<String> {
-    state.read(|e| e.categories().highway.names().to_vec())
-}
-
-#[tauri::command(async)]
-pub fn sac_scales(state: State<AppState>) -> Vec<String> {
-    state.read(|e| e.categories().sac_scale.names().to_vec())
-}
-
-#[tauri::command(async)]
-pub fn mtb_scales(state: State<AppState>) -> Vec<String> {
-    state.read(|e| e.categories().mtb_scale.names().to_vec())
-}
-
-// Routing buffers
+category_getters!(surface_starts, surface_values, surfaces);
+category_getters!(highway_starts, highway_values, highways);
+category_getters!(sac_scale_starts, sac_scale_values, sac_scales);
+category_getters!(mtb_scale_starts, mtb_scale_values, mtb_scales);
 
 #[tauri::command(async)]
 pub fn anchor_indices(state: State<AppState>) -> Bytes {
-    Bytes::new(state.read(|e| u32s(&e.routing().anchor_indices)))
+    u32s(&state.read(|e| api::anchor_indices(e).to_vec()))
 }
 
 #[tauri::command(async)]
 pub fn anchor_zooms(state: State<AppState>) -> Bytes {
-    Bytes::new(state.read(|e| e.routing().anchor_zooms.clone()))
+    u8s(&state.read(|e| api::anchor_zooms(e).to_vec()))
 }
 
 #[tauri::command(async)]
 pub fn segment_starts(state: State<AppState>) -> Bytes {
-    Bytes::new(state.read(|e| u32s(&e.routing().segment_starts)))
+    u32s(&state.read(|e| api::segment_starts(e).to_vec()))
 }
 
 #[tauri::command(async)]
 pub fn segment_ids(state: State<AppState>) -> Vec<String> {
-    state.read(|e| {
-        e.routing()
-            .segment_ids
-            .iter()
-            .map(|id| id.0.to_string())
-            .collect()
-    })
+    state.read(api::segment_ids)
 }
 
 #[tauri::command(async)]
 pub fn routing_revision(state: State<AppState>) -> u32 {
-    state.read(|e| e.routing().revision)
+    state.read(api::routing_revision)
 }
diff --git a/tauri/src/commands/storage.rs b/tauri/src/commands/storage.rs
index 15c113289..df0266e82 100644
--- a/tauri/src/commands/storage.rs
+++ b/tauri/src/commands/storage.rs
@@ -6,8 +6,8 @@
 use serde::Serialize;
 use tauri::State;
 
-use crate::dto::Outcome;
 use crate::state::AppState;
+use gpx_engine::api::Outcome;
 
 /// What opening the storage found.
 #[derive(Serialize)]
diff --git a/tauri/src/lib.rs b/tauri/src/lib.rs
index 176905878..b9a21a9ce 100644
--- a/tauri/src/lib.rs
+++ b/tauri/src/lib.rs
@@ -1,8 +1,8 @@
 //! The desktop shell of gpx.studio. The engine of the files (`gpx-rs/engine`) runs in this
 //! process, and the frontend talks to it through the commands of `commands`.
 
+mod bytes;
 mod commands;
-mod dto;
 mod state;
 
 use commands::*;
@@ -59,10 +59,10 @@ fn with_engine<R: tauri::Runtime>(builder: tauri::Builder<R>) -> tauri::Builder<
             edit::extract,
             edit::elevation,
             edit::clean,
-            routing::route,
-            routing::insert_anchor,
-            routing::change_loop_start,
-            routing::split,
+            edit::route,
+            edit::insert_anchor,
+            edit::change_loop_start,
+            edit::split,
             // queries
             queries::file_order,
             queries::file_structure,
diff --git a/tauri/src/state.rs b/tauri/src/state.rs
index 54f6477dd..9dc4a357d 100644
--- a/tauri/src/state.rs
+++ b/tauri/src/state.rs
@@ -8,14 +8,10 @@ use std::sync::mpsc::{self, Sender};
 use std::sync::{Mutex, MutexGuard};
 use std::thread;
 
-use gpx_engine::{Action, Engine};
-
-use crate::dto::Outcome;
+use gpx_engine::Engine;
 
 type Job = Box<dyn FnOnce(&mut Engine) + Send>;
 
-/// What the commands talk to. The engine is the same as in the browser (`gpx-rs`); here it lives in
-/// the process of the app, and the frontend reaches it through the commands only.
 pub struct AppState {
     jobs: Mutex<Sender<Job>>,
     /// The settings of the frontend, as JSON strings by key.
@@ -65,43 +61,3 @@ impl AppState {
         self.settings.lock().unwrap()
     }
 }
-
-/// Executes an action and tells what it did, see `Outcome`.
-pub fn execute(engine: &mut Engine, action: Action) -> Outcome {
-    match engine.execute(action) {
-        Ok(outcome) => Outcome::new(&outcome, None),
-        Err(error) => Outcome::failed(error.to_string()),
-    }
-}
-
-/// Executes an action on the engine. The values the action uses are moved to the engine thread.
-macro_rules! act {
-    ($state:expr, $action:expr) => {
-        $state.run(move |engine| $crate::state::execute(engine, $action))
-    };
-}
-
-/// Executes a command (the command can borrow what it uses).
-macro_rules! edit {
-    ($state:expr, $command:expr) => {
-        act!($state, ::gpx_engine::Action::Edit($command))
-    };
-}
-
-/// Like `edit!`, but does nothing if the selection is not the one of `revision` anymore (the
-/// indices of the routing buffers only mean something for their revision).
-macro_rules! edit_at {
-    ($state:expr, $revision:expr, $command:expr) => {{
-        let revision = $revision;
-        $state.run(move |engine| {
-            if engine.routing().revision != revision {
-                return $crate::dto::Outcome::failed(
-                    "the selection changed since the routing buffers were read",
-                );
-            }
-            $crate::state::execute(engine, ::gpx_engine::Action::Edit($command))
-        })
-    }};
-}
-
-pub(crate) use {act, edit, edit_at};
diff --git a/tauri/src/tests.rs b/tauri/src/tests.rs
index 2fb486a70..2b9d061a3 100644
--- a/tauri/src/tests.rs
+++ b/tauri/src/tests.rs
@@ -60,7 +60,7 @@ impl App {
         let mut data = vec![];
         let mut lengths = vec![];
         for name in names {
-            let file = std::fs::read(format!("../gpx-rs/engine/data/{name}.gpx")).unwrap();
+            let file = std::fs::read(format!("../gpx-rs/data/{name}.gpx")).unwrap();
             lengths.push(file.len());
             data.extend(file);
         }
@@ -77,8 +77,10 @@ impl App {
 
 fn f64s(bytes: &[u8]) -> Vec<f64> {
     bytes
-        .chunks_exact(8)
-        .map(|chunk| f64::from_le_bytes(chunk.try_into().unwrap()))
+        .as_chunks::<8>()
+        .0
+        .iter()
+        .map(|chunk| f64::from_le_bytes(*chunk))
         .collect()
 }
 
diff --git a/wasm/.gitignore b/wasm/.gitignore
new file mode 100644
index 000000000..01d0a0845
--- /dev/null
+++ b/wasm/.gitignore
@@ -0,0 +1 @@
+pkg/
diff --git a/gpx-rs/wasm/Cargo.toml b/wasm/Cargo.toml
similarity index 77%
rename from gpx-rs/wasm/Cargo.toml
rename to wasm/Cargo.toml
index d7dcd03ef..ded307bb9 100644
--- a/gpx-rs/wasm/Cargo.toml
+++ b/wasm/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "gpx-rs"
+name = "gpx-wasm"
 version = "0.1.0"
 edition = "2024"
 
@@ -8,9 +8,11 @@ crate-type = ["cdylib", "rlib"]
 
 [dependencies]
 console_error_panic_hook = "0.1.7"
-gpx-engine = { path = "../engine" }
+gpx-engine = { path = "../gpx-rs" }
 idb = "0.6.5"
 js-sys = "0.3.106"
+serde = "1"
+serde-wasm-bindgen = "0.6"
 uuid = { version = "1.26.1", features = ["js"] }
 wasm-bindgen = "0.2"
 wasm-bindgen-futures = "0.4.79"
diff --git a/wasm/README.md b/wasm/README.md
new file mode 100644
index 000000000..949ca28bc
--- /dev/null
+++ b/wasm/README.md
@@ -0,0 +1,20 @@
+# wasm
+
+The engine of [`../gpx-rs`](../gpx-rs) for the browser: WebAssembly, exposed to the page through
+`wasm-bindgen`. Each exported function is a thin wrapper over `gpx_engine::api` (see `../gpx-rs/src/api`)
+that parses what the page sends and turns the result into JS objects (`src/convert.rs`, with
+`serde-wasm-bindgen`) or typed arrays. The storage in the browser (IndexedDB) is here too, as it
+is specific to the browser.
+
+```
+wasm-pack build --target bundler
+```
+
+The website imports the result as `gpx-wasm` (`pkg/`). The functions are tested in Node (it needs
+`wasm-pack`, which fetches the test runner the first time):
+
+```
+wasm-pack test --node
+```
+
+`src/ts.rs` declares the TypeScript types of the objects that cross.
diff --git a/gpx-rs/wasm/src/command/edit.rs b/wasm/src/command/edit.rs
similarity index 58%
rename from gpx-rs/wasm/src/command/edit.rs
rename to wasm/src/command/edit.rs
index 1e2201ed1..d07f5e729 100644
--- a/gpx-rs/wasm/src/command/edit.rs
+++ b/wasm/src/command/edit.rs
@@ -1,34 +1,29 @@
 //! Editing the metadata, the style and the structure of the files.
 
-use gpx_engine::{self as engine, Command};
+use gpx_engine::api;
 use wasm_bindgen::prelude::*;
 
-use crate::ts::Outcome;
-
 use crate::session::*;
+use crate::ts::Outcome;
 
 // Edit commands
 
 #[wasm_bindgen]
 pub fn metadata(name: &str, desc: &str) -> Outcome {
-    edit(Command::Metadata(engine::Metadata { name, desc }))
+    run(|e| api::metadata(e, name, desc))
 }
 
 #[wasm_bindgen]
 pub fn style(color: Option<String>, opacity: Option<f64>, width: Option<f64>) -> Outcome {
-    edit(Command::Style(engine::Style {
-        color: color.as_deref(),
-        opacity,
-        width,
-    }))
+    run(|e| api::style(e, color.as_deref(), opacity, width))
 }
 
 #[wasm_bindgen]
 pub fn new_track() -> Outcome {
-    edit(Command::NewTrack(engine::NewTrack))
+    run(api::new_track)
 }
 
 #[wasm_bindgen]
 pub fn new_track_segment() -> Outcome {
-    edit(Command::NewTrackSegment(engine::NewTrackSegment))
+    run(api::new_track_segment)
 }
diff --git a/gpx-rs/wasm/src/command/files.rs b/wasm/src/command/files.rs
similarity index 67%
rename from gpx-rs/wasm/src/command/files.rs
rename to wasm/src/command/files.rs
index 3d9361efa..e891502d2 100644
--- a/gpx-rs/wasm/src/command/files.rs
+++ b/wasm/src/command/files.rs
@@ -1,6 +1,6 @@
 //! Creating, loading, deleting, moving, copying and pasting files and their elements.
 
-use gpx_engine::{self as engine, Action, Command};
+use gpx_engine::api;
 use wasm_bindgen::prelude::*;
 
 use crate::convert::*;
@@ -14,12 +14,7 @@ use crate::ts::*;
 /// hold that trackpoint (at `ele`, 0 by default).
 #[wasm_bindgen]
 pub fn new_file(name: &str, lng: Option<f64>, lat: Option<f64>, ele: Option<f64>) -> Outcome {
-    let trackpoint = lng.zip(lat).map(|(lng, lat)| engine::NewTrackpoint {
-        lng,
-        lat,
-        ele: ele.unwrap_or_default(),
-    });
-    edit(Command::New(engine::New { name, trackpoint }))
+    run(|e| api::new_file(e, name, lng, lat, ele))
 }
 
 /// Loads files as a single command (one undo step). The files are in `data`, one after the
@@ -28,49 +23,33 @@ pub fn new_file(name: &str, lng: Option<f64>, lat: Option<f64>, ele: Option<f64>
 /// skipped, the first one that was read is selected.
 #[wasm_bindgen]
 pub fn load_files(data: &[u8], lengths: &[u32], names: Vec<String>) -> Outcome {
-    if lengths.len() != names.len() {
-        return fail(format!(
-            "{} lengths for {} names",
-            lengths.len(),
-            names.len()
-        ));
-    }
-    let mut files = Vec::with_capacity(names.len());
-    let mut offset = 0;
-    for (length, name) in lengths.iter().zip(&names) {
-        let end = offset + *length as usize;
-        let Some(data) = data.get(offset..end) else {
-            return fail(format!("the data of {name} is shorter than its length"));
-        };
-        files.push(engine::Load { data, name });
-        offset = end;
-    }
-    edit(Command::LoadFiles(engine::LoadFiles { files }))
+    let lengths: Vec<usize> = lengths.iter().map(|length| *length as usize).collect();
+    run(|e| api::load_files(e, data, &lengths, &names))
 }
 
 #[wasm_bindgen]
 pub fn duplicate() -> Outcome {
-    edit(Command::Duplicate(engine::Duplicate))
+    run(api::duplicate)
 }
 
 /// Deletes the selected elements. With `whole_files`, the files holding the selected elements are
 /// deleted instead, even if only a track or a waypoint is selected.
 #[wasm_bindgen]
 pub fn delete(whole_files: bool) -> Outcome {
-    edit(Command::Delete(engine::Delete { whole_files }))
+    run(|e| api::delete(e, whole_files))
 }
 
 #[wasm_bindgen]
 pub fn delete_all() -> Outcome {
-    edit(Command::DeleteAll(engine::DeleteAll))
+    run(api::delete_all)
 }
 
 /// Moves the files to `index` among the other files, in the given order (not undoable).
 /// `file_ids_bytes`: concatenated 16-byte UUIDs.
 #[wasm_bindgen]
 pub fn reorder(file_ids_bytes: &[u8], index: usize) -> Outcome {
-    match file_ids(file_ids_bytes) {
-        Some(file_ids) => execute(Action::Reorder { file_ids, index }),
+    match uuid_list(file_ids_bytes) {
+        Some(ids) => run(|e| api::reorder(e, &ids, index)),
         None => fail("the file ids are not a list of UUIDs"),
     }
 }
@@ -80,13 +59,13 @@ pub fn reorder(file_ids_bytes: &[u8], index: usize) -> Outcome {
 /// Puts the selected elements in the clipboard. Nothing happens when nothing is selected.
 #[wasm_bindgen]
 pub fn copy() -> Outcome {
-    execute(Action::Copy)
+    run(api::copy)
 }
 
 /// Like `copy`, but the elements are moved when they are pasted.
 #[wasm_bindgen]
 pub fn cut() -> Outcome {
-    execute(Action::Cut)
+    run(api::cut)
 }
 
 /// Pastes the clipboard according to the selection (see `can_paste`). What is pasted is always
@@ -95,13 +74,13 @@ pub fn cut() -> Outcome {
 /// the first time (and the clipboard is not cut after that), then it is copied.
 #[wasm_bindgen]
 pub fn paste() -> Outcome {
-    edit(Command::Paste(engine::Paste))
+    run(api::paste)
 }
 
 /// Whether the clipboard can be pasted with the current selection.
 #[wasm_bindgen]
 pub fn can_paste() -> bool {
-    with_engine(|e| e.can_paste()).unwrap_or(false)
+    with_engine(api::can_paste).unwrap_or(false)
 }
 
 /// Moves elements (given as a `Selection`) to a place of the file tree, keeping their ids, like
@@ -113,8 +92,9 @@ pub fn can_paste() -> bool {
 /// waypoints of a file.
 #[wasm_bindgen]
 pub fn move_elements(what: Selection, to: MoveTarget) -> Outcome {
-    match parse_selection(&what).zip(parse_move_target(&to)) {
-        Some((what, to)) => edit(Command::Move(engine::Move { what, to })),
+    // a negative index is the start, an infinite one is the end
+    match from_js::<api::Selection>(&what).zip(from_js::<api::MoveTarget>(&to)) {
+        Some((what, to)) => run(|e| api::move_elements(e, what, to)),
         None => fail("the elements or the target are not valid"),
     }
 }
diff --git a/gpx-rs/wasm/src/command/history.rs b/wasm/src/command/history.rs
similarity index 62%
rename from gpx-rs/wasm/src/command/history.rs
rename to wasm/src/command/history.rs
index 3dcfaf15e..60e341a5a 100644
--- a/gpx-rs/wasm/src/command/history.rs
+++ b/wasm/src/command/history.rs
@@ -1,30 +1,29 @@
 //! Undo and redo.
 
-use gpx_engine::Action;
+use gpx_engine::api;
 use wasm_bindgen::prelude::*;
 
-use crate::ts::Outcome;
-
 use crate::session::*;
+use crate::ts::Outcome;
 
 // Undo-redo
 
 #[wasm_bindgen]
 pub fn undo() -> Outcome {
-    execute(Action::Undo)
+    run(api::undo)
 }
 
 #[wasm_bindgen]
 pub fn redo() -> Outcome {
-    execute(Action::Redo)
+    run(api::redo)
 }
 
 #[wasm_bindgen]
 pub fn can_undo() -> bool {
-    with_engine(|e| e.can_undo()).unwrap_or(false)
+    with_engine(api::can_undo).unwrap_or(false)
 }
 
 #[wasm_bindgen]
 pub fn can_redo() -> bool {
-    with_engine(|e| e.can_redo()).unwrap_or(false)
+    with_engine(api::can_redo).unwrap_or(false)
 }
diff --git a/gpx-rs/wasm/src/command/mod.rs b/wasm/src/command/mod.rs
similarity index 100%
rename from gpx-rs/wasm/src/command/mod.rs
rename to wasm/src/command/mod.rs
diff --git a/wasm/src/command/routing.rs b/wasm/src/command/routing.rs
new file mode 100644
index 000000000..83a32caeb
--- /dev/null
+++ b/wasm/src/command/routing.rs
@@ -0,0 +1,66 @@
+//! The commands that refer to trackpoints by their index in the routing buffers.
+
+use gpx_engine::api;
+use wasm_bindgen::prelude::*;
+
+use crate::convert::*;
+use crate::ids::*;
+use crate::session::*;
+use crate::ts::*;
+use crate::types::*;
+
+// Routing
+//
+// The indices of the trackpoints and of the anchors are the ones of the routing buffers: they only
+// mean something for the `revision` they were read with (`routing_revision`), and the commands
+// that use them do nothing if the selection is not the one of that revision anymore.
+
+/// Replaces the trackpoints `start..end` of the selection by the given ones, in a single segment
+/// (see `RoutingBuffer`). A pure insertion if `start == end`, a pure removal without new points.
+/// `attributes` holds the surface, highway, SAC scale and MTB scale of the new points, as
+/// intervals, and `anchors` the indices among the new points of the ones that become anchors.
+/// Does nothing, and says why, if the revision of the routing buffers is not the given one.
+#[wasm_bindgen]
+#[allow(clippy::too_many_arguments)]
+pub fn route(
+    revision: u32,
+    start: u32,
+    end: u32,
+    lng: &[f64],
+    lat: &[f64],
+    ele: &[f64],
+    attributes: RouteAttributes,
+    anchors: &[u32],
+) -> Outcome {
+    let Some(attributes) = from_js::<api::RouteAttributes>(&attributes) else {
+        return fail("the attributes of the route are not valid");
+    };
+    if !same_len(lng, lat, ele) {
+        return fail("lng, lat and ele differ in length");
+    }
+    run(|e| api::route(e, revision, start, end, lng, lat, ele, &attributes, anchors))
+}
+
+/// Makes an anchor of the point of the selected segments that is the closest to the coordinates,
+/// inserting a trackpoint on the path if none is there. Does nothing, and says why, if the
+/// revision of the routing buffers is not the given one.
+#[wasm_bindgen]
+pub fn insert_anchor(revision: u32, lng: f64, lat: f64) -> Outcome {
+    run(|e| api::insert_anchor(e, revision, lng, lat))
+}
+
+/// Makes the trackpoint `index` of the selection the start of its segment, which is a loop (the
+/// trackpoints before it go to the end, and the loop closes on it). Does nothing, and says why, if the revision of the
+/// routing buffers is not the given one.
+#[wasm_bindgen]
+pub fn change_loop_start(revision: u32, index: u32) -> Outcome {
+    run(|e| api::change_loop_start(e, revision, index))
+}
+
+/// Cuts the file, the track or the segment (see `SplitType`) of the trackpoint `at` of the
+/// selection in two, there: the trackpoint ends the first part and starts the second one. Does
+/// nothing, and returns false, if the revision of the routing buffers is not the given one.
+#[wasm_bindgen]
+pub fn split(revision: u32, at: u32, split_type: SplitType) -> Outcome {
+    run(|e| api::split(e, revision, at, split_type.into()))
+}
diff --git a/gpx-rs/wasm/src/command/tools.rs b/wasm/src/command/tools.rs
similarity index 64%
rename from gpx-rs/wasm/src/command/tools.rs
rename to wasm/src/command/tools.rs
index b4914ca30..55a1ef58c 100644
--- a/gpx-rs/wasm/src/command/tools.rs
+++ b/wasm/src/command/tools.rs
@@ -1,6 +1,6 @@
 //! The tools: reversing, cropping, reducing, timestamps, merging, cleaning...
 
-use gpx_engine::{self as engine, Command, LngLat, LngLatBounds};
+use gpx_engine::api;
 use wasm_bindgen::prelude::*;
 
 use crate::ts::Outcome;
@@ -12,31 +12,28 @@ use crate::types::*;
 
 #[wasm_bindgen]
 pub fn reverse() -> Outcome {
-    edit(Command::Reverse(engine::Reverse))
+    run(api::reverse)
 }
 
 /// Adds to each selected segment a reversed copy of itself (without repeating its last point), so that it goes back to where it
 /// started.
 #[wasm_bindgen]
 pub fn round_trip() -> Outcome {
-    edit(Command::RoundTrip(engine::RoundTrip))
+    run(api::round_trip)
 }
 
 /// Keeps the trackpoints `start` to `end` (both included) of the selection, counted over its
 /// segments one after the other, and removes the others (and what is left empty).
 #[wasm_bindgen]
 pub fn crop(start: u32, end: u32) -> Outcome {
-    if start > end {
-        return fail(format!("the range {start}..{end} is reversed"));
-    }
-    edit(Command::Crop(engine::Crop { start, end }))
+    run(|e| api::crop(e, start, end))
 }
 
 /// Removes the trackpoints of the selection that are less than `tolerance` meters away from the
 /// line of their neighbours, except the ends of the segments.
 #[wasm_bindgen]
 pub fn reduce(tolerance: f64) -> Outcome {
-    edit(Command::Reduce(engine::Reduce { tolerance }))
+    run(|e| api::reduce(e, tolerance))
 }
 
 /// Sets the timestamps of the selection, which starts at `start_time` (ms since the epoch): the
@@ -44,41 +41,32 @@ pub fn reduce(tolerance: f64) -> Outcome {
 /// previous one at `speed` (km/h).
 #[wasm_bindgen(js_name = changeTimestamps)]
 pub fn change_timestamps(start_time: f64, speed: f64, ratio: f64) -> Outcome {
-    edit(Command::Time(engine::Time {
-        start_time: start_time as i64,
-        kind: engine::TimeKind::Change { speed, ratio },
-    }))
+    run(|e| api::change_timestamps(e, start_time, speed, ratio))
 }
 
 /// Makes up timestamps for the selection, which starts at `start_time` (ms since the epoch) and
 /// lasts `total_time` seconds.
 #[wasm_bindgen(js_name = createArtificialTimestamps)]
 pub fn create_artificial_timestamps(start_time: f64, total_time: f64) -> Outcome {
-    edit(Command::Time(engine::Time {
-        start_time: start_time as i64,
-        kind: engine::TimeKind::Artificial { total_time },
-    }))
+    run(|e| api::create_artificial_timestamps(e, start_time, total_time))
 }
 
 /// Merges the selection into its first element (see `MergeType`). `remove_gaps` brings the parts
 /// that are connected closer in time, if they have timestamps.
 #[wasm_bindgen]
 pub fn merge(type_: MergeType, remove_gaps: bool) -> Outcome {
-    edit(Command::Merge(engine::Merge {
-        type_: type_.into(),
-        remove_gaps,
-    }))
+    run(|e| api::merge(e, type_.into(), remove_gaps))
 }
 
 #[wasm_bindgen]
 pub fn extract() -> Outcome {
-    edit(Command::Extract(engine::Extract))
+    run(api::extract)
 }
 
 /// Sets the elevation of the trackpoints of the selection, one elevation per trackpoint.
 #[wasm_bindgen]
 pub fn elevation(ele: &[f64]) -> Outcome {
-    edit(Command::Elevation(engine::Elevation { ele }))
+    run(|e| api::elevation(e, ele))
 }
 
 #[wasm_bindgen]
@@ -91,19 +79,5 @@ pub fn clean(
     trkpt: bool,
     wpt: bool,
 ) -> Outcome {
-    edit(Command::Clean(engine::Clean {
-        bounds: LngLatBounds {
-            sw: LngLat {
-                lng: west,
-                lat: south,
-            },
-            ne: LngLat {
-                lng: east,
-                lat: north,
-            },
-        },
-        type_: type_.into(),
-        trkpt,
-        wpt,
-    }))
+    run(|e| api::clean(e, west, south, east, north, type_.into(), trkpt, wpt))
 }
diff --git a/wasm/src/command/waypoints.rs b/wasm/src/command/waypoints.rs
new file mode 100644
index 000000000..ba3f6e1fe
--- /dev/null
+++ b/wasm/src/command/waypoints.rs
@@ -0,0 +1,76 @@
+//! Creating, editing, moving and deleting waypoints.
+
+use gpx_engine::api;
+use wasm_bindgen::prelude::*;
+
+use crate::ts::Outcome;
+
+use crate::ids::*;
+use crate::session::*;
+
+#[wasm_bindgen]
+pub fn new_waypoint(
+    lng: f64,
+    lat: f64,
+    ele: f64,
+    name: &str,
+    desc: &str,
+    icon: &str,
+    link: &str,
+) -> Outcome {
+    run(|e| api::new_waypoint(e, lng, lat, ele, name, desc, icon, link))
+}
+
+/// Moves a waypoint of a file, whatever is selected.
+#[wasm_bindgen]
+pub fn move_waypoint(file_id: &str, waypoint_id: &str, lng: f64, lat: f64, ele: f64) -> Outcome {
+    match parse_uuid(file_id).zip(parse_uuid(waypoint_id)) {
+        Some((file_id, waypoint_id)) => {
+            run(|e| api::move_waypoint(e, file_id, waypoint_id, lng, lat, ele))
+        }
+        None => fail("the file or waypoint id is not a UUID"),
+    }
+}
+
+/// Deletes a waypoint of a file, whatever is selected.
+#[wasm_bindgen]
+pub fn delete_waypoint(file_id: &str, waypoint_id: &str) -> Outcome {
+    match parse_uuid(file_id).zip(parse_uuid(waypoint_id)) {
+        Some((file_id, waypoint_id)) => run(|e| api::delete_waypoint(e, file_id, waypoint_id)),
+        None => fail("the file or waypoint id is not a UUID"),
+    }
+}
+
+/// Changes a waypoint of a file, whatever is selected: its name, description, icon, link, position
+/// and elevation. The strings that are empty remove the field.
+#[wasm_bindgen]
+#[allow(clippy::too_many_arguments)]
+pub fn update_waypoint(
+    file_id: &str,
+    waypoint_id: &str,
+    lng: f64,
+    lat: f64,
+    ele: f64,
+    name: &str,
+    desc: &str,
+    icon: &str,
+    link: &str,
+) -> Outcome {
+    match parse_uuid(file_id).zip(parse_uuid(waypoint_id)) {
+        Some((file_id, waypoint_id)) => run(|e| {
+            api::update_waypoint(
+                e,
+                file_id,
+                waypoint_id,
+                lng,
+                lat,
+                ele,
+                name,
+                desc,
+                icon,
+                link,
+            )
+        }),
+        None => fail("the file or waypoint id is not a UUID"),
+    }
+}
diff --git a/wasm/src/convert.rs b/wasm/src/convert.rs
new file mode 100644
index 000000000..6482bb039
--- /dev/null
+++ b/wasm/src/convert.rs
@@ -0,0 +1,28 @@
+//! Turning what the shared interface (`gpx_engine::api`) gives into JS objects and back.
+
+use gpx_engine::api;
+use serde::{Serialize, de::DeserializeOwned};
+use wasm_bindgen::prelude::*;
+
+use crate::ts::Outcome;
+
+/// A plain JS object (absent fields are `undefined`) with what `value` holds.
+pub(crate) fn to_js<T: Serialize + ?Sized>(value: &T) -> JsValue {
+    value
+        .serialize(&serde_wasm_bindgen::Serializer::new().serialize_maps_as_objects(true))
+        .expect("the data can be turned into a JS value")
+}
+
+/// What `value` holds, `None` if it is not what `T` is.
+pub(crate) fn from_js<T: DeserializeOwned>(value: &JsValue) -> Option<T> {
+    serde_wasm_bindgen::from_value(value.clone()).ok()
+}
+
+/// `undefined` when there is nothing.
+pub(crate) fn optional_js<T: Serialize>(value: Option<T>) -> JsValue {
+    value.as_ref().map_or(JsValue::UNDEFINED, to_js)
+}
+
+pub(crate) fn outcome_js(outcome: &api::Outcome) -> Outcome {
+    to_js(outcome).unchecked_into()
+}
diff --git a/gpx-rs/wasm/src/idb.rs b/wasm/src/idb.rs
similarity index 100%
rename from gpx-rs/wasm/src/idb.rs
rename to wasm/src/idb.rs
diff --git a/wasm/src/ids.rs b/wasm/src/ids.rs
new file mode 100644
index 000000000..7dde0b2b7
--- /dev/null
+++ b/wasm/src/ids.rs
@@ -0,0 +1,17 @@
+//! Ids, which cross as strings (one id) or as concatenated 16-byte UUIDs (several).
+
+use uuid::Uuid;
+
+pub(crate) fn uuid_list(bytes: &[u8]) -> Option<Vec<Uuid>> {
+    let (chunks, rest) = bytes.as_chunks::<16>();
+    rest.is_empty()
+        .then(|| chunks.iter().map(|c| Uuid::from_bytes(*c)).collect())
+}
+
+pub(crate) fn parse_uuid(id: &str) -> Option<Uuid> {
+    Uuid::parse_str(id).ok()
+}
+
+pub(crate) fn same_len(a: &[f64], b: &[f64], c: &[f64]) -> bool {
+    a.len() == b.len() && b.len() == c.len()
+}
diff --git a/gpx-rs/wasm/src/lib.rs b/wasm/src/lib.rs
similarity index 100%
rename from gpx-rs/wasm/src/lib.rs
rename to wasm/src/lib.rs
diff --git a/gpx-rs/wasm/src/persistence.rs b/wasm/src/persistence.rs
similarity index 91%
rename from gpx-rs/wasm/src/persistence.rs
rename to wasm/src/persistence.rs
index 41708b8cf..96e7e36fc 100644
--- a/gpx-rs/wasm/src/persistence.rs
+++ b/wasm/src/persistence.rs
@@ -3,11 +3,11 @@
 use std::cell::{Cell, RefCell};
 use std::rc::Rc;
 
-use gpx_engine::{self as engine, Engine, Persister, Storage};
-use js_sys::Object;
+use gpx_engine::{self as engine, Engine, Persister, Storage, api};
+use serde::Serialize;
 use wasm_bindgen::prelude::*;
 
-use crate::convert::{outcome_object, set};
+use crate::convert::{outcome_js, to_js};
 use crate::idb::IdbStorage;
 use crate::session::*;
 use crate::ts::{Outcome, StorageOpened};
@@ -137,7 +137,7 @@ pub async fn open_storage(
     let mut persister = Persister::default();
     let outcome = restore_engine(persister.restore(&storage).await).map_err(to_js_error)?;
     let newer = outcome.is_none();
-    let outcome = outcome.unwrap_or_else(|| outcome_object(&engine::Outcome::default(), None));
+    let outcome = outcome.unwrap_or_else(api::Outcome::failed_none);
     let settings = storage.load_settings().await.map_err(to_js_error)?;
 
     PERSISTER.with(|slot| *slot.borrow_mut() = Some(persister));
@@ -153,14 +153,17 @@ pub async fn open_storage(
         notify(|listeners| &listeners.newer);
     }
 
-    let settings_object = Object::new();
-    for (key, value) in settings {
-        set(&settings_object, &key, value);
+    /// What opening the storage found, see `StorageOpened` in `ts`.
+    #[derive(Serialize)]
+    struct Opened {
+        settings: std::collections::BTreeMap<String, String>,
+        outcome: api::Outcome,
     }
-    let opened = Object::new();
-    set(&opened, "settings", settings_object);
-    set(&opened, "outcome", outcome);
-    Ok(opened.unchecked_into())
+    Ok(to_js(&Opened {
+        settings: settings.into_iter().collect(),
+        outcome,
+    })
+    .unchecked_into())
 }
 
 /// Overwrites the files of the engine with what was read, and tells what that did. If what is
@@ -168,12 +171,12 @@ pub async fn open_storage(
 /// returned: the persister does not write anymore (see `Persister::save`).
 fn restore_engine(
     read: Result<engine::Restored, engine::StorageError>,
-) -> Result<Option<Outcome>, engine::StorageError> {
+) -> Result<Option<api::Outcome>, engine::StorageError> {
     match read {
         Ok(restored) => Ok(Some(
             match with_engine_mut(|engine| engine.restore(restored)) {
-                Some(outcome) => outcome_object(&outcome, None),
-                None => outcome_object(&engine::Outcome::default(), None),
+                Some(outcome) => api::Outcome::new(&outcome, None),
+                None => api::Outcome::failed_none(),
             },
         )),
         Err(engine::StorageError::Newer) => Ok(None),
@@ -211,19 +214,21 @@ pub async fn sync_storage() -> Result<Outcome, JsValue> {
         storage(),
         PERSISTER.with(|persister| persister.borrow_mut().take()),
     ) else {
-        return Ok(outcome_object(&engine::Outcome::default(), None));
+        return Ok(outcome_js(&api::Outcome::failed_none()));
     };
     SAVING.set(true);
     let result = async {
         if !persister.is_behind(&*storage).await? {
-            return Ok(outcome_object(&engine::Outcome::default(), None));
+            return Ok(outcome_js(&api::Outcome::failed_none()));
         }
         let outcome = restore_engine(persister.restore(&*storage).await)?;
         DIRTY.set(false);
         if outcome.is_none() {
             notify(|listeners| &listeners.newer);
         }
-        Ok(outcome.unwrap_or_else(|| outcome_object(&engine::Outcome::default(), None)))
+        Ok(outcome_js(
+            &outcome.unwrap_or_else(api::Outcome::failed_none),
+        ))
     }
     .await;
     PERSISTER.with(|slot| *slot.borrow_mut() = Some(persister));
diff --git a/wasm/src/queries/coordinates.rs b/wasm/src/queries/coordinates.rs
new file mode 100644
index 000000000..cbf07ef3b
--- /dev/null
+++ b/wasm/src/queries/coordinates.rs
@@ -0,0 +1,33 @@
+//! The coordinates of the trackpoints and waypoints, as flat typed arrays.
+
+use gpx_engine::api;
+use js_sys::Float64Array;
+use wasm_bindgen::prelude::*;
+
+use crate::ids::*;
+use crate::session::*;
+
+// Coordinates buffers
+//
+// Like the statistics buffers, these are copies. They are flat `[lng, lat, ...]` arrays. Compare `rev` / `waypointsRev` of the file structures with the previous ones to know which
+// buffers actually changed.
+
+fn coordinates(
+    id: Option<uuid::Uuid>,
+    f: impl FnOnce(&gpx_engine::Engine, uuid::Uuid) -> &[f64],
+) -> Float64Array {
+    id.and_then(|id| with_engine(|e| Float64Array::from(f(e, id))))
+        .unwrap_or_else(|| Float64Array::new_with_length(0))
+}
+
+/// Coordinates of the trackpoints of a segment (empty if the id is unknown).
+#[wasm_bindgen]
+pub fn segment_coordinates(segment_id: &str) -> Float64Array {
+    coordinates(parse_uuid(segment_id), api::segment_coordinates)
+}
+
+/// Coordinates of the waypoints of a file (empty if the id is unknown).
+#[wasm_bindgen]
+pub fn waypoint_coordinates(file_id: &str) -> Float64Array {
+    coordinates(parse_uuid(file_id), api::waypoint_coordinates)
+}
diff --git a/wasm/src/queries/files.rs b/wasm/src/queries/files.rs
new file mode 100644
index 000000000..5cc64df1d
--- /dev/null
+++ b/wasm/src/queries/files.rs
@@ -0,0 +1,125 @@
+//! The files, their structure and statistics, the selection and the clipboard.
+
+// File order and structures
+//
+// The files are described by one ordered list of ids and one structure object per file, so that
+// the UI can react to what changed only: after each action, the outcome tells which structures to
+// (re)read or drop and whether the order changed. Ids are UUID strings. The trackpoints of a
+// segment and the waypoints of a file are in the same order as the coordinates of their buffers
+// (see below).
+
+use gpx_engine::{ExportOptions, api};
+use wasm_bindgen::prelude::*;
+
+use crate::convert::*;
+use crate::ids::*;
+use crate::session::*;
+use crate::ts::*;
+
+/// Ids of the files in display order.
+#[wasm_bindgen]
+pub fn file_order() -> FileOrder {
+    to_js(&with_engine(api::file_order).unwrap_or_default()).unchecked_into()
+}
+
+/// Structure of a file, `undefined` if the id is unknown.
+#[wasm_bindgen]
+pub fn file_structure(file_id: &str) -> FileStructure {
+    let structure =
+        parse_uuid(file_id).and_then(|id| with_engine(|e| api::file_structure(e, id)).flatten());
+    optional_js(structure).unchecked_into()
+}
+
+/// Global statistics of a file, `undefined` if the id is unknown.
+#[wasm_bindgen]
+pub fn file_statistics(file_id: &str) -> GlobalStatistics {
+    let statistics =
+        parse_uuid(file_id).and_then(|id| with_engine(|e| api::file_statistics(e, id)).flatten());
+    optional_js(statistics).unchecked_into()
+}
+
+/// Global statistics of the whole selection (the arrays of the statistics buffers cover it).
+#[wasm_bindgen]
+pub fn selection_statistics() -> GlobalStatistics {
+    optional_js(with_engine(api::selection_statistics)).unchecked_into()
+}
+
+/// A file as GPX (UTF-8 bytes), `undefined` if it does not exist. The options say which data of the trackpoints
+/// to keep, and with `as_route` that the segments are written as routes (`rte`) instead of tracks:
+/// the anchors are the route points, and the trackpoints between them the points of their path.
+#[wasm_bindgen]
+#[allow(clippy::too_many_arguments)]
+pub fn export_file(
+    file_id: &str,
+    time: bool,
+    hr: bool,
+    cad: bool,
+    atemp: bool,
+    power: bool,
+    osm: bool,
+    as_route: bool,
+) -> Option<Vec<u8>> {
+    let id = parse_uuid(file_id)?;
+    let options = ExportOptions {
+        time,
+        hr,
+        cad,
+        atemp,
+        power,
+        osm,
+        as_route,
+    };
+    with_engine(|e| api::export_file(e, id, options)).flatten()
+}
+
+/// The data that some files have, so that the ones that none has are not offered when exporting
+/// them: a bit for the time (1), heart rate (2), cadence (4), temperature (8), power (16) and the
+/// OpenStreetMap data (32). `file_ids` are concatenated UUIDs.
+#[wasm_bindgen]
+pub fn exportable_data(file_ids: &[u8]) -> u8 {
+    let Some(ids) = uuid_list(file_ids) else {
+        return 0;
+    };
+    with_engine(|e| api::exportable_data(e, &ids)).unwrap_or(0)
+}
+
+/// Global statistics of the trackpoints from `start` to `end` (both included) of the selection,
+/// as indexed by the statistics buffers. `undefined` when the range is not in the selection.
+#[wasm_bindgen]
+pub fn slice_statistics(start: usize, end: usize) -> GlobalStatistics {
+    optional_js(with_engine(|e| api::slice_statistics(e, start, end)).flatten()).unchecked_into()
+}
+
+/// The current selection (ids are UUID strings).
+#[wasm_bindgen]
+pub fn selection() -> Selection {
+    to_js(&with_engine(api::selection).unwrap_or(api::Selection::Empty)).unchecked_into()
+}
+
+/// All the data of a waypoint of a file, `undefined` if it does not exist.
+#[wasm_bindgen]
+pub fn waypoint(file_id: &str, waypoint_id: &str) -> WaypointDetails {
+    let details = parse_uuid(file_id)
+        .zip(parse_uuid(waypoint_id))
+        .and_then(|(file_id, id)| with_engine(|e| api::waypoint(e, file_id, id)).flatten());
+    optional_js(details).unchecked_into()
+}
+
+/// A trackpoint of a segment of a file, `undefined` if it does not exist.
+#[wasm_bindgen]
+pub fn trackpoint(file_id: &str, segment_id: &str, index: usize) -> TrackpointDetails {
+    let details =
+        parse_uuid(file_id)
+            .zip(parse_uuid(segment_id))
+            .and_then(|(file_id, segment_id)| {
+                with_engine(|e| api::trackpoint(e, file_id, segment_id, index)).flatten()
+            });
+    optional_js(details).unchecked_into()
+}
+
+/// What was copied or cut and is waiting to be pasted, `undefined` if nothing: the kind of the
+/// elements and their ids (UUID strings).
+#[wasm_bindgen]
+pub fn clipboard() -> Clipboard {
+    optional_js(with_engine(api::clipboard).flatten()).unchecked_into()
+}
diff --git a/gpx-rs/wasm/src/queries/mod.rs b/wasm/src/queries/mod.rs
similarity index 100%
rename from gpx-rs/wasm/src/queries/mod.rs
rename to wasm/src/queries/mod.rs
diff --git a/gpx-rs/wasm/src/queries/routing.rs b/wasm/src/queries/routing.rs
similarity index 69%
rename from gpx-rs/wasm/src/queries/routing.rs
rename to wasm/src/queries/routing.rs
index d9a98afa7..796944058 100644
--- a/gpx-rs/wasm/src/queries/routing.rs
+++ b/wasm/src/queries/routing.rs
@@ -1,6 +1,6 @@
 //! The anchors of the routing tool among the trackpoints of the selection.
 
-use gpx_engine as engine;
+use gpx_engine::api;
 use js_sys::{Uint8Array, Uint32Array};
 use wasm_bindgen::prelude::*;
 
@@ -13,42 +13,36 @@ use crate::ts::*;
 // The anchors of the routing tool among the trackpoints of the selection (the numbering is the one
 // of the statistics buffers). The ends of the segments are always anchors.
 
-pub(crate) fn with_routing<T>(f: impl FnOnce(&engine::RoutingBuffer) -> T) -> Option<T> {
-    ENGINE.with(|engine| engine.borrow().as_ref().map(|e| f(e.routing())))
-}
-
 /// The index in the selection of each anchor.
 #[wasm_bindgen]
 pub fn anchor_indices() -> Uint32Array {
-    with_routing(|r| Uint32Array::from(&r.anchor_indices[..]))
+    with_engine(|e| Uint32Array::from(api::anchor_indices(e)))
         .unwrap_or_else(|| Uint32Array::new_with_length(0))
 }
 
 /// The lowest map zoom level at which each anchor is shown.
 #[wasm_bindgen]
 pub fn anchor_zooms() -> Uint8Array {
-    with_routing(|r| Uint8Array::from(&r.anchor_zooms[..]))
+    with_engine(|e| Uint8Array::from(api::anchor_zooms(e)))
         .unwrap_or_else(|| Uint8Array::new_with_length(0))
 }
 
 /// Index in the selection of the first trackpoint of each selected segment that has some.
 #[wasm_bindgen]
 pub fn segment_starts() -> Uint32Array {
-    with_routing(|r| Uint32Array::from(&r.segment_starts[..]))
+    with_engine(|e| Uint32Array::from(api::segment_starts(e)))
         .unwrap_or_else(|| Uint32Array::new_with_length(0))
 }
 
 /// The id of each selected segment that has trackpoints, as `segment_starts`.
 #[wasm_bindgen]
 pub fn segment_ids() -> StringList {
-    with_routing(|r| array(&r.segment_ids, |id| id.0.to_string().into()))
-        .unwrap_or_default()
-        .unchecked_into()
+    to_js(&with_engine(api::segment_ids).unwrap_or_default()).unchecked_into()
 }
 
 /// Changes when the selected segments or their trackpoints change: the indices in the selection
 /// are only valid while it stays the same.
 #[wasm_bindgen]
 pub fn routing_revision() -> u32 {
-    with_routing(|r| r.revision).unwrap_or_default()
+    with_engine(api::routing_revision).unwrap_or_default()
 }
diff --git a/wasm/src/queries/statistics.rs b/wasm/src/queries/statistics.rs
new file mode 100644
index 000000000..7595b1aa3
--- /dev/null
+++ b/wasm/src/queries/statistics.rs
@@ -0,0 +1,105 @@
+//! The statistics of the selection, as typed arrays, and the categories they refer to.
+
+use gpx_engine::api;
+use js_sys::{BigInt64Array, Float64Array, Uint8Array, Uint32Array};
+use wasm_bindgen::prelude::*;
+
+use crate::convert::*;
+use crate::session::*;
+use crate::ts::*;
+
+// Statistics buffers
+//
+// Each getter returns a copy of the buffer, as a new JS typed array.
+
+macro_rules! stats_getter {
+    ($name:ident, $array:ident) => {
+        #[wasm_bindgen]
+        pub fn $name() -> $array {
+            with_engine(|e| $array::from(api::$name(e)))
+                .unwrap_or_else(|| $array::new_with_length(0))
+        }
+    };
+}
+
+stats_getter!(total_distance, Float64Array);
+stats_getter!(elevation_gain, Float64Array);
+stats_getter!(elevation_loss, Float64Array);
+stats_getter!(slope, Float64Array);
+stats_getter!(slope_segment_slope, Float64Array);
+stats_getter!(slope_segment_distance, Float64Array);
+stats_getter!(lng, Float64Array);
+stats_getter!(lat, Float64Array);
+stats_getter!(ele, Float64Array);
+
+// The optional values are `undefined` when no trackpoint of the selection has one, else they have
+// an entry per trackpoint, the missing ones being NaN (`NO_TIME` for the timestamps, 0 before the
+// first trackpoint that has them for the cumulative distances and durations).
+macro_rules! optional_stats_getter {
+    ($name:ident, $array:ident) => {
+        #[wasm_bindgen]
+        pub fn $name() -> Option<$array> {
+            with_engine(|e| api::$name(e).map($array::from)).flatten()
+        }
+    };
+}
+
+optional_stats_getter!(moving_distance, Float64Array);
+// Durations since the start of the selection, in milliseconds.
+optional_stats_getter!(total_time, BigInt64Array);
+optional_stats_getter!(moving_time, BigInt64Array);
+optional_stats_getter!(speed, Float64Array);
+// Timestamps in milliseconds since the epoch (`NO_TIME`, the smallest i64, when missing).
+optional_stats_getter!(timestamps, BigInt64Array);
+
+/// Value of the timestamps of the trackpoints that have none.
+#[wasm_bindgen]
+pub fn no_time() -> i64 {
+    gpx_engine::NO_TIME
+}
+
+optional_stats_getter!(hr, Float64Array);
+optional_stats_getter!(cad, Float64Array);
+optional_stats_getter!(atemp, Float64Array);
+optional_stats_getter!(power, Float64Array);
+
+// Surface, highway, SAC scale and MTB scale of the trackpoints, as intervals of trackpoints that
+// have the same value: `<name>_starts` holds the index of the first trackpoint of each interval,
+// and `<name>_values` its value (0 when unknown, else 1 + the index in `surfaces()`,
+// `highways()`, `sac_scales()` or `mtb_scales()`). A value that is unknown for every trackpoint is
+// a single interval.
+macro_rules! categories_getters {
+    ($starts:ident, $values:ident, $names:ident) => {
+        #[wasm_bindgen]
+        pub fn $starts() -> Uint32Array {
+            with_engine(|e| Uint32Array::from(api::$starts(e)))
+                .unwrap_or_else(|| Uint32Array::new_with_length(0))
+        }
+
+        #[wasm_bindgen]
+        pub fn $values() -> Uint8Array {
+            with_engine(|e| Uint8Array::from(api::$values(e)))
+                .unwrap_or_else(|| Uint8Array::new_with_length(0))
+        }
+
+        /// The names of the category, in the order of their codes. The list only grows: a name
+        /// keeps its index.
+        #[wasm_bindgen]
+        pub fn $names() -> StringList {
+            to_js(&with_engine(|e| api::$names(e).to_vec()).unwrap_or_default()).unchecked_into()
+        }
+    };
+}
+
+categories_getters!(surface_starts, surface_values, surfaces);
+categories_getters!(highway_starts, highway_values, highways);
+categories_getters!(sac_scale_starts, sac_scale_values, sac_scales);
+categories_getters!(mtb_scale_starts, mtb_scale_values, mtb_scales);
+
+/// For each trackpoint of the selection (numbered as in the statistics), the highest tolerance
+/// (m) of `reduce` that keeps it: infinite for the ends of the segments.
+#[wasm_bindgen]
+pub fn reduction_distances() -> Float64Array {
+    with_engine(|e| Float64Array::from(&api::reduction_distances(e)[..]))
+        .unwrap_or_else(|| Float64Array::new_with_length(0))
+}
diff --git a/gpx-rs/wasm/src/selection.rs b/wasm/src/selection.rs
similarity index 53%
rename from gpx-rs/wasm/src/selection.rs
rename to wasm/src/selection.rs
index 89f428b10..f21338d79 100644
--- a/gpx-rs/wasm/src/selection.rs
+++ b/wasm/src/selection.rs
@@ -1,12 +1,11 @@
 //! Changing what is selected.
 
-use gpx_engine::{self as engine, Action};
+use gpx_engine::api;
 use wasm_bindgen::prelude::*;
 
-use crate::ts::Outcome;
-
 use crate::ids::*;
 use crate::session::*;
+use crate::ts::Outcome;
 use crate::types::SelectMode;
 
 // Selection
@@ -15,12 +14,10 @@ use crate::types::SelectMode;
 /// selecting nothing deselects everything. See `SelectMode`.
 #[wasm_bindgen]
 pub fn select(file_ids_bytes: &[u8], mode: SelectMode) -> Outcome {
-    select_elements(
-        file_ids(file_ids_bytes).map(|ids| engine::Selection::File {
-            file_ids: ids.into_iter().collect(),
-        }),
-        mode,
-    )
+    match uuid_list(file_ids_bytes) {
+        Some(ids) => run(|e| api::select(e, &ids, mode.into())),
+        None => fail("the ids are not UUIDs"),
+    }
 }
 
 /// Selects all the elements of the same kind as the selected ones, in the same place: all the
@@ -28,7 +25,7 @@ pub fn select(file_ids_bytes: &[u8], mode: SelectMode) -> Outcome {
 /// files when nothing is selected.
 #[wasm_bindgen]
 pub fn select_all() -> Outcome {
-    execute(Action::SelectAll)
+    run(api::select_all)
 }
 
 /// Moves the selection to the next (`down`) or previous element of the same kind, like the arrow
@@ -36,7 +33,7 @@ pub fn select_all() -> Outcome {
 /// otherwise it replaces it.
 #[wasm_bindgen]
 pub fn arrow_select(down: bool, add: bool) -> Outcome {
-    execute(Action::ArrowSelect { down, add })
+    run(|e| api::arrow_select(e, down, add))
 }
 
 // The elements below cross as the id of their file (UUID string) and, like the files, as
@@ -44,27 +41,12 @@ pub fn arrow_select(down: bool, add: bool) -> Outcome {
 // with the selection when it holds elements of the same kind in the same place (same file, same
 // track for segments), otherwise they replace it.
 
-pub(crate) fn select_elements(selection: Option<engine::Selection>, mode: SelectMode) -> Outcome {
-    match selection {
-        Some(selection) => execute(Action::Select {
-            selection,
-            mode: mode.into(),
-        }),
-        None => fail("the ids are not UUIDs"),
-    }
-}
-
 #[wasm_bindgen]
 pub fn select_tracks(file_id: &str, track_ids_bytes: &[u8], mode: SelectMode) -> Outcome {
-    select_elements(
-        parse_file_id(file_id)
-            .zip(uuid_list(track_ids_bytes))
-            .map(|(file_id, ids)| engine::Selection::Track {
-                file_id,
-                trk_ids: ids.into_iter().map(engine::TrackId).collect(),
-            }),
-        mode,
-    )
+    match parse_uuid(file_id).zip(uuid_list(track_ids_bytes)) {
+        Some((file_id, ids)) => run(|e| api::select_tracks(e, file_id, &ids, mode.into())),
+        None => fail("the ids are not UUIDs"),
+    }
 }
 
 #[wasm_bindgen]
@@ -74,37 +56,30 @@ pub fn select_segments(
     segment_ids_bytes: &[u8],
     mode: SelectMode,
 ) -> Outcome {
-    select_elements(
-        parse_file_id(file_id)
-            .zip(uuid::Uuid::parse_str(track_id).ok())
-            .zip(uuid_list(segment_ids_bytes))
-            .map(|((file_id, trk_id), ids)| engine::Selection::TrackSegment {
-                file_id,
-                trk_id: engine::TrackId(trk_id),
-                trkseg_ids: ids.into_iter().map(engine::TrackSegmentId).collect(),
-            }),
-        mode,
-    )
+    match parse_uuid(file_id)
+        .zip(parse_uuid(track_id))
+        .zip(uuid_list(segment_ids_bytes))
+    {
+        Some(((file_id, track_id), ids)) => {
+            run(|e| api::select_segments(e, file_id, track_id, &ids, mode.into()))
+        }
+        None => fail("the ids are not UUIDs"),
+    }
 }
 
 /// Selects the node standing for all the waypoints of a file.
 #[wasm_bindgen]
 pub fn select_waypoint_group(file_id: &str, mode: SelectMode) -> Outcome {
-    select_elements(
-        parse_file_id(file_id).map(|file_id| engine::Selection::Waypoints { file_id }),
-        mode,
-    )
+    match parse_uuid(file_id) {
+        Some(file_id) => run(|e| api::select_waypoint_group(e, file_id, mode.into())),
+        None => fail("the ids are not UUIDs"),
+    }
 }
 
 #[wasm_bindgen]
 pub fn select_waypoints(file_id: &str, waypoint_ids_bytes: &[u8], mode: SelectMode) -> Outcome {
-    select_elements(
-        parse_file_id(file_id)
-            .zip(uuid_list(waypoint_ids_bytes))
-            .map(|(file_id, ids)| engine::Selection::Waypoint {
-                file_id,
-                wpt_ids: ids.into_iter().map(engine::WaypointId).collect(),
-            }),
-        mode,
-    )
+    match parse_uuid(file_id).zip(uuid_list(waypoint_ids_bytes)) {
+        Some((file_id, ids)) => run(|e| api::select_waypoints(e, file_id, &ids, mode.into())),
+        None => fail("the ids are not UUIDs"),
+    }
 }
diff --git a/gpx-rs/wasm/src/session.rs b/wasm/src/session.rs
similarity index 50%
rename from gpx-rs/wasm/src/session.rs
rename to wasm/src/session.rs
index 24b4b326e..2366f6bf9 100644
--- a/gpx-rs/wasm/src/session.rs
+++ b/wasm/src/session.rs
@@ -1,11 +1,11 @@
-//! The engine that every function talks to, and the way actions reach it.
+//! The engine that every function talks to, and the way commands reach it.
 
 use std::cell::RefCell;
 
-use gpx_engine::{self as engine, Action, Command, Engine};
+use gpx_engine::{Engine, api};
 use wasm_bindgen::prelude::*;
 
-use crate::convert::outcome_object;
+use crate::convert::outcome_js;
 use crate::persistence::schedule_save;
 use crate::ts::Outcome;
 
@@ -15,25 +15,20 @@ thread_local! {
 
 /// What a call that does nothing returns, when the reason is in its arguments rather than in the
 /// engine: the call is not made.
-pub(crate) fn fail(message: impl AsRef<str>) -> Outcome {
-    outcome_object(&engine::Outcome::default(), Some(message.as_ref()))
+pub(crate) fn fail(message: impl Into<String>) -> Outcome {
+    outcome_js(&api::Outcome::failed(message))
 }
 
-/// Runs an action and tells what it did, see `Outcome` in `ts`.
-pub(crate) fn execute(action: Action) -> Outcome {
-    let outcome = match with_engine_mut(|engine| engine.execute(action)) {
-        Some(Ok(outcome)) => outcome,
-        Some(Err(error)) => return fail(error.to_string()),
-        None => return fail("the engine is not started"),
+/// Makes a call of the shared interface that edits the files or changes the selection, and tells
+/// what it did, see `Outcome` in `ts`. What changed in the files is saved.
+pub(crate) fn run(call: impl FnOnce(&mut Engine) -> api::Outcome) -> Outcome {
+    let Some(outcome) = with_engine_mut(call) else {
+        return fail("the engine is not started");
     };
-    if outcome.changed && (outcome.diff.is_some() || outcome.order_changed) {
+    if outcome.saves {
         schedule_save();
     }
-    outcome_object(&outcome, None)
-}
-
-pub(crate) fn edit(command: Command) -> Outcome {
-    execute(Action::Edit(command))
+    outcome_js(&outcome)
 }
 
 #[wasm_bindgen]
diff --git a/gpx-rs/wasm/src/tests.rs b/wasm/src/tests.rs
similarity index 98%
rename from gpx-rs/wasm/src/tests.rs
rename to wasm/src/tests.rs
index f4f79ed1f..ab084d18f 100644
--- a/gpx-rs/wasm/src/tests.rs
+++ b/wasm/src/tests.rs
@@ -13,9 +13,9 @@ use crate::session::*;
 use crate::ts::Outcome;
 use crate::types::*;
 
-const SIMPLE: &[u8] = include_bytes!("../../engine/data/simple.gpx");
-const WITH_TIME: &[u8] = include_bytes!("../../engine/data/with_time.gpx");
-const WITH_SURFACE: &[u8] = include_bytes!("../../engine/data/with_surface.gpx");
+const SIMPLE: &[u8] = include_bytes!("../../gpx-rs/data/simple.gpx");
+const WITH_TIME: &[u8] = include_bytes!("../../gpx-rs/data/with_time.gpx");
+const WITH_SURFACE: &[u8] = include_bytes!("../../gpx-rs/data/with_surface.gpx");
 
 thread_local! {
     static LAST: std::cell::RefCell<JsValue> = const { std::cell::RefCell::new(JsValue::UNDEFINED) };
diff --git a/gpx-rs/wasm/src/ts.rs b/wasm/src/ts.rs
similarity index 100%
rename from gpx-rs/wasm/src/ts.rs
rename to wasm/src/ts.rs
diff --git a/gpx-rs/wasm/src/types.rs b/wasm/src/types.rs
similarity index 100%
rename from gpx-rs/wasm/src/types.rs
rename to wasm/src/types.rs
diff --git a/website/package-lock.json b/website/package-lock.json
index 5d80bbb81..6ebd6cc74 100644
--- a/website/package-lock.json
+++ b/website/package-lock.json
@@ -15,7 +15,7 @@
                 "chart.js": "^4.5.1",
                 "chartjs-plugin-zoom": "^2.2.0",
                 "file-saver": "^2.0.5",
-                "gpx-rs": "file:../gpx-rs/pkg",
+                "gpx-wasm": "file:../wasm/pkg",
                 "jszip": "^3.10.1",
                 "mapillary-js": "^4.1.2",
                 "maplibre-gl": "^5.21.1",
@@ -92,6 +92,11 @@
         },
         "../gpx-rs/pkg": {
             "name": "gpx-rs",
+            "version": "0.1.0",
+            "extraneous": true
+        },
+        "../wasm/pkg": {
+            "name": "gpx-wasm",
             "version": "0.1.0"
         },
         "node_modules/@algolia/abtesting": {
@@ -3948,8 +3953,8 @@
                 "url": "https://github.com/sponsors/sindresorhus"
             }
         },
-        "node_modules/gpx-rs": {
-            "resolved": "../gpx-rs/pkg",
+        "node_modules/gpx-wasm": {
+            "resolved": "../wasm/pkg",
             "link": true
         },
         "node_modules/graceful-fs": {
diff --git a/website/package.json b/website/package.json
index b8756d0ca..f4a51d1e3 100644
--- a/website/package.json
+++ b/website/package.json
@@ -74,7 +74,7 @@
         "chart.js": "^4.5.1",
         "chartjs-plugin-zoom": "^2.2.0",
         "file-saver": "^2.0.5",
-        "gpx-rs": "file:../gpx-rs/pkg",
+        "gpx-wasm": "file:../wasm/pkg",
         "jszip": "^3.10.1",
         "mapillary-js": "^4.1.2",
         "maplibre-gl": "^5.21.1",
diff --git a/website/src/lib/engine/backend/tauri.ts b/website/src/lib/engine/backend/tauri.ts
index 45b34d477..764a81a4f 100644
--- a/website/src/lib/engine/backend/tauri.ts
+++ b/website/src/lib/engine/backend/tauri.ts
@@ -1,5 +1,5 @@
 import { invoke } from '@tauri-apps/api/core';
-import type { RouteAttributes, StorageOpened } from 'gpx-rs';
+import type { RouteAttributes, StorageOpened } from 'gpx-wasm';
 import type { Backend } from './types';
 
 /** An array that a command returns as its bytes. */
diff --git a/website/src/lib/engine/backend/types.ts b/website/src/lib/engine/backend/types.ts
index 1ab899e40..491136efe 100644
--- a/website/src/lib/engine/backend/types.ts
+++ b/website/src/lib/engine/backend/types.ts
@@ -9,13 +9,13 @@ import type {
     StorageOpened,
     TrackpointDetails,
     WaypointDetails,
-} from 'gpx-rs';
+} from 'gpx-wasm';
 import type { MergeType, SelectMode, SplitType } from '../types';
 
 /**
  * What the facade needs of the engine of the files, wherever it runs: the WASM module in the
  * browser (`wasm.ts`), or the Rust process of the desktop app, through its commands (`tauri.ts`).
- * Both give the same results: see `gpx-rs/wasm` for what each function does.
+ * Both give the same results: see `gpx-rs/src/api` for what each function does.
  *
  * Everything is asynchronous, because the desktop app is reached through messages. Ids are
  * hyphenated UUID strings, the arrays of numbers are typed arrays, and what the functions that
diff --git a/website/src/lib/engine/backend/wasm.ts b/website/src/lib/engine/backend/wasm.ts
index 033092ed5..9da58b5c7 100644
--- a/website/src/lib/engine/backend/wasm.ts
+++ b/website/src/lib/engine/backend/wasm.ts
@@ -1,7 +1,7 @@
 import type { Backend } from './types';
 import type { MergeType, SelectMode, SplitType } from '../types';
 
-type Wasm = typeof import('gpx-rs');
+type Wasm = typeof import('gpx-wasm');
 
 /** A call of the module, which is synchronous, as an asynchronous one. */
 const lift =
@@ -21,9 +21,9 @@ function idsToBytes(ids: string[]): Uint8Array {
     return bytes;
 }
 
-/** The engine in the page, as the WebAssembly module of `gpx-rs`. */
+/** The engine in the page, as the WebAssembly module of `wasm`. */
 export async function createWasmBackend(): Promise<Backend> {
-    const w: Wasm = await import('gpx-rs');
+    const w: Wasm = await import('gpx-wasm');
     w.start();
 
     const mode = (m: SelectMode) =>
diff --git a/website/src/lib/engine/engine.test.ts b/website/src/lib/engine/engine.test.ts
index b880385af..ddd1a42c6 100644
--- a/website/src/lib/engine/engine.test.ts
+++ b/website/src/lib/engine/engine.test.ts
@@ -1,5 +1,5 @@
-// The frontend side of the engine, against the real engine (the WASM module of `gpx-rs`, which has
-// to be built: `wasm-pack build wasm --target bundler --out-dir ../pkg` in `gpx-rs`).
+// The frontend side of the engine, against the real engine (the WASM module of `wasm`, which has
+// to be built: `wasm-pack build --target bundler` in `wasm`).
 import assert from 'node:assert/strict';
 import { readFileSync } from 'node:fs';
 import { beforeEach, describe, it } from 'node:test';
@@ -16,7 +16,7 @@ import {
 
 function fixture(name: string): Uint8Array {
     return new Uint8Array(
-        readFileSync(new URL(`../../../../gpx-rs/engine/data/${name}.gpx`, import.meta.url))
+        readFileSync(new URL(`../../../../gpx-rs/data/${name}.gpx`, import.meta.url))
     );
 }
 
diff --git a/website/src/lib/engine/engine.ts b/website/src/lib/engine/engine.ts
index 62cdb70b5..bbaa02b77 100644
--- a/website/src/lib/engine/engine.ts
+++ b/website/src/lib/engine/engine.ts
@@ -9,7 +9,7 @@ import {
 } from '$lib/engine/file-visibility';
 import { categoryIntervals } from '$lib/engine/trackpoint-categories';
 import { selectedElementIds, type FileTreeNode } from '$lib/engine/selection-helpers';
-import type { RouteAttributes } from 'gpx-rs';
+import type { RouteAttributes } from 'gpx-wasm';
 import { loadBackend, type Backend } from './backend';
 import { readFileState } from './file-state';
 import { StatisticsReader } from './statistics';
diff --git a/website/src/lib/engine/file-visibility.test.ts b/website/src/lib/engine/file-visibility.test.ts
index 84b6db04a..5443261d1 100644
--- a/website/src/lib/engine/file-visibility.test.ts
+++ b/website/src/lib/engine/file-visibility.test.ts
@@ -1,6 +1,6 @@
 import { describe, it } from 'node:test';
 import assert from 'node:assert/strict';
-import type { FileStructure } from 'gpx-rs';
+import type { FileStructure } from 'gpx-wasm';
 import {
     isHidden,
     isSegmentHidden,
diff --git a/website/src/lib/engine/file-visibility.ts b/website/src/lib/engine/file-visibility.ts
index d2f3c7dfd..8b413c2df 100644
--- a/website/src/lib/engine/file-visibility.ts
+++ b/website/src/lib/engine/file-visibility.ts
@@ -1,4 +1,4 @@
-import type { FileStructure } from 'gpx-rs';
+import type { FileStructure } from 'gpx-wasm';
 
 /**
  * Visibility the user set explicitly, by element id (file, track, segment, waypoint, or the
diff --git a/website/src/lib/engine/selection-helpers.test.ts b/website/src/lib/engine/selection-helpers.test.ts
index 4e6b59d96..b23279a01 100644
--- a/website/src/lib/engine/selection-helpers.test.ts
+++ b/website/src/lib/engine/selection-helpers.test.ts
@@ -1,6 +1,6 @@
 import { describe, it } from 'node:test';
 import assert from 'node:assert/strict';
-import type { Clipboard, FileStructure, Selection } from 'gpx-rs';
+import type { Clipboard, FileStructure, Selection } from 'gpx-wasm';
 import type { VisibilityState } from '$lib/engine/file-visibility';
 import {
     elementId,
diff --git a/website/src/lib/engine/selection-helpers.ts b/website/src/lib/engine/selection-helpers.ts
index 5f47b276a..0184e76db 100644
--- a/website/src/lib/engine/selection-helpers.ts
+++ b/website/src/lib/engine/selection-helpers.ts
@@ -1,4 +1,4 @@
-import type { Clipboard, Selection } from 'gpx-rs';
+import type { Clipboard, Selection } from 'gpx-wasm';
 import { isHidden, waypointsKey, type VisibilityState } from '$lib/engine/file-visibility';
 
 /**
diff --git a/website/src/lib/engine/storage.ts b/website/src/lib/engine/storage.ts
index a1d7f70c1..4b4abee4b 100644
--- a/website/src/lib/engine/storage.ts
+++ b/website/src/lib/engine/storage.ts
@@ -1,6 +1,6 @@
 import { LEGACY_IMPORTED_KEY, readLegacyData } from '$lib/storage/legacy-import';
 import { parseVisibility, VISIBILITY_KEY, type Visibility } from '$lib/engine/file-visibility';
-import type { Outcome, StorageOpened } from 'gpx-rs';
+import type { Outcome, StorageOpened } from 'gpx-wasm';
 import type { Backend } from './backend';
 
 /** Name of the IndexedDB database that keeps the files and the settings. */
diff --git a/website/src/lib/engine/types.ts b/website/src/lib/engine/types.ts
index a605794b4..7e643ce76 100644
--- a/website/src/lib/engine/types.ts
+++ b/website/src/lib/engine/types.ts
@@ -2,7 +2,7 @@ import type { Readable } from 'svelte/store';
 import type { Feature, FeatureCollection, LineString, Point } from 'geojson';
 import type { Visibility } from '$lib/engine/file-visibility';
 import type { CategoryIntervals } from '$lib/engine/trackpoint-categories';
-import type { FileStructure, GlobalStatistics } from 'gpx-rs';
+import type { FileStructure, GlobalStatistics } from 'gpx-wasm';
 
 export type {
     Clipboard,
@@ -17,7 +17,7 @@ export type {
     TrackNode,
     SegmentNode,
     WaypointNode,
-} from 'gpx-rs';
+} from 'gpx-wasm';
 
 /**
  * How a merge puts the selected elements together: `connect` makes a single segment of their
diff --git a/website/src/lib/scripts/example-statistics.ts b/website/src/lib/scripts/example-statistics.ts
index 3fd56ad04..3a8fe7a2f 100644
--- a/website/src/lib/scripts/example-statistics.ts
+++ b/website/src/lib/scripts/example-statistics.ts
@@ -6,8 +6,8 @@
  *
  *     npm run generate:example
  *
- * The engine has to be built (`wasm-pack build wasm --target bundler --out-dir ../pkg`, in
- * `gpx-rs`).
+ * The engine has to be built (`wasm-pack build --target bundler`, in
+ * `wasm`).
  */
 import fs from 'fs';
 import path from 'path';
@@ -16,26 +16,26 @@ import prettier from 'prettier';
 
 const here = path.dirname(fileURLToPath(import.meta.url));
 const example = path.resolve(here, '../data/example');
-const packageDirectory = path.resolve(here, '../../../../gpx-rs/pkg');
+const packageDirectory = path.resolve(here, '../../../../wasm/pkg');
 
 export const exampleGPX = path.join(example, 'example.gpx');
 export const exampleData = path.join(example, 'example-data.ts');
 
 /** Whether the engine is built. */
 export function engineIsBuilt() {
-    return fs.existsSync(path.join(packageDirectory, 'gpx_rs_bg.wasm'));
+    return fs.existsSync(path.join(packageDirectory, 'gpx_wasm_bg.wasm'));
 }
 
 /** Loads the engine in Node: the package is made for bundlers, which import the wasm file. */
 async function loadEngine() {
-    const glue = await import(pathToFileURL(path.join(packageDirectory, 'gpx_rs_bg.js')).href);
+    const glue = await import(pathToFileURL(path.join(packageDirectory, 'gpx_wasm_bg.js')).href);
     const { instance } = await WebAssembly.instantiate(
-        fs.readFileSync(path.join(packageDirectory, 'gpx_rs_bg.wasm')),
-        { './gpx_rs_bg.js': glue }
+        fs.readFileSync(path.join(packageDirectory, 'gpx_wasm_bg.wasm')),
+        { './gpx_wasm_bg.js': glue }
     );
     glue.__wbg_set_wasm(instance.exports);
     (instance.exports.__wbindgen_start as () => void)();
-    return glue as typeof import('gpx-rs');
+    return glue as typeof import('gpx-wasm');
 }
 
 type Values = Float64Array | BigInt64Array | undefined;