vectorcraft/docs/development.md

Development

Web build

apps/vectorcraft-web runs the same VectorcraftApp in the browser through eframe's web runner. The renderer is wgpu: WebGPU where the browser has it, WebGL2 otherwise. It is Rust only; the only JavaScript is the glue wasm-bindgen generates.

brew install trunk                 # or: cargo install trunk --locked
rustup target add wasm32-unknown-unknown
cd apps/vectorcraft-web
trunk build --release              # writes ../../dist/web (index.html, .js glue, .wasm)
trunk serve --release              # dev server on http://127.0.0.1:8766

Any static file server works for dist/web, for example python3 -m http.server 8766 inside that directory. The release .wasm is about 17.5 MB, or 7.1 MB gzipped, so serve it with compression.

URL flag: ?webgl forces the WebGL2 backend.

How the web shell (apps/vectorcraft-web/src/web.rs) differs from desktop:

• Open sets Services::open_async, which shows rfd::AsyncFileDialog. The bytes arrive in Services::inbox, which the app drains every frame.
• Save / Save As / Export go through Services::download: a Blob, an object URL and a temporary <a download>, all created from Rust. There is no save dialog, so the suggested name becomes the download name.
• Drag-and-drop: WebShell takes the frame's dropped_files before the app sees them, reads each with DroppedFile::bytes_async and pushes the bytes into the inbox. (The app's synchronous drop path is compiled out on wasm32.)
• No control server: browsers can't listen on TCP. To automate the web build, drive headless Chrome with --remote-debugging-port.
• Quick smoke test: "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" --headless=new --enable-unsafe-webgpu --screenshot=web.png --window-size=1440,900 --virtual-time-budget=15000 http://127.0.0.1:8766/ (headless Chrome on macOS gets a real WebGPU adapter).

Desktop graphics processor

The canvas is rasterized on the CPU (vectorcraft-render, vello_cpu); the GPU (wgpu, through eframe) only composites the canvas texture and draws the UI. The desktop app (apps/vectorcraft/src/main.rs) therefore asks wgpu for the power-saving adapter by default, which is the integrated GPU on hybrid-graphics laptops. Presenting frames rendered on a discrete GPU through the integrated one made the window flicker on some laptops (#306). A machine with one GPU gets that GPU either way.

• Preferences › Performance › Graphics Processor (gpuPreference: powerSaving or highPerformance) picks the other one. The adapter is chosen when the window opens, so a change applies after a restart.
• The WGPU_POWER_PREF environment variable (low, high or none) overrides the preference.
• Help › About and the control channel's ui.inspect (graphicsAdapter) show the adapter in use, and the app logs it at startup.

Fonts: craft-fonts (optional build input)

Font files are never committed to this repository. Fonts shared by the Crafting Apps live in storytold/craft-fonts; the rules are in craftrules standards/fonts.md. To add a font, add it there. (The Latin fonts in assets/fonts/ predate the rule and stay.)

VectorCraft builds, tests and runs without craft-fonts. To embed its Japanese fonts (BIZ UDPGothic for UI text, Shippori Mincho and BIZ UDMincho for document text), point the CRAFT_FONTS_DIR build option at a checkout:

git clone https://github.com/storytold/craft-fonts ../craft-fonts
CRAFT_FONTS_DIR="$PWD/../craft-fonts" cargo run --release -p vectorcraft
CRAFT_FONTS_DIR="$PWD/../craft-fonts" cargo xtask ci   # also runs the Japanese-glyph tests

• crates/text/build.rs reads the checkout's fonts/manifest.txt and embeds every font it lists as vectorcraft_text::CRAFT_FONTS (empty without CRAFT_FONTS_DIR). Give it an absolute path: build scripts run in the crate's directory (a relative path is taken from the workspace root as a convenience, but CI and the docs always use absolute paths). Nothing is downloaded, and craft-fonts is never a Cargo.toml dependency. A bad path is a build warning, or an error with CRAFT_FONTS_REQUIRED=1 (release builds).
• Web (wasm32) builds embed only BIZ UDPGothic Regular (+4.7 MB of .wasm), to stay well under static hosts' per-file limits (Cloudflare Pages: 25 MiB). Shippori Mincho, which this repo used to embed everywhere, was 8.7 MB, so the web build is still smaller than before.
• Document text: the Japanese faces join the font database after the bundled fonts (Mincho first), so they are the fallback for Japanese after the requested font; installed system fonts come after.
• UI: theme::install_fonts adds them at the end of every egui family (BIZ UDPGothic first), after the UI fonts and before the installed fonts ui_fonts.rs discovers for other scripts.
• Tests that need Japanese glyphs skip with a message when built without craft-fonts. The FreeBSD CI job and every release job (release.yml) check craft-fonts out at a pinned commit; release packages carry each embedded font's OFL-<family>.txt.

Localisation

Strings in code stay English and are the default lookup keys. crates/ui-egui/src/i18n maps them to display text at render time from one catalog per language (i18n/<code>.tsv; the format is documented in the header of zh-hant.tsv). Command ids, menu paths used for logic, ui.menu.list, the control channel, the CLI and MCP always use the English ids and labels, so agents and scripts never see translated text.

Languages shipped: English (en, the source), Traditional Chinese (zh-hant, complete, in the vocabulary used in Taiwan; zh-TW, zh-HK, zh-MO and zh-Hant-* locales all resolve to it), Japanese (ja, complete), Czech (cs, every menu label) and Brazilian Portuguese (pt-br, every menu label and every tl! literal). Untranslated text falls back to English until its rows are added. Simplified Chinese locales (zh-CN, zh-SG, zh-Hans) fall back to English until a zh-hans catalog is registered: the resolver already tells the two scripts apart, so the Traditional catalog is never shown to a Simplified locale.

• tl!("…") translates a literal into the language the UI is drawn in; i18n::t(s) is the same for a &str. tr(lang, s) takes the language; tr_ctx when one English word needs different translations; tr_id(lang, command_id, label) for menu items (keyed by command id, English label as the fallback); tn / trn(lang, n, one, other) for plurals; fmt fills {name} placeholders, which a translation may reorder.
• The shared widgets (widgets::check, dropdown, menu_item, the buttons, label_row, tooltips of icon_button…), the menus, the dock, the toolbar, the dialog frame and panels::empty_state translate the text they are given, so a panel mostly needs its literals wrapped in tl! to be covered by the tests.
• The language is VectorCraft › Language (the app.language UI command, {lang: auto|<code>}) or Edit › Preferences › User Interface › Language; both set the interfaceLanguage preference (auto or a language code; auto follows the system locale: VECTORCRAFT_LOCALE, then LC_ALL/LC_MESSAGES/LANG/LANGUAGE, the macOS preferred languages, the Windows user locale). The web build has no locale detection yet and starts in English. The Preferences dialog previews the chosen language before OK.
• To add a language: add <code>.tsv and one row in i18n::LANGUAGES (code, native name, catalog, plural rule). The Language menu, the dropdown, locale matching and the catalog tests (well-formed, no duplicates, placeholders and ellipses agree, command ids exist, every row of a partial catalog is a string the UI shows, the UI fonts have every glyph, no Simplified characters in zh-hant) pick it up. Set complete_menus once every menu string and tl! literal is translated; i18n::tests then enforce it (VECTORCRAFT_I18N_DUMP=strings.txt cargo test -p vectorcraft-ui-egui dump_source_strings lists them).
• Translations are clean-room: written from the meaning of the English text in ordinary vocabulary, never from another product's localisation resources. Product and technology names stay in Latin letters.
• Not translated on purpose: status-bar messages and errors (agents and tests read them), names that are user data (layers, swatches, fonts, documents), the tab title's colour mode. Not done yet: locale-aware number and date formats, right-to-left layout, locale detection on the web. Chinese and Japanese UI text is drawn with craft-fonts' BIZ UDPGothic when the build embeds it (see Fonts above), else with an installed system font; the glyph test checks Latin-script catalogs always and the CJK ones only with craft-fonts. A Traditional Chinese UI font is still to be added to craft-fonts for the web build.

Vendor names gate

cargo xtask brands (part of cargo xtask ci) fails when user-visible text names another vendor's products or company: string literals in Rust sources (command labels and params docs, menus, panels, MCP tool definitions), Cargo.toml descriptions and packaging files. Comments and test code are not checked. Say "the reference app" or name the feature itself. A line that must keep an old name, such as an alias that files or preferences from earlier versions still use, carries a brand-ok comment.

Robustness: VectorCraft never crashes

A crash takes the user's unsaved work with it, and much of what the app reads is untrusted: SVG, PDF, .ai and .vectorcraft files, pasted data, MCP and control-channel messages, command parameters. Shipped code therefore never panics. Anything that can fail returns Result (or Option), the caller handles or propagates it, and the user sees an error message.

Enforced by lints

Cargo.toml denies these clippy lints for the whole workspace, and cargo xtask ci runs clippy with -D warnings:

Banned in shipped code	Use instead
x.unwrap(), x.expect("…")	x?, x.ok_or(err)?, let Some(v) = x else { return … }, if let, unwrap_or / unwrap_or_default / unwrap_or_else
v.last().unwrap(), v.pop().unwrap()	if let Some(l) = v.last_mut(), let Some((last, rest)) = v.split_last() else { … }
panic!, unreachable!() in a match arm	return an error (EngineError::Other, bad(C, "…")) or a sensible default
todo!, unimplemented!	don't merge unfinished paths; return an error that says what isn't supported

clippy.toml allows unwrap, expect and panic inside #[test] and #[cfg(test)] code. Integration-test files under tests/ and examples/, and the testkit crate, opt out with #![allow(clippy::unwrap_used, clippy::expect_used, clippy::panic)]. Tests use panic!("…") instead of unreachable!().

Not caught by lints: avoid implicit panics too

• Indexing and slicing: v[i] and &s[a..b] panic when out of range. When the index comes from data (a file, a parameter, another document), use v.get(i) / s.get(a..b). Slicing a &str also panics off a UTF-8 boundary.
• Arithmetic: integer division or % by zero, usize subtraction that can go below zero (write i + 1 == n instead of i == n - 1, or use saturating_sub), and as casts from non-finite floats.
• Unbounded work: cap counts, sizes and allocations read from input. Image dimensions, repeat counts, line breaks and recursion depth all need a limit.
• Encoders and decoders: propagate their errors. Writing an empty file is a silent failure, not a fix.

Don't silence the lint by discarding errors. let _ = … and .ok() are for failures that really don't matter, with a comment saying why.

The safety net

vectorcraft_engine::guard::catch_panic wraps every entry point:

• Session::execute restores the active document, selection and interaction as they were before the top-level command and returns EngineError::Internal.
• Tool events (Session::pointer, tool_key, tool_text) reset the tool and cancel its drag.
• The MCP server answers the request with a JSON-RPC internal error and keeps serving.
• VectorcraftApp::logic and ui lose one frame and show the error in the status bar; each control-channel request is guarded on its own.

The net exists for bugs, not as a substitute for Result. On wasm a panic aborts the app, so the web build has no net at all.

Fuzzing

Untrusted input has property tests that must never panic:

• crates/engine/tests/import_fuzz.rs: garbage, hostile and mutated SVG and PDF, and swatch (.vcswatches, .gpl), graphic style (.vcstyles) and flattener preset (.vcflattener) libraries, loaded and used, then rendered and exported.
• crates/engine/tests/command_sweep.rs: every command with junk parameters.
• crates/format/tests/prop_format.rs: garbage and mutated .vectorcraft files.
• crates/mcp/tests/protocol_props.rs: malformed MCP messages.

CI runs a few dozen cases each. Before touching an importer, run a deeper search, e.g. PROPTEST_CASES=20000 cargo test --release -p vectorcraft-engine --test import_fuzz. When it finds a panic, fix the code and add the input as a regular test.