# ui/ — the `codegraph ui` viewer The browser reader for an indexed project: Svelte 5 + Vite, built as static files and served by the CLI over loopback. An npm workspace of the engine, so `npm ci` at the repo root installs its toolchain; nothing here is a runtime dependency of the engine and nothing here is published to npm on its own. Design spec (every token, size and measurement): `../docs/design/codegraph-ui-design-spec.md`. ## Build ```bash npm run build # from the repo root: tsc -> copy-assets -> this app npm run build:ui # just this app, plus the dist assertion npm run dev -w ui # Vite dev server on 127.0.0.1:5174 npm run check -w ui # svelte-check ``` `npm run build` emits **`dist/viewer/`** (`index.html` + hashed assets). `scripts/check-ui-build.mjs` then asserts the tree is complete, so a broken UI build fails the release instead of shipping a CLI that serves a 404. The same check runs again in `scripts/build-bundle.sh` (after the bundle stage copies `dist`) and in `scripts/pack-npm.sh` (after each archive is unpacked). ### Why `dist/viewer` and not `dist/ui` `src/ui/` is the engine's **terminal** UI (shimmer progress and its worker) and tsc compiles it to `dist/ui/`. Pointing Vite there deletes those modules — the CLI then dies at startup with `Cannot find module '../ui/shimmer-progress'` — and would also leave the static server handing out compiled engine internals. `check-ui-build.mjs` re-asserts the compiled engine is intact after every UI build so that mistake cannot land twice. ## Layout ``` src/ main.ts fonts + tokens, mounts App into index.html's #app app.css design tokens (light/dark), reset, shell grid App.svelte top bar / trail bar / main, global keys lib/router.svelte.ts hash router: #/s/, #/file/, #/map, #/flow, #/entry lib/trail.svelte.ts the walked path; mirrored into the `t` query param lib/kinds.ts kind glyph letters lib/map-model.ts the Map's deterministic layered layout (pure) lib/flow-model.ts the Flow strip's card/link geometry + the end cap — a DAG (pure) lib/filecode-model.ts the whole-file view: fixed line height, arcs, paging (pure) lib/entry-model.ts the entry-points panel: rows, file groups, flow arming (pure) lib/live.svelte.ts /api/events: two counters every screen refreshes from lib/toast.svelte.ts the one transient note ("Index updated · reloaded") components/ TopBar, TrailBar, KindGlyph, DriftBanner, Toast, map/, flow/, symbol/, file/, entry/ views/ one component per route ``` Fonts (Archivo Variable, IBM Plex Mono) are vendored through `@fontsource*` and emitted into `dist/viewer/assets`: a local reader must work offline and must not announce the project to a font CDN. ## Routes | hash | view | |---|---| | `#/` | nothing selected | | `#/s/?hl=&t=` | symbol view | | `#/file/?hl=` | file view — outline in source order | | `#/file/?src=1` | file view — the whole file's source, with ports and call arcs | | `#/map?root=&depth=&tests=1` | module map | | `#/flow?from=&to=` | flow strip — the call path between two symbols | | `#/flow?symbols=a,b,c` | flow strip — `codegraph_explore`'s own question | | `#/flow?t=` | flow strip — the trail you walked, read as a flow | | `#/entry` | entry points — routes, files that run something, tests, hubs | ## Entry points `#/entry` draws `/api/entrypoints` as file groups, reusing the Symbol view's `.filegroup` / `.row` shapes rather than inventing a second visual language for "a list of code, grouped by where it lives". Three things about it are decisions, not accidents: - **Routes group by where the URL is REGISTERED, not where it is served.** A router file is the shape a reader already has in mind; handlers scatter across a package. The payload carries both, and the row's meta line names the handler and its `file:line`. - **A row offers a flow only if it names a callable symbol.** `/api/flow` searches the graph by NAME, and a file has none the path finder can look up — so route and hub rows carry a `Flow ›` chip and file and test rows do not. A chip that always failed would be worse than no chip. - **No empty Routes box.** A project with fewer than three resolvable routes is not a routed app, and the section is absent rather than empty; the panel falls back to the files that run something and the tests that exercise them. `buildEntryPanel` is pure and keeps `panel.rows` exactly equal to the sections it draws, the same identity the search palette rests its keyboard on. ## Where the graph stops A flow that does not reach everything it was asked about carries a `boundary` on the wire, and `buildFlowLayout` turns it into an extra 240px node one column past the symbol the path stopped at, joined by a dotted `2 4` link labelled "end of static path" that deliberately has **no arrowhead** — an arrow would point at a continuation, and the absence of one is the finding. Two rules hold it together: - **The cap's height is arithmetic, like a card's.** `endCapText()` builds every sentence the cap shows and `endCapHeight()` measures them; the component then renders exactly what was measured. Change the wording in one and the other moves with it — they are the same function read twice. - **One cap per stopping symbol, not per flow.** Two paths that run out at the same place ran out for the same reason, and two caps side by side would read as two different findings. The verdict itself is not computed here or in the server: it is `findDynamicBoundaries` in `src/graph/dynamic-boundary-report.ts`, the same detector `codegraph_explore` announces boundaries with. ## Live updates The viewer never polls. `lib/live.svelte.ts` holds one `EventSource` on `/api/events` for the life of the page and exposes two counters: - **`indexTick`** — the graph moved (somebody synced). Every screen refetches: a rail is an answer about the whole graph, and a symbol gains a caller when some *other* file is edited, so filtering by the focused file would leave the rails quietly wrong. One request per sync. - **`diskTick`** — source files changed on disk and the index has not caught up. Only the screen showing one of those files reacts, and what it does is draw a drift banner. `liveRefresh(file, refresh)` is the three lines of bookkeeping that turns a counter into a single call; the Map and the Flow strip instead read `live.indexTick` straight inside the effect that already fetches them. Reconnection is ours, not `EventSource`'s: each failure closes the stream and schedules ONE retry on a backoff that ends after eight attempts (~90 s), at which point the top bar says "Not live" and nothing more is requested until the tab is focused again. A `degraded` event — the server's watcher gave up — is shown the same way and never answered with a poll. Node ids and file paths are encoded per slash-separated segment, so `#/file/src/mcp/tools.ts` stays readable and still round-trips a segment containing a reserved character. Build hashes with `symbolHref()` / `fileHref()` / `mapHref()` / `flowHref()` rather than by hand.