[colbymchenry]

Problem

The default ignore list skips every folder named build, at any depth, as build output (DEFAULT_IGNORE_DIRS → build/). JVM source roots were already exempt (#1642). JS/TS apps keep real source there too. luci-go's milo/ui keeps its whole LUCI "build" feature in src/build/ (src/build/legacy/build_page/build_page.tsx, src/build/pages/builder_page/…). A fresh index of it had 0 files under src/build/, so its routes' 19 lazy loads into @/build/... could never link, and none of that feature was visible to codegraph_explore.

The rule

Inside a src/ folder, a folder named build (any case) is walked. Only the files no compiler or bundler writes are indexed from it:

• Indexed: TypeScript (.ts, .tsx, .mts, .cts, ArkTS .ets), .jsx, .vue, .svelte and .astro.
• Still left out: .d.ts declarations, JavaScript (.js, .mjs, .cjs) and every other type, since a build may have written them. Every build/ folder outside src/ also stays out, whatever it holds.

Unchanged:

• The other defaults still apply inside such a folder (src/build/node_modules/, src/build/dist/).
• JVM packages named build keep every file, as with codegraph explore "RealtimePlusService" No relevant code found for "RealtimePlusService" #1642.
• The project's own root rules still win:
  • a .gitignore or codegraph.json exclude of the folder excludes it;
  • re-including the folder or a file (!src/build/, the documented opt-in) keeps every type in it, as before.

Implementation, all in src/extraction/index.ts:

• '!**/src/**/build/' joins DEFAULT_IGNORE_PATTERNS.
• buildDefaultIgnore / defaultsOnlyIgnore return a matcher whose ignores() applies the per-file rule on top of the patterns.
• Every consumer goes through those two factories: the git listing, the filesystem walk, the git-status sync, ScopeIgnore (scoped sync and the watcher), and the include collector. So the indexer, sync and watcher share one scope (Watcher scope diverges from indexer scope (.git/info/exclude, nested .gitignore) and every file event forces a full-project reconcile — 174k handles, 1.5-142s per single-file sync #1728).
• The rule reads paths only, never the disk, so it can't drift between the processes that evaluate it.
• Extensionless paths are left alone: they are directories, and a watcher event for a removed folder arrives without a trailing slash (Directory deletion not cascading to child file records in index #1285).

Why this rule: measured first

1. Sourcegraph regex search, file:(^|/)src/(.+/)?build/, exhaustive: 200,725 files in 3,572 repos, grouped into 8,147 build/ folders. Leaving out folders inside another default-ignored folder (a committed node_modules etc.) and JVM roots:
   • 741 folders (585 repos) hold TypeScript, JSX, Vue, Svelte or Astro files. They are source: packages/next/src/build, astro's src/core/build, docusaurus, nx executors, twenty, payload, mastra, pnpm, backstage, kibana, shopware, stencil, nitro, vitepress, RuoYi's src/views/tool/build/*.vue, milo. Six also hold output markers. These are mixed folders (a build script beside its output), and one of them only has TypeScript inside its own committed node_modules/, which stays excluded.
   • 568 folders (423 repos) hold only JavaScript. About half are output or vendored distributions: pdf.js and its pdf.worker.js, three.js, toastr, bootstrap plugins, YUI, CRA and Vite builds of apps nested under src/, Chrome devtools extension builds, Symfony Encore and Laravel public/build, WordPress wp-includes/build, Moodle amd/build, Vaadin bundles, Sphinx HTML. The rest is real JavaScript (SvelteKit's src/exports/vite/build/*.js, three-mesh-bvh, Yoast).
   • No output folder holds TypeScript or components. That is the signal the rule uses.
2. Path-only vetoes don't separate the two. Excluding static/, public/, assets/, resources/, webapp/ or wwwroot/ ancestors would drop source (astro's src/assets/build, primate's src/public/build, komodo's ui/src/resources/build, shopware) and still keep 60+ output folders.
3. A folder beside a package.json under src/ is either output (only JavaScript) or build tooling (kibana's src/dev/build, shopware's Vite plugins, both TypeScript). The per-file rule handles both without reading the disk.
4. GitHub code search, which only matches path prefixes, so root src/build/ only. 4,648 .ts, 151 .tsx, 117 .vue files against 2,176 .js. 479 folders were classified by listing each repo's tree:
   • 229 hold hand-written files and no output markers;
   • every output folder is JS-only, among them Flutter web builds, Sphinx HTML and cx_Freeze or py2app bundles. The bundles hold copied .py, which is why Python stays out of the rule.
5. The old kits (cgjsx, cgroute, cglzb; 50 JS/TS repos): milo's three folders were the only build/ folders below src/. All three are TypeScript.

Considered and not done:

• "Imported from indexed source" as the signal. Tests and servers import build output (require('../build/main.js'), a SvelteKit adapter's build/handler.js). The scope would also depend on file contents, so the watcher and sync would need persisted state to agree with the indexer.
• Reading each folder's contents. That needs the disk, so the decision could drift between the indexer, a long-lived watcher and scoped sync.

Verification

• __tests__/src-build-folders.test.ts, 6 tests:
  • scope parity for filesystem, untracked and tracked enumeration (buildDefaultIgnore, buildScopeIgnore, scanDirectory, scanDirectoryAsync, every folder on the way walkable);
  • explicit-rule precedence and the !src/build/ opt-in;
  • a milo-shaped React Router app: its lazy routes into @/build/... link, and an edit, a new page and new output under src/build/ go through getGitChangedFiles and cg.sync();
  • the watcher: a source edit there is pending and syncs scoped, output and outside-src events are dropped, and a removed subfolder schedules the full reconcile.
• Red on main, green here. All 6 fail against the src/extraction/index.ts of origin/main 24ea3c5 and pass with the change.
• The react-router-lazy-barrel.test.ts header said its fixture had to avoid build/. That comment is updated.
• tsc --noEmit is clean.
• Full suite on origin/main f43432c plus this change (kernel built, CODEGRAPH_KERNEL_EXPECT=1, --maxWorkers=4 --minWorkers=1): 7,595 tests, 7,515 passed, 0 failed, 80 skipped.
• On 6e68a11, the head this PR sits on (one Go-only commit later, fix(go): a constant in a const ( … ) group keeps its own doc comment #2680, which changed the kernel): rebuilt the kernel and reran tsc plus the new and touched test files, fix(go): a constant in a const ( … ) group keeps its own doc comment #2680's own test, extraction.test.ts (including the codegraph explore "RealtimePlusService" No relevant code found for "RealtimePlusService" #1642 suite), watcher.test.ts and every kernel parity suite: 19 files, 1,073 tests, all passed, none skipped.

A/B on real repos

Arms: origin/main 24ea3c5, and this branch on it. They differ only in dist/extraction/index.js, and both carry the same kernel. Each repo was indexed fresh with codegraph init -y and dumped with scripts/dump-graph.mjs.

Repo	Files	Edges touching new files	Elsewhere
luci-go milo/ui (git)	2,499 → 2,694 (+190 src/build/, +5 generated protos in src/proto/**/build/)	+4,966	−15 / +5 edges, −62 failed refs
milo/ui, plain folder (filesystem walk)	identical to the git checkout, in both arms
nitro	800 → 870	+2,329	−18 / +9 edges, −529 failed refs
astro (packages/astro)	3,070 → 3,119	+3,117	−19 / +9 edges, −581 failed refs
inventree frontend	571 → 580	+893	−3 edges, −10 failed refs
RuoYi-Vue3	161 → 167 (.vue)	+299	−1 edge, +1 unresolved
vitepress	275 → 280	+261	−8 failed refs
docusaurus (packages/docusaurus)	269 → 272	+130	−13 failed refs

milo: every one of the 19 lazy-route refs into @/build/... now links.

22 controls byte-identical between arms:

• Real build output under src/:
  • kkFileView's vendored pdf.js builds in server/src/main/resources/static/;
  • a CRA app's build/ nested in Games-and-Go's src/, and Mimi.jl's src/explorer/mimiexplorer-app/build;
  • calm-hub's Vite output in src/main/webapp/build;
  • phpip's Laravel src/public/build;
  • Reactime's devtools src/extension/build;
  • ziya's hashed src/build.
• Root CRA builds beside package.json: supertokens/dashboard, mihailgaberov/chat.
• Other cases:
  • vue-element-admin's root build/ tooling;
  • pypa/build's Python src/build/ package, which stays out because it isn't JS/TS;
  • SvelteKit's JS-only src/exports/vite/build.
• No build folder below src/: excalidraw, bulletproof-react, react-redux-realworld, proshop-v2, takenote, create-t3-turbo, matx, mantis, Folo, ghostfolio.

Triage of every edge that changed outside the newly indexed files:

• Wrong links on main, now right (20).
  • milo: 8 useBuildsClient calls and imports from @/build/hooks/prpc_clients had been name-matched to a namesake in src/common/hooks/.
  • nitro (8): imports of ./build/assets.ts, ../../src/build/virtual/{app,cache,public-assets}.ts and ../../src/build/unbundled/plugins.ts had been guessed onto other files and now resolve as imports.
  • astro (2): remote.test.ts imports dist/assets/build/remote.js and now reaches src/assets/build/remote.ts.
  • inventree (2): two routes now reach their page components instead of the lazy declarations in router.tsx.
• Same edge, lower confidence (23): these keep their target and drop from 0.9 to 0.7, because the new files add namesakes.
• Wrong before and after (9). All target outside libraries or dist builds, so name matching guessed one project namesake on main and another, at lower confidence, here:
  • astro: Rollup's plugin-context this.getModuleInfo() (6 calls), import build from '../dist/core/build/index.js' and zod's z.output;
  • nitro: a chained }).start().
• Wrong link now unresolved (1, RuoYi). import download from './download' passed as $download had been linked to a download function in src/utils/request.js. With a third namesake it is left unresolved, and silent beats wrong.
• Displaced by the JSX child cap (1, inventree). PartDetail renders more than MAX_JSX_CHILDREN (30) components. BuildOrderTable from src/tables/build/ now takes the 30th slot, and the later PageDetail tag falls past the cap. It has 30 children in both arms.
• Regression (2, milo), from an existing resolver gap.
  • src/gitiles/components/commit_table/context/index.ts writes export { DefaultExpandedProvider, … } from './context'. The named re-exports resolve by name match, not through ./context, on main too.
  • On main the only candidate was the right one. Now src/build/components/build_table/context.ts declares the same two constants, and the match moves there.
  • A five-file fixture reproduces the wrong link on main with no build folder involved: export { Provider } from './context' links to another file's Provider. I'll fix that separately (see Follow-ups).

Cost: the extra files only. Index times are within noise (milo 35.5 s → 32.0 s, nitro 7.6 s → 8.3 s, astro 17.8 s → 16.0 s).

Upgrading: codegraph sync with this build adds the src/build/ files to an index main built, on the git path (docusaurus) and in a plain folder (milo), so no re-index is needed.

Follow-ups (separate PRs)

1. Named re-exports (export { X } from './m') resolve through the module they name, not by name.
2. The same rule for Go, Rust and C#, whose toolchains never write source into a build folder. The survey has 87 such folders in 64 repos for Go (golang/go's src/go/build), 294 in 222 for Rust (turbopack, tauri, dioxus) and 130 in 77 for C# (roslyn, dotnet/wpf). PHP (WordPress writes build/*.php) and Python (frozen apps copy .py into build/) are not safe.

Not done:

• JavaScript-only source folders named build (SvelteKit's src/exports/vite/build). In the survey they are as often output as source, and no path-only signal tells them apart.
• Build folders outside src/ (config/build/*.ts webpack configs, VS Code's build/ tooling).

🤖 Generated with Claude Code