Daily dead-code sweep 2026-10-16: the orphaned js/preferences.js

[EnesYilmazcode]

Daily automated dead-code sweep. node --test baseline was green before starting (942 tests, 938 pass, 4 skipped, 0 fail).

Open sweep PRs checked against first

Nine daily-sweep PRs are already open and unmerged: #178, #176, #175, #169, #148, #147, #146, #144, #143. I read every diff before looking for anything new. Between them they already claim: createWatch's id/open getters (state.js), attachGestures's priorTouchAction + teardown return (map.js), generation getter (directions.js), the i-bin/i-tick sprite symbols (index.html), MATRIX_MAX/matrix() (directions.js), TERM_NAMES (state.js), the #chips compatibility shim (index.html, expiry met), inBounds (campus.js), bestGap/inScheduledHours (engine.js/state.js), and allWeekCodes (state.js). None of that is touched here.

Finding: js/preferences.js is a whole module nothing in production reaches

Most certain — this is a full module, not just an export, and the proof is exhaustive rather than coverage-sampled.

• js/preferences.js (18 lines: the ROOM_FEATURES table and roomFeatureLabels()) is referenced exactly once anywhere in the repository outside itself: scripts/test/preferences.test.mjs's import. A case-insensitive grep for preferences across the whole tree turns up nothing else — no <script> tag, no static import, no dynamic import().
• The module graph from index.html's two script tags (js/pwa.js, js/app.js) was traced by hand: js/app.js has one dynamic import() in the whole codebase, and it targets js/dev.js, not this file. There is no computed/templated import path (import(\./${x}.js`)`-style) anywhere that could reach it at runtime.
• It is not in sw.js's SHELL_ASSETS precache list, so the service worker never fetches it either.
• git log on the file shows the real story: commit b9397a6 ("Remove the room needs filter", 2026-09-23, Enes's own commit) deleted the feature that called roomFeatureLabels() from index.html and js/app.js, but only trimmed js/preferences.js down to its current 18 lines instead of deleting it, and left its test alongside it.
• scripts/test/screens.test.mjs:826 already independently asserts the room screen's rendered markup does not reference roomFeatureLabels — a test written to pin down exactly the fact that makes this module dead.

Because this module is never loaded by any browser-reachable path (not merely "uncovered in the states I drove"), no runtime coverage run could add anything a complete module-graph trace hasn't already shown — there's no execution state in which Chrome would ever request the file. I did not spin up a coverage capture for this reason; the evidence here is a full trace of every static and dynamic import edge in the app, not a sample.

What would make me wrong: a reference to js/preferences.js or preferences that the grep missed (e.g. hidden in a binary/data file, which I did not scan), or some other way for a browser to fetch an un-imported .js file under /Vacant/ that I haven't considered.

Follow-on fix

privacy.html states the exact count of JavaScript files under js/, and scripts/test/follow.test.mjs checks that count against readdirSync. Removing the file drops the count from 15 to 14; privacy.html is updated to match (14 is written as a numeral, same as the test expects for counts above twelve).

sw.js's gzip figures are untouched — js/preferences.js was never part of SHELL_ASSETS, so nothing to re-stamp.

Not removed, not proven

Nothing else from this run. I ran the existing static checker (scripts/check-dead-code.mjs) for candidates and cross-referenced its "export used nowhere" logic (which is blind to test-only-reachable exports, same gap the prior sweep PRs exploited) against all nine open PRs' diffs; the one new survivor was the module above.

Verification

• node --test: 941 tests, 937 pass, 0 fail, 4 skipped (942→941 total from the one removed test; 938→937 pass).
• node scripts/check-dead-code.mjs: no dead code.
• No screenshots touch js/preferences.js or anything in its dead path, so scripts/shoot.mjs --check was not run for this change.

🤖 Generated with Claude Code

https://claude.ai/code/session_016RTHekdsXHLYUvG6qYHA4J

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