test(ui): the knob matrix — every control the round-4 defects lived behind

Six specs driving the user-reported controls the way a human does,
encoding the sweep rules COVERAGE.md now states: menus/modals assert
VISIBILITY (never DOM text — hidden menus' text is why the 2026-10-30
panel sweep certified dead controls), geometry asserts the z-ladder
via elementFromPoint and viewport containment via boundingBox, every
click must produce an observable outcome (PUT fired, class flipped,
chip text swapped) and zero new console problems — the silent
CSP-throw family (theme buttons, connective chip, invisible op menu)
now fails a test instead of surviving to a user's mouse.

Covers: theme picker (interpolation regression from eb57b720),
pencil-glyph vs card-body contract, builder field menu / op menu
(full non-empty vocabulary) / connective both directions, the
Smart→Episodes create-modal seed, the picker overlay's ladder and
height, and the chain-order select's persistence round-trip.

Fixtures self-create/self-delete under test-prefixed names; localStorage
token + selectedLibrary=__all__ are seeded because the API login
establishes only the cookie; run the folder with --workers=1 (the login
route rate-limits and all suites share testuser — a parallel worker's
login revokes another's mid-run).

tests/ui/COVERAGE.md

@@ -92,3 +92,35 @@ in a real browser against the dev stack. Outcomes + reusable gotchas:
   with queue=collection: play links → chain hops keep the param; order
   controls appear ONLY in feed mode (player + feed page share the
   persisted override).
+
+## 2026-10-31 — round 4: user-reported control defects → knob matrix (automated)
+
+The panel sweep's blind spot, proven by the user's own two minutes:
+DOM-text snapshots show HIDDEN menus' text — "the field menu opened"
+was an illusion; the menus never VISIBLY opened, the op menu rendered
+zero items, `closeCollectionModal` removed the hidden confirm dialog
+instead of the modal, and the theme buttons died silently
+(`selectTheme(opt.Name)` — templ gotcha #1, since the CSP migration).
+
+Now automated: `knob_matrix.spec.ts` (6 specs — theme picker PUTs,
+pencil-glyph vs card body at real coordinates, builder field/op menus
+with toBeVisible + non-empty items + connective both directions, the
+Smart→Episodes create-modal seed, picker modal ladder+geometry via
+`elementFromPoint`/`boundingBox`, chain-order select persistence).
+Run: `cd tests/ui && BH_FEED=<feed uuid> npx playwright test
+--workers=1` — **`--workers=1` is load-bearing**: the login endpoint
+rate-limits and every suite shares `testuser`, so a parallel worker's
+login revokes another's mid-run (symptom: `session has expired` pages).
+
+Standing rules for every sweep from now on:
+- Menus/modals assert VISIBILITY (toBeVisible / computed display /
+  screenshot), never DOM text; every toggle click has an asserted
+  observable outcome (request fired, class flipped, value changed).
+- Geometry asserts where geometry is the bug (z-ladder via
+  `elementFromPoint`, sheet within viewport via `boundingBox`).
+- Zero new console errors per interaction; the only tolerated noise is
+  the two cancelled-transition shapes swallowed by main.ts's gate —
+  new noise gets fixed at the source, never filtered.
+- API-mutating tests seed localStorage token + selectedLibrary=__all__
+  (the mutators read the bearer from localStorage; library-scoped views
+  correctly hide episodes).