phase: 91_admin_theme_tab

All verification is complete — this pass needed no code changes. Final report:

**Phase 91 — Admin Theme tab: final verification pass (all 6 tasks already in `complete/`)**

- Verified pre-paint theming end-to-end: `ui_settings` store + resolver, admin `GET/PUT /api/ui-settings`, `CachingMiddleware` inline-`<style id="bor-theme">` injection before `</head>` (incl. `/shared/<token>` prefix branch, unit-pinned), CSP sha256 exemption for the inline tag, Theme tab shell + `theme.js` editor, CSS-file theming fully retired.
- No defects found; zero changes made — working tree left exactly as the task executors left it.
- Tests: `uv run pytest --cov=app` → 1841 passed, 0 failed (TOTAL coverage **99%**; theming/ui_settings/caching all 100%); `uv run pytest tests/e2e/test_admin_theme_tab.py -v --no-cov` → **5 passed** in isolation.
- Lint/types: `uv run ruff check .` → All checks passed; `uv run pyright` → 0 errors, 0 warnings.
- Criteria: (1) unset deployment byte-identical, no `#bor-theme` anywhere — ✓ (unit no-op test + E2E reset byte-compare); `rg "BOR_THEME|themes/"` → single hit is the permitted doc-history comment in `frontend/index.html`. (2) admin-only gate + 403s for anonymous and token users — ✓ (E2E test 3). (3) saved theme inline before `</head>` on every page incl. `/shared/<token>`, computed `--brand` on first paint for admin + anonymous — ✓ (E2E test 2 + unit). (4) reset → byte-identical; 5 contrast pairs warn <4.5:1, non-blocking — ✓ (E2E tests 4–5). (5) suite green, >90% coverage, lint clean — ✓. (6) commit deferred to harness per rules.
- Notable: `.agents/PLAN.md` is absent from the repo — the phase overview's Design section was used as the binding spec; no deviation resulted.
- Next pending phase: **none** — 91 is the last phase in `todo/`.

tests/unit/test_wide_column_css.py

@@ -168,20 +168,23 @@ def test_tuning_shell_stays_hardcoded_46rem() -> None:
 
 def test_no_other_hardcoded_46rem_rule_remains() -> None:
     """After the switch, the form columns are the ONLY rules with a
-    literal max-width: 46rem: .tuning-shell (phase 27) and
+    literal max-width: 46rem: .tuning-shell (phase 27),
     .doc-edit-shell (phase 59, task 06 — the doc edit screen is a
     FORM column, not a reading column, so it must not ride
     --chat-column and phase 58's wide-desktop doubling must never
-    stretch the form). Every reading column rides the token (the
-    --chat-column base declaration is the other non-rule occurrence
-    of 46rem)."""
+    stretch the form), and .theme-shell (phase 91 task 04 — the
+    admin Theme editor is a form column too: the palette grid +
+    fieldsets must never ride the wide-desktop doubling). Every
+    reading column rides the token (the --chat-column base
+    declaration is the other non-rule occurrence of 46rem)."""
     css = _css()
-    assert css.count("max-width: 46rem") == 2, (
-        "only the form columns (.tuning-shell, .doc-edit-shell) may "
-        "keep a literal max-width: 46rem"
+    assert css.count("max-width: 46rem") == 3, (
+        "only the form columns (.tuning-shell, .doc-edit-shell, "
+        ".theme-shell) may keep a literal max-width: 46rem"
     )
     assert "max-width: 46rem" in _rule_block(css, ".tuning-shell")
     assert "max-width: 46rem" in _rule_block(css, ".doc-edit-shell")
+    assert "max-width: 46rem" in _rule_block(css, ".theme-shell")
 
 
 def test_comments_cite_the_wide_override_with_provenance() -> None: