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/`.

frontend/assets/header.js

@@ -219,6 +219,13 @@ export async function initSharedHeader() {
   // pages) is a no-op. A token user (role "user") never sees it.
   const navTokens = document.querySelector("#nav-tokens");
   if (navTokens) navTokens.hidden = !admin;
+  // Phase 91 (task 04): the Theme nav link (the shell's seventh view —
+  // the phase-34 one-bar contract ships it on every page's nav) —
+  // admin-only, the same ship-hidden / reveal-for-admin contract as
+  // the Tokens link above. Null-safe: a page without the link is a
+  // no-op. A token user (role "user") never sees it.
+  const navTheme = document.querySelector("#nav-theme");
+  if (navTheme) navTheme.hidden = !admin;
   // Phase 34: the steering panel (phase 15) is module-owned. The
   // navbar #steering-toggle was removed at owner request (2026-08-28)
   // — the panel ships hidden and is only kept fresh. Admin: refresh