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/`.

app/api/config.py

@@ -1,12 +1,27 @@
 """Public app metadata (display name + version) for the frontend brand
 layer, the phase-59 docs-push flag (the "Save as doc" gating), and the
-phase-62 UI customization strings (composer placeholder, footer line,
-theme file name)."""
+phase-62 UI customization strings (composer placeholder, footer line).
+
+Phase 91 (task 01): the three UI strings are now the EFFECTIVE values —
+the ``ui_settings`` row (admin Theme tab) over the env values (B1: DB
+wins when set, env is the fallback), resolved by the SAME
+:func:`app.core.theming.effective_settings` resolver the
+``/api/ui-settings`` API uses, so the brand layer and the tab can never
+disagree. The route opens a short-lived session (the sync-endpoint
+house pattern — the route is sync, matching the middleware world).
+
+Phase 91 (task 03): the retired CSS-file theming's ``theme`` key is
+deleted with the mechanism — the five keys below are the entire
+contract (the colors never rode this endpoint; the server injects
+them pre-paint, :mod:`app.core.theming`).
+"""
 from __future__ import annotations
 
 from fastapi import APIRouter, Depends
 
 from app.config import Settings, get_settings
+from app.core import theming
+from app.db import SessionLocal
 
 router = APIRouter(tags=["config"])
 
@@ -15,17 +30,25 @@ router = APIRouter(tags=["config"])
 def app_config(settings: Settings = Depends(get_settings)) -> dict[str, str | bool]:  # noqa: B008
     """Public app metadata for the frontend brand layer (phase 39) +
     the phase-59 ``docs_repo_configured`` flag + the phase-62 UI
-    customization keys (``input_placeholder``, ``footer_text``,
-    ``theme``) — all display strings, the SAME boot fetch (no new
-    network surface) and the same public posture as ``app_name``
-    (no secrets). Values are passed through verbatim: the frontend
-    brand layer treats an empty string as "keep the template default"
-    (the unset => byte-identical contract)."""
+    customization keys (``input_placeholder``, ``footer_text``) — all
+    display strings, the SAME boot fetch (no new network surface) and
+    the same public posture as ``app_name`` (no secrets). Phase 91:
+    ``app_name`` / ``input_placeholder`` / ``footer_text`` are the
+    EFFECTIVE values (the admin Theme tab's ``ui_settings`` row over
+    the env values — DB-over-env, B1); the frontend brand layer treats
+    an empty string as "keep the template default" (the unset =>
+    byte-identical contract). Phase 91 (task 03): the retired
+    CSS-file theming's ``theme`` key is gone — the five keys are the
+    entire response."""
+    db = SessionLocal()
+    try:
+        effective = theming.effective_settings(db, settings)
+    finally:
+        db.close()
     return {
-        "app_name": settings.app_name,
+        "app_name": effective["app_name"],
         "version": settings.app_version,
         "docs_repo_configured": settings.docs_configured,
-        "input_placeholder": settings.input_placeholder,
-        "footer_text": settings.footer_text,
-        "theme": settings.theme,
+        "input_placeholder": effective["input_placeholder"],
+        "footer_text": effective["footer_text"],
     }