feat(brand): configurable app name — BOR_APP_NAME drives /api/config + the frontend brand layer

One env var (BOR_APP_NAME, default "Brain of Reese") now drives the app's
display name everywhere (TODO.md L12 — owner ask: "a way to customize the
name for 'Brain of'. Should be an env var."). The existing app_name setting
is the source of truth (phase locked decision — no new variable, no rename);
with the variable unset the app is byte-identical to before.

Endpoint (A10 public/stateless, no secrets):
  GET /api/config → exactly {app_name, version} (app/api/config.py, the
  health.py pattern; registered before the static mount). Integration tests:
  anonymous 200, default values, a Settings override follows, key set is
  exactly two keys — no other setting may leak in later.

Frontend brand layer (A11 — runtime fetch, static templates stay static):
  assets/brand.js — a CLASSIC script, first on all six pages, so its top
  level runs at parse time: window.BOR_BRAND = "Brain of Reese"
  synchronously (the default renders immediately, no blank flash), then a
  no-store fetch of /api/config applies the name — document.title (global
  replace), every .brand-text (a name starting "Brain of " keeps the bold
  split Brain of <strong>rest</strong>, any other name renders plain; the
  operator-controlled name is HTML-escaped before innerHTML), a TreeWalker
  over text nodes (script/style rejected — page source never rewritten),
  and the aria-label/placeholder/meta-content attributes. Fetch failure
  keeps the default + console.warn (the loadHealth house style).
  app.js (status labels, typing label, elapsed-hint aria, tool labels) and
  document.js (viewer titles) read window.BOR_BRAND at CALL time via
  brand() — a label set after the fetch lands carries the configured name.
  Containerfile: esbuild minify line for brand.js (classic, like markdown.js);
  the phase-33 ?v= cache-busting picks the new asset ref up automatically.

E2E (A16 — one story, one file, isolated): test_configurable_brand.py boots
a SECOND app instance (same DB/mock-LLM/admin-auth env block, port APP_PORT+1,
BOR_APP_NAME="Brain of Testy") — the shared conftest server keeps the
default name so every other suite's title/label assertions stay untouched —
and asserts /api/config on both instances, the index title/brand/greeting/
#messages aria-label, the sources + login page titles, and one pre-token
chat turn (think out loud marker) whose #send-status reads "Brain of Testy
is thinking"; the no-op regression pins the shared server's default bytes.

Docs: .env.example App section + README configuration reference — what it
affects (titles, header brand, status labels, aria text), the default, the
bold-split rendering rule.

Gates: 695 unit+integration passed, app/ coverage 99% (>90%), story E2E
green in isolation (two consecutive runs), brand-string suites (smoke,
shared header, header consistency, chat persistence) green, ruff + pyright
clean.

.agent/phases/todo/39_configurable_brand/00_phase.md

@@ -0,0 +1,39 @@
+# Phase 39 — Configurable app name (brand)
+
+**Source:** `TODO.md` L12 — "Also need a way to customize the name for 'Brain of'. Should be an env var."
+**Story:** `.agent/user_stories/configurable-brand.md`
+**Context:** `app/config.py` (`app_name`, already `BOR_APP_NAME`, currently used only for the OpenAPI title at `app/main.py:48`), the five templates (`frontend/*.html` — the `.brand-text` spans, the `<title>`s, the meta descriptions, the index empty-state h1, the `aria-label`s), `frontend/assets/app.js` (status labels ~L107/112, the elapsed-hint aria ~L540), `frontend/assets/document.js` (page titles L147/152), `app/api/health.py` (the public stateless endpoint pattern), `app/core/caching.py` (phase 33: `?v=` rewriting of `assets/…` refs — automatic for any new asset file), the `Containerfile` esbuild stage (explicit per-asset lines, L17–23).
+
+## Objective
+Make **one env var** (`BOR_APP_NAME`, default "Brain of Reese") drive the app's display name everywhere — titles, the header brand, the status labels, the aria text, the greeting — via a public `/api/config` endpoint + a small `brand.js`, with zero behavior change when the variable is unset.
+
+## Dependencies
+- `34_consistent_navbar` (todo — runs before this phase) — the standard five-page header (the `.brand-text` nodes this phase re-skins).
+- `01_infrastructure` (complete) — the public stateless endpoint pattern (`app/api/health.py`).
+
+## Tasks
+1. `01_config_endpoint.md` — public `GET /api/config` → `{app_name, version}` + tests.
+2. `02_frontend_branding.md` — `brand.js` + the template/JS de-hard-coding + the Containerfile build line.
+3. `03_e2e_docs_commit.md` — the story E2E (its own app instance with the overridden name), `.env.example` + README, commit, move the phase dir.
+
+## Testing & Quality
+- Unit/integration: the endpoint (200, the values, anonymous access, exactly two keys — no settings may leak later).
+- E2E (mandatory, A16): `tests/e2e/test_configurable_brand.py` — a **second** app instance booted with `BOR_APP_NAME` overridden; run in isolation.
+- Coverage: **>90%** on `app/`.
+- Regression: the default-name behavior is byte-identical — the existing suites (which assert "Brain of Reese" titles/labels against the shared conftest server) stay green **unchanged**.
+
+## Completion Criteria
+- [ ] `GET /api/config` (anonymous) → `{"app_name": "Brain of Reese", "version": "0.1.0"}` by default; the response key set is exactly `{app_name, version}`.
+- [ ] With `BOR_APP_NAME="Brain of Testy"`: the index title "Brain of Testy"; the header `.brand-text` renders `Brain of <strong>Testy</strong>`; the empty-state h1 "Hey! I'm Brain of Testy."; the `#messages` aria-label "Conversation with Brain of Testy"; the chat status label "Brain of Testy is thinking"; the other pages' titles carry the name; the document viewer title "… · Brain of Testy".
+- [ ] With the variable unset: the existing E2E + unit suites green unchanged (no rename leak).
+- [ ] `uv run pytest` green; `uv run pytest --cov=app --cov-report=term-missing` >90%; `uv run pytest tests/e2e/test_configurable_brand.py -v --no-cov` green in isolation.
+- [ ] `uv run ruff check . && uv run pyright` clean.
+- [ ] UI Structure Check (AGENTS.md rule 5) + no CDN (rule 6).
+- [ ] One `--no-gpg-sign` commit; phase directory moved to `.agent/phases/complete/`.
+
+## Locked decisions
+- **The existing `app_name` setting is the source of truth (owner permission 2026-08-26)** — `BOR_APP_NAME` (default "Brain of Reese"); no new variable, no setting rename.
+- **A11 honoured** — runtime fetch + JS application (no build-time template injection, no Jinja, no CDN); the static templates stay static.
+- **A10 honoured** — `/api/config` is public and stateless; the response carries no secrets (exactly `app_name` + `version`).
+- **Runtime fetch, brief flash accepted (owner permission 2026-08-26)** — the default name renders immediately and is replaced when `/api/config` answers (LAN latency; no re-paint machinery for in-flight turns — a mid-turn label keeps the previous name for that turn).
+- **A16/A17 honoured** — one new story E2E suite + one atomic `--no-gpg-sign` commit.

.agent/phases/todo/39_configurable_brand/03_e2e_docs_commit.md

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+# Task 03 — Story E2E + docs + commit
+
+**Phase:** `39_configurable_brand` · **Source:** `TODO.md:12 — "Also need a way to customize the name for 'Brain of'. Should be an env var."`
+**Story:** `.agent/user_stories/configurable-brand.md`
+
+## Objective
+The story's isolated Playwright suite against an app instance booted with the overridden name, the env docs, and the phase commit.
+
+## Work
+1. `tests/e2e/test_configurable_brand.py` (the story gate — one story, one file, run in isolation):
+   - A **second app instance** — the shared `app_server` conftest fixture keeps the default name (the other suites' title/label assertions depend on it). Copy the conftest `app_server` env block (same DB, the mock-LLM base URL, `BOR_ADMIN_PASSWORD`/`BOR_SESSION_SECRET`, `BOR_STATIC_DIR`, `BOR_RELEVANCE_THRESHOLD`) with two changes: `BOR_APP_NAME="Brain of Testy"` and a distinct port (`APP_PORT + 1` per the conftest convention). A session-scoped fixture **inside the test file**, started after `mock_llm` is available.
+   - Assertions (custom instance): index `document.title` == `"Brain of Testy"`; the `.brand-text` `innerHTML` == `Brain of <strong>Testy</strong>`; the empty-state h1 text == `"Hey! I'm Brain of Testy."`; the `#messages` `aria-label` == `"Conversation with Brain of Testy"`; the sources page title `"Sources · Brain of Testy"`; the login page title `"Sign in · Brain of Testy"`; one chat turn with a pre-token window (the `think out loud` marker) → the button label shows `"Brain of Testy is thinking"`.
+   - Default-name assertion (cheap regression in the same file): the shared conftest server's index title still == `"Brain of Reese"`.
+   - The chat-turn assertion works on the default (possibly empty) KB — a deflected answer is fine; the label assertion is pre-token, so no DB seeding is required.
+2. `.env.example` — document `BOR_APP_NAME` in the App section (the display name on all pages; default "Brain of Reese").
+3. README — the configuration section: `BOR_APP_NAME` (what it affects: titles, the header brand, the status labels, the aria text; the default; the bold-split rendering rule: names starting "Brain of " bold the remainder, any other name renders in normal weight).
+4. Regression pass: `uv run pytest` + the coverage gate (>90%) + the isolated story E2E + the suites that assert brand strings (`test_smoke.py`, `test_shared_header.py`, `test_header_consistency.py`, `test_chat_persistence.py`) green.
+5. Commit — one atomic `--no-gpg-sign` Conventional Commits commit for the whole phase (AGENTS.md rule 8), e.g. `feat(brand): configurable app name — BOR_APP_NAME drives /api/config + the frontend brand layer`; move the phase directory to `.agent/phases/complete/`.
+
+## Testing & Quality
+- The gates above are this task's quality bar (A16: one story, one isolated E2E file, coverage >90%).
+
+## Completion Criteria
+- [ ] The story E2E is green in isolation, deterministic across two consecutive runs (custom-name instance + the default-name assertion).
+- [ ] The step-4 regression list green; coverage >90%.
+- [ ] `uv run ruff check . && uv run pyright` clean.
+- [ ] One `--no-gpg-sign` commit; phase directory moved to `.agent/phases/complete/`.