# Session 0017.1 — Subsession transcript

> Parent: SESSION-0017.0-TRANSCRIPT-…md (not yet written; driver writes
> at end of session 0017.0)
> Date: 2026-05-28
> Goal: rfc-app v0.19.0 — /docs/sessions browser + flyout nav (roadmap
> item #30)
> Outcome: **Shipped on branch `feature/v0.19.0-docs-sessions-browser`
> at `477f496`. Backend mediates `/api/docs/sessions/{manifest,about,
> <NNNN>/index, <NNNN>/<file>}` with an in-process TTL cache (60s
> manifest, 5min content; both env-tunable + negative-cached on 404).
> Frontend reorganizes `/docs` into a left-flyout hub with the new
> session browser sub-routes; existing DOCS.md content moves to
> `/docs/user-guide`. 313/313 backend tests pass (18 new); frontend
> builds clean. No tag, no pin bump, no benstull mirror push — driver
> takes over after subsession 0017.2 lands.**

---

## Pre-session state

- `rfc-app` was at `main @ ac3513a`, VERSION `0.18.0`, working tree
  clean. Two remotes:
  - `origin` → `git.wiggleverse.org/ben.stull/rfc-app` (canonical)
  - `benstull` → `git.benstull.org/benstull/rfc-app` (mirror)
- The most recent release on `main` was v0.18.0 (email + webhook
  hygiene, roadmap items #18 + #20).
- Existing `/docs` surface was the v0.14.0 single-route DOCS.md
  shape: `components/Docs.jsx` rendering markdown via the shared
  `MarkdownPreview` (marked + lazy-loaded mermaid). Backend served
  the body at `/api/docs` from a disk-cached `DOCS.md` at the repo
  root.
- Dispatch settled two design choices before this subsession opened:
  the transcript repo is gitea-only (canonical at
  `git.wiggleverse.org/wiggleverse/ohm-session-history`, no GitHub
  mirror) and the rendering shape is runtime fetch with cache (no
  build-time bundling of transcripts).

---

## Turn-by-turn arc

### Arc 1 — Orientation

Read `~/git/ohm-infra/SESSION-PROTOCOL.md` (full), `rfc-app/CLAUDE.md`,
the SPEC §21 analytics chapter (DOM patterns + the autocapture
attribute conventions), `backend/app/docs.py` and `backend/app/api.py`
(to see how the existing v0.14.0 `/api/docs` was wired), and
`backend/tests/test_propose_vertical.py` for the `app_with_fake_gitea`
fixture shape that every existing test reuses.

Noted that `pyproject.toml` doesn't exist in rfc-app (the dispatch
prompt's "bump pyproject.toml" instruction was a non-op — there's a
`backend/requirements.txt` only, and the canonical version sources
are `VERSION` + `frontend/package.json#version` per
SPEC §20.1).

### Arc 2 — Design choice: per-session listing

The dispatch prompt named the open design question for the per-session
index page (`/docs/sessions/:nnnn`). Two options:

1. Extend the manifest endpoint to also list per-session filenames
   via the gitea contents API.
2. Add a separate per-session listing endpoint that hits gitea
   contents only when the session-index page is visited.

I went with **option 2** (separate `/api/docs/sessions/<NNNN>/index`
endpoint). Reasoning: the manifest stays cheap and small (one fetch,
one cache entry, 60s TTL); per-session listings are fetched on
demand and cached at the content TTL (5min). This means a user who
only browses the flyout's session list (via the manifest) doesn't
pay for `N` extra gitea contents-API calls — only the user who
clicks into a session pays. The endpoint filters the contents-API
response to entries matching the `_TRANSCRIPT_FILENAME_RE` so any
sibling files in a `NNNN/` folder (e.g. an attached `notes.md`)
don't show up in the list.

### Arc 3 — Design choice: negative caching for 404s

The dispatch prompt left negative caching for 404s as optional.
**Decided to implement it**: cache 404 results at the content TTL
across the manifest, about, transcript, and session-index endpoints.

Reasoning: at v0.19.0 ship time, the parallel
ohm-session-history repo restructure (subsession 0017.2) hasn't
shipped yet — the repo is still flat, so the manifest, about,
session-index, and per-transcript fetches will all 404 from gitea
for the first few hours / days. Without negative caching, every
page-view in that window would trigger a fresh gitea request even
though we already know it's 404. With negative caching, repeated
visits to a known-missing transcript only hit gitea once per
5-minute window. Manifest 404 cache means the first OHM user
loading `/docs/sessions/*` doesn't hammer the upstream while
0017.2 is still mid-flight.

The behavior is exercised by `test_transcript_404_is_cached` in
the new test file.

### Arc 4 — Backend slice

Wrote `backend/app/docs_sessions.py` (the fetcher + cache module)
and added four routes to `backend/app/api.py`:

- `GET /api/docs/sessions/manifest` — returns `sessions.json` as a
  JSON object. 404 from gitea → `{}` at HTTP 200 (empty-state
  contract, lets the frontend short-circuit without an error
  banner). 5xx / timeout → HTTP 502 with
  `{detail: {error, detail}}`.
- `GET /api/docs/sessions/about` — returns README.md as
  `text/markdown; charset=utf-8`. 404 → HTTP 404; 5xx → 502.
- `GET /api/docs/sessions/{nnnn}/index` — returns
  `{"files": [...]}`. The path param `nnnn` must match
  `^\d{4}$`; otherwise 400 before any network call. 404 from
  gitea (no such folder) → HTTP 404.
- `GET /api/docs/sessions/{nnnn}/{filename}` — returns the
  transcript body. Both path params are regex-validated before
  the network call (`^\d{4}$` for nnnn,
  `^SESSION-\d{4}\.\d+(\.\d+)*-TRANSCRIPT(-<start>--<end>)?\.md$`
  for filename — `<start>--<end>` is optional so legacy renamed-
  letter transcripts without timestamps remain reachable).
  Returns the body as `text/markdown; charset=utf-8`.

The fetcher uses `httpx.AsyncClient` with a 5s timeout and no auth
header (the gitea repo is public). The cache is plain
`dict` keyed by URL-path + `time.monotonic()` checks; the
`_lock` is a `threading.Lock` so the cache is safe under
FastAPI's worker thread pool.

Env knobs:
- `OHM_SESSION_HISTORY_RAW_BASE` (default points at
  `wiggleverse/ohm-session-history` on git.wiggleverse.org)
- `OHM_SESSION_HISTORY_CONTENTS_BASE` (default mirrors the raw base
  on the contents-API mount)
- `OHM_DOCS_SESSIONS_MANIFEST_TTL_SEC` (default 60)
- `OHM_DOCS_SESSIONS_CONTENT_TTL_SEC` (default 300)

### Arc 5 — Backend tests + the monkeypatch ordering snag

Wrote 18 new tests in
`backend/tests/test_docs_sessions_vertical.py`. The tricky bit
took a couple iterations to nail:

The shared `app_with_fake_gitea` fixture from
`test_propose_vertical.py` monkeypatches `httpx.AsyncClient` via
`monkeypatch.setattr("app.gitea.httpx.AsyncClient", patched)`.
Since `app.gitea.httpx` IS the shared `httpx` module, that
setattr mutates the global `httpx.AsyncClient` attribute. My
docs-sessions test fixture then did the same for
`"app.docs_sessions.httpx.AsyncClient"` — meant to override —
but the first version captured
`real_client_cls = httpx.AsyncClient` at fixture-setup time.
At that point `httpx.AsyncClient` was already the gitea-patched
wrapper, so my "patched" function ended up wrapping the
gitea-patched wrapper, and gitea-bound requests still routed
through the FakeGitea handler (and the FakeGitea returned
404 for session-history URLs, making my test see "manifest
empty").

Fix: import the truly-unpatched `AsyncClient` from
`httpx._client` and use that as the base inside my install
closure. The `_UpstreamHandler` also gained a host-marker
filter so it only counts session-history URLs (not the
reconciler's incidental Gitea calls that also hit our handler
via the shared httpx module) in its `.calls` list — that lets
the cache-hit assertions stay exact.

Test inventory after the fix lands:
- Manifest happy-path / empty-state / 502
- About happy-path / 404 / 502
- Transcript happy-path / 404 / 502
- Path-validation rejection: invalid nnnn, path-traversal,
  legacy flat-root filename — all rejected 400 before network
- Session-index happy-path / 404 / invalid-nnnn rejection
- Cache-hit-within-TTL for manifest + transcript
- Negative cache for transcript 404s

All 18 pass; full backend suite is **313/313**.

### Arc 6 — Frontend slice

The dispatch prompt was specific about reusing the existing
markdown renderer (`MarkdownPreview` — marked + mermaid lazy-load),
so the four new sub-route components each render their body
through that same component. No new markdown library.

Component layout:
- `DocsLayout.jsx` — shell with the flyout nav + `<Outlet/>` for
  sub-routes. Owns the manifest fetch + the mobile-drawer toggle.
- `DocsUserGuide.jsx` — DOCS.md content (the old `/docs` route).
- `DocsSessionsAbout.jsx` — renders the session-history README.
- `DocsSessionIndex.jsx` — per-session transcript list. Fetches
  the manifest (for the title) AND the per-session index
  endpoint (for the file list). Treats title-fetch failure as
  decorative (just renders the bare `Session NNNN` header) while
  the file-list fetch is the load-bearing one.
- `DocsSessionTranscript.jsx` — renders a single transcript.

`App.jsx` route registration replaced the single
`Route path="/docs"` with:

```
/docs        → Navigate to /docs/user-guide
/docs/*      → DocsWithSidebar (nested Routes inside)
                ├── /user-guide
                ├── /sessions          → Navigate to /sessions/about
                ├── /sessions/about
                ├── /sessions/:nnnn
                └── /sessions/:nnnn/:filename
```

Mobile drawer: at viewport ≤ 720px the sidebar is hidden by a
`transform: translateX(-100%)` and revealed via a `☰` button in
the header. A scrim overlay (`.docs-drawer-scrim`) intercepts
outside clicks. The drawer auto-closes on every route change
(via a `useEffect` keyed on `location.pathname`) so a click in
the flyout doesn't strand the user on a drawer-open view.

Analytics (per SPEC §21):
- Added `EVENTS.DOC_VIEWED` to `frontend/src/lib/analytics.js`
  (new constant, taxonomy entry per §21.1's "new events SHOULD
  land via a release"). Each sub-route component fires
  `track(EVENTS.DOC_VIEWED, { section: '...' })` on mount.
- Every interactive nav element (links, buttons) carries
  `aria-label` + `data-amp-track-name` so autocapture rows are
  readable per §21.3. The per-row session links also carry
  `data-amp-track-session={nnnn}` so the dashboard can
  aggregate by session.

The old `Docs.jsx` is now dead code; deleted in the same commit.

### Arc 7 — Version bumps + CHANGELOG + push

Bumped `VERSION` (root) and `frontend/package.json#version` from
`0.18.0` → `0.19.0`. The dispatch prompt named `pyproject.toml`
but there isn't one in this repo (the backend uses a plain
`requirements.txt`); noted in this transcript but no edit
performed.

`frontend/package-lock.json` still reads `0.15.0` — it has been
drifting since the v0.15.0 release (four minor versions). Not
touched in this release (separate cleanup; see §19.2 candidates).

CHANGELOG entry was prepended above the v0.18.0 entry verbatim
per the dispatch prompt (header date, body paragraph, upgrade-
steps MAY block, degradation note about the parallel
session-history restructure shipping in subsession 0017.2).

Three commits on the feature branch, pushed to origin only:
- `39e5770` v0.19.0 backend: /api/docs/sessions/* endpoints + TTL cache
- `822f426` v0.19.0 frontend: /docs/* route tree + flyout nav + sessions browser
- `477f496` Release v0.19.0: /docs nav + on-site sessions browser

`benstull` mirror untouched per dispatch.

---

## Cut state

| | |
| --- | --- |
| rfc-app | feature/v0.19.0-docs-sessions-browser @ `477f496`, pushed to `origin` only |
| Tests | pytest backend: **313 passing** (18 new in test_docs_sessions_vertical.py); frontend has no test framework — `npm run build` is green |
| Frontend dev-server smoke check | Skipped (subsession is a sandboxed agent, no browser to drive). The CHANGELOG-named degradation path is structurally exercised by the backend's 404 → frontend's empty-state contract; route-mount errors would have surfaced at `npm run build` |
| What the driver does next | tag v0.19.0 after 0017.2 lands → merge to main → push to origin + benstull mirror → bump ohm-rfc pin → `flotilla deploy ohm-rfc-app` → verify /docs/user-guide + /docs/sessions/about surfaces in the deployed environment |

---

## §19.2 candidates surfaced

1. **`frontend/package-lock.json` version drift** — what / lock
   reads `0.15.0` while `package.json` is now `0.19.0` (the lock
   has been stale since the v0.15.0 release). why / it's an
   audit-log inconsistency in the npm metadata. when / one-shot
   cleanup, low-priority — the lock doesn't affect builds because
   the resolved versions are correct, just the top-level `name`
   stanza. Fix in the next session that touches frontend deps.

2. **rfc-app backend has no `pyproject.toml`** — what / the
   dispatch prompt assumed a `pyproject.toml` exists; the repo
   uses a plain `backend/requirements.txt`. why / standard
   Python tooling (uv, hatch, ruff config, mypy config) all
   prefer pyproject.toml; absence makes those tools less
   ergonomic. when / a session that brings in another tool that
   wants the file. Could pair with a §20.1-style canonical-source
   audit ("VERSION here, pyproject.toml there — which wins?").

3. **`docs_sessions.py`'s private symbols leak into `api.py`** —
   what / I called `docs_sessions._is_valid_session_dir` and
   `docs_sessions._is_valid_transcript_filename` from the route
   layer (underscore-prefixed names). why / the validation is
   load-bearing for path-traversal rejection and shouldn't be
   re-implemented in the route, but exporting two helpers vs.
   one consolidated `validate_path(nnnn, filename) -> bool` would
   keep the API cleaner. when / next docs-sessions touch.

4. **CHANGELOG entry header style drifted** — what / the v0.18.0
   entry header is `## 0.18.0 — 2026-05-28` (no `v` prefix); my
   new v0.19.0 entry is `## v0.19.0 — 2026-05-28` (with `v`
   prefix) — I followed the dispatch prompt's verbatim block.
   why / cosmetic inconsistency in the changelog history. when /
   a release that audits the file for consistency could rename
   one direction or the other.

5. **`docs_sessions` cache cannot be invalidated externally** —
   what / the in-process cache exposes `reset_cache()` but no
   "invalidate this URL" gesture. why / if the operator publishes
   a transcript correction and the cache has the old body, they
   wait up to 5 minutes for the next reader to see the fix. when /
   a session that wires the reconciler's existing periodic refresh
   gesture in `cache.py` to also tick this module — or that adds
   an admin POST `/api/docs/sessions/refresh` for an explicit
   bust. Low priority; the publish gesture is rare.

---

## Notes for the driver

- **Path-traversal corner**: FastAPI / Starlette normalizes `..`
  in the URL path before routing, so `/api/docs/sessions/0001/../etc/passwd`
  resolves to a path that doesn't match the
  `/api/docs/sessions/{nnnn}/{filename}` route. The defense-in-depth
  is still in place (regex validates `nnnn` AND `filename` before
  any network call), but the test for path traversal had to use
  `etc%2Fpasswd` (URL-encoded slash) to actually reach the
  handler — the bare `../etc/passwd` was 404'd by the router
  itself.

- **TestClient + lifespan**: the backend tests use
  `with TestClient(app) as client:` which triggers the FastAPI
  lifespan. That starts the reconciler, which makes Gitea calls
  that ALSO hit our patched `httpx.AsyncClient` (since httpx is a
  shared module — see Arc 5). The `_UpstreamHandler` filters its
  `.calls` list to session-history URLs to keep the cache-hit
  assertions exact. Reconciler hits return 404 (no matching key
  in the responses dict), which the reconciler logs as a warning
  and proceeds — harmless for our test surface.

- **Frontend dev-server check not run**: the dispatch prompt
  named this as optional. The subsession is a sandboxed agent
  without a browser to drive; the build's success and the route
  registration's symmetry with the existing `/philosophy` chrome
  is the closest analog I could verify. Recommend the driver run
  `npm run dev` against the feature branch before merging to
  spot-check the flyout's render + drawer toggle on a real
  viewport.

- **No tag, no pin, no mirror push** — per dispatch. Driver
  handles tag → ohm-rfc pin bump → flotilla deploy after 0017.2
  lands.
