Cover the push providers with tests and document the subsystem

Unit tests for the provider registry, both providers' registration parsing, the
APNs payload translation, provider token signing and caching, header and status
mapping against a mock transport, provider grouping and the delivery timeout
clamp, plus service tests for the configuration surface, the retention sweep and
the per-provider metrics. Api tests cover the provider listing on GET
/push.json, registration with and without an explicit provider, idempotency and
the rejection of an unknown or unconfigured provider.

Provider settings in unit tests are supplied by monkeypatching the provider's
setting reader rather than writing site_settings, because the unit tier shares
its database with the running api-tier server.

devplacepy/push/CLAUDE.md documents the protocol, how to add a provider, the
invariants and the APNs specifics; the root, routers and services files point at
it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

devplacepy/routers/CLAUDE.md

@@ -45,7 +45,7 @@ Prefixes are wired in `main.py`:
 | `/dbapi` | dbapi/ package - **primary-administrator-only, strictly READ-ONLY** generic database API over `dataset` (never inserts/updates/deletes/restores; the write surface was removed because it bypassed every per-route admin safeguard). `tables.py` (`GET /tables`, `GET /{table}/schema`), `crud.py` (read only: `GET /{table}` + `GET /{table}/{key}/{value}`, `?include_deleted`), `query.py` (`POST /query` hard SELECT-only validated read-only run; `POST /query/async` + `GET /query/{uid}` + `WS /query/{uid}/ws` via `DbApiJobService` kind `dbquery`), `nl.py` (`POST /nl` natural-language->SQL via the AI gateway, returns validated SELECT, `execute=true` runs it read-only). **Auth = the PRIMARY administrator only** (the earliest-created Admin, `utils.is_primary_admin` / `database.get_primary_admin_uid` - the same identity that gates backup downloads) by session/api_key (`services/dbapi/policy.py`); every other administrator is refused like a member, and there is **no internal-key path** - the gateway `internal_gateway_key()` is NOT accepted (no service-to-service access). SQL validated by `services/dbapi/validate.py` (sqlglot classify + suspicious-flag + read-only `EXPLAIN` dry-run). Devii tools `db_*` are read-only (list/get/query/nl; no write tools) and flagged `requires_primary_admin=True`, so they are added to the LLM tool list ONLY for the primary administrator (every other session never sees them and Devii is unaware they exist). `services/pubsub/policy.py` resolves its own admin/internal actor and does NOT reuse `dbapi.policy.caller_for`, so the primary-admin restriction does not leak onto the pub/sub bus. See `devplacepy/services/dbapi/CLAUDE.md` |
 | `/quizzes` | quizzes/ package - **Quizzes**: `index.py` (hub, create, import, detail, export, edit, delete, publish, per-quiz leaderboard, cross-quiz scoreboard), `questions.py` (builder page + question CRUD + reorder), `attempts.py` (start/resume, play, answer, finish, results). The hub `GET /quizzes` is the approved three-column `.feed-layout` reused verbatim from `/feed`: filters + search left (`?filter=all|todo|done|mine|drafts`, `?search=`, `?page=`), the quiz list centre with the **New quiz** and **Create quiz with Devii** actions, and the cross-quiz **scoreboard** rail right (score per user, best attempt per quiz, 15s display cache). Publishing is terminal - every write on a published quiz is a 400 and there is no unpublish route. See `devplacepy/services/quiz/CLAUDE.md` |
 | `/game` | game/ package - the **Code Farm** idle game (`index.py` + `farm.py`): `GET /game` (page), `GET /game/state`, `GET /game/leaderboard?board=`, `POST /game/{plant,harvest,buy-plot,upgrade,fertilize,daily,grant,perk,prestige,legacy,mastery,quests/claim}`, `POST /game/{defense/upgrade,defense/downgrade,infrastructure/buy,cosmetics/buy,cosmetics/equip}`, plus social `GET /game/farm/{username}` and `POST /game/farm/{username}/{water,steal}`. See `devplacepy/services/game/CLAUDE.md` |
-| (none) | push.py - web push + PWA: `GET`/`POST /push.json` (VAPID public key / subscription register), `GET /service-worker.js`, `GET /manifest.json` |
+| (none) | push.py - push + PWA: `GET /push.json` (VAPID public key + the providers accepting registrations), `POST /push.json` (register with any active provider; a body without `provider` is a `webpush` body, so existing clients are unchanged; an unknown, disabled or unconfigured provider is a 400), `GET /service-worker.js`, `GET /manifest.json`. Provider protocol and delivery live in `devplacepy/push/` - see `devplacepy/push/CLAUDE.md` |
 | (none) | docs.py (docs/ package) - the documentation site (prose pages + API reference). See `routers/docs/CLAUDE.md` for the deep detail on this tree (`DOCS_PAGES`, audience tiers, prose rendering pipeline) |
 | `/pubsub` | pubsub.py - **database-free** publish/subscribe bus. `WS /pubsub/ws` (subscribe/unsubscribe/publish frames, `foo.*` wildcards), `POST /pubsub/publish` + `GET /pubsub/topics` (admin/internal). Lock-owner-gated WS (`4013` retry) so subscribers converge on one worker; topic authz in `services/pubsub/policy.py` (`user.{uid}.*` private, `public.*` shared, admin/internal anywhere, guests opt-in). In-process `services.pubsub.publish(topic, data)` for backends; frontend `app.pubsub`. See `devplacepy/services/pubsub/CLAUDE.md` |
 | (none) | seo.py - `/robots.txt`, `/sitemap.xml` |