feat(trigger-service): store adapters + provider wiring (TS-IMPL-008)

[toddysm]

What

Implements TS-IMPL-008 — the persistence seam for Trigger Service: thin store adapters over the SPL MetadataStoreProvider plus the provider-selection wiring.

Changes

• stores/ package
  • base.py — TriggerMetadataStore Protocol: the narrow subset of MetadataStoreProvider Trigger Service writes to (the eight Subscription / SubscriptionSelector / ResumeSubscription / DedupKey / Schedule methods). Both the Postgres adapter and the in-process backend satisfy it structurally.
  • subscriptions.py / resume.py / schedules.py — SubscriptionStore, ResumeSubscriptionStore, ScheduleStore: thin async adapters that map the wire/domain models in models.py onto the locked SPL rows (+ their free-form JSON blobs) and delegate to the provider.
• providers.py
  • InMemoryTriggerMetadataStore — faithful in-process backend (immutable put_subscription, not-found ValueError on state/next-fire updates, TTL-aware reserve-or-read dedup) plus dev/test read accessors.
  • Providers bundle + load_providers() — selects in-memory by default (empty/memory sentinel) or custos_pg.PgMetadataAdapter when TRIGGER_METADATA_STORE is a DSN. LazyPool defers connection; the factory opens no socket. No new schema invented.
• dependencies.py — get_providers / get_metadata_store FastAPI helpers (mirror auth-service).
• app.py — lifespan binds the providers bundle + store adapters onto app.state; new optional providers= injection point for tests.

Acceptance criteria

• CRUD round-trips against the in-memory MetadataStoreProvider.
• Provider selection honors the TRIGGER_METADATA_STORE env knob; no new schema invented.

Quality gates

• ruff format / ruff check clean
• mypy src tests (strict) clean
• pytest — 221 passed, 99.8% coverage (floor 90%)

Closes #638

[Copilot]

Pull request overview

Implements Trigger Service’s persistence seam (TS-IMPL-008) by introducing thin domain↔SPL store adapters, provider selection/wiring (in-memory default vs Postgres via TRIGGER_METADATA_STORE), and wiring these into FastAPI lifespan/dependencies, with accompanying tests.

Changes:

• Added custos_trigger.stores/* adapters (SubscriptionStore, ResumeSubscriptionStore, ScheduleStore) over the SPL MetadataStoreProvider write surface.
• Added custos_trigger.providers with InMemoryTriggerMetadataStore + load_providers() DSN-based selection and a Providers bundle.
• Wired providers + stores into create_app() lifespan and exposed them via dependency helpers; added tests covering the wiring and CRUD round-trips.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/services/trigger-service/tests/test_stores.py	New CRUD round-trip tests for store adapters over the in-memory backend.
src/services/trigger-service/tests/test_providers.py	New tests for DSN selection and in-memory backend semantics (dedup, schedule updates, etc.).
src/services/trigger-service/tests/test_dependencies.py	New tests validating dependency helpers and lifespan wiring onto app.state.
src/services/trigger-service/tests/conftest.py	New shared fixtures (frozen clock + providers bundle).
src/services/trigger-service/src/custos_trigger/stores/subscriptions.py	SubscriptionStore adapter mapping domain Subscription ↔ SPL rows/selectors.
src/services/trigger-service/src/custos_trigger/stores/schedules.py	ScheduleStore adapter for SPL schedule persistence.
src/services/trigger-service/src/custos_trigger/stores/resume.py	ResumeSubscriptionStore adapter for SPL resume subscription persistence.
src/services/trigger-service/src/custos_trigger/stores/base.py	TriggerMetadataStore Protocol defining the narrow SPL write surface used by Trigger Service.
src/services/trigger-service/src/custos_trigger/stores/init.py	Package exports + documentation for the store adapter layer.
src/services/trigger-service/src/custos_trigger/providers.py	In-memory backend + Providers bundle + load_providers() env/DSN selection.
src/services/trigger-service/src/custos_trigger/dependencies.py	FastAPI dependencies to retrieve providers bundle / metadata store.
src/services/trigger-service/src/custos_trigger/app.py	Lifespan wiring for providers + store adapters; optional providers injection for tests.
design/components/trigger-service/todos.md	Marks TS-IMPL-008 as completed.

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