feat(trigger-service): resume-subscription RPCs (TS-IMPL-016)

[toddysm]

TS-IMPL-016: Resume RPCs RegisterResumeSubscription / CancelResumeSubscription (REQ-081)

Implements the internal Dapr method routes the Workflow Service calls across each waitFor: step's lifecycle.

What

• POST /RegisterResumeSubscription — register (or idempotently re-register) a one-shot resume wait keyed on the (runId, stepId, eventKey) triple:
  • Replay of a still-live wait returns the existing subscriptionId with no write.
  • Divergent selector → original wins + a resume.subscription.divergent audit event.
  • A wait whose prior row has lapsed past its TTL is treated as a fresh registration.
  • The CEL selector is compiled at register time (malformed → 422 Problem+JSON).
  • TTL parsed from the request ISO-8601 duration (e.g. PT24H), falling back to TRIGGER_RESUME_DEFAULT_TTL_SECONDS.
• POST /CancelResumeSubscription — idempotent cancel; a clean 204 no-op for unknown/expired keys.

How

• Routes match the exact wire shapes the WF DaprTriggerServiceClient sends ({runId, stepId, eventKey, selector, ttl} → {subscriptionId}; cancel {runId, stepId, eventKey} → 2xx).
• These are internal service-to-service calls authenticated at the Dapr mesh layer (mTLS + app-id), not via the call-context envelope — both method paths are added to the call-context middleware bypass set (the WF caller propagates no x-custos-callctx header).
• A resume registration carries no workspace; the globally-unique (runId, stepId, eventKey) triple keys it, so rows partition under a reserved workspace sentinel. resume_id is a deterministic NUL-joined SHA-256 of the triple.
• New ResumeReadable capability Protocol + ResumeSubscriptionStore.get (mirrors the SubscriptionReadable pattern) for the idempotency lookup.
• New RPC wire models (RegisterResumeRequest / RegisterResumeResponse / CancelResumeRequest).
• create_app gains an audit_sink param wiring the resume RPCs and the internally-built dispatcher to one shared sink (defaults to NoopAuditSink until TS-IMPL-019); resume-default-TTL is bound on app.state.

Tests

tests/test_rpc_routes.py drives the routes through a real TestClient over the in-process store: response shape, idempotency, divergence-audits-original-wins, TTL-expiry refresh, TTL parsing/fallback, invalid-selector 422, missing-field 400, cancel (known/unknown/then-reregister), middleware-bypass assertion, ISO-8601 duration parser table, and the read-capability guard.

Gates: ruff check / ruff format --check / mypy src tests clean; 417 passed, total coverage 98.98% (rpc.py 100%).

Closes #646

[Copilot]

Pull request overview

This PR adds the Trigger Service’s internal Dapr service-invocation RPC surface that the Workflow Service uses to register/cancel one-shot “resume waits” for waitFor: steps, keyed idempotently by (runId, stepId, eventKey). It also wires the needed app dependencies (audit sink, default TTL, call-context bypass) and introduces tests that exercise the RPC contract end-to-end against the in-memory metadata store.

Changes:

• Add internal RPC routes POST /RegisterResumeSubscription and POST /CancelResumeSubscription with idempotency/divergence-audit semantics and ISO-8601 TTL handling.
• Introduce a ResumeReadable capability + ResumeSubscriptionStore.get() for idempotency lookups, and expose new RPC wire models.
• Wire app state/dependencies for audit_sink and default resume TTL; add call-context middleware bypass paths and comprehensive route tests.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/services/trigger-service/src/custos_trigger/api/routes/rpc.py	Implements the two internal resume RPC endpoints, ID derivation, TTL parsing/resolution, and audit emission.
src/services/trigger-service/src/custos_trigger/app.py	Mounts the new router and wires audit_sink + resume_default_ttl_seconds into app.state; passes audit sink into the internally-built dispatcher.
src/services/trigger-service/src/custos_trigger/dependencies.py	Adds FastAPI dependencies for audit sink, resume store, and default TTL.
src/services/trigger-service/src/custos_trigger/middleware/callctx.py	Adds the resume RPC method paths to the call-context bypass set.
src/services/trigger-service/src/custos_trigger/models.py	Adds wire models for register/cancel resume RPC request/response bodies.
src/services/trigger-service/src/custos_trigger/stores/base.py	Adds the ResumeReadable protocol capability for optional resume-row read-back.
src/services/trigger-service/src/custos_trigger/stores/resume.py	Adds ResumeSubscriptionStore.get() and supporting types/errors for idempotency reads.
src/services/trigger-service/src/custos_trigger/stores/init.py	Re-exports new resume store capability/error/types.
src/services/trigger-service/src/custos_trigger/api/routes/init.py	Exposes the new resume RPC router for app mounting.
src/services/trigger-service/tests/test_rpc_routes.py	New end-to-end tests for route shape, idempotency, divergence auditing, TTL handling, selector validation, cancel behavior, and bypass set.
design/components/trigger-service/todos.md	Marks TS-IMPL-016 as complete.

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