feat: expose executor job observability

docs/architecture/memind-orchestrator-boundary.md

@@ -114,7 +114,28 @@ The `build_plan` node creates the deterministic preview job
 `<runId>:executor-preview` with idempotency key
 `<runId>:build_plan:v1`. The stored result is terminal `blocked` state with
 `executor_dispatch_not_implemented`; it is a durable audit and recovery
-boundary, not an execution claim.
+boundary, not an execution claim. If the run identifier is unsafe or would
+overflow the 128-character Job id boundary, the graph substitutes a stable
+SHA-256-derived opaque prefix.
+
+Phase 3.4 adds the append-only `executor-job-event-v1` contract. Job snapshots
+remain in `executor_jobs`, while cursor-addressable events live in
+`executor_job_events`. A transaction commits the initial snapshot and event
+together; later state transitions lock the job row and commit the updated
+snapshot and next event together. This prevents a visible state transition
+without its corresponding audit event.
+
+The read boundary is deliberately narrower than an execution control API:
+
+```text
+GET /v1/executor-jobs/:jobId
+GET /v1/executor-jobs/:jobId/events?after=<cursor>&limit=<limit>
+```
+
+There is no HTTP submit, retry, claim, or executor cancel endpoint in this
+phase. memindadm resolves the job reference stored in LangGraph plan state and
+shows the job snapshot and events beside Native and graph state. The payload
+contains no task instruction, secret, absolute path, or executor SDK object.
 
 The implemented internal API is:
 
@@ -124,6 +145,8 @@ GET /v1/runs/:id
 POST /v1/runs/:id/resume
 POST /v1/runs/:id/cancel
 GET /v1/runs/:id/events?after=<cursor>
+GET /v1/executor-jobs/:jobId
+GET /v1/executor-jobs/:jobId/events?after=<cursor>&limit=<limit>
 ```
 
 External state changes must use an idempotency key derived from run, graph
@@ -164,8 +187,9 @@ read LangGraph checkpoint state and node events.
 
 Canary readiness is also a Memind control-plane projection. It excludes
 synthetic smoke runs and evaluates operational health, durable checkpoint state,
-sample volume, session coverage, success rate, latency coverage, P95 latency,
-Native terminal coverage, and sample freshness. The result is advisory:
+durable Executor Job storage, sample volume, session coverage, success rate,
+latency coverage, P95 latency, Native terminal coverage, and sample freshness.
+The result is advisory:
 `manual_canary_review` never mutates routing configuration or transfers
 execution ownership.