**Root cause:** ServiceAdapter dispatcher sets X-Upstream-Path to template strings like `/v1/poimen/executions/{id}/stream` with literal `{id}`. The handler extracted `{id}` as the workflow ID instead of the actual value.
**Fix:** All handlers read `workflow_id` from query params (`?workflow_id=xxx`). Paths changed to flat resource names without path parameters.
**API contract:**
```
GET /executions — list
GET /executions/detail?workflow_id=xxx — describe
GET /executions/history?workflow_id=xxx — history
GET /executions/stream?workflow_id=xxx — SSE
POST /executions/signal?workflow_id=xxx — signal
DELETE /executions/detail?workflow_id=xxx — terminate
```
All accessed via `X-Service: poimen` + `X-Resource: <name>` headers.
---------
Reviewed-on: #42
- New internal/temporal/poimen.go: PoimenHandler with typed REST endpoints
POST /v1/poimen/plan — call PlannerActivity (stub until workflows#23)
POST /v1/poimen/execute — start DAG/Orchestrator/Routing workflows
GET /v1/poimen/executions — list Poimen workflow executions
GET /v1/poimen/executions/:id — describe execution
GET /v1/poimen/executions/:id/history — activity event history
GET /v1/poimen/executions/:id/stream — SSE events (delegates to sse.go)
POST /v1/poimen/executions/:id/signal — pause/resume/cancel
DELETE /v1/poimen/executions/:id — terminate workflow
- New internal/serviceadapter/poimen_adapter.go: ServiceAdapter spec + factory
- Wire PoimenHandler in cmd/gateway/main.go via ServiceAdapter registry
- Workflow type registry: dag->DAGWorkflow, orchestrator->OrchestratorWorkflow,
routing->RoutingWorkflow (all on poimen-worker task queue)
Closes#32Closes#34