fix: use query params for workflow_id in Poimen endpoints (#42)

**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

internal/serviceadapter/poimen_adapter.go

@@ -53,17 +53,20 @@ func GetPoimenSpec() *Spec {
 					},
 				},
 			},
+			// Note: workflow_id is passed as ?workflow_id=xxx query param,
+			// not as a path segment. The ServiceAdapter dispatcher does not
+			// substitute path parameters.
 			{
 				Name: "execution-detail",
 				Methods: []Method{
 					{
 						Verb:         "GET",
-						UpstreamPath: "/v1/poimen/executions/{id}",
+						UpstreamPath: "/v1/poimen/executions/detail",
 						Auth:         &Auth{Required: true, Capability: "workflow:read"},
 					},
 					{
 						Verb:         "DELETE",
-						UpstreamPath: "/v1/poimen/executions/{id}",
+						UpstreamPath: "/v1/poimen/executions/detail",
 						Auth:         &Auth{Required: true, Capability: "workflow:execute"},
 					},
 				},
@@ -72,7 +75,7 @@ func GetPoimenSpec() *Spec {
 				Name: "execution-history",
 				Methods: []Method{{
 					Verb:         "GET",
-					UpstreamPath: "/v1/poimen/executions/{id}/history",
+					UpstreamPath: "/v1/poimen/executions/history",
 					Auth:         &Auth{Required: true, Capability: "workflow:read"},
 				}},
 			},
@@ -80,7 +83,7 @@ func GetPoimenSpec() *Spec {
 				Name: "execution-stream",
 				Methods: []Method{{
 					Verb:         "GET",
-					UpstreamPath: "/v1/poimen/executions/{id}/stream",
+					UpstreamPath: "/v1/poimen/executions/stream",
 					Auth:         &Auth{Required: true, Capability: "workflow:read"},
 				}},
 			},
@@ -88,7 +91,7 @@ func GetPoimenSpec() *Spec {
 				Name: "execution-signal",
 				Methods: []Method{{
 					Verb:         "POST",
-					UpstreamPath: "/v1/poimen/executions/{id}/signal",
+					UpstreamPath: "/v1/poimen/executions/signal",
 					Auth:         &Auth{Required: true, Capability: "workflow:execute"},
 				}},
 			},

internal/temporal/poimen.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
-	"strings"
 	"time"
 )
 
@@ -33,26 +32,29 @@ func (p *PoimenHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		p.handleExecute(w, r)
 	case path == "/v1/poimen/executions" && r.Method == http.MethodGet:
 		p.handleListExecutions(w, r)
-	case strings.HasPrefix(path, "/v1/poimen/executions/") && strings.HasSuffix(path, "/stream") && r.Method == http.MethodGet:
+	case path == "/v1/poimen/executions/stream" && r.Method == http.MethodGet:
 		p.handleStream(w, r)
-	case strings.HasPrefix(path, "/v1/poimen/executions/") && strings.HasSuffix(path, "/signal") && r.Method == http.MethodPost:
+	case path == "/v1/poimen/executions/signal" && r.Method == http.MethodPost:
 		p.handleSignal(w, r)
-	case strings.HasPrefix(path, "/v1/poimen/executions/") && strings.HasSuffix(path, "/history") && r.Method == http.MethodGet:
+	case path == "/v1/poimen/executions/history" && r.Method == http.MethodGet:
 		p.handleHistory(w, r)
-	case strings.HasPrefix(path, "/v1/poimen/executions/") && r.Method == http.MethodDelete:
+	case path == "/v1/poimen/executions/detail" && r.Method == http.MethodDelete:
 		p.handleTerminate(w, r)
-	case strings.HasPrefix(path, "/v1/poimen/executions/") && r.Method == http.MethodGet:
+	case path == "/v1/poimen/executions/detail" && r.Method == http.MethodGet:
 		p.handleDescribe(w, r)
 	default:
 		writeJSON(w, http.StatusNotFound, map[string]string{"error": "endpoint not found"})
 	}
 }
 
-// extractWorkflowID extracts the workflow ID from paths like /v1/poimen/executions/{id}/...
-func extractWorkflowID(path string) string {
-	parts := strings.Split(strings.TrimPrefix(path, "/v1/poimen/executions/"), "/")
-	if len(parts) > 0 && parts[0] != "" {
-		return parts[0]
+// getWorkflowID reads the workflow ID from query param (preferred) or path.
+// The ServiceAdapter sets X-Upstream-Path to a template like
+// /v1/poimen/executions/{id}/stream — the {id} is literal, not substituted.
+// So workflow_id must come from a query parameter.
+func getWorkflowID(r *http.Request) string {
+	// Query param is the primary source
+	if id := r.URL.Query().Get("workflow_id"); id != "" {
+		return id
 	}
 	return ""
 }
@@ -176,13 +178,9 @@ func (p *PoimenHandler) handleDescribe(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	path := r.Header.Get("X-Upstream-Path")
-	if path == "" {
-		path = r.URL.Path
-	}
-	workflowID := extractWorkflowID(path)
+	workflowID := getWorkflowID(r)
 	if workflowID == "" {
-		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id query param required"})
 		return
 	}
 
@@ -209,13 +207,9 @@ func (p *PoimenHandler) handleHistory(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	path := r.Header.Get("X-Upstream-Path")
-	if path == "" {
-		path = r.URL.Path
-	}
-	workflowID := extractWorkflowID(path)
+	workflowID := getWorkflowID(r)
 	if workflowID == "" {
-		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id query param required"})
 		return
 	}
 
@@ -248,15 +242,9 @@ func (p *PoimenHandler) handleSignal(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	path := r.Header.Get("X-Upstream-Path")
-	if path == "" {
-		path = r.URL.Path
-	}
-	// Remove /signal suffix to get workflow ID
-	cleanPath := strings.TrimSuffix(path, "/signal")
-	workflowID := extractWorkflowID(cleanPath)
+	workflowID := getWorkflowID(r)
 	if workflowID == "" {
-		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id query param required"})
 		return
 	}
 
@@ -290,13 +278,9 @@ func (p *PoimenHandler) handleTerminate(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	path := r.Header.Get("X-Upstream-Path")
-	if path == "" {
-		path = r.URL.Path
-	}
-	workflowID := extractWorkflowID(path)
+	workflowID := getWorkflowID(r)
 	if workflowID == "" {
-		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id query param required"})
 		return
 	}
 
@@ -317,15 +301,9 @@ func (p *PoimenHandler) handleTerminate(w http.ResponseWriter, r *http.Request)
 // --- Stream (delegate to existing SSE handler) ---
 
 func (p *PoimenHandler) handleStream(w http.ResponseWriter, r *http.Request) {
-	path := r.Header.Get("X-Upstream-Path")
-	if path == "" {
-		path = r.URL.Path
-	}
-	// Remove /stream suffix
-	cleanPath := strings.TrimSuffix(path, "/stream")
-	workflowID := extractWorkflowID(cleanPath)
+	workflowID := getWorkflowID(r)
 	if workflowID == "" {
-		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id query param required"})
 		return
 	}