v0.21.1: Add GET /api/config endpoint for live config content

New endpoint returns raw controller.yaml content (text/yaml) for Hub
live diff and pull operations. Same auth as other config endpoints.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## Changelog
 
+### v0.21.1 — Config Content Endpoint (2026-02-20)
+- **`GET /api/config`**: New endpoint returning raw controller.yaml content (text/yaml). Used by Hub for live config diff and pull operations. Same auth as other config endpoints (Bearer token or session cookie).
+
 ### What was just completed (2026-02-20 session 64)
 - **v0.21.0 — Hub Monitoring Takeover (Controller-side, Phases 5+6):**
 

controller/README.md

@@ -1066,6 +1066,7 @@ Self-update endpoints accept session auth OR `Authorization: Bearer <hub_api_key
 |--------|----------|-------------|
 | POST | `/api/config/apply` | Apply new controller.yaml from Hub (atomic write) |
 | GET | `/api/config/hash` | Get SHA256 hash of current controller.yaml |
+| GET | `/api/config` | Get raw controller.yaml content (text/yaml) for live diff and pull |
 
 Config endpoints accept session auth OR `Authorization: Bearer <hub_api_key>` (same as self-update). The `/api/config/apply` endpoint:
 - Accepts raw YAML body (the generated config from Hub)
@@ -1162,6 +1163,7 @@ See `docker-compose.yml` for the full volume configuration.
 - [x] Disaster recovery (v0.15.5) — Hub-based infra backup, auto-mount by UUID, restore UI with full-page takeover
 - [x] Controller self-update (v0.16.0) — Watchtower-style pull + restart, Settings page UI, API key auth, auto-update scheduling
 - [x] Hub-managed config (v0.20.0) — Config apply endpoint (`POST /api/config/apply`), config hash in reports for sync comparison
+- [x] Config content endpoint (v0.21.1) — `GET /api/config` returns raw YAML for Hub live diff and pull operations
 
 ### In Progress / Planned
 

controller/internal/api/router.go

@@ -89,6 +89,10 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	case path == "/config/hash" && req.Method == http.MethodGet:
 		r.configHash(w, req)
 
+	// GET /api/config — return raw controller.yaml content
+	case path == "/config" && req.Method == http.MethodGet:
+		r.configContent(w, req)
+
 	// GET /api/stacks/{name}/deploy-fields
 	case hasSuffix(path, "/deploy-fields") && req.Method == http.MethodGet:
 		r.getDeployFields(w, req, extractName(path, "/deploy-fields"))
@@ -978,6 +982,16 @@ func (r *Router) configHash(w http.ResponseWriter, _ *http.Request) {
 	writeJSON(w, http.StatusOK, apiResponse{OK: true, Data: map[string]string{"hash": hash, "path": filepath.Base(r.configPath)}})
 }
 
+func (r *Router) configContent(w http.ResponseWriter, _ *http.Request) {
+	data, err := os.ReadFile(r.configPath)
+	if err != nil {
+		writeJSON(w, http.StatusInternalServerError, apiResponse{OK: false, Error: "failed to read config"})
+		return
+	}
+	w.Header().Set("Content-Type", "text/yaml; charset=utf-8")
+	w.Write(data)
+}
+
 func writeJSON(w http.ResponseWriter, status int, v interface{}) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)