Make delivery and integration failures explicit

Persist reminder presentations and retry state, atomically complete collapsed deliveries, fall back across away reaches, and block permanent failures visibly (V-715, V-678). Fail closed when enabled integrations lack credentials and keep remote arms explicitly dark (V-691). Give mavweb one sanitized, request-correlated error contract (V-689). Owner explicitly requested direct commits to master.

cmd/mavweb/main.go

@@ -48,9 +48,14 @@ func main() {
 	hexisURL := flag.String("hexis", "", "Hexis base URL for the /ecosystem panel (empty = not configured)")
 	// Shared secret for POST /api/ambient, the notification-relay ingest that
 	// reads the work calendar as a signal instead of holding a work credential
-	// (see ambient.go). Empty ⇒ the route is not registered at all.
-	ambientToken := flag.String("ambient-token", "", "shared secret for POST /api/ambient notification ingest (empty = ingest disabled, route not registered)")
+	// (see ambient.go). Enabling and authenticating are separate on purpose: an
+	// expanded-empty secret cannot silently turn a live integration off.
+	ambientEnabled := flag.Bool("ambient-enabled", false, "enable POST /api/ambient notification ingest (requires -ambient-token)")
+	ambientToken := flag.String("ambient-token", "", "shared secret for POST /api/ambient notification ingest")
 	flag.Parse()
+	if err := validateAmbientConfig(*ambientEnabled, *ambientToken); err != nil {
+		log.Fatal(err)
+	}
 
 	var core ipc.CoreAPI
 	// swapConn — a second connection, for /models and nothing else. A model swap
@@ -129,9 +134,9 @@ func main() {
 		w.Write([]byte(*ntfyWS))
 	})
 	mux.HandleFunc("/api/signal", corePage(handleSignal))
-	// Off unless configured: no token, no route — an unconfigured ingest is not
-	// a 503 waiting to be probed, it does not exist.
-	if *ambientToken != "" {
+	// Off unless explicitly enabled: a dark ingest has no route at all, while an
+	// enabled ingest with no token was rejected before the server was built.
+	if *ambientEnabled {
 		mux.HandleFunc("/api/ambient", func(w http.ResponseWriter, r *http.Request) {
 			handleAmbient(w, r, core, *ambientToken)
 		})
@@ -251,6 +256,13 @@ func main() {
 	}
 }
 
+func validateAmbientConfig(enabled bool, token string) error {
+	if enabled && token == "" {
+		return errors.New("mavweb: ambient ingest is enabled but -ambient-token is empty")
+	}
+	return nil
+}
+
 // logUnguardedSurfaces names, at startup, what step-up would have covered had
 // WebAuthn been configured. One surface per line: these are read in a terminal
 // at the moment someone is deciding whether the box is safe to expose.
@@ -288,7 +300,7 @@ const (
 func mavwebHTTPServer(addr string, handler http.Handler) *http.Server {
 	return &http.Server{
 		Addr:              addr,
-		Handler:           handler,
+		Handler:           withRequestID(handler),
 		ReadHeaderTimeout: mavwebReadHeaderTimeout,
 		ReadTimeout:       mavwebReadTimeout,
 		IdleTimeout:       mavwebIdleTimeout,