diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3809642..a872cff 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 ## Changelog
 
+### v0.185.1 — E-2: the offer endpoints were mounted where nothing routed to them (2026-07-29)
+
+Registered as `/api/backup-target` inside `ServeStorageAPI`'s switch — which `main.go` mounts ONLY at
+`/api/storage/`. Live result: `{"ok":false,"error":"endpoint not found"}` while every unit test
+passed, because the tests called the handlers directly and never travelled the mount. Caught by the
+first live call, which is exactly why the live call is part of the procedure.
+
+Moved to `/api/storage/backup-target[/assign]`. `TestBackupTargetRoutesLiveUnderTheStorageAPIMount`
+now asserts the dispatcher's own source contains both paths, so a handler that nothing routes to
+fails the suite — the repo's seam-wiring rule ("a feature is not shipped until its entry point is
+reachable"), applied to a route rather than a button.
+
 ### v0.185.0 — E-2 Parts 3+4: the offer, and the honest degraded state (2026-07-29) — MinAgent 0.113.0
 
 The half that makes the rest work. A degraded backup target recorded only in config is the
diff --git a/controller/internal/web/backup_target_offer.go b/controller/internal/web/backup_target_offer.go
index 6934bda..ee9c239 100644
--- a/controller/internal/web/backup_target_offer.go
+++ b/controller/internal/web/backup_target_offer.go
@@ -136,7 +136,7 @@ func degradedMessageFor(st BackupTargetState) string {
 	return backupTargetDegradedText
 }
 
-// handleBackupTargetState serves GET /api/backup-target — the dashboard's source for the degraded
+// handleBackupTargetState serves GET /api/storage/backup-target — the dashboard's source for the degraded
 // banner and the offer.
 func (s *Server) handleBackupTargetState(w http.ResponseWriter, r *http.Request) {
 	st := s.resolveBackupTargetState(r.Context())
@@ -157,7 +157,7 @@ func (s *Server) handleBackupTargetState(w http.ResponseWriter, r *http.Request)
 	writeDiskJSON(w, http.StatusOK, true, "", out)
 }
 
-// handleBackupTargetAssign is the ACCEPTANCE of the offer — POST /api/backup-target/assign.
+// handleBackupTargetAssign is the ACCEPTANCE of the offer — POST /api/storage/backup-target/assign.
 //
 // NOTHING calls this except an explicit customer action. Registration does not, the drive-gate does
 // not, and no scheduler does (E-2 §3: a drive never acquires a role by appearing). Declining is
diff --git a/controller/internal/web/backup_target_offer_test.go b/controller/internal/web/backup_target_offer_test.go
index ac6d6da..0d2c626 100644
--- a/controller/internal/web/backup_target_offer_test.go
+++ b/controller/internal/web/backup_target_offer_test.go
@@ -1,6 +1,7 @@
 package web
 
 import (
+	"os"
 	"strings"
 	"testing"
 )
@@ -59,3 +60,39 @@ func TestUnknownStateRendersNothing(t *testing.T) {
 			"of degradation", msg)
 	}
 }
+
+// REACHABILITY — the repo's seam-wiring rule, and it already bit once here.
+//
+// These handlers were first registered as /api/backup-target inside ServeStorageAPI's switch, which
+// main.go mounts ONLY at "/api/storage/". The endpoints returned "endpoint not found" on a live box
+// while every unit test passed, because the tests called the handlers directly and never travelled
+// the mount. A feature is not shipped until its entry point is reachable.
+func TestBackupTargetRoutesLiveUnderTheStorageAPIMount(t *testing.T) {
+	// main.go: mux.Handle("/api/storage/", ... ServeStorageAPI). Anything the switch answers MUST
+	// therefore begin with that prefix or it is dead on arrival.
+	for _, p := range []string{
+		"/api/storage/backup-target",
+		"/api/storage/backup-target/assign",
+	} {
+		if !strings.HasPrefix(p, "/api/storage/") {
+			t.Fatalf("%s is outside the /api/storage/ mount and would 404 in production", p)
+		}
+	}
+	src := storageAPISource(t)
+	for _, want := range []string{`"/api/storage/backup-target"`, `"/api/storage/backup-target/assign"`} {
+		if !strings.Contains(src, want) {
+			t.Errorf("ServeStorageAPI does not dispatch %s — the handler exists but nothing routes to it", want)
+		}
+	}
+}
+
+// storageAPISource reads the dispatcher's own source, so the assertion is about what the router
+// actually contains rather than about a constant the test itself defines.
+func storageAPISource(t *testing.T) string {
+	t.Helper()
+	b, err := os.ReadFile("storage_handlers.go")
+	if err != nil {
+		t.Fatalf("read storage_handlers.go: %v", err)
+	}
+	return string(b)
+}
diff --git a/controller/internal/web/storage_handlers.go b/controller/internal/web/storage_handlers.go
index 94d196f..cbefe33 100644
--- a/controller/internal/web/storage_handlers.go
+++ b/controller/internal/web/storage_handlers.go
@@ -356,9 +356,9 @@ func (s *Server) ServeStorageAPI(w http.ResponseWriter, r *http.Request) {
 		s.handleStorageRegister(w, r)
 	// E-2 Parts 3+4. State drives the degraded banner and the OFFER; assign is the offer's
 	// ACCEPTANCE and the ONLY writer of the role — registration above deliberately does not set it.
-	case r.URL.Path == "/api/backup-target" && r.Method == http.MethodGet:
+	case r.URL.Path == "/api/storage/backup-target" && r.Method == http.MethodGet:
 		s.handleBackupTargetState(w, r)
-	case r.URL.Path == "/api/backup-target/assign" && r.Method == http.MethodPost:
+	case r.URL.Path == "/api/storage/backup-target/assign" && r.Method == http.MethodPost:
 		s.handleBackupTargetAssign(w, r)
 	case r.URL.Path == "/api/storage/migrate" && r.Method == http.MethodPost:
 		s.handleStorageMigrate(w, r)