security(music): ensure read permission via authz

tests/api/favorites.hurl

@@ -159,3 +159,77 @@ Authorization: Bearer {{token}}
 HTTP 200
 [Asserts]
 jsonpath "$.items" count == 0
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 12 — Cross-tenant regression (post-Drive AuthZ audit,
+#           Round 1 HIGH). Before this fix, `POST /api/favorites/…`
+#           accepted any UUID and enrolled it; the listing endpoint
+#           then JOINed back to storage.files/folders and returned
+#           name/mime/size/drive_id for anything the caller had
+#           managed to add — an information oracle over the whole
+#           tenant. Now the write path calls `authz.require(Read, …)`
+#           per item; a caller with no grant gets 404 (anti-enum)
+#           + `authz.denied` audit line. See
+#           `docs/plan/authz_audit/rest_storage.md`.
+# ─────────────────────────────────────────────────────────────
+
+# Create a second, unprivileged user. Idempotent: `HTTP *` accepts
+# either 201 (first run) or 409 (subsequent runs). The login below
+# is the actual precondition — if it succeeds we know the user
+# exists with the expected password.
+POST {{base_url}}/api/admin/users
+Authorization: Bearer {{token}}
+Content-Type: application/json
+{ "username": "fav_mallory", "password": "FavMalloryPassword1!", "email": "fav_mallory@example.com", "role": "user" }
+
+HTTP *
+
+
+POST {{base_url}}/api/auth/login
+Content-Type: application/json
+{ "username": "fav_mallory", "password": "FavMalloryPassword1!" }
+
+HTTP 200
+[Captures]
+mallory_token: jsonpath "$.access_token"
+
+
+# Step 12a — Single-add on admin's file: 404 (anti-enum shape).
+POST {{base_url}}/api/favorites/file/{{file_id}}
+Authorization: Bearer {{mallory_token}}
+
+HTTP 404
+
+
+# Step 12b — Single-add on admin's folder: 404.
+POST {{base_url}}/api/favorites/folder/{{test1_id}}
+Authorization: Bearer {{mallory_token}}
+
+HTTP 404
+
+
+# Step 12c — Batch: must fail wholesale on the first denial. A partial
+#           success would still leak "which items are valid" — the same
+#           oracle we're closing.
+POST {{base_url}}/api/favorites/batch
+Authorization: Bearer {{mallory_token}}
+Content-Type: application/json
+{
+  "items": [
+    { "item_id": "{{file_id}}",  "item_type": "file"   },
+    { "item_id": "{{test1_id}}", "item_type": "folder" }
+  ]
+}
+
+HTTP 404
+
+
+# Step 12d — Mallory's favorites list is EMPTY — no partial success
+#           slipped through.
+GET {{base_url}}/api/favorites/resources
+Authorization: Bearer {{mallory_token}}
+
+HTTP 200
+[Asserts]
+jsonpath "$.items" count == 0