{"record":{"id":"b619237b31f260cc","repo":"rohitg00/ai-engineering-from-scratch","slug":"state-secret-must-not-be-empty","errorCode":null,"errorMessage":"state secret must not be empty","messagePattern":"state secret must not be empty","errorType":"exception","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"certifications/claude/lessons/11-mcp-server-design-and-integration/code/main.py","lineNumber":75,"sourceCode":"            \"string\": lambda value: isinstance(value, str),\n        }\n        for name, value in arguments.items():\n            if name not in properties:\n                continue\n            expected = properties[name].get(\"type\")\n            if expected not in checks:\n                raise ValueError(f\"unsupported schema type for {name}: {expected!r}\")\n            if not checks[expected](value):\n                raise ValueError(f\"{name} must be {expected}\")\n        return arguments\n\n\nclass RequestStateSigner:\n    \"\"\"Produces an opaque, integrity-protected MRTR requestState value.\"\"\"\n\n    def __init__(self, secret: bytes) -> None:\n        if not secret:\n            raise ValueError(\"state secret must not be empty\")\n        self.secret = secret\n\n    def issue(self, method: str, tool: str, arguments: dict[str, Any]) -> str:\n        payload = json.dumps(\n            {\"method\": method, \"tool\": tool, \"arguments\": arguments},\n            sort_keys=True,\n            separators=(\",\", \":\"),\n        ).encode(\"utf-8\")\n        encoded = base64.urlsafe_b64encode(payload).decode(\"ascii\").rstrip(\"=\")\n        signature = hmac.new(self.secret, encoded.encode(\"ascii\"), hashlib.sha256).hexdigest()\n        return f\"{encoded}.{signature}\"\n\n    def verify(self, token: str, method: str, tool: str, arguments: dict[str, Any]) -> None:\n        if not isinstance(token, str) or \".\" not in token:\n            raise ValueError(\"requestState is malformed\")\n        encoded, supplied_signature = token.rsplit(\".\", 1)\n        expected_signature = hmac.new(\n            self.secret, encoded.encode(\"ascii\"), hashlib.sha256","sourceCodeStart":57,"sourceCodeEnd":93,"githubUrl":"https://github.com/rohitg00/ai-engineering-from-scratch/blob/39ea8a1c6d0b61f071226eff7ede4d4105fed820/certifications/claude/lessons/11-mcp-server-design-and-integration/code/main.py#L57-L93","documentation":"Error \"state secret must not be empty\" thrown in rohitg00/ai-engineering-from-scratch.","triggerScenarios":"Thrown at certifications/claude/lessons/11-mcp-server-design-and-integration/code/main.py:75 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"39ea8a1c6d0b61f071226eff7ede4d4105fed820","analyzedAt":"2026-08-26T03:13:46.626Z","schemaVersion":2},"datasetVersion":"2026-08-26T07:17:17.940Z"}