{
  "id": "message.pin_not_found",
  "category": "target_resolution",
  "summary": "The message to pin could not be resolved.",
  "match_any": [
    {
      "error_code": 400,
      "description_exact": "Bad Request: message to pin not found"
    }
  ],
  "scope": {
    "method_examples": [
      "pinChatMessage"
    ],
    "exhaustive": false
  },
  "possible_causes": [
    "The message identifier is missing or nonpositive.",
    "The bot cannot access messages in the chat.",
    "A message lookup failed and its original error was replaced."
  ],
  "diagnostic_limits": "The response does not distinguish a deleted message from an incorrect identifier, missing access or a masked lookup error.",
  "evidence": [
    {
      "source": "server-10.3",
      "path": "telegram-bot-api/Client.cpp",
      "lines": [
        16054,
        16065
      ],
      "note": "The pinChatMessage path checks the target as \"message to pin\"."
    },
    {
      "source": "server-10.3",
      "path": "telegram-bot-api/Client.cpp",
      "lines": [
        9084,
        9102
      ],
      "note": "Missing identifiers and unavailable message access produce this operation-specific fallback."
    },
    {
      "source": "server-10.3",
      "path": "telegram-bot-api/Client.cpp",
      "lines": [
        7390,
        7399
      ],
      "note": "Failed lookups use the same fallback when an empty result is not allowed."
    },
    {
      "source": "server-10.3",
      "path": "telegram-bot-api/Client.cpp",
      "lines": [
        85,
        108
      ],
      "note": "The fallback replaces only errors normalized to code 400."
    },
    {
      "source": "server-10.3",
      "path": "telegram-bot-api/Client.cpp",
      "lines": [
        165,
        205
      ],
      "note": "Adds the code-specific prefix and lowercases only the initial character of ordinary messages."
    }
  ],
  "example": {
    "method": "pinChatMessage",
    "response": {
      "ok": false,
      "error_code": 400,
      "description": "Bad Request: message to pin not found"
    }
  },
  "evidence_level": "source_derived",
  "guidance": {
    "action": "inspect_message_target_and_access",
    "repeat_request": "after_relevant_change",
    "preconditions": [
      "Check the chat and message identifiers together, then confirm the bot can access the target message."
    ]
  }
}