# Get Session Chat

Source: https://recoupable.dev/docs/api-reference/sessions/get-chat

Get session chat

## GET /api/sessions/{sessionId}/chats/{chatId}

Full OpenAPI specification: https://recoupable.dev/docs/spec/sessions.json

## Authentication

This operation requires one of the security alternatives in the specification below. Security scheme definitions are included where present in the published specification.

[Authentication guide](https://recoupable.dev/docs/authentication)

## Operation and referenced schemas

```json
{
  "openapi": "3.1.0",
  "info": {
    "title": "Recoup API - Sessions",
    "description": "Sessions — sandboxed runs of an LLM-driven agent with tool use, lifecycle hooks, and persistence. Each session pairs one Vercel Sandbox with one or more chat threads.",
    "license": {
      "name": "MIT"
    },
    "version": "1.0.0"
  },
  "servers": [
    {
      "url": "https://api.recoupable.dev"
    }
  ],
  "security": [
    {
      "ApiKeyAuth": []
    },
    {
      "BearerAuth": []
    }
  ],
  "paths": {
    "/api/sessions/{sessionId}/chats/{chatId}": {
      "get": {
        "summary": "Get session chat",
        "description": "Returns the chat's persisted UI message stream plus its current streaming state so callers can hydrate or refresh a chat view. `messages` is an array of `parts` payloads — one per `chat_messages` row — ordered by `created_at` ascending (ties broken by id). `isStreaming` is derived from `activeStreamId`.",
        "parameters": [
          {
            "name": "sessionId",
            "in": "path",
            "required": true,
            "description": "The id of the parent session.",
            "schema": {
              "type": "string"
            }
          },
          {
            "name": "chatId",
            "in": "path",
            "required": true,
            "description": "The id of the chat being fetched.",
            "schema": {
              "type": "string"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Chat retrieved successfully.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/SessionChatResponse"
                }
              }
            }
          },
          "401": {
            "description": "Unauthorized — invalid or missing API key / Bearer token.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          },
          "403": {
            "description": "Forbidden — the authenticated account does not own this session.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          },
          "404": {
            "description": "Not found — no session exists with the given id, the chat does not exist, or the chat belongs to a different session.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "SessionChatResponse": {
        "type": "object",
        "description": "Response body for `GET /api/sessions/{sessionId}/chats/{chatId}`. Carries the full chat row plus its streaming state and persisted UI message stream — enough for both initial render and in-tab refresh.",
        "required": [
          "chat",
          "isStreaming",
          "messages"
        ],
        "properties": {
          "chat": {
            "$ref": "#/components/schemas/Chat"
          },
          "isStreaming": {
            "type": "boolean",
            "description": "True when `chat.activeStreamId` is non-null."
          },
          "messages": {
            "type": "array",
            "description": "Persisted UI message stream — one serialized `UIMessage` per `chat_messages` row, ordered by `created_at` ascending (ties broken by `id`). Each item is the full message object, not a bare parts array.",
            "items": {
              "type": "object",
              "description": "A serialized `UIMessage` as stored by the agent.",
              "required": [
                "id",
                "role",
                "parts"
              ],
              "properties": {
                "id": {
                  "type": "string",
                  "description": "Message id."
                },
                "role": {
                  "type": "string",
                  "enum": [
                    "user",
                    "assistant"
                  ]
                },
                "parts": {
                  "type": "array",
                  "description": "Ordered message parts (text, tool calls, data parts, etc.).",
                  "items": {
                    "type": "object",
                    "additionalProperties": true
                  }
                }
              },
              "additionalProperties": true
            }
          }
        }
      },
      "Error": {
        "type": "object",
        "required": [
          "status",
          "error"
        ],
        "properties": {
          "status": {
            "type": "string",
            "enum": [
              "error"
            ],
            "description": "Always `\"error\"` for error responses."
          },
          "error": {
            "type": "string",
            "description": "Human-readable error message."
          }
        }
      },
      "Chat": {
        "type": "object",
        "required": [
          "id",
          "sessionId",
          "title",
          "modelId",
          "createdAt",
          "updatedAt"
        ],
        "properties": {
          "id": {
            "type": "string",
            "description": "Chat id (nanoid)."
          },
          "sessionId": {
            "type": "string",
            "description": "Owning session id."
          },
          "title": {
            "type": "string",
            "description": "Display title for the chat. The initial chat created with a session is titled `New chat`."
          },
          "modelId": {
            "type": "string",
            "description": "AI Gateway model identifier the chat is configured to use (e.g. `openai/gpt-5.4`)."
          },
          "activeStreamId": {
            "type": "string",
            "nullable": true,
            "description": "Id of an in-flight assistant stream, if one is active."
          },
          "lastAssistantMessageAt": {
            "type": "string",
            "format": "date-time",
            "nullable": true,
            "description": "Timestamp of the most recent assistant message in this chat."
          },
          "createdAt": {
            "type": "string",
            "format": "date-time"
          },
          "updatedAt": {
            "type": "string",
            "format": "date-time"
          }
        }
      }
    },
    "securitySchemes": {
      "ApiKeyAuth": {
        "type": "apiKey",
        "in": "header",
        "name": "x-api-key"
      },
      "BearerAuth": {
        "type": "http",
        "scheme": "bearer"
      }
    }
  }
}
```