# Create Session

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

Create session

## POST /api/sessions

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": {
      "post": {
        "summary": "Create session",
        "description": "Creates a new agent session and an initial empty chat in a single transaction. The session is created in the `provisioning` lifecycle state — a separate orchestration step claims it and starts the sandbox.",
        "requestBody": {
          "required": false,
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/CreateSessionRequest"
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "Session and initial chat created successfully.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/CreateSessionResponse"
                }
              }
            }
          },
          "400": {
            "description": "Invalid request body — either malformed JSON or a field failed validation.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          },
          "401": {
            "description": "Unauthorized — invalid or missing API key / Bearer token.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          },
          "500": {
            "description": "Server error — the session could not be persisted.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "CreateSessionRequest": {
        "type": "object",
        "description": "All fields are optional. An empty body is valid and creates a personal session — the server provisions (or reuses) a workspace repo at `recoupable/<accountId>` for the authenticated user. Include `organizationId` to create an org session instead — the server provisions (or reuses) `recoupable/<organizationId>`. The caller never constructs repo URLs.",
        "properties": {
          "title": {
            "type": "string",
            "description": "Display title for the session. When omitted, the server generates one."
          },
          "organizationId": {
            "type": "string",
            "format": "uuid",
            "description": "Recoupable organization id. When provided, the session is created against the org's workspace repo (`recoupable/<organizationId>`) and the caller must have access to that organization. When omitted, the session is personal and uses the caller's own workspace repo (`recoupable/<accountId>`)."
          },
          "artistId": {
            "type": "string",
            "format": "uuid",
            "description": "Artist account id to associate the session with. When provided, the session is created in the context of that artist — used by the chat sidebar to filter chats by artist. Optional; omit for a session with no artist context."
          }
        }
      },
      "CreateSessionResponse": {
        "type": "object",
        "required": [
          "session",
          "chat"
        ],
        "properties": {
          "session": {
            "$ref": "#/components/schemas/Session"
          },
          "chat": {
            "$ref": "#/components/schemas/Chat"
          }
        }
      },
      "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."
          }
        }
      },
      "Session": {
        "type": "object",
        "description": "Agent session returned by [`POST /api/sessions`](/api-reference/sessions/create), [`GET /api/sessions/{sessionId}`](/api-reference/sessions/get), and [`PATCH /api/sessions/{sessionId}`](/api-reference/sessions/patch). The api serializes every field listed in `required` on each response, including `isNewBranch` (boolean, from the non-null `sessions.is_new_branch` column) and `artistId` (UUID or null).",
        "required": [
          "id",
          "userId",
          "artistId",
          "title",
          "status",
          "isNewBranch",
          "globalSkillRefs",
          "lifecycleVersion",
          "createdAt",
          "updatedAt"
        ],
        "properties": {
          "id": {
            "type": "string",
            "description": "Session id (nanoid)."
          },
          "userId": {
            "type": "string",
            "format": "uuid",
            "description": "Owning account id. Named `userId` here for compatibility with existing clients; on the server side this is the account_id foreign key into the accounts table."
          },
          "title": {
            "type": "string"
          },
          "status": {
            "type": "string",
            "enum": [
              "running",
              "completed",
              "failed",
              "archived"
            ]
          },
          "repoOwner": {
            "type": "string",
            "nullable": true,
            "description": "GitHub repo owner if the session is bound to a repository."
          },
          "repoName": {
            "type": "string",
            "nullable": true
          },
          "branch": {
            "type": "string",
            "nullable": true
          },
          "cloneUrl": {
            "type": "string",
            "nullable": true,
            "description": "Clone URL the sandbox should fetch from."
          },
          "isNewBranch": {
            "type": "boolean",
            "description": "Always present on session responses. True when this session created and pushed a new branch (not committing back to the original); false otherwise."
          },
          "globalSkillRefs": {
            "type": "array",
            "description": "Skills attached to the agent at provision time.",
            "items": {
              "type": "object",
              "additionalProperties": true
            }
          },
          "sandboxState": {
            "type": "object",
            "nullable": true,
            "additionalProperties": true,
            "description": "Sandbox runtime state (Vercel Sandbox)."
          },
          "lifecycleState": {
            "type": "string",
            "nullable": true,
            "enum": [
              "provisioning",
              "active",
              "hibernating",
              "hibernated",
              "restoring",
              "archived",
              "failed"
            ],
            "description": "Lifecycle orchestration state for the sandbox."
          },
          "lifecycleVersion": {
            "type": "integer",
            "description": "Optimistic concurrency token for lifecycle transitions."
          },
          "lastActivityAt": {
            "type": "string",
            "format": "date-time",
            "nullable": true
          },
          "sandboxExpiresAt": {
            "type": "string",
            "format": "date-time",
            "nullable": true
          },
          "hibernateAfter": {
            "type": "string",
            "format": "date-time",
            "nullable": true
          },
          "lifecycleRunId": {
            "type": "string",
            "nullable": true
          },
          "lifecycleError": {
            "type": "string",
            "nullable": true
          },
          "linesAdded": {
            "type": "integer",
            "nullable": true,
            "description": "Lines added across the session's diff. Defaults to 0; null when stats have not been computed."
          },
          "linesRemoved": {
            "type": "integer",
            "nullable": true,
            "description": "Lines removed across the session's diff. Defaults to 0; null when stats have not been computed."
          },
          "snapshotUrl": {
            "type": "string",
            "nullable": true
          },
          "snapshotCreatedAt": {
            "type": "string",
            "format": "date-time",
            "nullable": true
          },
          "snapshotSizeBytes": {
            "type": "integer",
            "nullable": true
          },
          "cachedDiff": {
            "type": "object",
            "nullable": true,
            "additionalProperties": true
          },
          "cachedDiffUpdatedAt": {
            "type": "string",
            "format": "date-time",
            "nullable": true
          },
          "createdAt": {
            "type": "string",
            "format": "date-time"
          },
          "updatedAt": {
            "type": "string",
            "format": "date-time"
          },
          "artistId": {
            "type": [
              "string",
              "null"
            ],
            "format": "uuid",
            "description": "Artist account id this session was created in the context of, or `null` when no artist was associated. Set via `POST /api/sessions { artistId }`; surfaces here for clients (e.g. the chat sidebar) that filter sessions/chats by artist."
          }
        }
      },
      "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"
      }
    }
  }
}
```