> ## Documentation Index
> Fetch the complete documentation index at: https://docs.3ngram.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Open or re-activate an agent session by its natural key (SessionStart). Idempotent: startup inserts, resume reuses the row and advances activation_epoch, and neither restamps the briefing.



## OpenAPI

````yaml /api-reference/openapi.json post /api/v1/agent-sessions/open
openapi: 3.1.0
info:
  description: >-
    The /api/v1 REST mirror of the 3ngram memory core
    (docs/concepts/architecture.mdx: one core, N transports). Authenticate with
    an X-API-Key header or a session Bearer token.
  title: 3ngram REST API
  version: v1
servers:
  - description: 3ngram platform
    url: https://api.3ngram.ai
security:
  - apiKey: []
  - sessionBearer: []
paths:
  /api/v1/agent-sessions/open:
    post:
      summary: >-
        Open or re-activate an agent session by its natural key (SessionStart).
        Idempotent: startup inserts, resume reuses the row and advances
        activation_epoch, and neither restamps the briefing.
      operationId: openAgentSession
      requestBody:
        content:
          application/json:
            schema:
              additionalProperties: false
              properties:
                agent:
                  maxLength: 64
                  minLength: 1
                  pattern: ^[a-z0-9][a-z0-9-]*$
                  type: string
                briefedMemories:
                  items:
                    additionalProperties: false
                    properties:
                      id:
                        format: uuid
                        pattern: >-
                          ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$
                        type: string
                      status:
                        maxLength: 64
                        minLength: 1
                        type: string
                      topic:
                        maxLength: 256
                        minLength: 1
                        type: string
                    required:
                      - id
                      - topic
                      - status
                    type: object
                  maxItems: 100
                  type: array
                project:
                  maxLength: 256
                  minLength: 1
                  type: string
                scope:
                  maxLength: 64
                  minLength: 1
                  pattern: ^[a-z0-9][a-z0-9-]*$
                  type: string
                selector:
                  default:
                    kind: all
                  oneOf:
                    - additionalProperties: false
                      properties:
                        kind:
                          const: all
                          type: string
                      required:
                        - kind
                      type: object
                    - additionalProperties: false
                      properties:
                        kind:
                          const: scope
                          type: string
                        scope:
                          maxLength: 64
                          minLength: 1
                          pattern: ^[a-z0-9][a-z0-9-]*$
                          type: string
                      required:
                        - kind
                        - scope
                      type: object
                    - additionalProperties: false
                      properties:
                        kind:
                          const: project
                          type: string
                        project:
                          maxLength: 256
                          minLength: 1
                          type: string
                      required:
                        - kind
                        - project
                      type: object
                    - additionalProperties: false
                      properties:
                        includeUnscoped:
                          default: false
                          description: >-
                            Also match memories in the scope written with NO
                            project (project IS NULL). Default false: strict
                            scope AND project intersection.
                          type: boolean
                        kind:
                          const: scope_project
                          type: string
                        project:
                          maxLength: 256
                          minLength: 1
                          type: string
                        scope:
                          maxLength: 64
                          minLength: 1
                          pattern: ^[a-z0-9][a-z0-9-]*$
                          type: string
                      required:
                        - kind
                        - scope
                        - project
                      type: object
                sessionId:
                  maxLength: 256
                  minLength: 1
                  type: string
                source:
                  enum:
                    - startup
                    - resume
                  type: string
              required:
                - agent
                - sessionId
                - source
              type: object
        required: true
      responses:
        '200':
          content:
            application/json:
              schema:
                additionalProperties: false
                properties:
                  activationEpoch:
                    exclusiveMinimum: 0
                    maximum: 9007199254740991
                    type: integer
                  briefingDeliveredAt:
                    anyOf:
                      - format: date-time
                        pattern: >-
                          ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$
                        type: string
                      - type: 'null'
                  created:
                    type: boolean
                  lastSeenAt:
                    format: date-time
                    pattern: >-
                      ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$
                    type: string
                  openedAt:
                    format: date-time
                    pattern: >-
                      ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$
                    type: string
                  reopened:
                    type: boolean
                  sessionRunId:
                    format: uuid
                    pattern: >-
                      ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$
                    type: string
                  source:
                    enum:
                      - startup
                      - resume
                    type: string
                required:
                  - sessionRunId
                  - activationEpoch
                  - source
                  - created
                  - reopened
                  - openedAt
                  - lastSeenAt
                  - briefingDeliveredAt
                type: object
          description: Success
        '409':
          content:
            application/json:
              schema:
                additionalProperties: false
                properties:
                  error:
                    enum:
                      - conflict
                    type: string
                required:
                  - error
                type: object
          description: >-
            A startup open reused a natural key already opened with different
            project, scope or selector
components:
  securitySchemes:
    apiKey:
      in: header
      name: X-API-Key
      type: apiKey
    sessionBearer:
      scheme: bearer
      type: http

````