> ## Documentation Index
> Fetch the complete documentation index at: https://docs.intelligence-management-platform.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Compact a session

> Summarises older messages in the session into a compact checkpoint message, reducing the context window footprint. Returns a 409 if a response is currently streaming for the session. Returns a 422 if the session history is too short to benefit from compaction. The `x-exulu-model-override` header is accepted to choose the summarisation model.



## OpenAPI

````yaml /openapi/openapi.json post /agents/litellm/compact/{instance}
openapi: 3.1.0
info:
  title: IMP REST API
  version: 1.0.0
  description: >-
    REST endpoints of the IMP backend. GraphQL covers entity CRUD; REST covers
    agent runs, media, files, and system utilities. All requests require
    authentication unless the agent is public.
servers:
  - url: '{baseUrl}'
    variables:
      baseUrl:
        default: http://localhost:9001
        description: >-
          Base URL of your IMP backend. Self-hosted deployments typically run on
          port 9001.
security:
  - apiKey: []
  - bearer: []
tags:
  - name: Agents
    description: Endpoints for running, compacting, and querying agent instances.
  - name: Sessions
    description: Endpoints for managing files attached to agent sessions.
  - name: Media
    description: Transcription, speech synthesis, and image generation.
  - name: System
    description: Platform health and configuration utilities.
  - name: Budgets
    description: >-
      LiteLLM tag-budget management for users, roles, teams, projects, agents,
      and routines. Access requires `super_admin` or a role with
      `budget_management` write scope.
  - name: Skills
    description: >-
      Skills are versioned bundles of files (markdown, scripts, assets) mounted
      into the agent sandbox. These endpoints manage the skill registry and
      individual skill files.
  - name: Uploads
    description: >-
      Uppy-compatible S3 companion routes for single-part and multipart file
      uploads. Accept the standard API key. The `internal-key` header (set to
      `INTERNAL_SECRET`) is accepted only on `/s3/delete`, `/s3/download`,
      `/s3/list`, and `/s3/object` — it does **not** work on `/s3/sign` or the
      `/s3/multipart` routes.
  - name: Compliance
    description: >-
      GDPR / DSGVO operator endpoints for data-subject access (export) and
      erasure. Both require `super_admin`.
  - name: Artifacts
    description: >-
      Shareable artifact links — create, list, and revoke share links for files
      stored in S3.
paths:
  /agents/litellm/compact/{instance}:
    post:
      tags:
        - Agents
      summary: Compact a session
      description: >-
        Summarises older messages in the session into a compact checkpoint
        message, reducing the context window footprint. Returns a 409 if a
        response is currently streaming for the session. Returns a 422 if the
        session history is too short to benefit from compaction. The
        `x-exulu-model-override` header is accepted to choose the summarisation
        model.
      operationId: compactSession
      parameters:
        - name: instance
          in: path
          required: true
          description: Agent ID (UUID).
          schema:
            type: string
            format: uuid
        - name: session
          in: header
          required: true
          description: Agent session ID whose history should be compacted.
          schema:
            type: string
            format: uuid
        - name: x-exulu-model-override
          in: header
          required: false
          description: >-
            LiteLLM model ID to use for summarisation, overriding the agent's
            configured model.
          schema:
            type: string
      requestBody:
        required: false
        content:
          application/json:
            schema:
              type: object
              properties:
                steer:
                  type: string
                  description: >-
                    Optional freeform instruction appended to the compaction
                    prompt to guide what the summary should emphasise.
      responses:
        '200':
          description: Compaction result including the checkpoint message.
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
                description: >-
                  Result returned by compactSession — includes the generated
                  checkpoint message and the number of messages replaced.
        '400':
          description: >-
            Missing session header, missing instance, or agent has no model
            configured.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: >-
            Authentication failed or caller lacks access to the agent or
            session.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: Model not permitted for the calling user.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: Agent or session not found.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '409':
          description: A response is still streaming for this session.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '422':
          description: Session history is too short to compact.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
components:
  schemas:
    Error:
      type: object
      properties:
        detail:
          type: string
          description: Human-readable error message.
        message:
          type: string
          description: Human-readable error message (alternate key used on some endpoints).
  securitySchemes:
    apiKey:
      type: apiKey
      in: header
      name: x-api-key
      description: >-
        Organisation API key. Format: `sk_<secret>/<keyname>` — the secret
        portion, a literal slash, and the human-readable key name. The header
        `exulu-api-key` is accepted as an alias. A `Bearer ` prefix is tolerated
        and stripped. Keys with an agent scope are only valid for the scoped
        agent instance.
    bearer:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: >-
        NextAuth session JWT (HS256, signed with `NEXTAUTH_SECRET`). This is the
        token the IMP frontend uses automatically.

````