---
title: "Write a new revision of a posture (forward-only)"
method: PUT
path: "/postures/{posture_id}"
tags: ["Postures"]
---

# Write a new revision of a posture (forward-only)

`PUT /postures/{posture_id}`

## Request

- Base URL: `https://api.mnemom.ai/v1`
- URL: `https://api.mnemom.ai/v1/postures/{posture_id}`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-Mnemom-Api-Key`

Creates a new immutable revision; updates current_revision_id pointer. Authorization: only an owner/admin of the organization that owns the posture may write (a member with a lower role receives 403); a `posture_id` in an org the caller does not belong to returns the same 404 as a nonexistent posture, so the status never reveals that another tenant's posture exists. Platform-scoped default postures are immutable (403).

## Path parameters

- `posture_id` string, required

## Headers

- `Idempotency-Key` string, required

## Request body

- object
  - `body` PostureBody, required: Trust posture body (PostureBody v1.0). Matches the runtime validator at src/composition/posture-validate.ts EXACTLY — strict-unknown-field rejection (additionalProperties:false) at every level, so adding a field requires a posture_schema_version bump (ADR-023/ADR-045). Used as the `body` of POST /v1/postures and PUT /v1/postures/{id}.
    - `posture_schema_version` 'v1.0', required: Schema version pin. Must be exactly `v1.0`.
    - `sideband` object, required
      - `coherence` object, required
        - `enabled` boolean, required
        - `cadence_seconds` integer, required
        - `severity_on_fire` 'low' | 'medium' | 'high' | 'critical', required
        - `fire_on` object, required
          - `pairwise_governance_floor_below` number, nullable, required: Fire when pairwise governance floor drops below this; null disables.
          - `conflict_edge_count_exceeds` integer, nullable, required: Fire when conflict-edge count exceeds this; null disables.
          - `outlier_agents_count_exceeds` integer, nullable, required: Fire when outlier-agent count exceeds this; null disables.
      - `fault_line` object, required
        - `enabled` boolean, required
        - `cadence_seconds` integer, required
        - `severity_floor` 'low' | 'medium' | 'high' | 'critical', required
        - `use_reputation_scores` boolean, required
        - `severity_on_fire` 'low' | 'medium' | 'high' | 'critical', required
      - `fleet` object, required
        - `enabled` boolean, required
        - `cadence_seconds` integer, required
        - `severity_on_fire` 'low' | 'medium' | 'high' | 'critical', required
        - `patterns` object, required
          - `outliers` boolean, required
          - `cluster_partition` boolean, required
          - `min_pair_score_below` number, nullable, required: Flag pairs scoring below this; null disables.
    - `fleet_identification` object, required
      - `by` 'team_membership', required
    - `fan_out` object, required
      - `rule` 'per_named_affected_agent', required
  - `change_note` string: Optional note describing this revision, recorded in the posture's revision history.

## Response `200`

Updated posture with new revision.

- PostureRevision: Versioned posture body. Immutable by handler discipline (forward-only). Matches revisionForResponse() exactly.
  - `revision_id` string, required
  - `posture_id` string, required
  - `revision_no` integer, required
  - `body` object, required: The versioned posture body (PostureBody shape; older revisions may predate the v1.0 schema).
  - `change_summary` string, nullable, required
  - `authored_by` string, nullable, required
  - `authored_at` string, date-time, nullable, required

## Other responses

- `400`: Bad request
- `401`: Authentication required
- `403`: Forbidden
- `404`: Resource not found
- `409`: Resource conflict — the request cannot proceed because of a current state conflict (e.g., resource already exists, version mismatch, in-flight idempotency key with a different body).
- `429`: Rate-limit exceeded. The global per-IP limiter (100 requests/minute, applied to every `/v1/*` route) rejected this request. Back off until the window resets — `Retry-After` carries the cooldown in seconds and `X-RateLimit-Reset` the absolute reset time.
- `500`: Server error — request was well-formed but the server failed to fulfill it. Typically a downstream dependency (DB / RPC / external API) returned an unexpected error.

---

[API](https://skmtc.dev/mnemom/apis/mnemom-api.md) · [All operations](https://skmtc.dev/mnemom/apis/mnemom-api/llms.txt) · [OpenAPI document](https://skmtc.dev/mnemom/apis/mnemom-api/revisions/274b7a6ea182?raw)