LIMBFORGE EDIT-ANY-MEASUREMENT API CONTRACT
===========================================

Legacy current-record editing
-----------------------------
PUT /api/projects/{project_id}/measurements/{measurement_key}

Required JSON:
- value_mm
- status
- notes
- change_reason

Server-recorded:
- changed_by
- changed_at

Behaviour:
- Load the current record before changing it.
- Require a non-empty change_reason when a record already exists.
- Append the old and new values to measurement_revisions.
- Update the current measurements row transactionally.
- Supersede every affected immutable Design Forge snapshot.
- Never alter or delete an existing snapshot.

Measurement sessions
--------------------
POST /api/projects/{project_id}/sessions
GET  /api/projects/{project_id}/sessions
GET  /api/projects/{project_id}/sessions/{session_id}

Session-record editing
----------------------
PUT /api/projects/{project_id}/sessions/{session_id}/measurements/{measurement_key}

Required JSON:
- value_mm
- status
- notes
- change_reason

Behaviour:
- Confirm session belongs to the project.
- Load the existing session record.
- Require a reason when changing an existing record.
- Append revision history.
- Update measurement_session_records transactionally.
- Add snapshot supersession records where required.

Revision history
----------------
GET /api/projects/{project_id}/revisions
GET /api/projects/{project_id}/sessions/{session_id}/revisions

Safety
------
- OI-only definitions remain blocked for non-OI projects.
- Revision rows remain append-only.
- Snapshots remain immutable.
- Editing does not approve Forge generation.
- Editing does not unblock CoverCanvas manufacturing export.