| Code | HTTP | Meaning | Action |
|---|---|---|---|
VALIDATION_FAILED | 400 | Graph errors block activation | POST /validate, read errors[], fix each one, retry |
MISSING_FORM_ID | 400 | Node has no form_id | POST /forms then PATCH /nodes/:id |
MISSING_EDGE | 400 | conditional/split needs more edges | Add edges for all outcome paths |
ORPHANED_NODE | 400 | Node has no incoming edges | Add edge or DELETE /nodes/:id |
NO_END_REACHABLE | 400 | Branch has no end node | Add end node and connecting edge |
MISSING_ASSIGNEE | 400 | Human node has no assignee | PATCH /nodes/:id with assigneeEmail |
TRIGGER_NOT_SET | 400 | No trigger configured | POST /trigger before activating |
CONFLICT | 409 | Node ID exists or session activated | New ID or new session |
EXPIRED | 410 | Session past 24 hours | Create new session |
INTERNAL_ERROR | 500 | Activation rolled back | Nothing committed. Retry. |