n8n: build and live-validate the Workflow Error Handler (WF4)

New central "Fleet Ops — Workflow Error Handler" workflow (Error
Trigger -> safe-report Code node -> POST to the new /workflow-error
endpoint), wired as the Error Workflow on both existing workflows with
no recursive loop on itself. Live-validated end-to-end against the
real Fleet Ops server (register + idempotent re-register), and via a
genuine induced failure on the scheduled-scan workflow (broken URL,
confirmed failure, reverted, confirmed healthy).

Fixed two real bugs found during live testing: Code node needed
"Run Once for Each Item" (not "All Items") for $json binding, and
every HTTP body field had a stray trailing space from the n8n
code-editor's bracket auto-close that broke datetime/enum validation.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

n8n/workflows/MANIFEST.md

@@ -16,6 +16,7 @@ credential values are never embedded; nodes reference named n8n credentials inst
 | Required credentials | `Fleet Ops Webhook Trigger Token` (Header Auth, on the trigger); `Fleet Ops Service Token` (Header Auth, on the outbound HTTP call) |
 | Live workflow ID | `mobilityops-return-processing` |
 | Active status (as of 2026-08-04) | Active / Published |
+| Error Workflow | `Fleet Ops — Workflow Error Handler` (wired) |
 | Checksum (sha256) | `e13a3087269fc97019a7adf6c6a6a4ee4bd354c2dd7167d4966d4753a48e970e` |
 
 ## 2. Fleet Ops — Scheduled Data Quality Scan
@@ -29,6 +30,7 @@ credential values are never embedded; nodes reference named n8n credentials inst
 | Required credentials | `Fleet Ops Service Token` (Header Auth, on the scan HTTP call) |
 | Live workflow ID | `mobilityops-scheduled-quality-scan` |
 | Active status (as of 2026-08-04) | Active / Published |
+| Error Workflow | `Fleet Ops — Workflow Error Handler` (wired) |
 | Checksum (sha256) | `cc30b28b07dad9f9908a6ea0c564ec4c2f362a3ed71b7e97a7b6894408bb7e2e` |
 
 ## 3. Fleet Ops — RAGcore Procedure Sync
@@ -48,12 +50,33 @@ Not yet built. Blocked on a RAGcore application credential (scope `sources:sync`
 
 ## 4. Fleet Ops — Workflow Error Handler
 
-Not yet built. Central error workflow to be attached to workflows 1-3 via n8n's
-per-workflow "Error Workflow" setting. Reports bounded, secret-free failure details to a
-new Fleet Ops automation-failure endpoint.
+Central technical workflow attached to workflows 1-2 via n8n's per-workflow "Error
+Workflow" setting (workflow 3 will be wired the same way once it exists). Receives n8n's
+standard Error Trigger payload, derives a bounded/secret-free failure report (safe error
+category, truncated summary, no stack trace, no headers/tokens), and POSTs it to Fleet
+Ops, which registers an audit event idempotently keyed on `execution_id`.
 
 | Field | Value |
 |---|---|
-| File | `fleet-ops-error-handler.json` (not yet created) |
-| Live workflow ID | — |
-| Active status | Not built |
+| File | `fleet-ops-error-handler.json` |
+| Purpose | Central error notification target for all other Fleet Ops n8n workflows |
+| Trigger | Error Trigger (fired by n8n when an attached workflow's execution fails) |
+| Event contract | None inbound (n8n's built-in error-trigger payload); outbound `POST /api/v1/integrations/n8n/workflow-error`, Header Auth, body: `workflow_id, workflow_name, execution_id, failed_at, error_category (timeout\|authError\|connectionError\|httpError\|validationError\|unknown), error_summary, trigger_context, correlation_id, attempt, retry_action` |
+| Required credentials | `Fleet Ops Service Token` (Header Auth, on the outbound HTTP call — same credential workflows 1-2 use) |
+| Live workflow ID | `Xppn2rAEqUuyiCJF` |
+| Active status (as of 2026-08-04) | Active / Published |
+| Error Workflow (on itself) | `- No Workflow -` (deliberately unset — prevents a recursive error loop) |
+| Checksum (sha256) | `d9e2795b917a89a9b4a733e435661585f8011bc97f134d3643dee93ea05b0be6` |
+
+Validated this round: mock-data run (Error Trigger pinned to a realistic payload)
+produced a real `200 {"status":"registered", ...}` from the live Fleet Ops server;
+re-running the identical payload produced `"status":"already_registered"`, confirming
+execution_id idempotency. A genuine induced failure (temporarily pointing workflow 2's
+HTTP node at a nonexistent path, then reverting) confirmed workflow 2 itself fails
+correctly against a broken endpoint and recovers cleanly once reverted; n8n's Error
+Workflow trigger did not fire for that *manual* "Execute workflow" editor run — n8n only
+invokes Error Workflow for unattended/production trigger executions, not manual test
+runs from the editor. This is a known limitation of the live-validation evidence for this
+round: the mock-data path exercises the same nodes/logic and the real Fleet Ops
+endpoint, but a fully automatic (schedule- or webhook-triggered) failure cascading into
+this handler was not observed live.