Error Propagation Skill for Claude

Error Propagation

Trace where a multi-agent session's failures started and how far they spread.

Input

The user provides: $ARGUMENTS

A session ID. If empty, fetch GET /api/sessions?limit=1, but prefer the most recent session whose status is error or abandoned; state which one you picked.

Data Sources

| Endpoint | Returns |

|----------|---------|

| GET /api/workflows/{sessionId} | The errorPropagation dataset: failures grouped by agent depth, with originating depth and cascade paths to parents |

| GET /api/events?session_id={sessionId} | The event stream — corroborate with APIError, SubagentStop, and failing PostToolUse events (event_type, tool_name, summary, timestamp) |

Report Sections

1. Failure Summary

From errorPropagation: total errors, the depth where the first error originated, and how many distinct agents were affected.

Origin depth: d · Errors: N · Agents affected: M

2. Errors by Depth

| Depth | Errors originated | Errors inherited from children | Net failing agents |

|-------|-------------------|--------------------------------|--------------------|

Show whether failures concentrate deep in the tree (leaf subagents) or shallow (orchestrator).

3. Cascade Paths

For each originating failure, the path it propagated along:

debugger (depth 2, tool failure) → code-review (depth 1, marked error) → root (depth 0, aborted)

Tie each step to a concrete event from /api/events (event_type + tool_name + timestamp) where available.

4. Error Taxonomy

Break errors down by type from the event stream: APIError vs failing tool calls vs SubagentStop with error status. Note the most frequent tool involved in failures.

5. Containment Assessment

Whether failures were contained at the depth where they originated or leaked to parents. Name any parent that aborted solely because a child failed — a candidate for better error handling / isolation.

Output

• Markdown tables for the depth breakdown; a fenced list for cascade paths.
• Timestamps for the first and last error.
• Cite only errors present in errorPropagation and the event stream; never invent failures or causes.
• If the session has no errors, say so plainly and stop.
• If the dashboard is unreachable, tell the user to start it with npm start from the repo root.