Event Trace Skill for Claude

Event Trace

Build a chronological, annotated event timeline for a single session.

Input

The user provides: $ARGUMENTS

This is a session ID. It may also be:

• latest / last — trace the most recently updated session
• errors — trace the most recent session whose status is error

Data Sources

| Endpoint | Returns |

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

| GET /api/sessions?limit=N | session list (used to resolve latest/errors and the target id) |

| GET /api/sessions/:id | full session detail (status, model, cwd, started_at, ended_at, cost, nested agents + events) |

| GET /api/events?session_id=X | the ordered event stream: event_type, tool_name, summary, data, timestamp |

Report Sections

1. Resolve the session

If $ARGUMENTS is a raw id, use it. If latest/last, call

GET /api/sessions?limit=1. If errors, call

GET /api/sessions?limit=10&status=error and pick the newest. Confirm the id

resolves via GET /api/sessions/:id; if not, report it as missing and stop.

2. Session header

From GET /api/sessions/:id: id, status, model, cwd, started_at → ended_at,

total duration, cost (USD to 4 decimals), and counts (events, agents).

3. Ordered timeline

From GET /api/events?session_id=X, list every event in timestamp order. One row

per event:

| # | time | Δ since prev | event_type | tool_name | summary |

Cover all event types present: SessionStart, PreToolUse, PostToolUse, Stop,

SubagentStop, Compaction, APIError, TurnDuration, Notification, SessionEnd.

4. Gap & failure highlights

Annotate the timeline:

• Gaps: any Δ > 30s between consecutive events — mark ⏳ and note the wait.
• Unpaired tool calls: a PreToolUse with no matching PostToolUse (same

tool_name, next in stream) — mark ⚠️ "no completion recorded".

• Failures: APIError events and PostToolUse whose summary/data indicates

an error — mark ❌ with the error text.

• Compaction: mark ♻️ and note it resets the visible token baseline.
• Missing bookends: no SessionStart at the head or no Stop/SessionEnd at the

tail of an ended session — mark 🚩.

5. Verdict

One line: CLEAN, GAPS DETECTED, or FAILURES PRESENT — with the count of each

flag type and the single most likely thing to investigate next.

Output

• Markdown timeline table, events in strict timestamp order.
• Status glyphs inline: ✅ ok, ❌ error, ⚠️ warning/unpaired, ⏳ gap, ♻️ compaction, 🚩 missing bookend.
• Currency in USD to 4 decimals.
• Cite only event data returned by the API — do not invent timestamps or summaries.
• If the dashboard is unreachable, tell the user to start it with npm start from the repo root.