cancel

Cancel Task Harness Session

Stops an active task harness session while preserving progress for later resumption.

Overview

The cancel skill gracefully stops a running task harness session by:

• Finding active sessions with status "running"
• Updating session state to "cancelled" with timestamp
• Delegating to /cancel-ralph to stop iteration
• Preserving all progress for later /task-harness:resume

Session state and completed work are preserved, allowing the workflow to be resumed from where it stopped.

Prerequisites

• Active task harness session - At least one session with status "running"
• ralph-loop plugin - For the /cancel-ralph delegation

Instructions

Step 1: Find Active Sessions

Search .claude/task-harness/sessions/ for files where status == "running":

for f in .claude/task-harness/sessions/*.json; do
  status=$(jq -r '.status' "$f")
  if [[ "$status" == "running" ]]; then
    echo "Found active session: $(basename "$f" .json)"
  fi
done

Step 2: Handle Session Selection

If session-id provided: Use that session directly.

If no session-id and one active session: Cancel that session.

If no session-id and multiple active sessions: List them for user selection:

Active sessions:
  1. 1234567890-12345 (implement-auth) - 2/5 tasks
  2. 1234567891-54321 (fix-bugs) - 1/3 tasks

Specify session: /task-harness:cancel <session-id>

Step 3: Update Session State

Modify the session JSON to mark as cancelled:

jq '.status = "cancelled" | .completedAt = "2024-01-15T12:00:00Z" | .finalMessage = "Cancelled by user"' \
  "$STATE_FILE" > "$STATE_FILE.tmp" && mv "$STATE_FILE.tmp" "$STATE_FILE"

Step 4: Stop Ralph-Loop

Delegate to cancel the underlying iteration:

/cancel-ralph

Step 5: Display Summary

Show cancellation confirmation with resume instructions.

Output

Upon successful cancellation:

Task Harness Cancelled
======================
Session: 1234567890-12345
Harness: implement-auth-feature
Progress: 2/5 tasks completed
Cancelled during: Task 3 - Implement Auth Routes

To resume: /task-harness:resume 1234567890-12345

Error Handling

Error	Cause	Resolution
No active sessions	No sessions with status "running"	Check /task-harness:status for session states
Session not found	Invalid session ID provided	Use /task-harness:status to list valid IDs
Multiple sessions	Ambiguous without session ID	Specify the session ID explicitly

Examples

Example 1: Cancel Current Session

User: /task-harness:cancel

Skill: Finds single active session, cancels it

Result:
Task Harness Cancelled
======================
Session: 1234567890-12345
Progress: 3/5 tasks completed
Cancelled during: Task 4 - Write Tests

To resume: /task-harness:resume 1234567890-12345

Example 2: Cancel Specific Session

User: /task-harness:cancel 1234567890-12345

Skill: Cancels the specified session

Result: Session cancelled, progress preserved

Example 3: Multiple Active Sessions

User: /task-harness:cancel

Skill: Detects multiple active sessions

Result:
Multiple active sessions found:
  1. 1234567890-12345 (auth-feature) - 2/5 tasks
  2. 1234567891-54321 (bug-fixes) - 1/3 tasks

Please specify: /task-harness:cancel <session-id>

Resources

• {baseDir}/scripts/cleanup-harness.sh - Archive or delete old sessions
• {baseDir}/docs/yaml-schema.md - Session state documentation