Migrate Archive Command

You are implementing taskmanager:migrate-archive.

Purpose

This command migrates existing terminal tasks (done/canceled/duplicate) from tasks.json to tasks-archive.json. Use this when:

• tasks.json has grown too large (exceeds token limits)
• You have many completed tasks that haven't been archived yet
• You want to reduce file size without losing historical data

Arguments

• --dry-run or -n: Show what would be archived without making changes

Behavior

1. Load current state

1. Read .taskmanager/tasks.json.
2. Read .taskmanager/tasks-archive.json (create from template if not exists).
3. Count total tasks and terminal tasks.

2. Find archivable tasks

A task is archivable if:

1. Its status is terminal (done, canceled, or duplicate).
2. It does NOT already have archivedRef: true.
3. For parent tasks: All direct children are either already archived OR terminal.

Algorithm:

1. Flatten all tasks from the tree.
2. Filter for terminal tasks without archivedRef.
3. Sort by depth (deepest first) to archive leaves before parents.
4. For each candidate, verify all children are terminal/archived before archiving.

3. Dry-run mode (--dry-run)

If --dry-run flag is present:

1. List all tasks that would be archived:

   Tasks to archive (dry-run):
   - 1.2.3: "Implement user auth" (done)
   - 1.2.4: "Add login form" (done)
   - 1.2: "Authentication feature" (done) [parent]
   - 2.1: "Setup database" (canceled)
   
   Total: 4 tasks would be archived
   Estimated size reduction: ~12,000 tokens
   

2. Show projected file sizes:

   Current tasks.json: ~31,000 tokens
   After migration: ~19,000 tokens
   Archive size: ~12,000 tokens (added)
   

3. Do NOT modify any files.

4. Exit with summary.

4. Archive execution (without --dry-run)

For each archivable task (bottom-up, leaves first):

1. Copy to archive:

   • Read the full task object from tasks.json.
   • Add archivedAt: <current ISO timestamp>.
   • Append to tasks-archive.json.tasks[].

2. Replace with stub in tasks.json:

   • Keep only: id, title, status, parentId, priority, complexity, estimateSeconds, durationSeconds, completedAt
   • Add: archivedRef: true
   • Set: subtasks: []
   • Remove all other fields.

3. Update archive metadata:

   • Set tasks-archive.json.lastUpdated to current timestamp.

4. Log the archival:

   • Append to decisions.log: Migrated task <id> to archive

5. Write files

1. Write updated tasks-archive.json.
2. Write updated tasks.json with stubs.

6. Summary

Display migration results:

Migration complete:

Archived tasks: 15
- Leaf tasks: 12
- Parent tasks: 3

File sizes:
- tasks.json: 31,000 → 18,500 tokens (40% reduction)
- tasks-archive.json: 0 → 12,500 tokens

Next steps:
- Dashboard and metrics will continue to work (stubs retain metric fields)
- Use `taskmanager:dashboard` to verify
- Archived task details are preserved in tasks-archive.json

Error Handling

• If tasks.json cannot be parsed: Log error, abort.
• If archive already contains a task with same ID: Skip that task, warn user.
• If write fails: Log error, attempt rollback (restore original files).

Notes

• This command is idempotent: Running it again will only archive newly completed tasks.
• Already-stubbed tasks (with archivedRef: true) are skipped.
• Parent tasks are only archived after all children are archived.
• The archive preserves the complete task history including all metadata.