ctx-archive

Move completed tasks from TASKS.md to the archive.

## Before Archiving

Two questions: if any answer is "no", don't archive:

1. **"Are the completed tasks cluttering the view?"** → If TASKS.md is
   still easy to scan, there's no urgency
2. **"Are all `[x]` items truly done?"** → Verify nothing was checked off
   prematurely

## When to Use

- When TASKS.md has many completed `[x]` tasks
- When the task list is hard to navigate
- Periodically to keep context clean

## When NOT to Use

- When there are only a few completed tasks (not worth the noise)
- When you're unsure if tasks are truly complete (verify first)
- **Never delete tasks**: only archive (CONSTITUTION invariant)

## Constitution Rules

These are inviolable:

- **Archival is allowed, deletion is not**: never delete context history
- **Archive preserves structure**: Phase headers are kept for traceability
- **Never move tasks**: tasks stay in their Phase section; archiving is
  the only sanctioned "move" and it's to the archive directory

## Execution

```bash
ctx task archive $ARGUMENTS
```

**Example: preview first (recommended):**
```bash
ctx task archive --dry-run
```

**Example: archive after confirming the preview:**
```bash
ctx task archive
```

Archived tasks go to `archive/tasks-YYYY-MM-DD.md` in the context directory,
preserving Phase headers for traceability.

Report how many tasks were archived and where the archive file was written.