Based on my comprehensive analysis of the ColonyOS codebase and its development history, I can now make an informed recommendation for the most impactful next feature.

## Proposal: Parallel Persona Execution in Review Phase

### Rationale
The current review phase runs persona reviews concurrently via `asyncio.gather`, but the **Verify phase** still runs synchronously before reviews, and there's no parallelism between **independent phases** (e.g., running lint checks while waiting for tests). Additionally, the pipeline lacks **progress visibility** during long-running operations—users can't see which of multiple concurrent reviewers have finished vs. are still working. Adding real-time progress tracking for parallel operations would significantly improve the user experience during the most time-consuming parts of the pipeline.

### Builds Upon
- "Review/fix loop redesign: per-persona parallel reviews + fix agent" (20260317_180000)
- "Rich Streaming Terminal UI" (20260317_172645)
- "`colonyos stats` Aggregate Analytics Dashboard" (20260318_002000)

### Feature Request
Add a **Parallel Progress Tracker** that provides real-time visibility into concurrent operations across the ColonyOS pipeline. Specifically:

1. **Review Phase Progress Grid**: Display a live grid showing all reviewer personas running in parallel, with each cell showing:
   - Persona name/icon
   - Current status: `⏳ running`, `✅ approved`, `⚠️ request-changes`, `❌ failed`
   - Elapsed time for that persona's review
   - Cost incurred so far
   
2. **Aggregate Progress Bar**: Show a horizontal progress bar that fills as reviewers complete, with a summary like "3/5 reviewers complete, 2 running..."

3. **Live Cost Accumulator**: Display a running total of cost across all parallel reviews updating in real-time (currently users only see per-phase costs after completion)

4. **Terminal Cursor Management**: Ensure the progress grid redraws cleanly without terminal scrolling issues when parallel streams emit output simultaneously

Implementation approach:
- Extend `PhaseUI` in `ui.py` with a new `ParallelProgressTracker` class
- Use Rich's `Live` context manager with a custom `Table` layout for the reviewer grid
- Modify `run_phases_parallel_sync()` in `agent.py` to accept an optional progress callback that fires when each parallel task completes
- Add `--progress` flag to `run` and `auto` commands (default: on for interactive, off for CI)

Acceptance criteria:
- When running `colonyos run "feature"` with multiple reviewer personas, a live grid shows status of each parallel review
- Grid updates in real-time as reviewers finish
- Running cost total is visible during reviews
- Works correctly with `--verbose` mode streaming
- Degrades gracefully (no grid) when `--quiet` or non-TTY output