# Phase 5 Execution Plan

Milestone: `Phase 5 - Layout Robustness and JSON Import UX Hardening`

## Goals

1. Make drag/re-layout behavior measurable and regression-resistant.
2. Improve JSON import/apply reliability with validation-first messaging.
3. Ship richer fixture coverage and enforce readability budgets in CI.

## Workstreams

1. QA harness and metrics artifact
   - Extend `tests/ui-regression-runner.js` to capture:
     - initial compile metrics
     - post-drag metrics
     - post-drag auto-tidy metrics
     - dense fixture metrics
   - Emit machine-readable artifact:
     - `output/playwright/ui-metrics-report.json`

2. Layout/readability quality budgets
   - Enforce thresholds in UI regression runner with env overrides:
     - `UI_SAMPLE_MAX_*`
     - `UI_DRAG_MAX_*`
     - `UI_TIDY_MAX_*`
     - `UI_DENSE_MAX_*`
   - Keep defaults tuned to current deterministic behavior.

3. JSON import UX hardening
   - Validate with `/analyze` before applying/importing JSON.
   - Block apply/import when validation has errors.
   - Surface first warning/error and path for faster correction.
   - Keep deterministic change summary after successful apply.

4. Fixture pack expansion
   - Add representative fixtures beyond the baseline audio example:
     - `examples/dense-analog.json`
     - `examples/i2c-sensor-hub.json`
     - `examples/power-tree.json`
   - Maintain warning-clean default sample (`frontend/sample.schemeta.json`).

## Done Definition

1. `npm test` passes.
2. `npm run test:ui` passes with quality budgets.
3. `output/playwright/ui-metrics-report.json` is generated on every UI run.
4. Import/apply validation behavior is deterministic and user-visible.
5. Phase 5 issues `#24-#29` are closed and milestone is closed.