fix(u02): observe real audit guard evidence

[SUaDtL]

Summary

• Replaces U02's fictional safe-training-gate override exercise with a real, content-neutral H-05 guarded restore observation.
• Binds one unchanged protected log, one constrained observation note, selected-harness rendering, and focused desktop/mobile visual coverage.
• Records the user-approved SMARTS decision as append-only SD-ACA-021.

Root cause

The prior public lesson required a learner-authored override record even though that flow was not authentically verifiable. The new route demonstrates the existing guard without changing the protected audit trail and explicitly limits chronology/provenance claims.

Verification

• python -m unittest -q tests.test_checkpoints.U02AuditGuardObservationTests tests.test_lesson_actions tests.test_preview_site tests.test_project_state
• static Preview build and checker
• staged secret scan and diff check
• Playwright targeted U02 desktop/mobile test (2 passed)

[coderabbitai]

Warning

Review limit reached

@SUaDtL, you've reached your PR review limit, so we couldn't start this review.

Next review available in: 19 minutes

Enable usage-based reviews in Billing to review now. Otherwise, wait until the next included review is available.
You're only billed for reviews past your plan's rate limits ($0.25/file).

How can I continue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based reviews.

How do review limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please refer docs for additional details.

Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 19c82067-3697-47b6-b26f-d05f718e547d

📥 Commits

Reviewing files that changed from the base of the PR and between e7fb570 and 3c4ba7a.

⛔ Files ignored due to path filters (3)

• .codearbiter/overrides.log is excluded by !**/*.log
• tests/site/__screenshots__/u02-observation-desktop.png is excluded by !**/*.png
• tests/site/__screenshots__/u02-observation-mobile.png is excluded by !**/*.png

📒 Files selected for processing (20)

• README.md
• academy/actions/U02-override-audit-metrics.json
• academy/checkpoint.schema.json
• academy/checkpoints/U02-override-audit-metrics.json
• academy/lesson-action.schema.json
• academy/scenarios/U02-override-audit-metrics/files/scenario.json
• academy/tracks/power-user/U02-override-audit-metrics.md
• academy_engine/checkpoints.py
• academy_engine/lesson_actions.py
• docs/delivery/sprint-log.md
• scripts/build_preview_site.py
• scripts/check_preview_site.py
• site/assets/academy.css
• site/assets/academy.js
• tests/site/visual-baselines.json
• tests/site/visual.spec.mjs
• tests/test_checkpoints.py
• tests/test_lesson_actions.py
• tests/test_preview_site.py
• tests/test_project_state.py

---

_{Comment @coderabbitai help to get the list of available commands.}