feat(context): add CPG-03 projection continuation epoch

[Wibias]

Summary

• Stack CPG-03 on CPG-02.
• Add a test-first contract for the small continuation policy latch required to keep live projection representation stable across previous_response_id chains.
• Legacy chains without projection metadata must stay unprojected; unknown policies fail open to disabled; emergency disable can suspend an active epoch immediately.
• Persist only the versioned policy metadata, including through snapshot/spill. No receipts, refs, cursors, hashes, previews, or tool-result content are added by this state.

Stack

• Base: agent/context-projection-cp02 / PR feat(context): add CPG-02 shadow telemetry #17
• This PR must not merge before its parent.

TDD

• Initial commit is deliberately RED until epoch/state support is implemented.

[github-actions]

✅ Deterministic PR hygiene checks passed.

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

🗂️ Base branches to auto review (2)

• ^dev$
• ^preview$

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 7425ebd8-864a-4aed-80ba-192dcdc9200c

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

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