Advance Docs Agent to WP Codebox v0.12.28

[chubes4]

Summary

• advance the reusable runner and validation checkout to WP Codebox v0.12.28
• bind release provenance to commit 6457dcae4cb8cf8e76cd174377de8cbee3ee12cb and the two published asset digests
• record canonical repository-casing verification from Accept canonical GitHub repository casing wp-codebox#1875

How to test

1. Check out WP Codebox v0.12.28 at 6457dcae4cb8cf8e76cd174377de8cbee3ee12cb.
2. Run php tests/validate-docs-agent-packages.php.
3. Run php tests/validate-external-native-package-sources.php.
4. Run WP_CODEBOX_DIR=/path/to/wp-codebox php tests/validate-wp-codebox-run-agent-task-contract.php.
5. Run actionlint .github/workflows/*.yml.
6. Run php -l tests/validate-wp-codebox-run-agent-task-contract.php.
7. Run git diff --check origin/main...HEAD.

All commands pass locally.

Compatibility

No package, schema, extension-path, workflow-input, or backwards-compatibility impact. The runner release advances from v0.12.27 to v0.12.28; Docs Agent package provenance remains unchanged.

Source relationships

• Publication verification rejects canonical repository URL casing wp-codebox#1874
• Accept canonical GitHub repository casing wp-codebox#1875
• Project the nested runner workspace pull-request URL #162
• Project nested publication pull request URL #163

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode with OpenAI GPT-5.6 Sol
• Used for: Advanced the immutable release contract, verified asset provenance, updated deterministic coverage and documentation, and ran repository-native tests. Chris reviewed and owns the change.