testbot: include the test rules in the prompt, default to Opus 5

[jiaenren]

Description

Two changes to the testbot harness.

1. Put the test rules in the prompt. Testbot PRs keep failing ci-internal on pylint — #1253 opened with 9 errors, #1184 needed a "fix pylint failures" follow-up, #1245 a lint-fix commit.

TESTBOT_PROMPT.md told the generator to read TESTBOT_RULES.md, which is the only place documenting the bazel test <target>-pylint verification step and the "Test PUBLIC behavior only. Never call underscore-prefixed methods" rule. In the trace for run/30499270675 the generator made 23 Read calls and opened that file in none of them, so it followed neither.

The workflow now passes the rules in with the prompt, the same way coverage targets already are. No change to the rules themselves.

2. Default to Opus 5. bedrock-claude-opus-4-7 → bedrock-claude-opus-5 across the testbot generate and respond paths (workflow input default, both ANTHROPIC_MODEL fallbacks, testbot-respond.yaml, select_targets_agent.py, respond.py, README). draft-release-notes.yaml still defaults to 4-7 and is unchanged.

Issue - None

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Tests

  • Improved automated test generation with documented quality and verification requirements.
  • Clarified that project coding standards are applied automatically when generating tests.
  • Updated automated test generation, target selection, and review responses to use Claude Opus 5 by default.

• Documentation

  • Updated test automation documentation to reflect the new default model and configuration options.

[coderabbitai]

📝 Walkthrough

Walkthrough

The testbot workflows and scripts now default to Claude Opus 5. The generation workflow appends TESTBOT_RULES.md to the Claude prompt. The prompt and README document these updates.

Changes

Testbot configuration and prompts

Layer / File(s)	Summary
Prompt rules wiring src/scripts/testbot/TESTBOT_PROMPT.md, .github/workflows/testbot.yaml	The prompt documents the appended test rules. The workflow inserts TESTBOT_RULES.md before coverage targets.
Workflow model defaults .github/workflows/testbot.yaml	Manual dispatch, target selection, and test generation now default to Claude Opus 5.
Script and documentation defaults .github/workflows/testbot-respond.yaml, src/scripts/testbot/respond.py, src/scripts/testbot/select_targets_agent.py, src/scripts/testbot/README.md	The response workflow, scripts, and README examples now use Claude Opus 5.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: adelbertc, aruns-nv

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the two main changes: including test rules in the prompt and defaulting testbot to Opus 5.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch jiaenr/testbot-lint-verification

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