feat(start): announce auto-merge default before the run

[OGtwelve]

Summary

Auto-merge is on by default and merges PRs via a gh subprocess — outside Claude Code's tool boundary, so a host repo's git-guard hook can't intercept it. start now prints a prominent banner when auto-merge is active, pointing at the off switch. The default stays ON (non-breaking).

Changes

• cli_commands/workflow.py — new auto_merge_notice(auto_merge) helper; start prints it right after the run header when auto-merge is on.

Testing

• New tests in tests/cli/test_start_command.py: pure auto_merge_notice on/off, plus start shows the banner by default and suppresses it under --no-auto-merge.
• pytest, ruff check, ruff format --check, and mypy . clean.

Closes #104

Summary by CodeRabbit

• New Features
  • The start command now displays a yellow warning banner indicating auto-merge is enabled.
  • The banner is suppressed when auto-merge is disabled (including via the no-auto-merge option and related configuration).
• Tests
  • Added coverage to verify banner content and that startup output includes (or omits) the banner appropriately.

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📝 Walkthrough

Walkthrough

A new auto_merge_notice helper is added to workflow.py that returns a warning banner string when auto-merge is enabled, or None when disabled. The start command is updated to call this helper and print the banner when present. Matching unit and CLI tests validate both the helper output and the command's banner behavior.

Changes

Auto-merge warning banner

Layer / File(s)	Summary
auto_merge_notice helper and start command integration src/claude_task_master/cli_commands/workflow.py	Adds auto_merge_notice(auto_merge: bool) -> str | None returning a formatted warning string when auto-merge is on, and wires it into the start command to print the banner immediately after the startup lines.
Unit and CLI tests for auto-merge banner tests/cli/test_start_command.py	Imports auto_merge_notice and adds tests asserting the helper returns the expected banner text when True and None when False, plus CLI-level tests confirming the banner appears by default and is suppressed with --no-auto-merge.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related issues

• Reconsider auto-merge-on-by-default: subprocess merges bypass host git-guard hooks ai-task-master#73: The new banner surfaces “auto-merge ON” and disable guidance in start, matching the same user-facing auto-merge warning objective.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main user-facing change: announcing auto-merge before the run starts.
Linked Issues check	✅ Passed	The PR surfaces auto-merge prominently at startup and mentions both the subprocess behavior and the disable paths requested in #104.
Out of Scope Changes check	✅ Passed	The changes stay focused on the auto-merge warning banner and its tests, with no clear unrelated additions.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 60.00%.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/automerge-notice-104

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Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/claude_task_master/cli_commands/workflow.py`:
- Around line 33-35: The auto-merge banner in the workflow output is missing the
hook-bypass warning, so update the message returned by the relevant
workflow/banner helper to explicitly mention that merges run through gh outside
Claude Code’s tool boundary and that auto-merge can be disabled persistently.
Keep the existing auto-merge/--no-auto-merge guidance, but expand the text so
operators see the full warning in the banner.

In `@tests/cli/test_start_command.py`:
- Around line 48-85: The start-command tests only assert that
auto_merge_notice() is present or absent, so they miss regressions in the full
operator warning contract. Update test_auto_merge_notice_helper,
test_start_shows_auto_merge_banner_by_default, and
test_start_no_auto_merge_suppresses_banner to assert the complete banner content
from auto_merge_notice() and the start workflow output, including the
gh/tool-boundary warning and the persistent disable hint tied to
auto_merge_notice and app.invoke. Keep the tests deterministic by checking the
exact returned string/expected substrings rather than just the ON/OFF state.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📒 Files selected for processing (2)

• src/claude_task_master/cli_commands/workflow.py
• tests/cli/test_start_command.py

[OGtwelve]

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