fix(platform-integrations): make bob custom-mode merge robust

[illeatmyhat]

Follow-up to #258. Running the released installer (install --platform bob --mode lite --dir "$HOME") reported ✓ Merged custom mode 'evolve-lite' but did not actually add the mode to ~/.bob/settings/custom_modes.yaml.

Root cause — two combined faults in merge_yaml_custom_mode

1. Sentinel substring false-match. Detection used if start in existing. The install-evolve-lite marketplace mode documents the literal # >>>evolve:evolve-lite<<< inside its customInstructions. That substring made the merge think a block already existed → it took the replace branch → found no matching end sentinel → no-op'd, while still printing ✓. Detection is now a line-anchored start..end regex, so a sentinel literal quoted inside another mode is ignored.

2. Indentation mismatch. The inserted block hardcoded 2-space list indentation. A target written with 0-indent sequence items (yaml.safe_dump / marketplace tooling) became a 0-indent/2-indent mix = invalid YAML. The block now matches the indentation already used under customModes:.

remove_yaml_custom_mode is likewise line-anchored.

Test

Adds test_install_merges_mode_despite_sentinel_literal_in_another_mode, reproducing the exact failure (0-indent target whose text contains the sentinel literal) and asserting the mode merges, indentation stays consistent, and the pre-existing mode is preserved. Full suite: 213 passed.

🤖 Generated with Claude Code

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Improved YAML custom mode installation to correctly preserve indentation patterns
  • Enhanced sentinel detection to prevent accidental matches in quoted content, ensuring reliable custom mode merging during installation

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 4a0fea6b-535d-4bda-a49d-ee074b28af3c

📥 Commits

Reviewing files that changed from the base of the PR and between cbcf6b1 and c5f13cf.

📒 Files selected for processing (2)

• platform-integrations/install.sh
• tests/platform_integrations/test_idempotency.py

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📝 Walkthrough

Walkthrough

The platform installer now detects existing list-item indentation in custom modes and uses line-anchored regex matching for sentinel blocks to prevent false positives when sentinel text appears inside quoted content. A regression test validates these improvements.

Changes

Sentinel block robustness improvements

Layer / File(s)	Summary
Merge custom mode with indentation detection and line-anchored sentinel logic platform-integrations/install.sh	merge_yaml_custom_mode detects the indentation pattern of existing - list items under customModes: and uses matched indentation when inserting the sentinel block. Sentinel detection switches from substring replacement to line-anchored regex that requires markers at line start, preventing matches inside quoted content. Replaces existing block if found; appends otherwise.
Remove custom mode with line-anchored sentinel logic platform-integrations/install.sh	remove_yaml_custom_mode updates sentinel-removal regex to require line-anchored start/end markers with optional trailing newline, ensuring only real sentinel blocks are removed rather than incidental occurrences in custom instruction text.
Regression test for quoted sentinel boundary cases tests/platform_integrations/test_idempotency.py	New test constructs a custom_modes.yaml with a quoted # >>>evolve:evolve-lite<<< literal, runs Bob install in lite mode, and asserts the real evolve-lite sentinel block is properly merged, YAML indentation is consistent, and both modes appear in the result.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• AgentToolkit/altk-evolve#100: Introduced the portable installer with sentinel-based custom mode operations that this PR hardens.
• AgentToolkit/altk-evolve#123: Also modifies custom-mode sentinel block handling in platform-integrations/install.sh.

Suggested reviewers

• vinodmut
• gaodan-fang
• visahak

Poem

🐰 With regex anchors standing tall and true,
No quoted sentinels slip on through!
Indents aligned like rows of hay,
Our YAML blocks now merge the right way. ✨

🚥 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 accurately describes the main change: fixing the custom-mode merge logic in bob platform-integrations to be more robust by handling line-anchored sentinels and matching indentation.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

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✨ 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 fix/bob-mode-merge-sentinel

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