Deduplicate future follow-up issues across reviewers

[wwind123]

Summary

--approved-followups issue currently creates one GitHub issue per parsed future follow-up bullet. When multiple reviewers independently mention the same future follow-up, the tool creates duplicate issues.

This happened on PR #49:

• Claude created Follow up future review note: ensure_explicit_workdir does not validate that the explicit path's git remote matches `c #50 for explicit workdir remote validation.
• Gemini created Follow up future review note: **Remote validation for explicit workdirs**: As noted by the other reviewer, `ensure_expli #51 for the same explicit workdir remote validation.
• Follow up future review note: **Remote validation for explicit workdirs**: As noted by the other reviewer, `ensure_expli #51 was later closed manually as a duplicate of Follow up future review note: ensure_explicit_workdir does not validate that the explicit path's git remote matches `c #50.

Problem

Multi-reviewer loops commonly produce overlapping observations. Filing one issue per reviewer bullet creates issue noise and requires manual cleanup.

Proposed behavior

Before creating future follow-up issues, deduplicate follow-ups across reviewers.

Possible implementation levels:

• Start with exact/normalized dedupe: normalize markdown, lowercase, trim punctuation, collapse whitespace, and compare text/title keys.
• Prefer grouping same-heading items: if bullets start with the same bold title or first clause, merge them into one issue.
• For merged duplicates, preserve all reviewer attributions in the issue body.

Example issue body for merged items:

Future follow-up from approved reviews on PR #49.

Reviewers:
- Claude
- Gemini

Follow-up:
- Validate explicit workdir git remotes against the target repo.

Original reviewer notes:
- Claude: ...
- Gemini: ...

Acceptance criteria

• Duplicate or near-duplicate future follow-ups from multiple reviewers create one issue, not multiple.
• The created issue preserves reviewer attribution.
• The PR summary comment links to the single created issue.
• Tests cover duplicate future follow-ups from Claude and Gemini.
• Tests cover distinct future follow-ups still creating distinct issues, subject to the issue cap.

-- OpenAI Codex