[ROADMAP] Prioritize adjacent git merges in decomposition mode

[ncrispino]

Context:

During decomposition-mode runs, we want a follow-up improvement that makes git integration more central to each agent's workflow.

Goal:

Prioritize relevant peer branch comparison/merging earlier in decomposition mode so agents incorporate neighboring work before their final checklist pass and stop decision.

Suggested direction:

• Treat merge/diff of adjacent peer branches as a first-class decomposition behavior, not just a presenter-stage fallback.
• Prefer adjacency-aware integration rather than merge everything first.
• Ideally, decomposition metadata can eventually emit which peer branches are relevant to each owned subtask.
• Agents should likely prioritize git diff <branch> / git merge <branch> for those adjacent branches before the final checklist recheck.
• Keep ownership-first boundaries intact: merge relevant neighboring work without encouraging unrelated takeover.

Why:

This should improve integration quality and reduce late presenter-only conflict resolution in decomposition mode.

Possible future acceptance criteria:

• decomposition metadata can identify adjacent integration peers
• decomposition prompts explicitly prioritize relevant branch diff/merge work
• checklist-gated decomposition encourages merge-aware recheck before stop
• end-to-end test covers owned work + adjacent merge + recheck + stop

This is a reminder issue for later planning/implementation, not an immediate bug fix.