Challenge comparison for HOK-1403

Primary used claude-sonnet-4-6 (planner) + gpt-5.4 (coder) + claude-haiku-4-5-20251001 (reviewer) vs Challenger used claude-sonnet-4-6 (planner) + claude-sonnet-4-6 (coder) + claude-haiku-4-5-20251001 (reviewer)
Challenge type: coder-only

Recommended winner: challenger (claude-sonnet-4-6)
Other PR: #376

The task was to route branch-deletion messages into the logging section only. The challenger's fix is directly aligned: it reroutes the ✓ Closed window, ✓ Removed worktree, ✓ Deleted local branch, and ✓ Deleted remote branch log calls to the existing log "debug" level (a pattern already used for the adjacent ℹ Remote branch already deleted line). The primary instead tightens git stdout suppression (2>/dev/null → >/dev/null 2>&1), which addresses a related but secondary leak, and bundles in significant unrelated changes: a new _pane_metadata_unavailable helper with call sites in agent_pane_is_ready/agent_verify_launch, and flipping persisted_phase from planning to coding in the startup runner. Those unrelated edits expand blast radius well beyond the reported bug and could regress unrelated flows. The challenger's only scope slippage is a startup-handoff test stub and expectation flip, which is narrower and less risky than the primary's behavioral changes.