Grammar-constrained models (e.g. Qwen3.6-35B-MTP via llama.cpp) emit
`extra: { title: {} }` instead of `extra: { title: "<string>" }` because
the resolve schema declares `extra` as Record<string, unknown> with an
open value schema, leaving the model free to drop in an empty object.
The apply guard then threw 'Plan approval requires extra: { title: ... }'
on every retry, looping the model indefinitely (issue #1179).
Plan approval now uses a layered title resolution:
1. `extra.title` if it is a non-empty string (and sanitizes to non-empty)
2. First `# Heading` in the plan content
3. Filename stem of `planFilePath` (`'/data/workspaces/can1357__oh-my-pi__1179/.omp-session/2026-05-19T03-59-21-254Z_019e3e63-62a6-7000-be63-371f2cd6d67d/local/PLAN.md'` → `PLAN`)
4. Literal `plan` as a final safety net
Each candidate is run through `normalizePlanTitle`; rejected ones fall
through. Extracted as `resolvePlanTitle` in plan-mode/approved-plan.ts
so it's unit-testable.
Prompt language relaxed from MUST to SHOULD for `extra.title` in
plan-mode-active.md and plan-mode-tool-decision-reminder.md, noting the
fallback so models don't waste turns on a now-optional field.
Fixes#1179
roboomp
14198e2ed3