The /gsd:new-milestone workflow Step 5 rewrote STATE.md's Current Position
body but never touched the YAML frontmatter, so every downstream reader
(state.json, getMilestoneInfo, progress bars) kept reporting the stale
milestone until the first phase advance forced a resync. Asymmetric with
milestone.complete, which uses readModifyWriteStateMdFull.
Add a new `state milestone-switch` handler (both SDK and CJS) that atomically:
- Stomps frontmatter milestone/milestone_name with caller-supplied values
- Resets status to 'planning' and progress counters to zero
- Rewrites the ## Current Position section to the new-milestone template
- Preserves Accumulated Context (decisions, blockers, todos)
Wire the workflow Step 5 to invoke `state.milestone-switch` instead of the
manual body rewrite. Note the flag is `--milestone` not `--version`:
gsd-tools reserves `--version` as a globally-invalid help flag.
Red vitest in sdk/src/query/state-mutation.test.ts asserts the frontmatter
reset. Regression guard via node:test in tests/bug-2630-*.test.cjs runs
through gsd-tools end-to-end.
Fixes#2630
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
e973ff4cb6