Migrate cmdStatePlannedPhase and cmdStateMilestoneSwitch (state.cts) onto the
STATE.md Transition Module substrate (ADR-1769, epic #1769).
- Add {kind: 'plannedPhase'} and {kind: 'milestoneSwitch'} to
StateTransitionIntent, with plannedPhaseCore and milestoneSwitchCore in
src/state-transition.cts (consulting the field-classification table).
- plannedPhaseCore owns the template-aware Status/Last Activity updates, Total
Plans in Phase, Last Activity Description, and the Current Position section
(via the inlined mutateCurrentPositionForAdvance twin). The adapter keeps the
resync:false readModifyWriteStateMd wrapper (#500 RC1).
- milestoneSwitchCore owns the new-milestone reset: rebuilt frontmatter
(milestone/name/status='planning'/zeroed progress) + Current Position body
reset. The adapter keeps acquireStateLock + platformWriteSync (NOT
readModifyWriteStateMd — milestoneSwitch rebuilds frontmatter directly).
- Collapse both callbacks to transitionCore dispatches. The now-dead
updateCurrentPositionFields helper and KNOWN_STATUS_PATTERNS import are
removed (their behavior lives in the transition module's
mutateCurrentPositionForAdvance).
- Characterization tests pin the template-aware preserve-authored invariant,
Total Plans, Last Activity narrative, Current Position update, and the full
milestone reset (frontmatter + position body + gsd_state_version preserve +
Accumulated Context preserve).
All 58 transition + 177 state + phase + bug-2630/bug-905 regression tests pass.
Closes#1786
91704c9fcf