Phase 11 of epic #3180 (ADR-3180 §8.2/§8.3/§8.5) foundation. Extends the
already-merged Phase-10 PlanningSnapshot additively with three fields the
upcoming health-diagnostic rule table needs and Phase 10 never required:
- config: {value, scope, exists} — parsed .planning/config.json. `exists`
distinguishes absent (no diagnostic, non-answer) from present-but-invalid
(CONFIG_UNREADABLE diagnostic, corruption) — both collapse to scope
UNREADABLE, so a rule needs the extra bit to tell "not configured yet"
apart from "config.json is broken."
- agentInstall / worktreeHealth — not .planning/-sourced, wrap the existing
checkAgentsInstalled/inspectWorktreeHealth owners with the same arguments
cmdValidateHealth already passes them, so a later migration step reads
these fields instead of calling the owners itself.
Adds CONFIG_UNREADABLE to src/unusable-input.cts's UNUSABLE_REASON (eighth
#1879 site), mirroring STATE_UNREADABLE's exact shape from Phase 10.
Additive only — the four Phase-10 fields and worstScope/buildPhaseSnapshot
are unchanged; existing tests for them are untouched.
ADR-3180 epic #3180 Phase 10 (§8.1): tests for the not-yet-existing
src/planning-snapshot.cts (buildPlanningSnapshot, worstScope), the
not-yet-existing scripts/lint-planning-snapshot-bypass-drift.cjs guard,
and the new STATE_UNREADABLE reason on tests/unusable-input.test.cjs's
already-shipped UNUSABLE_REASON enum. RED by construction: the modules
under test do not exist yet.
