fix(#1729): resolve phase headers with a pre-colon parenthetical tag (#1765)

* fix(#1729): resolve phase headers with a pre-colon parenthetical tag

A phase header may carry a parenthetical tag between the number and the
colon, e.g. `### Phase 26 (Cluster B): Title`. Every phase-header regex
built `Phase\s+<num>` immediately against the colon delimiter, so the
tagged phase was invisible: the resolver returned found:false and, just
as bad, the capture-all enumeration/parse paths (roadmap analyze,
milestone listing + milestone-scope filter, verify, init/import, state
total_phases, validate, the command router, preamble stripping, and the
phase-remove renumbering rewrite) silently dropped, miscounted, or
failed to renumber it — wrong phase_count, progress_percent, next_phase,
or corrupt numbering after a removal.

The fix tolerates the tag at the header seam. Parameterized resolver
sites compose the exported OPTIONAL_PHASE_TAG_SOURCE fragment; literal
enumeration sites inline its character-for-character mirror
`(?:\s*\([^)\n]*\))?`, placed immediately before the colon so it cannot
alter an existing match (optional, single-line, one paren pair, no
capture-group shift). In the renumber-on-removal rewrite the tag is
folded into the re-emitted suffix capture so it survives verbatim. Both
forms are documented to change together and a drift-guard test asserts
their behavioral equivalence over a header corpus.

Deliberately excluded: roadmap-upgrade.cts (legacy one-time migration),
where tolerating the tag would silently drop it on header rewrite — that
needs its own data-preserving treatment. Known boundaries left for
follow-up: checklist/bullet-style phase entries (`- [ ] Phase N (tag):`)
and a malformed space-before-colon variant, both pre-existing.

Validated empirically against the issue's reproduction: `roadmap
get-phase 26` resolves and `roadmap analyze` lists Phase 26 with the tag
excluded from the name (phase_count 2, next 26); an all-tagged versioned
roadmap now scopes correctly instead of falling back to a pass-all
filter. Regression coverage in tests/phase.test.cjs asserts resolver
parity (pre- vs post-colon), padding tolerance (#3537), decimal
sub-phases, no cross-phase false match, the shared seam, enumeration
coherence, renumber-preserves-tag, and seam/mirror drift. Full unit
suite green (7291 pass, 0 fail); eslint + regression-name +
resolution-provenance + changeset lints pass. Reviewed by Codex
(no critical/high; the two enumeration misses it surfaced are folded in).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore(#1729): add changeset for pre-colon phase-tag fix

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/validate.cts

@@ -104,7 +104,8 @@ export function buildRoadmapPhaseVariants(roadmapContent: string): RoadmapPhaseV
   const roadmapPhaseVariants = new Set<string>();
   // Matches both legacy numeric (Phase 1:), decimal (Phase 2.1:), milestone-prefixed (Phase 2-01:),
   // and bracket-prefixed (### [GSD] Phase 2-01:) headings.
-  const phasePattern = /#{2,4}\s*(?:\[[^\]]+\]\s*)?Phase\s+([\w][\w.-]*)\s*:/gi;
+  // #1729: `(?:\s*\([^)\n]*\))?` tolerates a pre-colon ( ) tag (literal mirror of OPTIONAL_PHASE_TAG_SOURCE).
+  const phasePattern = /#{2,4}\s*(?:\[[^\]]+\]\s*)?Phase\s+([\w][\w.-]*)(?:\s*\([^)\n]*\))?\s*:/gi;
   let m: RegExpExecArray | null;
   while ((m = phasePattern.exec(roadmapContent)) !== null) {
     roadmapPhases.add(m[1]);