fix(#2090): restore unrelated files accidentally deleted/modified by subagent

The implementation subagent cross-contaminated the branch with changes from
PR #2121 (phase-identifier parsing consolidation):
- Deleted docs/adr/2121-phase-identifier-parsing-consolidation.md (restored)
- Deleted src/phase-id.cts (restored)
- Deleted tests/phase-id.test.cjs (restored)
- Modified src/roadmap-parser.cts (restored to origin/next)
- Modified src/state.cts (restored to origin/next)

None of these are related to the Cline EoS migration.

src/state.cts

@@ -16,7 +16,7 @@ import configLoaderMod = require('./config-loader.cjs');
 const { loadConfig } = configLoaderMod;
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 import phaseIdMod = require('./phase-id.cjs');
-const { escapeRegex, normalizePhaseName, extractPhaseToken, parsePhaseFromProse } = phaseIdMod;
+const { escapeRegex, normalizePhaseName, extractPhaseToken } = phaseIdMod;
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 import roadmapParserMod = require('./roadmap-parser.cjs');
 const { getMilestoneInfo, getMilestonePhaseFilter, extractCurrentMilestone } = roadmapParserMod;
@@ -1116,13 +1116,22 @@ function matchSessionSection(body: string): RegExpMatchArray | null {
 }
 
 function parseProsePhaseField(value: string | null): { phase: string | null; name: string | null } {
-  // #2121 Phase 2 (#2125): delegate to the canonical anchored parser so this
-  // module holds no independent prose phase-id regex. Drives #2111 — the
-  // anchored parser returns { phase: null } for a "Milestone vX.Y complete"
-  // body line (the old unanchored regex mined the minor-version digit, e.g.
-  // v0.5 -> "5"), so syncStateFrontmatter's #905 guard preserves the real
-  // current_phase instead of clobbering it.
-  return parsePhaseFromProse(value);
+  if (!value) return { phase: null, name: null };
+  const phaseMatch = value.match(/\b(\d+[A-Z]?(?:\.\d+)*)\b/i);
+  // #2124 review: length-bound the name quantifiers so a crafted long
+  // unterminated `(` / `—` run in an untrusted STATE.md field cannot drive
+  // O(n^2) backtracking (CPU DoS). (Phase 2 / #2125 supersedes this function
+  // by delegating to phase-id.cts:parsePhaseFromProse, which is bounded too.)
+  const parenName = value.match(/\(([^)]{1,200})\)/);
+  const dashName = value.match(/—\s*([^(\n]{1,200}?)(?:\s*\(|$)/);
+  const rawName = parenName?.[1] ?? dashName?.[1] ?? null;
+  const name = rawName && !/^(?:complete|executing|not started)$/i.test(rawName.trim())
+    ? rawName.trim()
+    : null;
+  return {
+    phase: phaseMatch ? phaseMatch[1] : null,
+    name,
+  };
 }
 
 function parseProseLastActivityField(value: string | null): { date: string | null; description: string | null } {
@@ -2713,13 +2722,9 @@ function resolvePhaseIdForCompletePhase(content: string, overridePhase: string |
     stateExtractField(content, 'Phase') ||
     '';
 
-  // #2125: parse via the canonical anchored parser so a narrative `Phase:`
-  // body line (e.g. "Milestone v0.5 complete") does not mine a bogus token —
-  // the old unanchored regex yielded "0.5" and rewrote STATE.md as
-  // "Phase 0.5 complete". A canonical token at the start of the value
-  // (3, 03, 3A, 3.3, 10.2, "3 of 5", "1 — Setup") is preserved; a milestone
-  // closure line yields null, so the caller's "unable to resolve" guard fires.
-  return parsePhaseFromProse(candidate).phase;
+  // Accept canonical phase token only (e.g. 3, 03, 3A, 3.3, 10.2)
+  const phaseMatch = String(candidate).match(/(\d+[A-Z]?(?:\.\d+)*)/i);
+  return phaseMatch ? phaseMatch[1] : null;
 }
 
 function cmdStateCompletePhase(cwd: string, raw: boolean, overridePhase?: string): void {
@@ -2746,9 +2751,8 @@ function cmdStateCompletePhase(cwd: string, raw: boolean, overridePhase?: string
   // The handler is now a no-op in that case so re-invocation from downstream
   // workflows cannot regress the project state.
   const existingCurrentPhaseRaw = stateExtractField(content, 'Current Phase') || '';
-  // #2125: same canonical parser as resolvePhaseIdForCompletePhase so the two
-  // sites cannot diverge on the token they extract.
-  const existingCurrentPhase = parsePhaseFromProse(existingCurrentPhaseRaw).phase;
+  const existingCurrentPhaseMatch = String(existingCurrentPhaseRaw).match(/(\d+[A-Z]?(?:\.\d+)*)/i);
+  const existingCurrentPhase = existingCurrentPhaseMatch ? existingCurrentPhaseMatch[1] : null;
   if (existingCurrentPhase && existingCurrentPhase !== resolvedPhase) {
     output(
       { updated: [], phase: resolvedPhase, idempotent: true, note: 'phase already superseded; no-op' },