diff --git a/.changeset/sunny-deer-roar.md b/.changeset/sunny-deer-roar.md
new file mode 100644
index 000000000..ce3ebed31
--- /dev/null
+++ b/.changeset/sunny-deer-roar.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 1552
+---
+roadmap analyze no longer reports phantom missing_phase_details for milestone-prefixed (M-NN) phase IDs
diff --git a/src/roadmap.cts b/src/roadmap.cts
index ab96cb63b..1c442c502 100644
--- a/src/roadmap.cts
+++ b/src/roadmap.cts
@@ -426,8 +426,11 @@ function cmdRoadmapAnalyze(cwd: string, raw: boolean): void {
   const totalSummaries = phases.reduce((sum, p) => sum + p.summary_count, 0);
   const completedPhases = phases.filter(p => p.disk_status === 'complete').length;
 
-  // Detect phases in summary list without detail sections (malformed ROADMAP)
-  const checklistPattern = /-\s*\[[ x]\]\s*\*\*Phase\s+(\d+[A-Z]?(?:\.\d+)*)/gi;
+  // Detect phases in summary list without detail sections (malformed ROADMAP).
+  // The char class must allow `-` (not just `.`) so dash-separated milestone-prefixed
+  // IDs (e.g. `1-01`) match the detail-heading scanner above; otherwise they truncate
+  // at the dash (`1-01` -> `1`) and every such phase reports a phantom missing detail.
+  const checklistPattern = /-\s*\[[ x]\]\s*\*\*Phase\s+(\d+[A-Z]?(?:[.-]\d+)*)/gi;
   const checklistPhases = new Set<string>();
   let checklistMatch: RegExpExecArray | null;
   while ((checklistMatch = checklistPattern.exec(content)) !== null) {
diff --git a/tests/roadmap.test.cjs b/tests/roadmap.test.cjs
index af4a60275..7061e9d4a 100644
--- a/tests/roadmap.test.cjs
+++ b/tests/roadmap.test.cjs
@@ -541,6 +541,40 @@ describe('roadmap analyze missing phase details', () => {
     const output = JSON.parse(result.output);
     assert.strictEqual(output.missing_phase_details, null, 'missing_phase_details should be null');
   });
+
+  test('does not report phantom missing details for milestone-prefixed (M-NN) phase IDs', () => {
+    // The checklist scanner truncated dash-separated IDs at the dash (1-01 -> 1)
+    // while the detail-heading scanner kept the full ID, so every milestone-prefixed
+    // ROADMAP spuriously reported the truncated major as a missing detail section.
+    fs.writeFileSync(
+      path.join(tmpDir, '.planning', 'ROADMAP.md'),
+      `# Roadmap
+
+- [ ] **Phase 1-01: Foundation** - Set up project
+- [ ] **Phase 1-02: API** - Build REST API
+- [ ] **Phase 2-01: Ship** - Release
+
+### Phase 1-01: Foundation
+**Goal:** Set up project
+
+### Phase 1-02: API
+**Goal:** Build REST API
+
+### Phase 2-01: Ship
+**Goal:** Release
+`
+    );
+
+    const result = runGsdTools('roadmap analyze', tmpDir);
+    assert.ok(result.success, `Command failed: ${result.error}`);
+
+    const output = JSON.parse(result.output);
+    assert.strictEqual(
+      output.missing_phase_details,
+      null,
+      'milestone-prefixed phases with matching detail sections should report no missing details'
+    );
+  });
 });
 
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