diff --git a/.changeset/noble-bears-munch.md b/.changeset/noble-bears-munch.md
new file mode 100644
index 000000000..0a4904317
--- /dev/null
+++ b/.changeset/noble-bears-munch.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 1665
+---
+**`check.decision-coverage-plan` no longer false-passes when CONTEXT.md decisions use the titled-colon bullet form** — `parseDecisions` recognized the colon-immediate (`- **D-NN:** text`) and em-dash (`- **D-NN — title** body`) forms but dropped the titled-colon form (`- **D-NN: Title.** body`, where a title sits between the colon and the closing `**`) via the parse-miss guard. When all decisions used the titled convention, the parser returned 0 decisions and the coverage gate passed vacuously. A third per-form regex (checked last, a strict superset of the colon form) now parses the titled-colon form; id and `[tags]` trackability are honored.
diff --git a/src/decisions.cts b/src/decisions.cts
index add518973..c6c19ff3f 100644
--- a/src/decisions.cts
+++ b/src/decisions.cts
@@ -71,6 +71,19 @@ const bulletColonRe = /^\s*-\s+\*\*D-([A-Za-z0-9][A-Za-z0-9_-]*)(?:\s*\[([^\]]+)
  */
 const bulletEmDashRe = /^\s*-\s+\*\*D-([A-Za-z0-9][A-Za-z0-9_-]*)(?:\s*\[([^\]]+)\])?[^*]*[—–][^*]*\*\*\s*(.*)$/;
 
+/**
+ * Titled-colon form: `- **D-NN[ [tags]]: Title.** body`
+ * A title sits between the colon and the closing `**` (so the `:**` anchor of
+ * bulletColonRe fails, and there is no em-dash for bulletEmDashRe). This is a strict
+ * superset of the colon-immediate form, so it MUST be checked AFTER bulletColonRe and
+ * bulletEmDashRe — it only catches bullets those two miss. The title run is `[^:*]*` (no
+ * colon, no `*`) so a genuinely-malformed bullet with a colon in the pre-separator run
+ * (e.g. `D-07 ratio 3:1:**`) still fails the anchor and falls through to the parse-miss
+ * guard — matching bulletColonRe's `[^:*]*` discipline that the separator colon is the
+ * only colon permitted before `**`. (#1639)
+ */
+const bulletTitledColonRe = /^\s*-\s+\*\*D-([A-Za-z0-9][A-Za-z0-9_-]*)(?:\s*\[([^\]]+)\])?[^:*]*:[^:*]*\*\*\s*(.*)$/;
+
 interface ParseDecisionLinesResult {
   decisions: Decision[];
   parseMisses: number;
@@ -150,6 +163,22 @@ function parseDecisionLines(block: string): ParseDecisionLinesResult {
       continue;
     }
 
+    // Titled-colon form: `- **D-NN[ [tags]]: Title.** body` (#1639). Checked LAST — it is
+    // a strict superset of bulletColonRe, so it only catches bullets the colon-immediate
+    // and em-dash forms missed (minimal blast radius). id + [tags] trackability honored;
+    // the body after the closing bold run is reported as text.
+    const titledColonMatch = line.match(bulletTitledColonRe);
+    if (titledColonMatch) {
+      flush();
+      const id = `D-${titledColonMatch[1]}`;
+      const tags = titledColonMatch[2]
+        ? titledColonMatch[2].split(',').map((t) => t.trim().toLowerCase()).filter(Boolean)
+        : [];
+      const trackable = !inDiscretion && !tags.some((t) => NON_TRACKABLE_TAGS.has(t));
+      current = { id, text: titledColonMatch[3] || '', category, tags, trackable };
+      continue;
+    }
+
     // Parse-miss guard (FIX B + #1343): a line that looks like a `D-NN` decision
     // bullet but failed both patterns — flush, warn, and record the miss.
     // parseMisses > 0 forces could-not-parse even when other decisions parsed.
diff --git a/tests/decisions.test.cjs b/tests/decisions.test.cjs
index 362f57a26..e1909329e 100644
--- a/tests/decisions.test.cjs
+++ b/tests/decisions.test.cjs
@@ -791,3 +791,40 @@ describe('FIX D: gap-checker surfaces decision could-not-parse even when require
     );
   });
 });
+
+// ─── Regression #1639: titled-colon bullet form '- **D-NN: Title.** body' ─────
+// Both bulletColonRe (':**' anchor) and bulletEmDashRe (em-dash) miss the form where a
+// title sits between the colon and the closing **, so it was dropped by the parse-miss
+// guard and check.decision-coverage-plan passed vacuously when all decisions were titled.
+describe('parseDecisions — titled-colon bullet form (#1639)', () => {
+  test('titled-colon bullet is parsed, not dropped', () => {
+    const md = '## Locked decisions\n- **D-01: Default sandbox ON.** body\n- **D-02: Reject unsigned.** body two\n';
+    const out = parseDecisions(md);
+    assert.equal(out.length, 2, 'should extract both titled-colon decisions (not 0)');
+    assert.equal(out[0].id, 'D-01');
+    assert.equal(out[1].id, 'D-02');
+  });
+
+  test('titled-colon coexists with colon-immediate and em-dash forms', () => {
+    const md = '## Locked decisions\n- **D-01:** plain colon\n- **D-02 — emdash** body\n- **D-03: Titled.** body\n';
+    const out = parseDecisions(md);
+    assert.equal(out.length, 3);
+    assert.deepEqual(out.map((d) => d.id), ['D-01', 'D-02', 'D-03']);
+  });
+
+  test('titled-colon with [tags] still parses id and tags', () => {
+    const md = '## Locked decisions\n- **D-01 [informational]: Title.** body\n';
+    const out = parseDecisions(md);
+    assert.equal(out.length, 1);
+    assert.equal(out[0].id, 'D-01');
+    assert.ok(out[0].tags.includes('informational'), `tags should include informational, got ${JSON.stringify(out[0].tags)}`);
+  });
+
+  test('all-titled CONTEXT.md parses every decision (no vacuous 0)', () => {
+    // The reporter case: 13 decisions all titled → previously all dropped → gate passed vacuously.
+    let md = '## Locked decisions\n';
+    for (let i = 1; i <= 13; i++) md += `- **D-${String(i).padStart(2, '0')}: Decision ${i}.** body\n`;
+    const out = parseDecisions(md);
+    assert.equal(out.length, 13, 'all 13 titled-colon decisions must parse (not vacuously 0)');
+  });
+});