diff --git a/src/api/schema.ts b/src/api/schema.ts
index 8f370ba..4d145df 100644
--- a/src/api/schema.ts
+++ b/src/api/schema.ts
@@ -88,7 +88,14 @@ const $defs = {
       fired: { type: 'boolean' },
       provenance: {
         oneOf: [
-          { type: 'string', enum: ['gap_tool_derived', 'earnings_suppressed_ppd_published'] },
+          {
+            type: 'string',
+            enum: [
+              'gap_tool_derived',
+              'earnings_suppressed_ppd_published',
+              'cohort_suppressed_ppd_published',
+            ],
+          },
           { type: 'null' },
         ],
       },
diff --git a/src/engine.ts b/src/engine.ts
index 40c72cd..6165d2c 100644
--- a/src/engine.ts
+++ b/src/engine.ts
@@ -42,7 +42,11 @@ function buildNoiseBandAnnotation(
   if (surfacedVerdict === 'NOT MEASURED') {
     return { fired: false, provenance: null, message: null };
   }
-  if (program.suppression.earn_suppressed || program.median_earn_p4 === null) {
+  // Privacy-suppressed earnings cell — the federal privacy rule withheld
+  // the cell-level value. Verdict still surfaces from the published OBBBA
+  // flag, but the noise-band test cannot run because there is no gap to
+  // threshold. Distinct from cohort-level suppression below.
+  if (program.suppression.earn_suppressed) {
     return {
       fired: true,
       provenance: 'earnings_suppressed_ppd_published',
@@ -50,6 +54,19 @@ function buildNoiseBandAnnotation(
         'Verdict is PPD-published; underlying earnings cell suppressed under federal privacy rule. Noise-band test is structurally inapplicable.',
     };
   }
+  // Cohort-level suppression — earnings not published at the 4-digit grain
+  // (typically because the cell's cohort is below the floor or the cell
+  // was not published at 4-digit despite the verdict being published via
+  // 2-digit pool flag). Per SPEC-DELTA §2.3 four-layer suppression, this
+  // is a structurally different cause from the privacy-rule case above.
+  if (program.median_earn_p4 === null) {
+    return {
+      fired: true,
+      provenance: 'cohort_suppressed_ppd_published',
+      message:
+        'Verdict is PPD-published; underlying earnings not published at 4-digit grain (cohort below floor or otherwise unavailable). Noise-band test is structurally inapplicable.',
+    };
+  }
   if (program.ep_gap_pct === null) {
     return { fired: false, provenance: null, message: null };
   }
diff --git a/src/types.ts b/src/types.ts
index 825e0c4..d6593e4 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -137,10 +137,31 @@ export interface CrossValidation {
 
 export interface NoiseBandAnnotation {
   fired: boolean;
-  /** Provenance string per chair greenlight (SPEC-DELTA §2.2). */
+  /**
+   * Provenance string per chair greenlight (SPEC-DELTA §2.2).
+   *
+   * - `gap_tool_derived` — verdict's noise-band gap was computed from
+   *   PPD-published earnings + benchmark; the percentage gap itself
+   *   is NOT a published PPD field.
+   * - `earnings_suppressed_ppd_published` — verdict surfaces from the
+   *   PPD-published OBBBA flag, but the underlying earnings cell is
+   *   suppressed under the federal privacy rule (`earn_suppressed=true`).
+   *   Noise-band test is structurally inapplicable.
+   * - `cohort_suppressed_ppd_published` — verdict surfaces from the
+   *   PPD-published OBBBA flag, but the underlying earnings cell is
+   *   not published because the cohort is below the floor or otherwise
+   *   unavailable at 4-digit grain (`median_earn_p4 IS NULL` while the
+   *   privacy-suppression flag is NOT the cause). Noise-band test is
+   *   structurally inapplicable for a cohort-level reason rather than a
+   *   privacy-rule reason; the distinction matters for explainability
+   *   per SPEC-DELTA §2.3 four-layer suppression model.
+   * - `null` — annotation not fired (verdict NOT MEASURED, gap outside
+   *   threshold, or no published gap to evaluate).
+   */
   provenance:
     | 'gap_tool_derived'
     | 'earnings_suppressed_ppd_published'
+    | 'cohort_suppressed_ppd_published'
     | null;
   message: string | null;
 }
diff --git a/tests/engine.test.ts b/tests/engine.test.ts
index 364bc82..4eb2ddb 100644
--- a/tests/engine.test.ts
+++ b/tests/engine.test.ts
@@ -249,6 +249,87 @@ describe('Engine — noise-band suppressed-earnings annotation', () => {
     expect(v.noise_band.fired).toBe(true);
     expect(v.noise_band.provenance).toBe('earnings_suppressed_ppd_published');
   });
+
+  // cp-j0gw.14 / R19 fourth annotation case (SPEC-DELTA §2.2).
+  // When the published OBBBA verdict surfaces but the underlying earnings
+  // are not published at the 4-digit grain for a cohort-level reason
+  // (median_earn_p4 IS NULL with earn_suppressed=false — typically cohort
+  // below floor or pool-inherited verdict), the noise-band test is still
+  // structurally inapplicable but for a different reason than the
+  // privacy-rule case above. The annotation must distinguish so the UI
+  // can explain WHY the noise band did not run, per SPEC-DELTA §2.3
+  // four-layer suppression model.
+  describe('fourth annotation case — cohort_suppressed_ppd_published', () => {
+    it('fires when verdict published but earnings null without privacy-rule suppression', () => {
+      const inst = makeInstitution([
+        makeProgram({
+          median_earn_p4: null,
+          ep_gap_pct: null,
+          ppd_fail_obbb: 1,
+          suppression: { cohort_suppressed: true, earn_suppressed: false },
+        }),
+      ]);
+      const r = analyzeInstitution(inst);
+      const v = r.programs[0]!;
+      expect(v.verdict).toBe('FAIL');
+      expect(v.noise_band.fired).toBe(true);
+      expect(v.noise_band.provenance).toBe('cohort_suppressed_ppd_published');
+      expect(v.noise_band.message).toMatch(/cohort below floor|not published at 4-digit/i);
+    });
+
+    it('keeps earnings_suppressed_ppd_published when earn_suppressed=true even if median_earn_p4 is null', () => {
+      // earn_suppressed wins over the cohort branch — the privacy-rule
+      // explanation is the more specific and user-relevant reason.
+      const inst = makeInstitution([
+        makeProgram({
+          median_earn_p4: null,
+          ep_gap_pct: null,
+          ppd_fail_obbb: 1,
+          suppression: { earn_suppressed: true, cohort_suppressed: true },
+        }),
+      ]);
+      const r = analyzeInstitution(inst);
+      const v = r.programs[0]!;
+      expect(v.noise_band.provenance).toBe('earnings_suppressed_ppd_published');
+    });
+
+    it('does not fire when surfaced verdict is NOT MEASURED', () => {
+      // When the cell never surfaces a verdict, no annotation fires —
+      // regardless of which suppression flag is set.
+      const inst = makeInstitution([
+        makeProgram({
+          median_earn_p4: null,
+          ep_gap_pct: null,
+          ppd_fail_obbb: null,
+          benchmark: null,
+          suppression: { cohort_suppressed: true },
+        }),
+      ]);
+      const r = analyzeInstitution(inst);
+      const v = r.programs[0]!;
+      expect(v.verdict).toBe('NOT MEASURED');
+      expect(v.noise_band.fired).toBe(false);
+      expect(v.noise_band.provenance).toBeNull();
+    });
+
+    it('does not fire when earnings are present (preserves gap_tool_derived path)', () => {
+      // Backward-compat sanity: the existing measurable-with-noise-band path
+      // still produces gap_tool_derived; the new fourth case only branches
+      // on median_earn_p4 IS NULL.
+      const inst = makeInstitution([
+        makeProgram({
+          median_earn_p4: 38270.0,
+          ep_gap_pct: 0.0606,
+          ppd_fail_obbb: 0,
+          suppression: { cohort_suppressed: false, earn_suppressed: false },
+        }),
+      ]);
+      const r = analyzeInstitution(inst);
+      const v = r.programs[0]!;
+      expect(v.noise_band.fired).toBe(true);
+      expect(v.noise_band.provenance).toBe('gap_tool_derived');
+    });
+  });
 });
 
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