diff --git a/packages/loopover-engine/src/review/screenshot-table-gate.ts b/packages/loopover-engine/src/review/screenshot-table-gate.ts
index 15e3d756b..bc741505e 100644
--- a/packages/loopover-engine/src/review/screenshot-table-gate.ts
+++ b/packages/loopover-engine/src/review/screenshot-table-gate.ts
@@ -77,7 +77,12 @@ export function normalizeScreenshotTableGateConfig(input: unknown, warnings: str
   const action = isScreenshotTableGateAction(record.action)
     ? record.action
     : (() => {
-        if (record.action !== undefined) warnings.push(`settings.requireScreenshotTable.action must be "close" or "advisory" (#4110 removed request_changes/comment as dead config surface); using the default "close".`);
+        // Derived from VALID_ACTIONS (mirrors normalizeSelfLoopAutonomy in ams-policy-spec.ts) so a future
+        // tier addition can't desynchronize this message again.
+        if (record.action !== undefined)
+          warnings.push(
+            `settings.requireScreenshotTable.action must be one of ${VALID_ACTIONS.join(", ")} (#4110 removed request_changes/comment as dead config surface); using the default "${DEFAULT_SCREENSHOT_TABLE_GATE.action}".`,
+          );
         return DEFAULT_SCREENSHOT_TABLE_GATE.action;
       })();
   const message = typeof record.message === "string" && record.message.trim().length > 0 ? record.message.trim() : undefined;
diff --git a/packages/loopover-engine/test/screenshot-table-gate.test.ts b/packages/loopover-engine/test/screenshot-table-gate.test.ts
new file mode 100644
index 000000000..d48044537
--- /dev/null
+++ b/packages/loopover-engine/test/screenshot-table-gate.test.ts
@@ -0,0 +1,29 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+import { normalizeScreenshotTableGateConfig } from "../dist/review/screenshot-table-gate.js";
+
+// #9996: the invalid-action warning was left naming only "close" or "advisory" after #9964 added the
+// non-destructive "block" tier -- an operator who mistyped the value was never told "block" exists.
+
+test("normalizeScreenshotTableGateConfig warns and mentions block for an invalid action", () => {
+  const warnings: string[] = [];
+  const config = normalizeScreenshotTableGateConfig({ enabled: true, action: "blok" }, warnings);
+  assert.equal(warnings.length, 1);
+  assert.match(warnings[0] ?? "", /block/);
+  assert.equal(config.action, "close");
+});
+
+test("normalizeScreenshotTableGateConfig pushes no action warning when action is absent", () => {
+  const warnings: string[] = [];
+  const config = normalizeScreenshotTableGateConfig({ enabled: true }, warnings);
+  assert.equal(warnings.length, 0);
+  assert.equal(config.action, "close");
+});
+
+test("normalizeScreenshotTableGateConfig resolves a valid block action with no warning", () => {
+  const warnings: string[] = [];
+  const config = normalizeScreenshotTableGateConfig({ enabled: true, action: "block" }, warnings);
+  assert.equal(warnings.length, 0);
+  assert.equal(config.action, "block");
+});
diff --git a/test/unit/screenshot-table-gate-engine.test.ts b/test/unit/screenshot-table-gate-engine.test.ts
index eb99f16b3..df1cdd3bb 100644
--- a/test/unit/screenshot-table-gate-engine.test.ts
+++ b/test/unit/screenshot-table-gate-engine.test.ts
@@ -235,6 +235,27 @@ describe("normalizeScreenshotTableGateConfig", () => {
     expect(warnings.some((w) => w.includes("action"))).toBe(true);
   });
 
+  it("#9996: the invalid-action warning names all three valid tiers, including block", () => {
+    const warnings: string[] = [];
+    const result = normalizeScreenshotTableGateConfig({ enabled: true, action: "blok" }, warnings);
+    expect(warnings.length).toBe(1);
+    expect(warnings[0]).toContain("block");
+    expect(result.action).toBe("close");
+  });
+
+  it("#9996: an absent action still pushes no warning", () => {
+    const warnings: string[] = [];
+    normalizeScreenshotTableGateConfig({ enabled: true }, warnings);
+    expect(warnings.length).toBe(0);
+  });
+
+  it("#9996: a valid block action resolves with no warning", () => {
+    const warnings: string[] = [];
+    const result = normalizeScreenshotTableGateConfig({ enabled: true, action: "block" }, warnings);
+    expect(result.action).toBe("block");
+    expect(warnings.length).toBe(0);
+  });
+
   it("rejects a non-string/empty message with a warning, falling back to undefined", () => {
     const warnings: string[] = [];
     const result = normalizeScreenshotTableGateConfig({ message: "   " }, warnings);
diff --git a/test/unit/screenshot-table-gate.test.ts b/test/unit/screenshot-table-gate.test.ts
index 5e77f324d..47ad62e5e 100644
--- a/test/unit/screenshot-table-gate.test.ts
+++ b/test/unit/screenshot-table-gate.test.ts
@@ -219,6 +219,27 @@ describe("normalizeScreenshotTableGateConfig", () => {
     expect(warnings.some((w) => w.includes("action"))).toBe(true);
   });
 
+  it("#9996: the invalid-action warning names all three valid tiers, including block", () => {
+    const warnings: string[] = [];
+    const result = normalizeScreenshotTableGateConfig({ enabled: true, action: "blok" }, warnings);
+    expect(warnings.length).toBe(1);
+    expect(warnings[0]).toContain("block");
+    expect(result.action).toBe("close");
+  });
+
+  it("#9996: an absent action still pushes no warning", () => {
+    const warnings: string[] = [];
+    normalizeScreenshotTableGateConfig({ enabled: true }, warnings);
+    expect(warnings.length).toBe(0);
+  });
+
+  it("#9996: a valid block action resolves with no warning", () => {
+    const warnings: string[] = [];
+    const result = normalizeScreenshotTableGateConfig({ enabled: true, action: "block" }, warnings);
+    expect(result.action).toBe("block");
+    expect(warnings.length).toBe(0);
+  });
+
   it("rejects a non-string/empty message with a warning, falling back to undefined", () => {
     const warnings: string[] = [];
     const result = normalizeScreenshotTableGateConfig({ message: "   " }, warnings);