diff --git a/.github/scripts/vuln-gate.mjs b/.github/scripts/vuln-gate.mjs
index 27f67207a..9026e7421 100644
--- a/.github/scripts/vuln-gate.mjs
+++ b/.github/scripts/vuln-gate.mjs
@@ -18,7 +18,7 @@
 //   dotnet list package --vulnerable --include-transitive --format json --output-version 1 \
 //     | node .github/scripts/vuln-gate.mjs --ecosystem nuget
 //
-// Flags: --level <low|moderate|high|critical>  (default high — blocks at or above)
+// Flags: --level <info|low|moderate|high|critical>  (default high — blocks at or above)
 //        --warn-only                           (report, always exit 0)
 //        --exceptions <path>                   (default .github/security-exceptions.json)
 //        --emit-allowlist                      (print live GHSA ids for dependency-review)
@@ -43,6 +43,12 @@ export function severityRank(severity) {
   return i < 0 ? UNKNOWN_RANK : i;
 }
 
+export function levelProblem(level) {
+  return SEVERITIES.includes(String(level ?? "").toLowerCase())
+    ? null
+    : `--level must be one of ${SEVERITIES.join(", ")}`;
+}
+
 // Both ecosystems point their advisory URLs at GitHub Security Advisories, so a
 // GHSA id is the one key that means the same thing on both sides — that is what
 // an exception is written against. Numeric npm ids / package coordinates are
@@ -172,14 +178,24 @@ function isLive(exception, now) {
   return Number.isFinite(dayStart) && now.getTime() < dayStart + ONE_DAY_MS;
 }
 
+function scopeOf(exception) {
+  return String(exception.ecosystem ?? "").toLowerCase();
+}
+
+function inScope(exception, ecosystem) {
+  const scope = scopeOf(exception);
+  return scope === "any" || scope === String(ecosystem).toLowerCase();
+}
+
 function matches(exception, finding, ecosystem) {
-  const scope = String(exception.ecosystem).toLowerCase();
-  if (scope !== "any" && scope !== ecosystem) return false;
+  if (!inScope(exception, ecosystem)) return false;
   return canonicalGhsa(exception.id) === finding.id;
 }
 
 export function gate({ findings, exceptions = [], ecosystem, level = "high", now = new Date() }) {
-  const floor = severityRank(level);
+  const problem = levelProblem(level);
+  if (problem) throw new Error(problem);
+  const floor = SEVERITIES.indexOf(String(level).toLowerCase());
   const atOrAbove = findings.filter((f) => severityRank(f.severity) >= floor);
 
   const valid = exceptions.filter(isValidException);
@@ -188,8 +204,6 @@ export function gate({ findings, exceptions = [], ecosystem, level = "high", now
     .filter((e) => !isValidException(e))
     .map((e) => ({ raw: e, problem: exceptionProblem(e) }));
 
-  const inScope = (e) => e.ecosystem === "any" || e.ecosystem.toLowerCase() === ecosystem;
-
   const suppressed = [];
   const blocking = [];
   for (const finding of atOrAbove) {
@@ -200,7 +214,7 @@ export function gate({ findings, exceptions = [], ecosystem, level = "high", now
 
   // Valid, in-scope, but past its window — surfaced so a lapsed entry gets
   // deleted instead of lingering as dead config.
-  const staleExceptions = valid.filter((e) => inScope(e) && !isLive(e, now));
+  const staleExceptions = valid.filter((e) => inScope(e, ecosystem) && !isLive(e, now));
 
   return {
     blocking,
@@ -295,12 +309,23 @@ async function readStdin() {
   return Buffer.concat(chunks).toString("utf8");
 }
 
-function loadExceptions(path) {
+export function loadExceptions(path, warn = console.error) {
+  let parsed;
   try {
-    return JSON.parse(readFileSync(path, "utf8")).exceptions ?? [];
-  } catch {
-    return []; // no file → empty allowlist, the normal case
+    parsed = JSON.parse(readFileSync(path, "utf8"));
+  } catch (err) {
+    if (err?.code === "ENOENT") return []; // no file → empty allowlist, the normal case
+    warn(`::warning::could not load security exceptions from ${path}: ${err.message}`);
+    return [];
+  }
+
+  const exceptions = parsed?.exceptions;
+  if (exceptions === undefined || exceptions === null) return [];
+  if (!Array.isArray(exceptions)) {
+    warn(`::warning::security exceptions from ${path} must contain an exceptions array`);
+    return [];
   }
+  return exceptions;
 }
 
 async function main() {
@@ -319,6 +344,13 @@ async function main() {
     return;
   }
 
+  const problem = levelProblem(options.level);
+  if (problem) {
+    console.error(`usage: vuln-gate.mjs --ecosystem npm|nuget [--level info|low|moderate|high|critical] [--warn-only] — ${problem}`);
+    process.exitCode = 2;
+    return;
+  }
+
   let parsed;
   try {
     parsed = extractJson(await readStdin());
diff --git a/.github/scripts/vuln-gate.test.mjs b/.github/scripts/vuln-gate.test.mjs
index 13ee93f2c..1f3afe6ad 100644
--- a/.github/scripts/vuln-gate.test.mjs
+++ b/.github/scripts/vuln-gate.test.mjs
@@ -9,6 +9,11 @@
 
 import test from "node:test";
 import assert from "node:assert/strict";
+import { spawnSync } from "node:child_process";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { fileURLToPath } from "node:url";
 import {
   advisoryId,
   emitAllowlist,
@@ -17,6 +22,8 @@ import {
   gate,
   isGhsaId,
   isValidException,
+  levelProblem,
+  loadExceptions,
   parseArgs,
   parseNpm,
   parseNuget,
@@ -28,6 +35,7 @@ import {
 const NOW = new Date("2026-07-24T00:00:00Z");
 const GHSA_ONE = "GHSA-aaaa-bbbb-cccc";
 const GHSA_TWO = "GHSA-dddd-eeee-ffff";
+const SCRIPT = fileURLToPath(new URL("./vuln-gate.mjs", import.meta.url));
 
 const finding = (over = {}) => ({
   id: GHSA_ONE, package: "left-pad@1.0.0", severity: "high", title: "", url: "", ...over,
@@ -307,3 +315,98 @@ test("parseArgs reads the flags and keeps sensible defaults", () => {
   });
   assert.equal(parseArgs(["--emit-allowlist"]).emitAllowlist, true);
 });
+
+test("levelProblem accepts supported case-insensitive thresholds and rejects bad values", () => {
+  for (const level of ["info", "LOW", "Moderate", "high", "CRITICAL"]) {
+    assert.equal(levelProblem(level), null);
+  }
+  assert.match(levelProblem("hihg"), /--level/);
+  assert.match(levelProblem(), /--level/);
+});
+
+test("gate: rejects an unknown configured threshold instead of lowering the floor", () => {
+  assert.throws(
+    () => gate({ findings: [finding({ severity: "critical" })], ecosystem: "npm", level: "hihg", now: NOW }),
+    /--level/,
+  );
+});
+
+test("CLI: a critical npm advisory blocks by default and a typoed level is a usage error", () => {
+  const report = JSON.stringify({
+    auditReportVersion: 2,
+    vulnerabilities: {
+      "left-pad": {
+        name: "left-pad",
+        severity: "critical",
+        via: [{
+          source: 1,
+          name: "left-pad",
+          severity: "critical",
+          title: "critical test advisory",
+          url: `https://github.com/advisories/${GHSA_ONE}`,
+        }],
+      },
+    },
+  });
+  const run = (level) => spawnSync(
+    process.execPath,
+    [SCRIPT, "--ecosystem", "npm", ...(level ? ["--level", level] : [])],
+    { cwd: process.cwd(), encoding: "utf8", input: report },
+  );
+
+  assert.equal(run().status, 1);
+  const invalid = run("hihg");
+  assert.equal(invalid.status, 2);
+  assert.match(invalid.stderr, /--level/);
+});
+
+test("gate: expired ANY and npm scopes are each reported stale", () => {
+  for (const ecosystem of ["ANY", "any", "NPM", "npm"]) {
+    const result = gate({
+      findings: [finding()],
+      exceptions: [exception({ ecosystem, expires: "2026-07-23" })],
+      ecosystem: "npm",
+      now: NOW,
+    });
+    assert.equal(result.blocking.length, 1, `${ecosystem} exception must not suppress after expiry`);
+    assert.equal(result.staleExceptions.length, 1, `${ecosystem} exception must be reported stale`);
+  }
+});
+
+test("loadExceptions: only a missing file is quiet; unusable files warn and suppress nothing", () => {
+  const dir = mkdtempSync(join(tmpdir(), "cluckwork-vuln-gate-"));
+  const path = join(dir, "exceptions.json");
+  const warnings = [];
+  const warn = (line) => warnings.push(line);
+
+  try {
+    assert.deepEqual(loadExceptions(path, warn), []);
+    assert.deepEqual(warnings, []);
+
+    warnings.length = 0;
+    assert.deepEqual(warnings, []);
+    assert.deepEqual(loadExceptions(dir, warn), []);
+    assert.equal(warnings.length, 1);
+    assert.ok(warnings[0].includes(dir));
+
+    warnings.length = 0;
+    writeFileSync(path, "not json", "utf8");
+    assert.deepEqual(loadExceptions(path, warn), []);
+    assert.equal(warnings.length, 1);
+    assert.ok(warnings[0].includes(path));
+
+    warnings.length = 0;
+    writeFileSync(path, JSON.stringify({ exceptions: {} }), "utf8");
+    assert.deepEqual(loadExceptions(path, warn), []);
+    assert.equal(warnings.length, 1);
+    assert.match(warnings[0], /array/i);
+
+    warnings.length = 0;
+    const valid = [exception()];
+    writeFileSync(path, JSON.stringify({ exceptions: valid }), "utf8");
+    assert.deepEqual(loadExceptions(path, warn), valid);
+    assert.deepEqual(warnings, []);
+  } finally {
+    rmSync(dir, { recursive: true, force: true });
+  }
+});