diff --git a/test/security-dashboard.test.ts b/test/security-dashboard.test.ts
new file mode 100644
index 000000000..fb5ff1701
--- /dev/null
+++ b/test/security-dashboard.test.ts
@@ -0,0 +1,143 @@
+import { describe, test, expect, beforeEach, afterEach } from 'bun:test';
+import { execSync, ExecSyncOptionsWithStringEncoding } from 'child_process';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+
+// Regression tests for #1947: the community security dashboard must FAIL CLOSED.
+// A backend error, an unreachable backend, or unparseable data must render
+// "unknown", never a reassuring "0 attacks / Good news" — reporting 0
+// when the real state is unknown is a fail-open on a security-signaling surface
+// (the same class the project's "4 security guards failing open" wave corrected).
+//
+// The dashboard fetches `${GSTACK_SUPABASE_URL}/functions/v1/community-pulse` via
+// curl. Tests put a fake curl first on PATH: when a fixture exists it writes the
+// body and prints HTTP 200; when no fixture exists it prints HTTP 000.
+
+const ROOT = path.resolve(import.meta.dir, '..');
+const BIN = path.join(ROOT, 'bin', 'gstack-security-dashboard');
+const HAS_JQ = (() => {
+  try {
+    execSync('command -v jq', { stdio: 'ignore' });
+    return true;
+  } catch {
+    return false;
+  }
+})();
+
+let tmpDir: string;
+let fixtureFile: string;
+let fakeBin: string;
+
+beforeEach(() => {
+  tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gstack-secdash-'));
+  const fnDir = path.join(tmpDir, 'functions', 'v1');
+  fs.mkdirSync(fnDir, { recursive: true });
+  fixtureFile = path.join(fnDir, 'community-pulse');
+  fakeBin = path.join(tmpDir, 'bin');
+  fs.mkdirSync(fakeBin, { recursive: true });
+  const curl = path.join(fakeBin, 'curl');
+  fs.writeFileSync(
+    curl,
+    `#!/bin/sh
+out=""
+while [ "$#" -gt 0 ]; do
+  if [ "$1" = "-o" ]; then
+    shift
+    out="$1"
+  fi
+  shift
+done
+if [ -f "${fixtureFile}" ]; then
+  cp "${fixtureFile}" "$out"
+  printf "200"
+  exit 0
+fi
+: > "$out"
+printf "000"
+exit 7
+`,
+  );
+  fs.chmodSync(curl, 0o755);
+});
+
+afterEach(() => {
+  fs.rmSync(tmpDir, { recursive: true, force: true });
+});
+
+function run(args: string, env: Record<string, string>): string {
+  const execOpts: ExecSyncOptionsWithStringEncoding = {
+    env: {
+      ...process.env,
+      PATH: `${fakeBin}${path.delimiter}${process.env.PATH ?? ''}`,
+      GSTACK_SUPABASE_ANON_KEY: 'test-anon-key',
+      ...env,
+    },
+    encoding: 'utf-8',
+    timeout: 20000,
+  };
+  // The dashboard exits 0 in every state (unknown included), so no try/catch.
+  return execSync(`bash ${BIN} ${args}`, execOpts);
+}
+
+function writeFixture(json: object) {
+  fs.writeFileSync(fixtureFile, JSON.stringify(json));
+}
+
+const reachableUrl = () => 'https://community.test';
+const unreachableUrl = () => 'https://community.test';
+
+describe('gstack-security-dashboard fail-closed (#1947)', () => {
+  test('unreachable backend reports "unknown", not "0 attacks"', () => {
+    const out = run('', { GSTACK_SUPABASE_URL: unreachableUrl() });
+    expect(out).toContain('Attacks detected last 7 days: unknown');
+    expect(out).toMatch(/backend error/i);
+    // The fail-open strings must NOT appear.
+    expect(out).not.toContain('Attacks detected last 7 days: 0');
+    expect(out).not.toContain('Good news');
+  });
+
+  test('backend error body without security data reports unknown instead of zero', () => {
+    writeFixture({ error: 'pulse_unavailable' });
+    const out = run('', { GSTACK_SUPABASE_URL: reachableUrl() });
+    expect(out).toContain('Attacks detected last 7 days: unknown');
+    expect(out).toMatch(/backend error/i);
+    expect(out).not.toContain('Good news');
+  });
+
+  test('--json surfaces an explicit error, not a fake all-zero security object', () => {
+    const out = run('--json', { GSTACK_SUPABASE_URL: unreachableUrl() }).trim();
+    const parsed = JSON.parse(out);
+    expect(parsed.security).toBeNull();
+    expect(parsed.status).toBe('unknown');
+    expect(parsed.reason).toBe('backend_error');
+    // Must NOT emit the old reassuring zero payload.
+    expect(out).not.toContain('"attacks_last_7_days":0');
+  });
+
+  test.if(HAS_JQ)('a GENUINE zero still reads as "0 / Good news" (no over-classify)', () => {
+    writeFixture({
+      status: 'ok',
+      security: { attacks_last_7_days: 0, top_attack_domains: [], top_attack_layers: [], verdict_distribution: [] },
+    });
+    const out = run('', { GSTACK_SUPABASE_URL: reachableUrl() });
+    expect(out).toContain('Attacks detected last 7 days: 0');
+    expect(out).toContain('Good news');
+    expect(out).not.toMatch(/unknown/i);
+  });
+
+  test.if(HAS_JQ)('a non-zero count from a healthy backend is reported verbatim', () => {
+    writeFixture({
+      status: 'ok',
+      security: {
+        attacks_last_7_days: 4,
+        top_attack_domains: [{ domain: 'evil.test', count: 4 }],
+        top_attack_layers: [],
+        verdict_distribution: [],
+      },
+    });
+    const out = run('', { GSTACK_SUPABASE_URL: reachableUrl() });
+    expect(out).toContain('Attacks detected last 7 days: 4');
+    expect(out).not.toMatch(/unknown/i);
+  });
+});