diff --git a/.dockerignore b/.dockerignore
index 7181b19c..792fe906 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -4,3 +4,19 @@ dist-demo
 coverage
 .git
 *.log
+
+# The standalone demo build is credential-free. Keep local configuration,
+# registry credentials, and private key material out of recursive build context.
+**/.env
+**/.env.*
+!**/.env.example
+**/.npmrc
+**/.pnpmrc
+**/.yarnrc*
+**/.pypirc
+**/pip.conf
+**/.netrc
+**/*.pem
+**/*.key
+**/*.p12
+**/*.pfx
diff --git a/src/dockerBuildContextSecurity.test.ts b/src/dockerBuildContextSecurity.test.ts
new file mode 100644
index 00000000..e11c3d76
--- /dev/null
+++ b/src/dockerBuildContextSecurity.test.ts
@@ -0,0 +1,126 @@
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+
+import { describe, expect, it } from 'vitest';
+
+const dockerIgnoreRules = readFileSync(resolve(process.cwd(), '.dockerignore'), 'utf8')
+  .split(/\r?\n/u)
+  .map((line) => line.trim())
+  .filter((line) => line.length > 0 && !line.startsWith('#'));
+
+function matchesPathSegment(pattern: string, value: string): boolean {
+  let previous = Array.from({ length: value.length + 1 }, (_, index) => index === 0);
+
+  for (const token of pattern) {
+    const current = Array.from({ length: value.length + 1 }, () => false);
+    if (token === '*') {
+      current[0] = previous[0] ?? false;
+      for (let index = 1; index <= value.length; index += 1) {
+        current[index] =
+          (previous[index] ?? false) || (current[index - 1] ?? false);
+      }
+    } else {
+      for (let index = 1; index <= value.length; index += 1) {
+        current[index] =
+          (previous[index - 1] ?? false) &&
+          (token === '?' || token === value[index - 1]);
+      }
+    }
+    previous = current;
+  }
+
+  return previous[value.length] ?? false;
+}
+
+function matchesDockerPattern(pattern: string, path: string): boolean {
+  const patternSegments = pattern.split('/').filter(Boolean);
+  const pathSegments = path.split('/').filter(Boolean);
+
+  if (patternSegments.length === 1) {
+    const [singlePattern = ''] = patternSegments;
+    return pathSegments.some((segment) =>
+      matchesPathSegment(singlePattern, segment),
+    );
+  }
+
+  const memo = new Map<string, boolean>();
+  function visit(patternIndex: number, pathIndex: number): boolean {
+    const key = `${patternIndex}:${pathIndex}`;
+    const cached = memo.get(key);
+    if (cached !== undefined) return cached;
+
+    let matched: boolean;
+    if (patternIndex === patternSegments.length) {
+      matched = pathIndex === pathSegments.length;
+    } else if (patternSegments[patternIndex] === '**') {
+      matched =
+        visit(patternIndex + 1, pathIndex) ||
+        (pathIndex < pathSegments.length && visit(patternIndex, pathIndex + 1));
+    } else {
+      matched =
+        pathIndex < pathSegments.length &&
+        matchesPathSegment(
+          patternSegments[patternIndex] ?? '',
+          pathSegments[pathIndex] ?? '',
+        ) &&
+        visit(patternIndex + 1, pathIndex + 1);
+    }
+
+    memo.set(key, matched);
+    return matched;
+  }
+
+  return visit(0, 0);
+}
+
+function isExcludedFromDockerContext(path: string): boolean {
+  let excluded = false;
+  for (const rule of dockerIgnoreRules) {
+    const negated = rule.startsWith('!');
+    const pattern = negated ? rule.slice(1) : rule;
+    if (matchesDockerPattern(pattern, path)) {
+      excluded = !negated;
+    }
+  }
+  return excluded;
+}
+
+describe('Docker build-context secret boundary', () => {
+  it('excludes local environment and package-registry credentials recursively', () => {
+    for (const privatePath of [
+      '.env',
+      '.env.production',
+      'demo/.env.local',
+      '.npmrc',
+      'packages/editor/.pnpmrc',
+      '.yarnrc.yml',
+      'nested/.netrc',
+    ]) {
+      expect(isExcludedFromDockerContext(privatePath), privatePath).toBe(true);
+    }
+  });
+
+  it('excludes common private-key and credential-container files recursively', () => {
+    for (const privatePath of [
+      'certificate.pem',
+      'secrets/signing.key',
+      'credentials/client.p12',
+      'credentials/client.pfx',
+    ]) {
+      expect(isExcludedFromDockerContext(privatePath), privatePath).toBe(true);
+    }
+  });
+
+  it('keeps explicit public examples and required build inputs in context', () => {
+    for (const publicPath of [
+      '.env.example',
+      'demo/.env.example',
+      'package.json',
+      'pnpm-lock.yaml',
+      'src/styles.css',
+      'demo/App.tsx',
+    ]) {
+      expect(isExcludedFromDockerContext(publicPath), publicPath).toBe(false);
+    }
+  });
+});
diff --git a/src/dockerPythonCredentialContextSecurity.test.ts b/src/dockerPythonCredentialContextSecurity.test.ts
new file mode 100644
index 00000000..ee60240a
--- /dev/null
+++ b/src/dockerPythonCredentialContextSecurity.test.ts
@@ -0,0 +1,13 @@
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+
+import { describe, expect, it } from 'vitest';
+
+const dockerIgnore = readFileSync(resolve(process.cwd(), '.dockerignore'), 'utf8');
+
+describe('Docker build-context Python credential boundary', () => {
+  it('excludes Python registry and installer credential files recursively', () => {
+    expect(dockerIgnore).toContain('**/.pypirc');
+    expect(dockerIgnore).toContain('**/pip.conf');
+  });
+});