diff --git a/.changeset/expo-native-module-contract.md b/.changeset/expo-native-module-contract.md
new file mode 100644
index 00000000000..a845151cc84
--- /dev/null
+++ b/.changeset/expo-native-module-contract.md
@@ -0,0 +1,2 @@
+---
+---
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6377781ef65..9919789d6c2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -280,6 +280,13 @@ jobs:
           filter: 'blob:none'
           show-progress: false
 
+      - name: Fetch Expo native release tags
+        run: |
+          git fetch --depth=1 --no-tags origin \
+            'refs/tags/@clerk/expo-native-components@*:refs/tags/@clerk/expo-native-components@*' \
+            'refs/tags/@clerk/expo-google-signin@*:refs/tags/@clerk/expo-google-signin@*' \
+            'refs/tags/@clerk/expo-biometrics@*:refs/tags/@clerk/expo-biometrics@*'
+
       - name: Setup
         id: config
         uses: $/.github/actions/init-blacksmith
diff --git a/packages/expo/AGENTS.md b/packages/expo/AGENTS.md
index 4e344934be7..76ef10db792 100644
--- a/packages/expo/AGENTS.md
+++ b/packages/expo/AGENTS.md
@@ -1,7 +1,8 @@
 # @clerk/expo
 
-These rules apply to everything in this package, including the Swift and Kotlin
-code under `ios/`, `apple/` and `android/`. They add to the root `AGENTS.md`.
+These rules apply to everything in this package, and to the Swift and Kotlin
+code under `packages/expo-native-components`, `packages/expo-google-signin` and
+`packages/expo-biometrics`. They add to the root `AGENTS.md`.
 
 ## Comments
 
diff --git a/packages/expo/src/specs/__tests__/nativeContract.test.ts b/packages/expo/src/specs/__tests__/nativeContract.test.ts
new file mode 100644
index 00000000000..bf84648d8b9
--- /dev/null
+++ b/packages/expo/src/specs/__tests__/nativeContract.test.ts
@@ -0,0 +1,12 @@
+import { resolve } from 'node:path';
+
+import { expect, test } from 'vitest';
+
+import { NATIVE_MODULES, nativeModuleContractErrors, shippedNativeFunctions } from './nativeModuleContract';
+
+const root = resolve(__dirname, '../../../../..');
+
+test.each(NATIVE_MODULES)('$spec matches $native and every $release release', ({ module, release, spec, native }) => {
+  const releases = shippedNativeFunctions(root, release, native);
+  expect(nativeModuleContractErrors({ root, module, spec, native, releases })).toEqual([]);
+});
diff --git a/packages/expo/src/specs/__tests__/nativeModuleContract.ts b/packages/expo/src/specs/__tests__/nativeModuleContract.ts
new file mode 100644
index 00000000000..8663afdb723
--- /dev/null
+++ b/packages/expo/src/specs/__tests__/nativeModuleContract.ts
@@ -0,0 +1,208 @@
+import { execFileSync } from 'node:child_process';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+
+import ts from 'typescript';
+
+const OPENERS: Record<string, string> = { '(': ')', '<': '>', '[': ']', '{': '}' };
+
+function splitTopLevel(text: string) {
+  const parts: string[] = [];
+  let depth = 0;
+  let current = '';
+  for (const char of text) {
+    if (char in OPENERS) {
+      depth++;
+    } else if (Object.values(OPENERS).includes(char) && depth > 0) {
+      depth--;
+    }
+    if (char === ',' && depth === 0) {
+      parts.push(current);
+      current = '';
+    } else {
+      current += char;
+    }
+  }
+  parts.push(current);
+  return parts.map(part => part.trim()).filter(Boolean);
+}
+
+function balanced(text: string, start: number) {
+  let depth = 0;
+  for (let i = start; i < text.length; i++) {
+    if (text[i] === '(') {
+      depth++;
+    } else if (text[i] === ')') {
+      depth--;
+      if (depth === 0) {
+        return text.slice(start + 1, i);
+      }
+    }
+  }
+  throw new Error(`Unbalanced parentheses at ${start}`);
+}
+
+function closureParams(source: string, braceIndex: number, language: 'swift' | 'kotlin') {
+  let i = braceIndex + 1;
+  while (/\s/.test(source[i])) {
+    i++;
+  }
+  let params: string[];
+  if (language === 'swift') {
+    params = source[i] === '(' ? splitTopLevel(balanced(source, i)) : [];
+  } else {
+    const end = source.indexOf('->', i);
+    params = end === -1 ? [] : splitTopLevel(source.slice(i, end));
+  }
+  return params.filter(param => !/:\s*Promise$/.test(param));
+}
+
+export const NATIVE_MODULES = [
+  {
+    module: 'ClerkExpo',
+    platform: 'ios',
+    release: '@clerk/expo-native-components',
+    spec: 'packages/expo/src/specs/NativeClerkModule.ts',
+    native: 'packages/expo-native-components/ios/ClerkExpoModule.swift',
+  },
+  {
+    module: 'ClerkExpo',
+    platform: 'android',
+    release: '@clerk/expo-native-components',
+    spec: 'packages/expo/src/specs/NativeClerkModule.android.ts',
+    native: 'packages/expo-native-components/android/src/main/java/expo/modules/clerk/ClerkExpoModule.kt',
+  },
+  {
+    module: 'ClerkGoogleSignIn',
+    platform: 'ios',
+    release: '@clerk/expo-google-signin',
+    spec: 'packages/expo/src/specs/NativeClerkGoogleSignIn.ts',
+    native: 'packages/expo-google-signin/ios/ClerkGoogleSignInModule.swift',
+  },
+  {
+    module: 'ClerkGoogleSignIn',
+    platform: 'android',
+    release: '@clerk/expo-google-signin',
+    spec: 'packages/expo/src/specs/NativeClerkGoogleSignIn.android.ts',
+    native:
+      'packages/expo-google-signin/android/src/main/java/expo/modules/clerk/googlesignin/ClerkGoogleSignInModule.kt',
+  },
+  {
+    module: 'ClerkExpoBiometrics',
+    platform: 'ios',
+    release: '@clerk/expo-biometrics',
+    spec: 'packages/expo-biometrics/src/ClerkExpoBiometricsModule.ts',
+    native: 'packages/expo-biometrics/ios/ClerkExpoBiometricsModule.swift',
+  },
+  {
+    module: 'ClerkExpoBiometrics',
+    platform: 'android',
+    release: '@clerk/expo-biometrics',
+    spec: 'packages/expo-biometrics/src/ClerkExpoBiometricsModule.ts',
+    native: 'packages/expo-biometrics/android/src/main/java/expo/modules/clerk/biometrics/ClerkExpoBiometricsModule.kt',
+  },
+] as const;
+
+export function parseNativeFunctions(source: string, file: string) {
+  const language = file.endsWith('.swift') ? 'swift' : 'kotlin';
+  const functions = new Map<string, number>();
+  for (const match of source.matchAll(/\b(?:Async)?Function\("([^"]+)"\)\s*\{/g)) {
+    functions.set(match[1], closureParams(source, match.index + match[0].length - 1, language).length);
+  }
+  return functions;
+}
+
+export function readSpecFunctions(file: string) {
+  const program = ts.createProgram([file], { noEmit: true, skipLibCheck: true, strict: true });
+  const checker = program.getTypeChecker();
+  const sourceFile = program.getSourceFile(file)!;
+  const moduleSymbol = checker.getSymbolAtLocation(sourceFile)!;
+  const defaultExport = checker.getExportsOfModule(moduleSymbol).find(symbol => symbol.name === 'default')!;
+  const type = checker.getNonNullableType(checker.getTypeOfSymbolAtLocation(defaultExport, sourceFile));
+  const functions = new Map<string, { arity: number; optional: boolean }>();
+  for (const property of checker.getPropertiesOfType(type)) {
+    if (property.name === 'addListener' || property.name === 'removeListeners') {
+      continue;
+    }
+    const signatures = checker
+      .getNonNullableType(checker.getTypeOfSymbolAtLocation(property, sourceFile))
+      .getCallSignatures();
+    if (signatures.length > 0) {
+      functions.set(property.name, {
+        arity: Math.max(...signatures.map(signature => signature.parameters.length)),
+        optional: Boolean(property.flags & ts.SymbolFlags.Optional),
+      });
+    }
+  }
+  return functions;
+}
+
+type Release = { tag: string; functions: Map<string, number> };
+
+export function shippedNativeFunctions(root: string, release: string, native: string): Release[] {
+  const tags = execFileSync('git', ['tag', '--list', `${release}@*`, '--sort=v:refname'], {
+    cwd: root,
+    encoding: 'utf8',
+  })
+    .split('\n')
+    .filter(line => /@\d+\.\d+\.\d+$/.test(line));
+  if (tags.length === 0) {
+    throw new Error(
+      `No ${release}@<version> release tag in this checkout. The native contract test reads the shipped native module from every release. Fetch them with: git fetch --depth=1 --no-tags origin 'refs/tags/${release}@*:refs/tags/${release}@*'`,
+    );
+  }
+  return tags.map(tag => ({
+    tag,
+    functions: parseNativeFunctions(
+      execFileSync('git', ['show', `${tag}:${native}`], { cwd: root, encoding: 'utf8' }),
+      native,
+    ),
+  }));
+}
+
+type ContractInput = {
+  root: string;
+  module: string;
+  spec: string;
+  native: string;
+  releases: Release[];
+};
+
+export function nativeModuleContractErrors({ root, module, spec, native, releases }: ContractInput) {
+  const specFunctions = readSpecFunctions(join(root, spec));
+  const nativeFunctions = parseNativeFunctions(readFileSync(join(root, native), 'utf8'), native);
+  const errors: string[] = [];
+  for (const [name, { arity, optional }] of specFunctions) {
+    if (!nativeFunctions.has(name)) {
+      errors.push(
+        `${module}.${name} is declared in ${spec} but ${native} has no Function("${name}")/AsyncFunction("${name}"). Add it natively, or remove it from the spec and from every JS caller.`,
+      );
+    } else if (nativeFunctions.get(name) !== arity) {
+      errors.push(
+        `${module}.${name} takes ${arity} argument(s) in ${spec} but ${nativeFunctions.get(name)} in ${native}. Change both sides together.`,
+      );
+    }
+    const missingFrom = releases.filter(release => !release.functions.has(name)).map(release => release.tag);
+    if (missingFrom.length > 0 && !optional) {
+      errors.push(
+        `${module}.${name} is missing from ${missingFrom.join(', ')}. Apps built on those releases do not have it, and OTA JS can still reach them. Declare it optional (${name}?(...)) in ${spec} and feature-detect before calling it.`,
+      );
+    }
+    for (const { tag, functions } of releases) {
+      const shippedArity = functions.get(name);
+      if (shippedArity !== undefined && shippedArity !== arity) {
+        errors.push(
+          `${module}.${name} takes ${shippedArity} argument(s) in ${tag} but ${spec} now passes ${arity}. Apps built on that release still run that binary, so keep ${name}(${shippedArity} args) as is and add a new optional function that you feature-detect (as configureWithOptions did for configure).`,
+        );
+      }
+    }
+  }
+  for (const name of nativeFunctions.keys()) {
+    if (!specFunctions.has(name)) {
+      errors.push(
+        `${module}.${name} is exposed by ${native} but missing from ${spec}. Declare it in the spec, or delete the native function.`,
+      );
+    }
+  }
+  return errors;
+}