diff --git a/app/src/main/java/app/closer/data/remote/FirebaseAuthDataSource.kt b/app/src/main/java/app/closer/data/remote/FirebaseAuthDataSource.kt
index 3d6c9cb2..88374ce0 100644
--- a/app/src/main/java/app/closer/data/remote/FirebaseAuthDataSource.kt
+++ b/app/src/main/java/app/closer/data/remote/FirebaseAuthDataSource.kt
@@ -3,11 +3,15 @@ package app.closer.data.remote
 import app.closer.BuildConfig
 import app.closer.domain.model.AuthState
 import app.closer.domain.model.GoogleSignInResult
+import app.closer.domain.repository.ChangePasswordException
 import app.closer.domain.repository.PasswordResetException
 import com.google.firebase.auth.EmailAuthProvider
 import com.google.firebase.auth.FirebaseAuth
 import com.google.firebase.auth.FirebaseAuthInvalidCredentialsException
 import com.google.firebase.auth.FirebaseAuthInvalidUserException
+import com.google.firebase.FirebaseTooManyRequestsException
+import com.google.firebase.auth.FirebaseAuthRecentLoginRequiredException
+import com.google.firebase.auth.FirebaseAuthWeakPasswordException
 import com.google.firebase.auth.GoogleAuthProvider
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
@@ -119,6 +123,60 @@ class FirebaseAuthDataSource @Inject constructor() {
                 .addOnFailureListener { cont.resumeWithException(it) }
         }
 
+    /**
+     * Changes the signed-in user's password: re-authenticates with [currentPassword] (Firebase requires
+     * a recent login to change credentials), then sets [newPassword]. Firebase specifics are translated
+     * into typed [ChangePasswordException]s so the UI never string-matches error messages. Firebase's own
+     * server-side throttling ([FirebaseTooManyRequestsException]) guards against brute-forcing the current
+     * password; we surface it as [ChangePasswordException.TooManyAttempts].
+     */
+    suspend fun changePassword(currentPassword: String, newPassword: String) {
+        val user = auth.currentUser ?: throw ChangePasswordException.ReauthRequired()
+        val email = user.email
+        val hasPasswordProvider = user.providerData.any { it.providerId == EmailAuthProvider.PROVIDER_ID }
+        if (email.isNullOrBlank() || !hasPasswordProvider) throw ChangePasswordException.NoPassword()
+
+        // 1) Prove it's really them with the current password.
+        try {
+            reauthenticate(user, EmailAuthProvider.getCredential(email, currentPassword))
+        } catch (e: FirebaseAuthInvalidCredentialsException) {
+            throw ChangePasswordException.WrongCurrentPassword()
+        } catch (e: FirebaseAuthInvalidUserException) {
+            throw ChangePasswordException.WrongCurrentPassword()
+        } catch (e: FirebaseTooManyRequestsException) {
+            throw ChangePasswordException.TooManyAttempts()
+        }
+
+        // 2) Set the new password.
+        try {
+            updatePassword(user, newPassword)
+        } catch (e: FirebaseAuthWeakPasswordException) {
+            throw ChangePasswordException.WeakNewPassword()
+        } catch (e: FirebaseAuthRecentLoginRequiredException) {
+            throw ChangePasswordException.ReauthRequired()
+        } catch (e: FirebaseTooManyRequestsException) {
+            throw ChangePasswordException.TooManyAttempts()
+        }
+    }
+
+    private suspend fun reauthenticate(
+        user: com.google.firebase.auth.FirebaseUser,
+        credential: com.google.firebase.auth.AuthCredential
+    ): Unit = suspendCancellableCoroutine { cont ->
+        user.reauthenticate(credential)
+            .addOnSuccessListener { cont.resume(Unit) }
+            .addOnFailureListener { cont.resumeWithException(it) }
+    }
+
+    private suspend fun updatePassword(
+        user: com.google.firebase.auth.FirebaseUser,
+        newPassword: String
+    ): Unit = suspendCancellableCoroutine { cont ->
+        user.updatePassword(newPassword)
+            .addOnSuccessListener { cont.resume(Unit) }
+            .addOnFailureListener { cont.resumeWithException(it) }
+    }
+
     suspend fun signInWithGoogle(idToken: String): GoogleSignInResult =
         suspendCancellableCoroutine { cont ->
             val credential = GoogleAuthProvider.getCredential(idToken, null)