diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8be58e4..4426589 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@
 - `mentions`: no hardcoded user; defaults to authenticated user or accepts `--user @handle`.
 - GraphQL query ID updater: correctly pairs `operationName` ↔ `queryId` (CreateTweet/CreateRetweet/etc).
 - `build:dist`: copies `src/lib/query-ids.json` into `dist/lib/query-ids.json` (keeps `dist/` in sync).
+- `--engine graphql`: strict GraphQL-only (disables Sweetistics fallback).
 
 ## 0.1.1 — 2025-12-26
 
diff --git a/README.md b/README.md
index 04dcdf8..82f06fb 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,8 @@ bird query-ids --fresh
 - `--engine graphql` — use Twitter/X GraphQL with cookies (Chrome/Firefox/env/flags).
 - `--engine sweetistics` — use Sweetistics API key (no browser cookies needed).
 
+Note: fallback to Sweetistics only happens in `--engine auto`. `--engine graphql` is strict (no fallback).
+
 Global options:
 - `--timeout <ms>`: abort requests after the given timeout (milliseconds).
 - `--plain`: stable output (no emoji, no color).
diff --git a/src/index.ts b/src/index.ts
index 2d71043..c0ba0fc 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -17,7 +17,12 @@ import JSON5 from 'json5';
 import kleur from 'kleur';
 import { resolveCliInvocation } from './lib/cli-args.js';
 import { resolveCredentials } from './lib/cookies.js';
-import { type EngineMode, resolveEngineMode, shouldUseSweetistics } from './lib/engine.js';
+import {
+  type EngineMode,
+  resolveEngineMode,
+  shouldAllowSweetisticsFallback,
+  shouldUseSweetistics,
+} from './lib/engine.js';
 import { extractTweetId } from './lib/extract-tweet-id.js';
 import { mentionsQueryFromUserOption, normalizeHandle } from './lib/normalize-handle.js';
 import {
@@ -429,7 +434,7 @@ program
     if (result.success) {
       console.log(`${p('ok')}Tweet posted successfully!`);
       console.log(`${l('url')}https://x.com/i/status/${result.tweetId}`);
-    } else if (sweetistics.apiKey) {
+    } else if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
       console.error(`${p('warn')}GraphQL tweet failed (${result.error}); trying Sweetistics fallback...`);
       const fallback = await new SweetisticsClient({
         baseUrl: sweetistics.baseUrl,
@@ -558,7 +563,7 @@ program
     if (result.success) {
       console.log(`${p('ok')}Reply posted successfully!`);
       console.log(`${l('url')}https://x.com/i/status/${result.tweetId}`);
-    } else if (sweetistics.apiKey) {
+    } else if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
       console.error(`${p('warn')}GraphQL reply failed (${result.error}); trying Sweetistics fallback...`);
       const fallback = await new SweetisticsClient({
         baseUrl: sweetistics.baseUrl,
@@ -657,7 +662,7 @@ program
         }
         console.log(formatStatsLine(result.tweet, output));
       }
-    } else if (sweetistics.apiKey) {
+    } else if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
       console.error(`${p('warn')}GraphQL read failed (${result.error}); trying Sweetistics fallback...`);
       const fallback = await new SweetisticsClient({
         baseUrl: sweetistics.baseUrl,
@@ -741,7 +746,7 @@ program
 
     if (result.success && result.tweets) {
       printTweets(result.tweets, { json: cmdOpts.json, emptyMessage: 'No replies found.' });
-    } else if (sweetistics.apiKey) {
+    } else if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
       console.error(`${p('warn')}GraphQL replies failed (${result.error}); trying Sweetistics fallback...`);
       const fallback = await new SweetisticsClient({
         baseUrl: sweetistics.baseUrl,
@@ -816,7 +821,7 @@ program
 
     if (result.success && result.tweets) {
       printTweets(result.tweets, { json: cmdOpts.json, emptyMessage: 'No thread tweets found.' });
-    } else if (sweetistics.apiKey) {
+    } else if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
       console.error(`${p('warn')}GraphQL thread failed (${result.error}); trying Sweetistics fallback...`);
       const fallback = await new SweetisticsClient({
         baseUrl: sweetistics.baseUrl,
@@ -893,7 +898,7 @@ program
 
     if (result.success && result.tweets) {
       printTweets(result.tweets, { json: cmdOpts.json, emptyMessage: 'No tweets found.' });
-    } else if (sweetistics.apiKey) {
+    } else if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
       console.error(`${p('warn')}GraphQL search failed (${result.error}); trying Sweetistics fallback...`);
       const fallback = await new SweetisticsClient({
         baseUrl: sweetistics.baseUrl,
@@ -988,7 +993,7 @@ program
       const who = await client.getCurrentUser();
       const handle = normalizeHandle(who.user?.username);
       if (!handle) {
-        if (sweetistics.apiKey) {
+        if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
           console.error(
             `${p('warn')}Could not determine current user (${who.error ?? 'Unknown error'}); trying Sweetistics fallback...`,
           );
@@ -1018,7 +1023,7 @@ program
 
     if (result.success && result.tweets) {
       printTweets(result.tweets, { json: cmdOpts.json, emptyMessage: 'No mentions found.' });
-    } else if (sweetistics.apiKey) {
+    } else if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
       console.error(`${p('warn')}GraphQL mentions failed (${result.error}); trying Sweetistics fallback...`);
       const fallback = await new SweetisticsClient({
         baseUrl: sweetistics.baseUrl,
@@ -1115,7 +1120,7 @@ program
       console.log(`${l('credentials')}${credentialSource}`);
     } else {
       // Fallback: try Sweetistics if available
-      if (sweetistics.apiKey) {
+      if (shouldAllowSweetisticsFallback(engine, Boolean(sweetistics.apiKey))) {
         const fallback = await new SweetisticsClient({
           baseUrl: sweetistics.baseUrl,
           apiKey: sweetistics.apiKey,
diff --git a/src/lib/engine.ts b/src/lib/engine.ts
index 54cf2fb..c303625 100644
--- a/src/lib/engine.ts
+++ b/src/lib/engine.ts
@@ -13,3 +13,7 @@ export function shouldUseSweetistics(engine: EngineMode, _hasApiKey: boolean): b
   if (engine === 'graphql') return false;
   return false; // auto: GraphQL primary, Sweetistics only as fallback
 }
+
+export function shouldAllowSweetisticsFallback(engine: EngineMode, hasApiKey: boolean): boolean {
+  return engine === 'auto' && hasApiKey;
+}
diff --git a/tests/engine.test.ts b/tests/engine.test.ts
index cf5f614..5c745f2 100644
--- a/tests/engine.test.ts
+++ b/tests/engine.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { resolveEngineMode, shouldUseSweetistics } from '../src/lib/engine.js';
+import { resolveEngineMode, shouldAllowSweetisticsFallback, shouldUseSweetistics } from '../src/lib/engine.js';
 
 describe('engine', () => {
   it('normalizes engine values and defaults to auto', () => {
@@ -19,4 +19,11 @@ describe('engine', () => {
     expect(shouldUseSweetistics('sweetistics', false)).toBe(true);
     expect(shouldUseSweetistics('graphql', true)).toBe(false);
   });
+
+  it('only allows Sweetistics fallback in auto mode', () => {
+    expect(shouldAllowSweetisticsFallback('auto', true)).toBe(true);
+    expect(shouldAllowSweetisticsFallback('auto', false)).toBe(false);
+    expect(shouldAllowSweetisticsFallback('graphql', true)).toBe(false);
+    expect(shouldAllowSweetisticsFallback('sweetistics', true)).toBe(false);
+  });
 });