diff --git a/packages/cli/src/browser/manager.ts b/packages/cli/src/browser/manager.ts
index 4ca5a4ab..eccbf162 100644
--- a/packages/cli/src/browser/manager.ts
+++ b/packages/cli/src/browser/manager.ts
@@ -107,12 +107,23 @@ export async function findBrowser(): Promise<BrowserResult | undefined> {
 }
 
 /**
- * Find or download a browser.
- * Resolution: env var -> cached download -> system Chrome -> auto-download.
+ * Find or download a browser suitable for rendering.
+ * Resolution: env var -> cached headless-shell -> auto-download.
+ *
+ * System Chrome is NOT used for rendering because it does not support
+ * the HeadlessExperimental.beginFrame CDP command required for
+ * deterministic frame capture, and older system Chrome versions are
+ * often incompatible with the version of puppeteer-core bundled in
+ * the engine (protocol mismatch → silent 120s timeout).
  */
 export async function ensureBrowser(options?: EnsureBrowserOptions): Promise<BrowserResult> {
-  const existing = await findBrowser();
-  if (existing) return existing;
+  // Env override and cached headless-shell are trusted.
+  // System Chrome is skipped — it causes silent render timeouts.
+  const fromEnv = findFromEnv();
+  if (fromEnv) return fromEnv;
+
+  const fromCache = await findFromCache();
+  if (fromCache) return fromCache;
 
   const platform = detectBrowserPlatform();
   if (!platform) {
diff --git a/packages/cli/src/commands/render.ts b/packages/cli/src/commands/render.ts
index 4f1ff681..c1587564 100644
--- a/packages/cli/src/commands/render.ts
+++ b/packages/cli/src/commands/render.ts
@@ -126,7 +126,17 @@ Examples:
       : join(rendersDir, `${project.name}_${datePart}_${timePart}${ext}`);
 
     // Ensure output directory exists
-    mkdirSync(dirname(outputPath), { recursive: true });
+    try {
+      mkdirSync(dirname(outputPath), { recursive: true });
+    } catch (err: unknown) {
+      const message = err instanceof Error ? err.message : String(err);
+      errorBox(
+        "Cannot create output directory",
+        `${dirname(outputPath)}: ${message}`,
+        "Check that you have write permission or specify a different path with --output.",
+      );
+      process.exit(1);
+    }
 
     const useDocker = args.docker ?? false;
     const useGpu = args.gpu ?? false;
@@ -246,7 +256,13 @@ async function renderDocker(
     });
     await producer.executeRenderJob(job, projectDir, outputPath);
   } catch (error: unknown) {
-    handleRenderError(error, options, startTime, true, "Check Docker is running: docker info");
+    handleRenderError(
+      error,
+      options,
+      startTime,
+      true,
+      renderHintForError(error, "Check Docker is running: docker info"),
+    );
   }
 
   const elapsed = Date.now() - startTime;
@@ -287,7 +303,13 @@ async function renderLocal(
   try {
     await producer.executeRenderJob(job, projectDir, outputPath, onProgress);
   } catch (error: unknown) {
-    handleRenderError(error, options, startTime, false, "Try --docker for containerized rendering");
+    handleRenderError(
+      error,
+      options,
+      startTime,
+      false,
+      renderHintForError(error, "Try --docker for containerized rendering"),
+    );
   }
 
   const elapsed = Date.now() - startTime;
@@ -302,6 +324,14 @@ function getMemorySnapshot() {
   };
 }
 
+function renderHintForError(error: unknown, fallback: string): string {
+  const message = error instanceof Error ? error.message : String(error);
+  if (message.includes("__hf not ready")) {
+    return "Composition may have zero duration. Add data-duration to the root element or ensure the GSAP timeline has tweens.";
+  }
+  return fallback;
+}
+
 function handleRenderError(
   error: unknown,
   options: RenderOptions,
diff --git a/packages/engine/src/services/browserManager.ts b/packages/engine/src/services/browserManager.ts
index 1262f1c7..03fd1bae 100644
--- a/packages/engine/src/services/browserManager.ts
+++ b/packages/engine/src/services/browserManager.ts
@@ -97,16 +97,22 @@ export async function acquireBrowser(
   const headlessShell = resolveHeadlessShellPath(config);
 
   // BeginFrame requires chrome-headless-shell AND Linux (crashes on macOS/Windows).
+  // System Chrome (google-chrome, chromium) does NOT support the
+  // HeadlessExperimental.beginFrame CDP command — only the dedicated
+  // chrome-headless-shell binary does.  Passing system Chrome as the
+  // executable causes a 120-second silent hang followed by a timeout.
   const isLinux = process.platform === "linux";
   const forceScreenshot = config?.forceScreenshot ?? DEFAULT_CONFIG.forceScreenshot;
+  const isHeadlessShellBinary = headlessShell ? /chrome-headless-shell/.test(headlessShell) : false;
   let captureMode: CaptureMode;
   let executablePath: string | undefined;
 
-  if (headlessShell && isLinux && !forceScreenshot) {
+  if (headlessShell && isLinux && isHeadlessShellBinary && !forceScreenshot) {
     captureMode = "beginframe";
     executablePath = headlessShell;
   } else {
-    // Screenshot mode with renderSeek: works on all platforms.
+    // Screenshot mode with renderSeek: works on all platforms, and
+    // as a fallback when system Chrome is the only available binary.
     captureMode = "screenshot";
     executablePath = headlessShell ?? undefined;
   }