feat: add --headed flag for debugging

.changeset/feat-headed-option.md

@@ -0,0 +1,5 @@
+---
+'heroshot': minor
+---
+
+Add `--headed` flag to run browser in visible mode for debugging slow captures or timeout issues

docs/docs/cli.md

@@ -177,6 +177,7 @@ heroshot --workers 4        # Capture with 4 parallel workers
 | ------------------- | --------------------------------------------------------------------- |
 | `--clean`           | Delete stale files from output directory (only works without pattern) |
 | `--workers <count>` | Number of parallel capture workers (default: 1)                       |
+| `--headed`          | Show browser window (for debugging slow captures or timeouts)         |
 
 The pattern matches against:
 
@@ -344,4 +345,8 @@ heroshot list --json
 # Verbose output (works with any command)
 heroshot -v
 heroshot config -v
+
+# Debug slow captures with visible browser window
+heroshot --headed
+heroshot dashboard --headed
 ```

eslint.config.js

@@ -89,6 +89,12 @@ export default tseslint.config(
             'ArrowFunctionExpression[params.length=1][params.0.type=Identifier][body.type=MemberExpression][body.computed=false]',
           message: 'Use destructuring in callback: prefer ({ prop }) => prop over f => f.prop',
         },
+        {
+          // bans `!!x` - prefer `Boolean(x)` for clarity
+          selector:
+            "UnaryExpression[operator='!'][argument.type='UnaryExpression'][argument.operator='!']",
+          message: 'Use Boolean(x) instead of !!x for explicit type coercion.',
+        },
       ],
 
       // Let TypeScript infer return types

src/cli/cli.ts

@@ -70,6 +70,7 @@ program
   .option('--save', 'Save screenshot definition to config')
   .option('--clean', 'Delete stale files in output directory')
   .option('--workers <count>', 'Number of parallel capture workers', Number.parseInt)
+  .option('--headed', 'Run browser in headed mode (visible window) for debugging')
   .action(async (url?: string, options?: ShotCommandOptions) => {
     const globalOptions = program.opts<GlobalOptions>();
     const success = await shotAction(url, options, globalOptions);

src/cli/handlers.ts

@@ -62,6 +62,7 @@ export async function handleUrlCapture(
     sessionKey,
     skipStaleCheck: true, // Don't check for stale files in oneshot mode
     viewportOnly: options?.viewportOnly,
+    headed: options?.headed,
   });
 
   if (options?.save && result.failed === 0) {
@@ -75,18 +76,23 @@ export async function handleUrlCapture(
   return result.failed === 0;
 }
 
+type DefaultCommandOptions = {
+  configPath: string;
+  sessionKey: string | undefined;
+  hasExplicitConfig: boolean;
+  clean?: boolean;
+  workers?: number;
+  headed?: boolean;
+};
+
 /**
  * Handle default command (setup or sync).
  */
-export async function handleDefaultCommand(
-  configPath: string,
-  sessionKey: string | undefined,
-  hasExplicitConfig: boolean,
-  clean?: boolean,
-  workers?: number
-): Promise<boolean> {
+export async function handleDefaultCommand(options: DefaultCommandOptions): Promise<boolean> {
+  const { configPath, sessionKey, hasExplicitConfig, clean, workers, headed } = options;
+
   if (existsSync(configPath)) {
-    const result = await sync({ configPath, sessionKey, clean, workers });
+    const result = await sync({ configPath, sessionKey, clean, workers, headed });
     return result.failed === 0;
   }
 
@@ -97,7 +103,7 @@ export async function handleDefaultCommand(
 
   const { hasScreenshots } = await setup();
   if (hasScreenshots) {
-    const result = await sync({ clean, workers });
+    const result = await sync({ clean, workers, headed });
     return result.failed === 0;
   }
   return true;
@@ -126,17 +132,19 @@ export async function shotAction(
       filter: url,
       clean: options?.clean,
       workers: options?.workers,
+      headed: options?.headed,
     });
     return result.failed === 0;
   }
 
-  return handleDefaultCommand(
+  return handleDefaultCommand({
     configPath,
-    globalOptions.sessionKey,
-    !!globalOptions.config,
-    options?.clean,
-    options?.workers
-  );
+    sessionKey: globalOptions.sessionKey,
+    hasExplicitConfig: Boolean(globalOptions.config),
+    clean: options?.clean,
+    workers: options?.workers,
+    headed: options?.headed,
+  });
 }
 
 /**

src/schema.ts

@@ -178,6 +178,8 @@ export const shotCommandOptionsSchema = shotCliOptionsSchema.extend({
   clean: z.boolean().optional(),
   /** Number of parallel capture workers */
   workers: z.number().int().min(1).optional(),
+  /** Run browser in headed mode (visible window) for debugging */
+  headed: z.boolean().optional(),
 });
 
 /** Global config */

src/sync/parallelCapture.ts

@@ -32,6 +32,7 @@ export type ParallelCaptureOptions = {
     bypassCSP?: boolean;
     reducedMotion?: 'reduce' | 'no-preference';
     userAgent?: string;
+    headed?: boolean;
   };
   workers: number;
   captureSpinner: ReturnType<typeof spinner>;
@@ -96,7 +97,7 @@ async function executeBatch(
 
   // Launch browser for this batch
   const { browser, context } = await launchBrowser({
-    headless: true,
+    headless: !browserOptions.headed,
     viewport: browserOptions.viewport,
     deviceScaleFactor: browserOptions.deviceScaleFactor,
     storageState: browserOptions.storageState,

src/sync/schemeCapture.ts

@@ -22,6 +22,7 @@ export type CaptureSchemeOptions = {
     bypassCSP?: boolean;
     reducedMotion?: 'reduce' | 'no-preference';
     userAgent?: string;
+    headed?: boolean;
   };
   colorScheme: 'light' | 'dark' | undefined;
   schemes: ('light' | 'dark')[];
@@ -49,7 +50,7 @@ export async function captureWithScheme(
   const results: ScreenshotResult[] = [];
 
   const { browser, context } = await launchBrowser({
-    headless: true,
+    headless: !browserOptions.headed,
     viewport: browserOptions.viewport,
     deviceScaleFactor: browserOptions.deviceScaleFactor,
     storageState: browserOptions.storageState,

src/sync/sync.ts

@@ -32,6 +32,7 @@ type CaptureContext = {
     bypassCSP?: boolean;
     reducedMotion?: 'reduce' | 'no-preference';
     userAgent?: string;
+    headed?: boolean;
   };
   schemes: ('light' | 'dark')[];
   workers: number;
@@ -130,6 +131,7 @@ export async function sync(options: SyncOptions = {}): Promise<SyncResult> {
   const browserOptions = {
     ...buildBrowserOptions(config),
     storageState,
+    headed: options.headed,
   };
 
   // Start capture

src/sync/types.ts

@@ -84,6 +84,8 @@ export type SyncOptions = {
   viewportOnly?: boolean;
   /** Number of parallel capture workers (default: 1) */
   workers?: number;
+  /** Run browser in headed mode (visible window) for debugging */
+  headed?: boolean;
 };
 
 /** Padding dimensions */