prepare v0.21 (#886)

skills/agent-browser/SKILL.md

@@ -181,6 +181,24 @@ agent-browser diff url <url1> <url2> --wait-until networkidle  # Custom wait str
 agent-browser diff url <url1> <url2> --selector "#main"  # Scope to element
 ```
 
+## Batch Execution
+
+Execute multiple commands in a single invocation by piping a JSON array of string arrays to `batch`. This avoids per-command process startup overhead when running multi-step workflows.
+
+```bash
+echo '[
+  ["open", "https://example.com"],
+  ["snapshot", "-i"],
+  ["click", "@e1"],
+  ["screenshot", "result.png"]
+]' | agent-browser batch --json
+
+# Stop on first error
+agent-browser batch --bail < commands.json
+```
+
+Use `batch` when you have a known sequence of commands that don't depend on intermediate output. Use separate commands or `&&` chaining when you need to parse output between steps (e.g., snapshot to discover refs, then interact).
+
 ## Common Patterns
 
 ### Form Submission
@@ -311,6 +329,8 @@ agent-browser --auto-connect snapshot
 agent-browser --cdp 9222 snapshot
 ```
 
+Auto-connect discovers Chrome via `DevToolsActivePort`, common debugging ports (9222, 9229), and falls back to a direct WebSocket connection if HTTP-based CDP discovery fails.
+
 ### Color Scheme (Dark Mode)
 
 ```bash