feat: add interactive demo scripts for SubprocessExecutor (CLI-9)

- Created comprehensive interactive demo showing all SubprocessExecutor features
- Added explanations before each command execution
- Implemented user command mode with customizable timeout and environment
- Demonstrated concurrent execution, error handling, and output streaming
- Added non-interactive test script for quick validation

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: dugshub

examples/subprocess_demo.py

@@ -0,0 +1,205 @@
+#!/usr/bin/env python3
+"""Interactive demo script showing SubprocessExecutor functionality."""
+
+import asyncio
+import sys
+from rich.console import Console
+from rich.prompt import Prompt, Confirm
+from rich.panel import Panel
+from rich.text import Text
+from cli_patterns.execution.subprocess_executor import SubprocessExecutor
+
+
+def wait_for_enter(message="Press Enter to continue..."):
+    """Wait for user to press enter."""
+    input(f"\n{message}")
+
+
+async def run_example(executor, title, explanation, command, **kwargs):
+    """Run an example command with title and wait for user."""
+    print(f"\n{title}")
+    print(f"What this will do: {explanation}")
+    print(f"Command: {command}")
+    print("-" * 50)
+
+    result = await executor.run(command, **kwargs)
+
+    print("\nResult Summary:")
+    print(f"  Exit code: {result.exit_code}")
+    print(f"  Success: {result.success}")
+    if result.timed_out:
+        print(f"  Timed out: True")
+    if result.interrupted:
+        print(f"  Interrupted: True")
+    if result.stderr and not result.success:
+        print(f"  Error: {result.stderr[:100]}...")
+
+    wait_for_enter()
+    return result
+
+
+async def user_command_loop(executor, console):
+    """Allow user to run custom commands."""
+    console.print(Panel.fit(
+        "[bold cyan]Interactive Command Mode[/bold cyan]\n"
+        "Enter commands to run them with the SubprocessExecutor.\n"
+        "Type 'exit' or 'quit' to leave.",
+        border_style="cyan"
+    ))
+
+    while True:
+        print()
+        command = Prompt.ask("[bold green]Enter command[/bold green]", default="exit")
+
+        if command.lower() in ['exit', 'quit']:
+            break
+
+        # Ask for optional parameters
+        use_timeout = Confirm.ask("Set a custom timeout?", default=False)
+        timeout = None
+        if use_timeout:
+            timeout = float(Prompt.ask("Timeout (seconds)", default="30"))
+
+        use_env = Confirm.ask("Add environment variables?", default=False)
+        env = None
+        if use_env:
+            env_vars = {}
+            console.print("[dim]Enter variables as KEY=VALUE, empty to finish[/dim]")
+            while True:
+                var = Prompt.ask("Environment variable", default="")
+                if not var:
+                    break
+                if '=' in var:
+                    key, value = var.split('=', 1)
+                    env_vars[key] = value
+            if env_vars:
+                env = env_vars
+
+        print("\n" + "=" * 50)
+        print(f"What this will do: Execute '{command}'")
+        if timeout:
+            print(f"  with timeout of {timeout} seconds")
+        if env:
+            print(f"  with environment variables: {env}")
+        print("Executing now...")
+        print("=" * 50)
+        result = await executor.run(command, timeout=timeout, env=env)
+        print("=" * 50)
+
+        print(f"\nExit code: {result.exit_code}")
+        print(f"Success: {result.success}")
+
+        if result.stdout:
+            show_output = Confirm.ask("Show full stdout?", default=True)
+            if show_output:
+                console.print(Panel(result.stdout, title="stdout", border_style="green"))
+
+        if result.stderr:
+            console.print(Panel(result.stderr, title="stderr", border_style="red"))
+
+
+async def main():
+    """Run subprocess executor demonstrations."""
+    console = Console()
+    executor = SubprocessExecutor(console=console)
+
+    console.print(Panel.fit(
+        Text("SubprocessExecutor Interactive Demo", justify="center", style="bold magenta"),
+        subtitle="Learn how CLI-9 works",
+        border_style="magenta"
+    ))
+
+    console.print("\n[bold]This demo will show you:[/bold]")
+    console.print("• Running successful commands")
+    console.print("• Handling command failures")
+    console.print("• Timeout management")
+    console.print("• Output capture")
+    console.print("• Custom environments")
+    console.print("• Concurrent execution")
+    console.print("• Interactive command mode\n")
+
+    wait_for_enter("Press Enter to start the demo...")
+
+    # Example 1: Simple successful command
+    await run_example(
+        executor,
+        "Example 1: Running a successful command",
+        "List the first 5 files in the current directory with details",
+        "ls -la | head -5"
+    )
+
+    # Example 2: Command that fails
+    await run_example(
+        executor,
+        "Example 2: Running a command that fails",
+        "Attempt to list a directory that doesn't exist to see error handling",
+        "ls /nonexistent/directory"
+    )
+
+    # Example 3: Command with timeout
+    await run_example(
+        executor,
+        "Example 3: Running a command with timeout (1 second)",
+        "Run a 5-second sleep command but timeout after 1 second",
+        "sleep 5",
+        timeout=1.0
+    )
+
+    # Example 4: Capturing output
+    await run_example(
+        executor,
+        "Example 4: Capturing command output",
+        "Echo a message and capture its output for programmatic use",
+        "echo 'Hello from subprocess!'"
+    )
+
+    # Example 5: Running with custom environment
+    await run_example(
+        executor,
+        "Example 5: Running with custom environment variable",
+        "Set a custom environment variable and echo its value",
+        "echo 'MY_CUSTOM_VAR=$MY_CUSTOM_VAR'",
+        env={"MY_CUSTOM_VAR": "Custom Value!"}
+    )
+
+    # Example 6: Running multiple commands concurrently
+    print("\nExample 6: Running multiple commands concurrently")
+    print("What this will do: Execute 3 commands in parallel with different sleep times")
+    print("Expected behavior: All tasks start together, finish at different times")
+    print("Commands: Three echo commands with different delays")
+    print("-" * 50)
+
+    tasks = [
+        executor.run("echo 'Task 1 running' && sleep 0.5 && echo 'Task 1 done'"),
+        executor.run("echo 'Task 2 running' && sleep 0.3 && echo 'Task 2 done'"),
+        executor.run("echo 'Task 3 running' && sleep 0.1 && echo 'Task 3 done'"),
+    ]
+
+    console.print("[yellow]Starting 3 parallel tasks...[/yellow]")
+    results = await asyncio.gather(*tasks)
+
+    print("\nAll tasks completed!")
+    for i, result in enumerate(results, 1):
+        lines = result.stdout.strip().split('\n')
+        print(f"  Task {i}: {lines[-1] if lines else 'No output'}")
+
+    wait_for_enter()
+
+    # Interactive mode
+    console.print("\n[bold yellow]Ready to try your own commands?[/bold yellow]")
+    if Confirm.ask("Enter interactive mode?", default=True):
+        await user_command_loop(executor, console)
+
+    console.print(Panel.fit(
+        "[bold green]Demo Complete![/bold green]\n"
+        "You've learned how the SubprocessExecutor works.\n"
+        "Use it in your CLI patterns for async command execution.",
+        border_style="green"
+    ))
+
+
+if __name__ == "__main__":
+    try:
+        asyncio.run(main())
+    except KeyboardInterrupt:
+        print("\n\nDemo interrupted by user. Goodbye!")

examples/subprocess_test.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+"""Quick test of SubprocessExecutor's interactive features."""
+
+import asyncio
+from rich.console import Console
+from cli_patterns.execution.subprocess_executor import SubprocessExecutor
+
+
+async def main():
+    """Test custom commands with SubprocessExecutor."""
+    console = Console()
+    executor = SubprocessExecutor(console=console)
+
+    # Test a few custom commands
+    commands = [
+        ("pwd", None, None),
+        ("echo 'Testing custom command'", None, None),
+        ("ls -la | grep examples", None, None),
+        ("date", None, None),
+        ("echo 'VAR is: $TEST_VAR'", None, {"TEST_VAR": "Hello World!"}),
+        ("python3 -c 'print(\"Python says hello!\")'", None, None),
+    ]
+
+    for cmd, timeout, env in commands:
+        print(f"\n{'='*60}")
+        print(f"Running: {cmd}")
+        if env:
+            print(f"With env: {env}")
+        print('='*60)
+
+        result = await executor.run(cmd, timeout=timeout, env=env)
+
+        print(f"\nResult:")
+        print(f"  Exit code: {result.exit_code}")
+        print(f"  Success: {result.success}")
+        if result.stdout:
+            print(f"  Output: {result.stdout.strip()}")
+        if result.stderr:
+            print(f"  Error: {result.stderr.strip()}")
+
+
+if __name__ == "__main__":
+    asyncio.run(main())