cmdorc 0.2.0

Async-first, trigger-driven shell command orchestrator for TUIs and agents

cmdorc: Command Orchestrator - Async, Trigger-Driven Shell Command Runner

cmdorc is a lightweight, async-first Python library for running shell commands in response to string-based triggers. Built for developer tools, TUIs (like VibeDir), CI automation, or any app needing event-driven command orchestration.

Zero external dependencies (pure stdlib + tomli for Python <3.11). Predictable. Extensible. No magic.

Inspired by Make/npm scripts - but instead of file changes, you trigger workflows with events like "lint", "tests_passed", or "deploy_ready".

Features

• Trigger-Based Execution - Fire any string event → run configured commands
• Auto-Events - command_started:Lint, command_success:Lint, command_failed:Tests, etc.
• Full Async + Concurrency Control - Non-blocking, cancellable, timeout-aware, with debounce
• Smart Retrigger Policies - cancel_and_restart or ignore
• Cancellation Triggers - Auto-cancel commands on certain events
• Rich State Tracking - Live runs, history, durations, output capture
• Template Variables - {{ base_directory }}, nested resolution, runtime overrides
• TOML Config + Validation - Clear, declarative setup with validation
• Cycle Detection - Prevents infinite trigger loops with clear warnings
• Frontend-Friendly - Perfect for TUIs (Textual, Bubble Tea), status icons (Pending/Running/Success/Failure/Cancelled), logs
• Minimal dependencies: Only tomli for Python <3.11 (stdlib tomllib for 3.11+)
• Deterministic, Safe Template Resolution with nested {{var}} support and cycle protection

See architecture.md for detailed design and component responsibilities.

Installation

pip install cmdorc

Requires Python 3.10+

Want to learn by example? Check out the examples/ directory for runnable demonstrations of all features - from basic usage to advanced patterns.

Quick Start

1. Create cmdorc.toml

[variables]
base_directory = "."
tests_directory = "{{ base_directory }}/tests"

[[command]]
name = "Lint"
triggers = ["changes_applied"]
command = "ruff check {{ base_directory }}"
cancel_on_triggers = ["prompt_send", "exit"]
max_concurrent = 1
on_retrigger = "cancel_and_restart"
debounce_in_ms = 500  # Wait 500ms after last trigger before running
timeout_secs = 300
keep_history = 3
loop_detection = true

[[command]]
name = "Tests"
triggers = ["command_success:Lint", "Tests"]
command = "pytest {{ tests_directory }} -q"
timeout_secs = 180
keep_history = 5
loop_detection = true

2. Run in Python

import asyncio
from cmdorc import CommandOrchestrator, load_config

async def main():
    config = load_config("cmdorc.toml")
    orchestrator = CommandOrchestrator(config)

    # Trigger a workflow
    await orchestrator.trigger("changes_applied")  # → Lint → (if success) Tests

    # Run a command and get handle for waiting
    handle = await orchestrator.run_command("Tests")
    result = await handle.wait()  # Blocks until complete (with optional timeout)
    print(f"Tests: {result.state.value} ({result.duration_str})")

    # Fire-and-forget (no await on handle.wait())
    handle = await orchestrator.run_command("Lint")  # Starts async
    # ... do other work ...
    await handle.wait()  # Wait later if needed

    # Pass runtime variables for this run only
    await orchestrator.run_command("Deploy", vars={"env": "production", "region": "us-east-1"})

    # Get status and history
    status = orchestrator.get_status("Tests")  # CommandStatus with active runs, etc.
    history = orchestrator.get_history("Tests", limit=5)  # List[RunResult]

    # Cancel running command
    await orchestrator.cancel_command("Lint", comment="User cancelled")

    # Or cancel everything
    await orchestrator.cancel_all()

    # Graceful shutdown
    await orchestrator.shutdown(timeout=30.0, cancel_running=True)

asyncio.run(main())

See it in action: Run examples/basic/01_hello_world.py or examples/basic/02_simple_workflow.py to see a working example immediately.

Core Concepts

Triggers & Auto-Events

• Any string can be a trigger: "build", "deploy", "hotkey:f5"
• Special auto-triggers (emitted automatically):
  • command_started:MyCommand - Command begins execution
  • command_success:MyCommand - Command exits with code 0
  • command_failed:MyCommand - Command exits non-zero
  • command_cancelled:MyCommand - Command was cancelled

Lifecycle Example

await orchestrator.trigger("build")

# If "build" triggers a command named "Compile":
# 1. command_started:Compile    ← can trigger other commands
# 2. ... subprocess runs ...
# 3. command_success:Compile    ← triggers on success

Example: See examples/basic/02_simple_workflow.py for a working workflow that chains Lint → Test using lifecycle triggers.

Cancellation

Use cancel_on_triggers to auto-cancel long-running tasks:

cancel_on_triggers = ["user_escape", "window_close"]

Concurrency & Retrigger Policy

max_concurrent = 1
on_retrigger = "cancel_and_restart"  # default
# or "ignore" to skip if already running
debounce_in_ms = 500  # Throttle rapid triggers

Trigger Chains (Breadcrumbs)

Every run tracks the sequence of triggers that led to its execution:

# Manual run
handle = await orchestrator.run_command("Tests")
print(handle.trigger_chain)  # []

# Triggered run
await orchestrator.trigger("user_saves")  # → Lint → Tests
handle = orchestrator.get_active_handles("Tests")[0]
print(handle.trigger_chain)
# ["user_saves", "command_started:Lint", "command_success:Lint"]

Use cases:

• Debugging: "Why did this command run?"
• UI Display: Show breadcrumb trail in status bar or logs
• Cycle Errors: See the full path that caused a cycle

Access via:

• RunHandle.trigger_chain - Live runs
• RunResult.trigger_chain - Historical runs (via get_history())

See examples/advanced/04_trigger_chains.py for a complete example.

API Highlights

await orchestrator.trigger("build")                    # Fire event
await orchestrator.cancel_command("Tests")             # Cancel specific
orchestrator.get_status("Lint")                        # → CommandStatus (IDLE, RUNNING, etc.)
orchestrator.get_history("Lint", limit=10)             # → List[RunResult]
orchestrator.list_commands()                           # → List[str] of command names

RunHandle (Returned from run_command)

handle = await orchestrator.run_command("Tests")
result = await handle.wait(timeout=30)  # Await completion (event-driven, no polling)

# Properties (read-only)
handle.state          # RunState: PENDING, RUNNING, SUCCESS, FAILED, CANCELLED
handle.success        # bool or None
handle.output         # str (stdout + stderr)
handle.duration_str   # "1m 23s", "452ms", "1h 5m", "1d 3h"
handle.is_finalized   # bool: True if completed
handle.start_time     # datetime.datetime or None
handle.end_time       # datetime.datetime or None
handle.comment        # str: Cancellation reason or note

RunResult (Accessed via RunHandle._result or history)

Internal data container; use RunHandle for public interaction.

Configuration

Load from TOML

orchestrator = CommandOrchestrator(load_config("cmdorc.toml"))

Example: See examples/basic/03_toml_config/ for a complete TOML-based workflow setup.

Or Pass Programmatically

from cmdorc import CommandConfig, CommandOrchestrator

commands = [
    CommandConfig(
        name="Format",
        command="black .",
        triggers=["Format", "changes_applied"]
    )
]

orchestrator = CommandOrchestrator(commands)

Example: See examples/basic/01_hello_world.py or examples/basic/02_simple_workflow.py for programmatic configuration patterns.

Introspection (Great for UIs)

orchestrator.get_active_handles("Tests")  # → List[RunHandle]
orchestrator.get_handle_by_run_id("run-uuid")  # → RunHandle or None
orchestrator.get_trigger_graph()  # → dict[str, list[str]] (triggers → commands)

Why cmdorc?

You're building a TUI, VSCode extension, or LLM agent that says:

"When the user saves → run formatter → then tests → show results live"

cmdorc is the battle-tested backend that handles:

• Async execution
• Cancellation on navigation
• State for your UI
• Safety (no cycles, no deadlocks)

Separate concerns: Let your UI be beautiful. Let cmdorc handle the boring parts: async, cancellation, state, safety.

See architecture.md for detailed component design.

Advanced Features

Lifecycle Hooks with Callbacks

orchestrator.on_event("command_started:Tests", lambda handle, context: ui.show_spinner())
orchestrator.on_event("command_success:Tests", lambda handle, context: ui.hide_spinner())

Example: See examples/advanced/01_callbacks_and_hooks.py for patterns including exact event matching, wildcard patterns, and lifecycle callbacks.

Template Variables

orchestrator = CommandOrchestrator(config, vars={"env": "production", "region": "us-west-2"})
# Now commands can use {{ env }} and {{ region }}

Example: See examples/basic/04_runtime_variables.py for variable resolution and templating patterns.

Concurrency & Retrigger Policies

Control how commands behave when triggered multiple times:

• max_concurrent - Limit parallel executions (0 = unlimited)
• on_retrigger - cancel_and_restart or ignore
• debounce_in_ms - Delay re-runs by milliseconds

Example: See examples/advanced/03_concurrency_policies.py for demonstrations of all concurrency control patterns.

Error Handling & Exceptions

Handle failures gracefully with cmdorc-specific exceptions:

• CommandNotFoundError - Command not in registry
• ConcurrencyLimitError - Too many concurrent runs
• DebounceError - Triggered too soon after last run

Example: See examples/advanced/02_error_handling.py for comprehensive error handling patterns and recovery strategies.

History Retention

keep_history = 10  # Keep last 10 runs for debugging

history = orchestrator.get_history("Tests")
for result in history:
    print(f"{result.run_id}: {result.state.value} in {result.duration_str}")

Example: See examples/basic/05_status_and_history.py for status tracking and history introspection patterns.

Testing & Quality

cmdorc maintains high quality standards:

• 343 tests with 94% code coverage
• Full async/await testing with pytest-asyncio
• Type hints throughout with PEP 561 compliance
• Linted with ruff for consistent style

Run tests locally:

pdm run pytest                          # Run all tests
pdm run pytest --cov=cmdorc            # With coverage
ruff check . && ruff format .           # Lint and format

Contributing

Contributions welcome! See CONTRIBUTING.md for:

• Development setup
• Running tests locally
• Code style guidelines
• Pull request process

License

MIT License - See LICENSE for details

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Made with ❤️ for async Python developers