How the `doctor` Command in Agent Reach Checks Channel Availability and Detects Active Backends

The doctor command iterates through all registered channels in agent_reach/doctor.py, invokes each channel's check() method to probe availability, and reads the active_backend attribute to identify which backend tool is currently serving the channel.

The doctor command in the Agent Reach repository provides a comprehensive health check system that verifies which platforms are ready for use and identifies the specific backend tools powering each channel. This diagnostic tool orchestrates availability checks across all registered channels by leveraging the extensible channel architecture defined in the codebase.

Core Health Check Implementation in doctor.py

The check_all Entry Point

The check_all function in agent_reach/doctor.py serves as the central orchestrator for the health check process. It retrieves all registered channels via agent_reach.channels.get_all_channels() and iterates over each channel to collect status information.

Channel Availability Verification

For every channel, the code invokes the channel's check(config) method, which returns a tuple of (status, message). This method performs the actual health probe, whether it's checking for a CLI tool's presence or verifying API connectivity.

The core iteration logic captures the returned status and active backend:

for ch in get_all_channels():
    try:
        status, message = ch.check(config)          # ← channel‑specific health probe

        active = getattr(ch, "active_backend", None) # ← backend actually serving the channel

    except Exception as e:
        status, message, active = "error", f"体检异常：{e}", None
    results[ch.name] = {
        "status": status,
        "name": ch.description,
        "message": message,
        "tier": ch.tier,
        "backends": ch.backends,
        "active_backend": active,
    }

Backend Detection and Active Backend Resolution

The Base Channel Implementation

In agent_reach/channels/base.py, the abstract Channel class defines the default check method. This implementation automatically marks the first declared backend as active:

def check(self, config=None) -> Tuple[str, str]:
    """Check if this channel's upstream tool is available."""
    self.active_backend = self.backends[0] if self.backends else "内置"
    return "ok", f"{'、'.join(self.backends) if self.backends else '内置'}"

Platform-Specific Backend Probing

Concrete channel subclasses override this method to perform real verification. These implementations typically:

• Use ordered_backends(config) to respect user-provided backend overrides
• Execute lightweight commands via agent_reach.probe.probe_command to verify binary functionality
• Set self.active_backend to the successfully verified backend, or None if no backends are usable

Report Generation and CLI Output

Data Aggregation

The check_all function captures results in a dictionary containing status, message, tier, backends, and the critical active_backend field for each channel.

Human-Readable Formatting

The format_report function in agent_reach/doctor.py transforms the raw data into a Rich-styled report for terminal display, showing availability status and active backends for each channel.

Practical Usage Examples

Running the Doctor Command

Execute the health check from your terminal:

python -m agent_reach.cli doctor

The above command prints a report such as:

Agent Reach 状态
========================================
图例：✅ 可用  [! ] 已装但需配置/登录  [X] 未安装

✅ 装好即用：
  ✅ GitHub — 已安装
  ✅ YouTube — 已安装（当前后端：yt-dlp）
...
状态：[green]7/9[/green] 个渠道可用

Programmatic Access

Access diagnostic data programmatically:

from agent_reach.doctor import check_all
from agent_reach.config import Config

cfg = Config()
status = check_all(cfg)
print(status["youtube"]["active_backend"])   # e.g. "yt-dlp"

Summary

• The doctor command is implemented in agent_reach/doctor.py with the check_all function orchestrating health checks
• Channel availability is determined by calling check(config) on each registered channel from agent_reach.channels.get_all_channels()
• Active backend detection relies on the active_backend attribute set during the check process
• The base implementation in agent_reach/channels/base.py defaults to the first backend, while concrete subclasses perform real tool verification
• Results are formatted via format_report for CLI display or accessible programmatically as dictionaries

Frequently Asked Questions

How does the doctor command handle channels with multiple backend options?

The check method in concrete channel implementations uses ordered_backends(config) to iterate through available backends in priority order. It probes each backend using agent_reach.probe.probe_command and sets active_backend to the first working backend, or leaves it as None if none respond successfully.

What happens if a channel check throws an exception?

In agent_reach/doctor.py, the check_all function wraps each channel check in a try-except block. If an exception occurs, it captures the error, sets the status to "error", and continues processing remaining channels rather than failing the entire diagnostic run.

Can I customize which backends the doctor command checks?

Yes, the check methods accept a config parameter that allows user overrides via ordered_backends(config). You can specify preferred backends in your Agent Reach configuration, and the health check will prioritize those backends when determining availability.

Where does the doctor command get the list of channels to check?

The command retrieves all registered channels from agent_reach.channels.get_all_channels(), which is defined in agent_reach/channels/__init__.py. This function returns all channel classes registered in the system, ensuring the doctor command checks every available platform.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}