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Automation Bridge and MCP

Status

Status: Off by default · Applies to: All radios

The automation bridge is an opt-in, local command channel into a running AetherSDR. A program on the same computer can read the app's state (radio, slices, panadapters, the widget tree), capture any window or the panadapter as a PNG, and, if you allow it, operate controls. The AetherSDR source tree also includes an MCP server that exposes the bridge to AI assistants such as Claude Code, Cursor, Copilot, Codex CLI and Gemini CLI.

It is mainly a developer and testing tool, but it is also a supported way for your own control-surface or automation software to drive AetherSDR. The full reference, including every verb, is docs/automation-bridge.md.

Requirements​

  • A client on the same computer. The bridge listens on a local socket (a Unix domain socket on macOS and Linux, a named pipe on Windows). There is no TCP port and no network exposure.
  • For the MCP server: Python 3 (no other dependencies).

Each request is one line (a bare command or a JSON object) and each reply is one line of JSON. On startup the app writes the socket path to aethersdr-automation.json in the system temp folder so clients can find it.

Setup​

Open Settings → Radio Setup... → Network and find the Advanced group:

ControlWhat it does
Agent Automation (MCP): Enabled / DisabledStarts or stops the bridge. Off by default. Enabling it with no token creates one. The setting is saved, so the bridge comes back at the next launch.
Access Token: with Copy and RotateThe shared secret clients must present. Rotate creates a new token and applies it immediately, locking out any client still using the old one.
Allow TX via MCP: "Enable transmit control"Lets bridge clients key the transmitter. Off by default; turning it on asks for a one-time confirmation.
Observe only: "Read-only (block all driving)"Blocks every action that changes anything; reads still work.

You can also start the bridge for a single run by launching with AETHER_AUTOMATION=1. In that case the Enabled/Disabled button is greyed out, because the environment variable wins.

Access token​

Every verb except ping is refused without the matching token. The token is kept in your operating system's secret store (macOS Keychain, Windows Credential Manager, or libsecret/KWallet on Linux), never in the settings database.

To give it to an MCP client, set AETHER_MCP_TOKEN only in the environment of the shell that launches your assistant, using a method that does not record it in shell history. The MCP server inherits it from there.

Keep the token out of shared configs. Do not put the literal token in a shell profile, in .mcp.json, or in any other MCP config file: that puts a live credential on disk and risks it landing in a commit or a backup. The token field's tooltip in Radio Setup suggests pasting it into the MCP config; follow this page and the docs instead.

Headless or CI runs can pass AETHER_MCP_TOKEN to AetherSDR directly; it overrides the keychain.

The token decides which client you have deliberately let in. It is not a wall against other programs running as your own user once your keychain is unlocked.

MCP server for AI assistants​

tools/aether_mcp.py in the AetherSDR repository (plain Python 3, no dependencies) wraps the bridge as a Model Context Protocol server.

  • Claude Code picks it up from the repository's .mcp.json; approve it on first use.
  • Other assistants: add it to your MCP config: 
    {"mcpServers": {"aethersdr-automation": {
       "command": "python3", "args": ["tools/aether_mcp.py"]}}}
    On Windows use python (or py -3).

It offers typed tools (bridge_status, dump_tree, grab_widget, get_state, get_log, invoke, tune, slice, pan, record, menu, connect, capture_audio, wait_for, assert_state and more), plus a raw bridge_command for everything else, a validate_ui_change prompt, and read-only state resources. The transmit verbs are deliberately reachable only through bridge_command.

Using transmit safety​

  • The bridge refuses to operate any control that keys the transmitter (MOX/PTT, TUNE, ATU, CWX send, packet/APRS send) through its generic "click this control" path, whoever is asking.
  • The dedicated transmit verbs (key, cwx, txtest, atu, transmit, …) work only when you have allowed TX: tick Allow TX via MCP, or launch with AETHER_AUTOMATION_ALLOW_TX=1.
  • A force-unkey watchdog drops a bridge-started transmission that runs too long (AETHER_AUTOMATION_TX_MAX_MS, default 20 s). It does not affect your own, DAX or TCI transmissions.
  • AETHER_AUTOMATION_NO_TX=1 pins TX off for that process even if you allowed it before.

You remain responsible for every emission the bridge makes on your behalf. See Before You Transmit.

Using observe-only mode​

Tick Observe only to hand a client visibility without control. The bridge then answers only pure reads (ping, get, the widget tree, screenshots, logs and similar) and refuses everything else. It is enforced inside AetherSDR, so a client cannot switch it off, and it takes effect immediately on a running bridge. ping and whoami report it as readOnly. Launching with AETHER_AUTOMATION_READONLY=1 pins it on.

Checking which build you are talking to​

ping needs no token and returns the app version plus the build identity: the git describe string, commit SHA, the release tag it is based on, commits since that tag, and whether the build had local changes. It is the same identity Help → About shows, so a test build can be told apart from a release with the same version number.

Reference​

Environment variables​

VariableEffect
AETHER_AUTOMATION=1Starts the bridge for this run; greys out the Enabled/Disabled button
AETHER_MCP_TOKENThe access token for an MCP client; passed to AetherSDR itself, it overrides the keychain
AETHER_AUTOMATION_ALLOW_TX=1Allows the dedicated transmit verbs
AETHER_AUTOMATION_NO_TX=1Pins TX off for the process
AETHER_AUTOMATION_TX_MAX_MSForce-unkey watchdog limit for bridge-started transmissions (default 20 s)
AETHER_AUTOMATION_READONLY=1Pins observe-only mode on
AETHER_AUTOMATION_SOCKET=<name>Overrides the socket name at launch

Known issues​

  • The VOX button refuses every bridge action, including switching VOX off, while the vox_toggle shortcut can still switch it on (#6053).
  • key ptt off and key mox off report success without checking that the transmitter actually unkeyed (#5252).

Troubleshooting​

Every verb except ping is refused​

The client is not presenting the matching access token.

  1. Copy the token with Copy in Settings → Radio Setup... → Network → Advanced.
  2. Set AETHER_MCP_TOKEN in the environment of the shell that launches your assistant, then restart the assistant.
  3. If the token was rotated, repeat with the new one.

Transmit verbs are refused​

TX is not allowed for bridge clients.

  1. Tick Allow TX via MCP and confirm, or launch with AETHER_AUTOMATION_ALLOW_TX=1.
  2. Check that the process was not launched with AETHER_AUTOMATION_NO_TX=1, which pins TX off.

Only reads work​

Observe-only mode is on.

  1. Untick Observe only in Settings → Radio Setup... → Network → Advanced.
  2. If it stays on, the process was launched with AETHER_AUTOMATION_READONLY=1; relaunch without it.

The Enabled/Disabled button is greyed out​

AetherSDR was launched with AETHER_AUTOMATION=1, and the environment variable wins.

  1. Relaunch without AETHER_AUTOMATION to control the bridge from Radio Setup.

The client reaches a different AetherSDR instance​

Each launch rewrites aethersdr-automation.json in the system temp folder, so with two instances running the discovery file points at the one started last.

  1. Launch each instance with its own AETHER_AUTOMATION_SOCKET=<name>.
  2. Point the client at that socket explicitly (for example tools/automation_probe.py --socket <path>).

See also​