ACP Host Integration

Digit can run as an ACP server, letting ACP-compatible hosts talk to Digit over stdio. Editors can render:

• chat messages
• tool activity
• file diffs
• terminal commands
• approval prompts
• streamed thinking / response chunks

Other hosts can use the same protocol to route collaboration events into Digit. ACP is a good fit when you want Digit to keep its existing identity, provider setup, memory, skills, and tools while another application owns the conversation transport.

What Digit exposes in ACP mode

Digit runs with a curated digit-acp toolset designed for editor workflows. It includes:

• file tools: read_file, write_file, patch, search_files
• terminal tools: terminal, process
• web/browser tools
• memory, todo, session search
• skills
• execute_code and delegate_task
• vision

It intentionally excludes things that do not fit typical editor UX, such as messaging delivery and cronjob management.

Installation

Install Digit normally, then add the ACP extra from the install checkout:

cd ~/.digit/digit && uv pip install -e '.[acp]'

This installs the agent-client-protocol dependency and enables:

• digit acp
• digit-acp
• python -m acp_adapter

Launching the ACP server

Any of the following starts Digit in ACP mode:

digit acp

digit-acp

python -m acp_adapter

Digit logs to stderr so stdout remains reserved for ACP JSON-RPC traffic.

For non-interactive checks:

digit acp --version
digit acp --check

Browser tools (optional)

Browser tools (browser_navigate, browser_click, etc.) depend on the agent-browser npm package and Chromium, which aren't part of the Python wheel. Install them with:

digit acp --setup-browser           # interactive (prompts before ~400 MB download)
digit acp --setup-browser --yes     # accept the download non-interactively

This is the standalone command. The terminal-auth flow (digit acp --setup) also offers the browser bootstrap as a follow-up question after model selection, so most users never need to run --setup-browser directly.

What it does:

• Installs Node.js 26 into ~/.digit/node/ if missing
• npm install -g agent-browser @askjo/camofox-browser into that prefix (no sudo needed — npm's --prefix points at the user-writable Digit-managed Node)
• Installs Playwright Chromium, or uses a detected system Chrome/Chromium when available

The bootstrap is idempotent — re-running it is fast and skips work that's already done.

Host setup

Buzz channels (relay bridge)

Buzz is a Nostr-based collaboration platform for people and agents. Its buzz-acp harness connects Buzz channels to any ACP agent over stdio:

Buzz relay <-- WebSocket --> buzz-acp <-- ACP over stdio --> Digit

This is a transport integration, not a second Digit installation. The subprocess launched by buzz-acp uses the same Digit configuration, credentials, memory, skills, and state as digit on that host.

(This is distinct from Buzz Desktop's managed runtime, which spawns Digit locally as a preset harness. The relay bridge is for joining Buzz channels as an agent identity, typically on a server.)

Prerequisites:

• Complete the ACP installation and digit acp --check above.
• Build buzz-acp and the buzz CLI from the Buzz repository (cargo build --release -p buzz-acp).
• Mint a dedicated Nostr keypair for Digit (buzz-admin generate-key) and register it as a relay member (buzz-admin add-member). Every agent needs its own identity — do not reuse a human keypair.
• Add that identity to the intended Buzz channels.

Start a bridge with:

export BUZZ_RELAY_URL="wss://community.example.com"
export BUZZ_PRIVATE_KEY="..."
export BUZZ_API_TOKEN="..."
export BUZZ_ACP_AGENT_COMMAND="digit"
export BUZZ_ACP_AGENT_ARGS="acp"

buzz-acp

BUZZ_API_TOKEN is needed only when the relay enforces token authentication. Do not commit or paste the private key or API token.

For a persistent server deployment, run buzz-acp under a service manager as the same operating-system user that owns the intended Digit home. Setup, key generation, channel discovery, and per-agent options are documented in the buzz-acp README.

The bridge discovers every Buzz channel where the Digit identity is a member and automatically subscribes when it is added to another channel. Buzz channel membership therefore remains the access boundary; Digit does not need a separate channel list in its own configuration.

To expose Digit ACP activity in the owner's Buzz Desktop, add:

export BUZZ_ACP_RELAY_OBSERVER="true"

This publishes encrypted kind 24200 observer frames addressed to the agent's owner (Buzz's NIP-AO). Desktop renders the live lifecycle, tool, response, and usage stream in the agent's Activity log. The relay treats these frames as ephemeral, so Desktop must be online before the turn starts; its local observer archive is the durable owner-side history.

Headless bridges answer ACP permission requests themselves because no editor is present to show approval dialogs — see Keep Buzz agents owner-only. Treat the bridge as privileged automation: use a dedicated operating-system account, restrict which Buzz users can prompt the agent (buzz-acp supports an owner-only respond gate via BUZZ_ACP_AGENT_OWNER), and grant membership only in channels where Digit is expected to work.

VS Code

Install the ACP Client extension.

To connect:

1. Open the ACP Client panel from the Activity Bar.
2. Select Digit from the built-in agent list.
3. Connect and start chatting.

If you want to define Digit manually, add it through VS Code settings under acp.agents:

{
  "acp.agents": {
    "Digit": {
      "command": "digit",
      "args": ["acp"]
    }
  }
}

Zed

Configure Digit as a custom agent server in Zed settings:

1. Open the Agent Panel.
2. Add a custom agent server with the following configuration:

{
  "agent_servers": {
    "digit": {
      "type": "custom",
      "command": "digit",
      "args": ["acp"]
    }
  }
}

3. Start a new Digit external-agent thread.

Prerequisites:

• Configure Digit provider credentials first with digit model, or set them in ~/.digit/.env / ~/.digit/config.yaml.

JetBrains

Use an ACP-compatible plugin and point it at digit acp or digit-acp.

Buzz Desktop

Buzz ships Digit as a preset runtime. With Digit installed the normal way, Buzz discovers it automatically — open Settings → Runtimes and Digit appears under your runtimes.

If discovery fails (older installs), make sure the ACP launcher resolves on a login-shell PATH:

command -v digit-acp || command -v digit

Recent installs write both digit and digit-acp launchers into ~/.local/bin; running digit update adds the digit-acp launcher to older installs. As a manual fallback, configure Buzz's agent command as digit with args ["acp"].

Model picker

Buzz Desktop (v0.5.1+) renders Digit' full model menu in the agent's runtime settings. The list comes from Digit itself over ACP: it shows every model from providers you have authenticated in Digit (the same inventory behind digit model and the /model command), so a model missing from the menu means its provider has no credentials configured on the Digit side.

Entry IDs take the form provider:model (e.g. openrouter:z-ai/glm-5.1), or custom:<name>:<model> for custom OpenAI-compatible endpoints defined in config.yaml. Picking a model applies to that agent's session; it does not change your Digit-wide default — use digit model for that.

Keep Buzz agents owner-only

Buzz creates every agent with Who can talk to this agent set to Owner only. Leave it there when the runtime is Digit.

Two behaviors combine on this path. The digit-acp toolset includes terminal and execute_code, and Buzz's ACP bridge answers Digit' permission requests itself with allow_once rather than surfacing them. A Digit agent in Buzz therefore runs shell commands on the host without prompting. I asked one to run rm -rf against a scratch directory and it deleted it, no prompt anywhere.

Selecting Anyone hands that same shell access to every author who can reach the channel. Buzz does not warn when you pick it.

Neither of the obvious mitigations works today:

• approvals.mode: manual does make Digit raise the permission request, but Buzz auto-approves it and the command still runs.
• platform_toolsets.acp does not narrow the ACP toolset, so it cannot be used to drop terminal.

!shutdown from the owner stops the agent in any mode, and Buzz ignores that command from everyone else.

Configuration and credentials

ACP mode uses the same Digit configuration as the CLI:

• ~/.digit/.env
• ~/.digit/config.yaml
• ~/.digit/skills/
• ~/.digit/state.db

Provider resolution uses Digit' normal runtime resolver, so ACP inherits the currently configured provider and credentials. Digit also advertises a terminal auth method (--setup) for first-run ACP clients; this opens Digit' interactive model/provider setup.

Host integration

These variables are set by an ACP host process (an editor or another agent harness) on the Digit subprocess it spawns. They are not user configuration — do not set them by hand in .env or config.yaml.

Variable	Value	Effect
DIGIT_ACP_SKIP_CONFIGURED_MCP	1	Skip starting the globally configured MCP servers from config.yaml before the ACP JSON-RPC loop begins.

Digit normally starts every MCP server configured in config.yaml before it enters the ACP JSON-RPC loop. A host that owns MCP itself — passing the session's servers explicitly through session/new — does not need that global startup, and an unrelated slow or interactive MCP server would otherwise delay initialize. Setting the marker to exactly 1 lets such a host skip it.

Only the global config.yaml discovery is skipped. MCP servers supplied by the ACP session through session/new are still registered, so a host loses no capability it asked for. Any other value (unset, empty, 0, false) keeps the default behavior, so an unrelated truthy-looking string cannot silently disable MCP.

Session behavior

ACP sessions are tracked by the ACP adapter's in-memory session manager while the server is running.

Each session stores:

• session ID
• working directory
• selected model
• current conversation history
• cancel event

The underlying AIAgent still uses Digit' normal persistence/logging paths, but ACP list/load/resume/fork are scoped to the currently running ACP server process.

Working directory behavior

ACP sessions bind the editor's cwd to the Digit task ID so file and terminal tools run relative to the editor workspace, not the server process cwd.

Approvals

Dangerous terminal commands can be routed back to the editor as approval prompts. ACP approval options are simpler than the CLI flow:

• allow once
• allow always
• deny

Whether you actually see a prompt is up to the host. A host is free to answer the request programmatically instead of showing it to you, in which case these options exist on the wire but never reach a human. Buzz Desktop does this, so treat that path as unattended execution regardless of your approvals setting.

On timeout or error, the approval bridge denies the request.

Session-scoped edit auto-approval

ACP exposes a third tier between allow once and allow always: Allow for session. Picking it from the editor's permission prompt records the approval inside the current ACP session only — every subsequent matching command in that session goes through without prompting, but a new ACP session (or restarting the editor) resets the slate and re-prompts the first time.

Option	Editor label	Scope	Persisted across restarts
allow_once	Allow once	This one tool call	No
allow_session	Allow for session	All matching calls in this ACP session	No — cleared when the session ends
allow_always	Allow always	All future sessions	Yes (written to the Digit permanent allowlist)
deny	Deny	This one tool call	No

allow_session is the right default for an editor workflow where you trust an agent for the duration of a task but don't want to grant a long-lived allowlist entry. The safety trade-off is straightforward: the broader the scope, the less the editor will interrupt you, and the more damage a misbehaving agent (or prompt injection) can do before you notice. Start with allow_once for unfamiliar commands; promote to allow_session once you've seen the agent run the same pattern correctly a few times; reserve allow_always for truly idempotent commands you trust forever (e.g. git status).

The ACP bridge maps these options onto Digit' internal approval semantics — allow_always writes a permanent allowlist entry the same way the CLI does, while allow_session only affects the in-process approval cache for the current ACP session.

Troubleshooting

ACP agent does not appear in the editor

Check:

• For manual/local development, verify the host command points to digit acp.
• Digit is installed and on your PATH.
• The ACP extra is installed (cd ~/.digit/digit && uv pip install -e '.[acp]').

ACP starts but immediately errors

Try these checks:

digit acp --version
digit acp --check
digit doctor
digit status

Missing credentials

ACP mode uses Digit' existing provider setup. Configure credentials with:

digit model

or by editing ~/.digit/.env. The terminal auth flow (digit acp --setup) can also trigger the interactive provider/model setup.

See also

• Buzz ACP harness
• ACP Internals
• Provider Runtime Resolution
• Tools Runtime