Environment Variables

Every FABRIC_* environment variable Fabric Agents reads — server, paths, runtimes, Web UI, automations, feature flags, and thin-client setup.

Fabric Agents is configurable through a small set of FABRIC_* environment variables. They're useful for running the headless server, thin-client setups, automations, CI pipelines, and debugging.

Most users don't need to set any of these — the desktop app works out of the box. The ones you're most likely to touch are in the Server & network and Thin-client tables.

Server & network

Used by the headless Fabric Agents server. See Workspaces → Remote workspaces for setup walkthrough.

Variable	Default	Purpose
`FABRIC_SERVER_TOKEN`	—	Required for server mode. Bearer token clients must present. Generate with `openssl rand -hex 32`.
`FABRIC_RPC_HOST`	`127.0.0.1`	WebSocket bind address. Set to `0.0.0.0` to accept remote connections.
`FABRIC_RPC_PORT`	`9100`	WebSocket bind port.
`FABRIC_RPC_TLS_CERT`	—	Path to a PEM certificate. Enables `wss://`. Required together with `FABRIC_RPC_TLS_KEY`.
`FABRIC_RPC_TLS_KEY`	—	Path to the matching PEM private key.
`FABRIC_RPC_TLS_CA`	—	PEM CA chain file for client-certificate verification. Optional.
`FABRIC_HEALTH_PORT`	`0`	HTTP port for a health endpoint. `0` disables it.

Thin-client (desktop connecting to a remote server)

Variable	Default	Purpose
`FABRIC_SERVER_URL`	—	`ws://` or `wss://` URL of the remote Fabric Agents server.
`FABRIC_WORKSPACE_ID`	—	Workspace ID on the remote server to connect to.
`FABRIC_TLS_CA`	—	PEM CA bundle for self-signed server certificates (client-side).

Example:

FABRIC_SERVER_URL=wss://203.0.113.5:9100 \
FABRIC_SERVER_TOKEN=<token> \
FABRIC_WORKSPACE_ID=ws-my-project \
bun run electron:start

Paths & assets

Mostly set automatically by the app. You usually only touch these when running in development or from source.

Variable	Default	Purpose
`FABRIC_APP_ROOT`	`cwd`	Root path for bundled assets and scripts.
`FABRIC_RESOURCES_PATH`	`cwd/resources`	Resources directory path.
`FABRIC_BUNDLED_ASSETS_ROOT`	—	Root of bundled assets. Set to repo root in dev, packaged app dir in production.
`FABRIC_CONFIG_DIR`	`~/.fabric-agent`	User config directory. Override for testing or multi-profile setups.
`FABRIC_SCRIPTS`	—	Scripts directory path. Set by the app at startup.

Runtimes

Paths to bundled language runtimes. Set automatically; override when debugging.

Variable	Purpose
`FABRIC_BUN`	Bun binary path.
`FABRIC_NODE`	Node.js binary path.
`FABRIC_UV`	Python `uv` binary path (for Python-based skills/tools).
`FABRIC_DEV_RUNTIME`	Set to `1` to resolve the Claude SDK and interceptor from the monorepo during development.

App state

Set automatically by the app. Read by internal code.

Variable	Purpose
`FABRIC_IS_PACKAGED`	`1` if running a packaged build, `0` in dev.
`FABRIC_VERSION`	App version string.
`FABRIC_DEBUG`	`1` or `true` to enable debug logging.
`FABRIC_HEADLESS`	`1` to run Electron without opening a window.
`FABRIC_INSTANCE_NUMBER`	For multi-instance dock icons / badges.
`FABRIC_DEEPLINK_SCHEME`	Override the `fabricagents://` protocol name.
`FABRIC_APP_NAME`	Override the window title.
`FABRIC_AGENT_SAFE_MODE`	`1` skips workspace config loading — recovery mode.

Web UI

When hosting the browser-based UI on the server.

Variable	Purpose
`FABRIC_WEBUI_DIR`	Path to the Web UI `dist/` directory. Setting this enables the Web UI.
`FABRIC_WEBUI_PASSWORD`	Extra password on the login page.
`FABRIC_WEBUI_SECURE_COOKIE`	Set `Secure` flag on the session cookie. Required when served over HTTPS.
`FABRIC_WEBUI_WS_URL`	Public `wss://` URL when the server is behind a reverse proxy.

Automation event injection

Set by Fabric Agents when invoking an automation's prompt action. Read these inside a command's $ARGUMENTS template or a shell automation to know the trigger context.

Variable	Purpose
`FABRIC_EVENT`	Event type: `SchedulerTick`, `LabelAdd`, `LabelRemove`, `PreToolUse`, `PostToolUse`, `SessionStart`, `SessionEnd`, `SessionStatusChange`, `FlagChange`, `PermissionModeChange`.
`FABRIC_EVENT_DATA`	Full event payload as a JSON string.
`FABRIC_SESSION_ID`	ID of the session the event came from.
`FABRIC_SESSION_NAME`	Name of the session.
`FABRIC_WORKSPACE_ID`	Workspace the session belongs to.
`FABRIC_LABEL`	Label name for `LabelAdd` / `LabelRemove` events.
`FABRIC_LOCAL_TIME`	`HH:MM` for `SchedulerTick`.
`FABRIC_LOCAL_DATE`	`YYYY-MM-DD` for `SchedulerTick`.

See Automations for how to wire these up.

Feature flags

Variable	Purpose
`FABRIC_FEATURE_FABRIC_AGENTS_CLI`	Enable/disable the `fabric-cli` feature exposure. `0` hides it in the UI.
`FABRIC_FEATURE_DEVELOPER_FEEDBACK`	Toggle developer-feedback-specific UI.
`FABRIC_ENABLE_1M_CONTEXT`	`false` to disable the 1M context window.
`FABRIC_EXTENDED_PROMPT_CACHE`	`true` to use the 1-hour prompt cache TTL.
`FABRIC_RICH_TOOL_DESCRIPTIONS`	`false` to disable the `_intent` / action metadata on tool calls.
`FABRIC_INTERCEPTOR_DISABLE_AUTO_INSTALL`	`1` skips auto-installing the network interceptor.
`FABRIC_LOCAL_MCP_ENABLED`	Enables local MCP server support.

LLM routing (internal)

Set by the Pi interceptor when routing requests to provider-specific endpoints. Don't set these by hand.

Variable	Purpose
`FABRIC_PI_MODEL_API`	API-type hint for a Pi model.
`FABRIC_PI_MODEL_PROVIDER`	Provider hint for a Pi model.
`FABRIC_PI_MODEL_BASE_URL`	Base-URL hint for a Pi model.

Browser tool

Tunables for the built-in Chromium browser tool.

Variable	Purpose
`FABRIC_BROWSER_OPEN_SETTLE_TIMEOUT_MS`	Max ms to wait for a browser launch to settle.
`FABRIC_BROWSER_OPEN_SETTLE_POLL_MS`	Poll interval while waiting for settle.

fabric-cli — the CLI reads FABRIC_SERVER_URL and FABRIC_SERVER_TOKEN.
Workspaces — thin-client and remote server setup.
Automations — how automations inject FABRIC_EVENT* and FABRIC_SESSION* variables.
config.json — persistent settings that these env vars override at runtime.

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