Configure PI WEB where your agents work.

Config files

PI WEB uses a global config file for machine-local settings and a project-local file for repository settings.

• Global config: $PI_WEB_CONFIG, or $XDG_CONFIG_HOME/pi-web/config.json, or ~/.config/pi-web/config.json.
• Project config: <project>/.pi-web/config.json for commit-able project settings.

Each PI WEB machine has its own config. When using Fleet/machine federation, Settings uses the selected machine for config that affects work running there: session daemon tools, PI WEB plugin enablement, external path access, and upload defaults. Gateway/browser-only settings stay local to the gateway: keyboard shortcuts, remote machine registry/tokens, and gateway host/port/allowed-hosts. Remote servers that do not advertise selected-machine settings support report those settings as unavailable instead of silently falling back to the gateway.

Pi package settings are separate from PI WEB config. They live in Pi's package-manager settings on the target machine and are managed by Pi (pi install, pi remove, pi update) or Settings → Pi packages. In a federated setup, Settings → Pi packages targets the currently selected machine. The PI WEB plugins config key only enables or disables discovered PI WEB browser plugins on the machine whose config you are editing; it does not install, remove, or update Pi packages.

If you installed services with a custom config path, rerun pi-web install --config /path/to/config.json after changing that path or after upgrading from a version that only applied the custom path to the web service. This regenerates service files so the web/API and session daemon use the same PI_WEB_CONFIG.

Reverse-proxy deployment paths

The deployment path is not a PI WEB config-file key or environment setting. The published client is portable: one build works at / and at canonical trailing-slash prefixes such as /ai/ or /test/ai/.

For a nested deployment, redirect the slashless prefix to the trailing-slash URL, strip the prefix before forwarding to PI WEB, and proxy authenticated HTTP and WebSocket traffic through the same location. Relative browser and PWA URLs then stay within that prefix. See the reverse proxy deployment example for complete Nginx configuration.

Precedence and reloads

Machine-global runtime values are resolved in this order:

defaults → global config file → environment overrides

Supported project-local settings are then applied for that project's workspaces. For upload defaults, <project>/.pi-web/config.json overrides the global value.

Environment overrides include PI_WEB_HOST, PI_WEB_PORT / PORT, PI_WEB_ALLOWED_HOSTS, PI_WEB_MAX_UPLOAD_BYTES, PI_WEB_SPAWN_SESSIONS, and PI_WEB_SUBSESSIONS.

• host / port: restart the gateway web/API service or process.
• maxUploadBytes: restart both the web/API process and the session daemon on that machine.
• spawnSessions / subsessions: restart the session daemon on that machine.
• pathAccess: applies on the next request; existing file views may need a browser refresh.
• uploads.defaultFolder: applies to newly opened Files upload dialogs and new direct drag/drop batches after config/workspace refresh.
• plugins: reload the browser tab after changing PI WEB plugin enablement.
• Pi package install/remove/update: not a PI WEB config key; after a mutation, type /reload in each idle PI WEB session on the target machine to refresh Pi runtime resources such as extensions, skills, prompt templates, themes, and context/system prompt files as supported by Pi. Reload the browser page separately for PI WEB browser plugin changes. A routine session daemon restart is not required.
• shortcuts: saved settings apply in the browser after config refresh/save.

Global config example

pi-web install creates the initial file. You can also save PI WEB config settings from Settings → General, Settings → PI WEB plugins, Settings → Keyboard, and Settings → Session daemon. Machine-affecting Settings fields target the selected machine; gateway host/port/allowed-hosts and keyboard shortcuts stay local. Pi package operations live separately under Settings → Pi packages.

{
  "host": "127.0.0.1",
  "port": 8504,
  "pathAccess": {
    "allowedPaths": ["~/SDKs", "/opt/reference"]
  },
  "uploads": {
    "defaultFolder": ".pi-web/uploads"
  },
  "maxUploadBytes": 67108864,
  "spawnSessions": true,
  "subsessions": false,
  "plugins": {
    "workspace-tasks": { "enabled": true },
    "updates": { "enabled": true },
    "info": { "enabled": false }
  },
  "shortcuts": {
    "core:view.chat": "mod+1",
    "core:session.stop": null
  }
}

Project-local config

Project-local config lives at <project>/.pi-web/config.json. Use it for settings that should follow a repository.

{
  "version": 1,
  "pathAccess": {
    "allowedPaths": ["~/SDKs", "/opt/reference"]
  },
  "uploads": {
    "defaultFolder": "manual/uploads"
  }
}

Project-local pathAccess.allowedPaths entries are merged after the global list and deduplicated. Paths must still be host-absolute or ~-prefixed; relative roots are not supported.

Project-local uploads.defaultFolder overrides the global upload destination for workspaces in that project. Current PI WEB servers include this workspace-effective value on local and federated workspace responses; older remote servers may omit it and the browser falls back to the global/default upload folder.

Plugins may own separate project files, such as .pi-web/tasks.json for the built-in Workspace Tasks plugin.

Config matrix

Use this table as the quick reference for where a setting can live, which environment variable overrides it, and whether project-local config overrides or merges with global config. Rows with JSON key — are runtime-only environment variables, not config-file keys. Global means machine-global. In Settings, selected-machine-safe global keys (pathAccess, uploads, maxUploadBytes, spawnSessions, subsessions, and plugins) are edited for the selected machine; gateway host/port/allowed-hosts, keyboard shortcuts, and machine registry/tokens stay local.

External path access

pathAccess.allowedPaths grants PI WEB's file explorer and absolute @ path completions access to specific filesystem roots outside the current workspace. By default, workspace-relative file reads stay inside the workspace and absolute paths are denied.

Accepted root forms:

• Unix absolute paths, for example /opt/reference.
• Home-relative paths, for example ~/SDKs.
• Windows absolute paths on Windows hosts, for example C:\Users\dev\SDKs.

When an absolute request is served, PI WEB expands ~, canonicalizes configured roots with realpath, requires roots to be existing directories, and rejects symlink escapes outside the allowed roots.

In Settings → General, external filesystem roots are saved on the selected machine. Gateway host, port, and allowed-hosts fields stay on the gateway config.

Manual upload defaults

The Files panel can upload files by dropping them onto the panel or by using the toolbar Upload button. uploads.defaultFolder sets the workspace-effective default destination. The built-in default is .pi-web/uploads; a project-local value overrides the global value for workspaces in that project.

The value must be a non-empty workspace-relative folder. PI WEB normalizes repeated separators and backslashes to /, and rejects absolute paths or .. traversal. In the upload dialog only, clearing the destination field uploads that batch to the workspace root.

Manual uploads use the workspace file-write path: paths stay workspace-relative, parent folder creation is enabled by default, and overwrite is disabled by default. Browser-owned XHR progress is shown per batch/file, and conflicts or errors stay visible in the upload progress UI.

For machine federation, Settings saves the global upload default on the selected machine. Current remote PI WEB servers also return workspace-effective upload defaults on workspace responses; older remote servers may omit them and the browser falls back to the global/default upload folder.

Session daemon tools

spawnSessions

Boolean. Controls whether agents receive the spawn_session tool. Defaults to true. Set it to false if you do not want an agent to start independent PI WEB sessions.

Environment override: PI_WEB_SPAWN_SESSIONS=0|1|true|false.

subsessions

Boolean. Beta. Controls whether agents receive the tracked-subsession tools: spawn_subsession, list_subsessions, check_subsession, read_subsession, and yield_to_subsessions. Defaults to false and also requires spawnSessions to be enabled.

Tracked subsessions are join-oriented. Calling spawn_subsession returns immediately, so the parent can continue independent work while the child runs. Work whose result the parent does not need to join belongs in the fire-and-forget spawn_session tool instead.

At a join point, after finishing its independent work, the parent calls yield_to_subsessions alone as the final action in its tool batch. Pi ends a tool batch early only when every result in that batch is terminating. If any tracked child is still working, the action ends the current agent run so the parent becomes idle. If none are working, it does not end the run and clearly reports that there is nothing to wait for.

A completion notice wakes an idle parent or queues behind in-flight work. Each notice lists any other tracked children still working, so the parent can continue work or call yield_to_subsessions again at the next join point. Further notices arrive automatically; do not poll.

list_subsessions, check_subsession, and read_subsession never yield or change control flow. They are for deliberate inspection or recovery, not completion polling. While a child works, agent-facing check_subsession and read_subsession withhold partial output and direct the parent to continue independent work or yield at the join point. Output becomes available when the child stops. In notices and inspection results, PI WEB guidance precedes a labeled marker and the child output or transcript always comes last.

In Settings → Session daemon, these keys are saved on the selected machine. Restart the session daemon on that machine after changing them.

Environment override: PI_WEB_SUBSESSIONS=0|1|true|false.

Optional completion tools

File and path @ completions work without extra tools. If fzf is available on the PI WEB server's PATH, PI WEB uses it to improve completion filtering and ranking; otherwise it falls back to built-in ranking.