Chat modes

Fleet Pi exposes the same chat surface in three distinct modes. The mode is sent on every /api/chat request as mode: "agent" | "plan" | "harness" and decides which tool allowlist the Pi runtime receives. The full list of available tools and per-mode allowlists lives in apps/web/src/lib/pi/plan-mode.ts.

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Agent mode

Agent mode is the default and the broadest. It enables full repo-scoped editing and the Pi-managed extension tools. Allowed tools

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Plan mode

Plan mode is read-only. The agent inspects the repo, asks focused follow-up questions, and produces numbered execution plans. Structured plan cards keep execute, stay, and refine actions visible after page refresh or session resume — backed by persisted custom session entries so legacy text parsing remains a fallback. Allowed tools read, bash (inspection only — mutating shell activity is blocked with an explicit reason), grep, find, ls, questionnaire, project_inventory, workspace_index, and the read-only autocontext_status family. Behavior contract

• Tool allowlist is inspection-only.
• Blocked shell commands return an explicit reason instead of silently mutating the repo.
• Plan state is emitted on the stream as plan events that include { executing, completed, total, todos, message, state }.
• Plan cards survive refresh because Plan mode persists structured entries to the Pi session file.

See evaluatePlanCommand and applyPlanModeSelection in apps/web/src/lib/pi/plan-mode.ts for the exact enforcement logic.

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Harness mode

Harness mode is for workspace-architecture work. It swaps general repo-mutation tools (write, edit) for the workspace-aware workspace_write and resource_install tools so durable changes always go through the adaptive workspace contract. Allowed tools read, bash, grep, find, ls, workspace_write, resource_install, questionnaire, web_fetch, plus the project-resource and autocontext-status families. When to use it

• Adding or changing canonical files under agent-workspace/memory/, plans/, skills/, evals/, or artifacts/.
• Installing Pi skills, prompts, extensions, themes, or packages.
• Authoring workspace policies or evaluation material that must include rationale.

workspace_write requires a rationale for protected or rationale-required areas. resource_install is the only supported way to add chat-installed Pi resources under agent-workspace/.pi/*.

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Slash commands

Type / in the chat input to open a scrollable, keyboard-navigable command menu. The menu is populated from GET /api/chat/commands, which returns the builtins below plus any active skills and prompts when skill slash commands are enabled. Keyboard shortcuts Selecting a command only inserts it into the input — you still submit the message to run it. This is discovery-only in the current release; no package, OAuth, or compact execution backends are wired up yet. Built-in commands Skill and prompt commands Active skills and prompts appear as slash commands (for example, /refactor-tech-debt from a prompt of that name) when enableSkillCommands is true in Pi settings. Names are normalized by replacing whitespace with -; entries that collide with a builtin are skipped. Disable the toggle in the Pi settings dialog or via POST /api/chat/settings to hide skill and prompt commands from the menu.

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Streaming behavior

Two streaming behaviors decide how prompts queued mid-stream are handled:

• streamingBehavior: "steer" — enqueue the message as a steering prompt for the active assistant turn.
• streamingBehavior: "followUp" — enqueue the message to run after the current turn finishes.

Steering and follow-up queues are surfaced on the stream as queue events.

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