Authoring Pi TypeScript extensions — ExtensionAPI, custom tools, commands, UI hooks, resources_discover, `registerProvider()`, and how extendResources merges skill paths after base reload. Use when the user builds or debugs pi extensions, registers tools, adds /commands, hooks events, integrates TUI components, or ships extension examples. Use for "how do I extend pi", "extension API", "registerTool", "registerProvider", even if pi-mono is not mentioned.
Installation
Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.
Authoring Pi TypeScript extensions — ExtensionAPI, custom tools, commands, UI hooks, resources_discover, `registerProvider()`, and how extendResources merges skill paths after base reload. Use when the user builds or debugs pi extensions, registers tools, adds /commands, hooks events, integrates TUI components, or ships extension examples. Use for "how do I extend pi", "extension API", "registerTool", "registerProvider", even if pi-mono is not mentioned.
compatibility
TypeScript/Node extension host; read pi-mono/packages/coding-agent for ExtensionAPI and loader behavior cited in this skill.
pi-mono/packages/coding-agent/src/core/resource-loader.ts — extendResources() appends paths via mergePaths after existing lastSkillPaths (late paths lose name collisions to earlier ones unless names differ).
pi-mono/packages/coding-agent/src/core/agent-session.ts — extension commands vs queued prompts; skill expansion hooks.
pi-mono/packages/coding-agent/docs/tui.md — extension TUI component integration with @mariozechner/pi-tui: Component rendering contract, overlay patterns, input handling in extension context.
pi-mono/packages/coding-agent/docs/custom-provider.md — registerProvider() for proxies, OAuth/SSO, custom APIs, and custom model definitions.
Invariants
Extensions can register tools, commands, themes, prompts, and extra skill paths; exact API surface is defined in docs and example modules — start from docs/extensions.md, not memory.
Dynamic resource discovery patterns live under pi-mono/packages/coding-agent/examples/extensions/ (e.g. dynamic-resources/ listing in examples README).
Workflows
New extension: Read docs/extensions.md, clone the closest examples/extensions/ template, then align with project AGENTS.md if working inside pi-mono.
Skills from extensions: Trace extendResources + mergePaths in resource-loader.ts to explain ordering with user/project/package skills.
Extension TUI: Read docs/tui.md for the Component rendering contract in extension context; combine with pi-tui skill for library-level APIs.
Custom providers via extension: See pi-mono/packages/coding-agent/docs/custom-provider.md for registerProvider() OAuth flows and proxy patterns (grounded in pi-cli-workspace).
Anti-patterns
Do not assert MCP support in core; optional via extension (see coding-agent README philosophy).
