Add pi as native target in CodeGraph installer

[Lokeraar]

Summary

Add pi as a native target in CodeGraph's install command so users can run codegraph install --target pi to automatically configure CodeGraph's MCP server for Pi (Android/Termux).

Changes Made

1. New file: src/installer/targets/pi.ts

   • Implements the AgentTarget interface for Pi
   • Configures MCP server entry to ~/.pi/agent/mcp.json (global) or .pi/mcp.json (local project)
   • Installs CodeGraph instructions to ~/.pi/agent/AGENTS.md (global) or .pi/AGENTS.md (local)
   • Uses standard mcpServers format (same as Claude/Cursor/opencode)
   • No permissions concept (Pi handles tool approval via its own UI)

2. Modified: src/installer/targets/types.ts

   • Added 'pi' to the TargetId union type

3. Modified: src/installer/targets/registry.ts

   • Imported piTarget from ./pi
   • Added piTarget to the ALL_TARGETS array

Testing Evidence (logs generated in IA-Generativa project)

All tests passed successfully:

1. Pi Global Install ✓ - Creates ~/.pi/agent/mcp.json and ~/.pi/agent/AGENTS.md
2. Pi Local Install ✓ - Creates .pi/mcp.json and .pi/AGENTS.md in project directory without affecting global config
3. Pi Auto-Detection ✓ - codegraph install --target auto correctly detects Pi as installed
4. Pi Uninstall ✓ - Correctly removes the configuration
5. Idempotency ✓ - Re-runs correctly report "Unchanged"

Verification Commands

# Install Pi target globally
codegraph install --target pi --location global --yes

# Install Pi target locally (project-scoped)
codegraph install --target pi --location local --yes

# Auto-detect installed targets (Pi will be detected)
codegraph install --target auto --location global --yes

# Uninstall Pi from local project
codegraph uninstall --target pi --location local

Note

This PR follows the exact pattern of existing targets like opencode.ts, with Pi-specific config paths (~/.pi/agent/). The pi-mcp-adapter package (v2.27.0 with @ff-labs/fff-node@0.10.5 override for Android compatibility) is used for MCP server configuration.

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Generated and tested on Android/Termux architecture aarch64/arm64.

[colbymchenry]

Thanks for the detailed writeup and the testing you did on Termux — and Pi requests keep coming (this is the fifth: #328, #495, #574, #184), so the demand is real and noted.

Two things block taking this as a first-class installer target right now:

1. Pi deliberately doesn't speak MCP. The project's own docs state the position: agents should write extensions on demand rather than install prebuilt MCP servers. That means ~/.pi/agent/mcp.json isn't Pi's config surface — it belongs to the third-party pi-mcp-adapter you mentioned. An installer target hard-coding another project's adapter paths would break silently whenever the adapter moves, and there's no upstream contract for us to track. Our install targets write config that the agent itself documents and owns.
2. The described implementation also writes a CodeGraph instructions block into AGENTS.md — we removed instructions-file writing from every target in CLAUDE.md instructions duplicate MCP server instructions — wastes tokens every turn #529 (the MCP initialize response is the single source of truth now), so that part wouldn't merge as-is regardless.

I've added this issue to the existing Pi row in #649 (the install-target hub). If Pi ships first-party MCP support, a target is genuinely one small file plus a registry entry and we'd take that PR gladly. Meanwhile the manual path works today: point the adapter (or anything MCP-capable) at codegraph serve --mcp.

Closing as consolidated into #649.