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.