Carlos Florêncio
52 lines
2.3 KiB
Markdown
52 lines
2.3 KiB
Markdown
# 0020: Pi project MCP config injection
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**Status:** accepted
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**Date:** 2026-06-16
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**Area:** backend
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## Context
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Kandev injects its session-scoped MCP server into ACP `session/new` and
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`session/load` requests. The Pi ACP adapter accepts those MCP parameters but
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does not wire them through to the underlying Pi CLI, so session tools such as
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`create_task_plan_kandev` and `ask_user_question_kandev` are unavailable in Pi
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sessions. Pi MCP extensions read project-local config from `.pi/mcp.json`, which
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gives Kandev a non-global injection point.
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## Decision
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Pi uses a dedicated `mcpconfig.PiStrategy` that writes or merges
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`<workspace>/.pi/mcp.json` under the `mcpServers` key. The strategy emits Pi's
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remote transport spelling (`streamable-http`) and preserves existing user
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settings and servers when the file already exists.
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For passthrough sessions, Pi declares the strategy on `PassthroughConfig`, using
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the existing passthrough MCP materialization path. For ACP sessions, Pi declares
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the same strategy on `RuntimeConfig.ProjectMCPStrategy`; the lifecycle manager
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materializes the file after the agentctl instance port is known and before the
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agent subprocess starts.
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## Consequences
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Pi sessions can discover Kandev's internal session MCP server through the Pi MCP
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adapter or extension without modifying global Pi configuration. Existing
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project-level `.pi/mcp.json` files are preserved and merged, while Kandev-owned
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files are tracked for cleanup.
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Remote executors whose agentctl-local port cannot be derived skip project-file
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materialization with a warning; in that case Pi protocol-mode sessions will not
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receive the project-local MCP tools. ACP `session/new` MCP injection remains in
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place for agents that consume it directly.
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No spec update is needed: this is an internal agent-runtime integration detail,
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not a new user-invocable product surface.
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## Alternatives Considered
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- Wait for Pi ACP to wire `session/new` MCP servers through to Pi. This would be
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cleaner but leaves Kandev's planning and question tools unavailable today.
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- Point Pi at Kandev's external MCP endpoint. Rejected because the external
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endpoint intentionally does not expose session-scoped tools.
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- Reuse Cursor's project-file strategy. Rejected because Pi's preferred remote
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transport shape uses `transport: "streamable-http"` and a different file path.
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