pi adapter does not attach tcode MCP servers (computer use / orchestrate / preview all unavailable on pi) #109

Status — partially improved, still open (reviewed 2026-08-22)

#189 added substantial pi extension support: extension dialogs and injected messages are surfaced natively, extension tools can pass through the approval gate, and project-extension trust is an explicit setting. Commit c600d8b4 also replaced the vague warning with one that names the unavailable tcode tool families.

The underlying capability gap remains. The current adapter still computes unattached_servers(&opts) at startup (crates/agent/src/pi.rs:328) and warns that pi has no MCP client of its own, so tcode's computer-use, orchestrate, and preview MCP servers are not attached to pi sessions.

Remaining decision

• If current pi exposes an MCP registration/configuration path, wire SessionOptions.mcp_servers through and add an end-to-end capability probe.
• If upstream still cannot attach MCP servers, add durable provider capability UI (not only a one-shot timeline warning), document the limitation, and link an upstream request.
• Do not treat project extensions as equivalent to tcode's per-session MCP registrations unless the security and lifecycle semantics actually match.

Acceptance criteria

Either all configured tcode MCP servers are usable from pi with regression coverage, or the unsupported capability is persistently visible before the user starts a pi session.

Effort: M · Risk: LOW