[Adapter] Support Pi CLI

[teseo]

Kind

implement

Goal

Integrate human.md with Pi through an extension that observes lifecycle events and enforces pre-tool decisions.

Non-goals

• Supporting the Pi desktop surface.
• Modifying Pi's policy or settings files outside the extension boundary.
• Duplicating policy logic inside the extension.

Invariants

• The adapter only translates Pi events to the neutral contract.
• Deny decisions prevent the tool call; advisory decisions remain visible.
• Session state is namespaced and cleaned up on session end.
• Extension load failure has an explicit documented mode.

Behavioral contract / States

Register Pi lifecycle and tool-call hooks, emit normalized events, apply the engine response, and report reason/message to the user. Unknown Pi events are logged as diagnostics without changing policy state.

Scope surface

Pi extension entrypoint, installer registration, fixtures, and adapter tests.

Acceptance

• Install the extension in a temporary Pi home and verify session start/end.
• Verify an allowed tool proceeds, a denied tool is blocked, and advisory output is shown.
• Run: python3 -m pytest tests/test_guard.py -v and the adapter-specific Pi test command documented in the repository.
• Add a smoke-test command that exits non-zero when the extension is not loaded.

Split triggers

• Pi's stable extension API cannot express blocking pre-tool decisions.
• Pi desktop exposes a different lifecycle than the CLI.

Dependencies / Parent

Blocked by: #1, #2, #3
Parent Epic: #15