Pi integration: agent_session_path is never reported on Windows #3726

Is this a reproducible bug?

• I confirm this is a reproducible bug, not a feature request, idea, question, contribution proposal, or direction check.
• I reproduced this bug on the version and environment reported below using the exact steps provided.

Current behavior

On Windows, pane.report_agent_session and pane.report_agent from the Pi integration (v8) contain agent_session_id but never agent_session_path, even when Pi reports a valid session file under C:\Users\<user>\.pi\agent\sessions\.... Session references from the Pi integration are therefore incomplete on Windows.

For reference: the OMP integration received an equivalent fix in #2092 (Windows session paths); the Pi integration (v8) still exhibits the limitation.

Expected behavior

agent_session_path is reported on Windows the same as on POSIX systems.

Reproduction

1. Herdr 0.9.0 (stable), Windows 11, herdr integration install pi
2. Pi coding agent 0.85.1 launched inside a Herdr pane
3. Send at least one prompt so a session exists
4. Inspect the session reference reported by the integration: it contains agent_session_id only, no agent_session_path

For contrast, sending the equivalent request over the socket API with a drive path ("agent_session_path": "C:\Users\...\sessions\<file>.jsonl") returns {"result":{"type":"ok"}}, and the path shows up in herdr agent list.

Impact

Pi session references are incomplete on Windows, which limits session restore/display in the agent views.

Environment

• Herdr version: 0.9.0
• Update channel (stable or preview): stable
• Operating system: Windows 11 (build 26200)
• Terminal: Herdr pane (pi TUI)
• Shell, if relevant: PowerShell 7.6.5
• Relevant config, if any: Pi integration v8 via herdr integration install pi; Pi coding agent 0.85.1