ACP session/list without cwd is scoped to process project #33036

Description

OpenCode's ACP session/list implementation currently does not conform to the ACP session-list behavior when the client omits cwd.

The ACP spec says session/list is for sessions known to the agent:

Lists existing sessions known to the agent.

https://agentclientprotocol.com/protocol/v1/schema#session-list

The dedicated Session List page says:

All parameters are optional. A request with an empty params object returns the first page of sessions.

and defines cwd as an optional filter:

Filter sessions by working directory. Must be an absolute path. Only sessions with a matching cwd are returned.

https://agentclientprotocol.com/protocol/v1/session-list#listing-sessions

OpenCode currently routes ACP session/list through the project-scoped /session endpoint, so an empty {} request is implicitly scoped to the ACP process working directory/project instead of returning the first page of known sessions. This makes registry-launched ACP clients report stale or empty history.

This nonconformance caused or explains:

• ACP unstable_listSessions only returns sessions for the current project #18575 — ACP session listing only returns current-project sessions
• [BUG] Zed ACP registry mode shows stale Recent sessions (unscoped /session) #16137 — Zed ACP registry mode shows stale Recent sessions because unscoped /session is tied to process cwd

Plugins

None

OpenCode version

Current dev branch; observed in ACP implementation

Steps to reproduce

1. Create OpenCode sessions in multiple project directories.
2. Start opencode acp from a directory that is not one of those projects, or via an ACP registry launch.
3. Send ACP session/list with cwd: null:

echo '{"jsonrpc": "2.0", "id": 1, "method": "initialize", "params": {"protocolVersion": 1, "clientCapabilities": {}}}
{"jsonrpc": "2.0", "id": 2, "method": "session/list", "params": {"cursor": null, "cwd": null}}' | opencode acp 

If your shell/process closes stdin before the second response is emitted, this equivalent delayed form keeps the pipe open long enough to observe the response:

{ printf '%s\n' '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":1,"clientCapabilities":{}}}'; sleep 1; printf '%s\n' '{"jsonrpc":"2.0","id":2,"method":"session/list","params":{"cursor":null,"cwd":null}}'; sleep 1; } | opencode acp

4. Observe OpenCode returns only sessions scoped to the process cwd/project, or an empty/stale list, instead of the first page of known sessions.

Screenshot and/or share link

N/A

Operating System

macOS; also reported by users on Linux

Terminal

N/A