Plugin Workspace Scope and Addressing

• Status: Todo
• Kind: Feature
• Authors: Jean Mertz git@jeanmertz.com
• Date: 2026-09-28
• Implements: 114
• Label: type=tracking

Tracking ticket for RFD 114.

Implementation plan

• Add the last-root record: Introduces metadata.local.json in the conversation's user-local directory with unknown-key preservation, makes projection sync replace only managed files, and writes last_root when a turn first persists. Reports last_root on list_conversations and read_events, adds expected_last_root to query with a lock-time check, and has jp-serve-web handle a dead record by sending the confirmation.
• Declare plugin workspace scope: Adds workspace_scope to DescribeResponse (default single) and derives the plugin dispatch's WorkspaceRequirement from it. Admits the plugin under the discovery configuration before describe, and again under the selected workspace's configuration for single, makes init's workspace/config fields conditional on scope, and rejects a plugin whose declaration disagrees with its requests.
• Expose list_workspaces: Projects roots::known_workspaces onto the wire, including per-root storage paths and the launch marker, giving a frontend enough to show a workspace list.
• Wire up addressing and the workspace registry: Adds WorkspaceRef to data and mutation requests (requiring root when a workspace has multiple live checkouts), lazily populates WorkspaceCtx per addressed checkout with per-checkout lock tracking, routes background tasks' destinations through the registry, implements idle-shutdown for unleased MCP server instances, and updates jp-serve-web to declare multi, address explicitly, and continue conversations via last_root/expected_last_root.