Add workspace ID to room table during agent runs

[ckelly17]

Overview

AgentRunner overlaid the workspace on the room only for the duration of a run — setting it
in memory via applyWorkspaceOverlay and restoring the original state in finally. A room
started by RunAgent therefore never had WORKSPACE_ID or options.workspace persisted to
the database, unlike a room created with CreateRoom(workspaceId=[...]).

The impact is that rooms belonging to an agent are invisible to GetWorkspaceRooms and any
other workspace-scoped query, making agent conversation history effectively undiscoverable from
the workspace.

Changes

One targeted change in AgentRunner.run():

Save WORKSPACE_ID and options.workspace when RunAgent starts a room with no messages.
After the room is loaded and the workspace is resolved, if the room has no messages yet — meaning
this is the first run against it — both fields are written to the database. The check on message
count ensures that rooms already in use keep their saved workspace and are not silently
re-pointed by a later run that passes a different workspaceId. Rooms with existing messages
still get the per-run overlay as before.

The save is gated on the workspace being active and viewable by the calling user, matching the
same access checks applied elsewhere in the agent pipeline.

Reproduction and Testing

All runs used workspace 4b862ba6 ("MCP Model Detection Test") and model engine aa876e7e
(Claude Sonnet 4-6 Vertex). Before/after state was observed via
GetWorkspaceRooms(workspaceId=["4b862ba6-..."]).

Before fix: only the room explicitly created with CreateRoom(workspaceId=[...]) appeared.
Every room started by RunAgent was absent regardless of how many times it was reused.

#	Room creation	In GetWorkspaceRooms before	In GetWorkspaceRooms after
1	RunAgent — new room, workspace passed	No	✓ f137466f
2	CreateRoom(workspaceId) then RunAgent	No	✓ a2a85513
3	CreateRoom(workspaceId) alone	✓ d6a880ce	✓ d6a880ce
4	Existing room with prior messages — rerun	No	Correctly absent — has messages, workspace not overwritten

After the fix, GetWorkspaceRooms returns all four rooms that belong to the workspace.
Existing rooms with prior messages are unaffected: they retain their persisted workspace and
still receive the per-run overlay for the duration of the run.

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

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