feat: add threaded Agent group chats

[ObservedObserver]

Agent discussions now start as group chats. Users choose Claude/Codex members, @ the Agents they want to hear from, and reply in threads. Creating a group starts no provider work. Private member chats remain separate, and returning preserves the selected thread and unsent draft.

“Continue together” adds an optional goal inside a thread without requiring Planner/Reviewer roles. Agents publish new findings and record agreement as explicit assessments. Completion requires current agreement from everyone, resolved issues, and settled turns. Pause, updates, recovery, and turn limits stay visible beside the conversation.

“Compare plans” remains an optional menu action. It reuses member settings in independent comparison sessions and returns the recommendation to an editable group draft. Source evidence is supplied to reviewers and the decision writer, and follow-up checks use the existing workflow governance. The preview now checks actual capacity before enabling Run.

The runtime persists thread-scoped messages, cursors, pending attention, and goal revisions. Read/post/assess tools bind identity to the caller. Mixed-provider acceptance also corrected repeated acknowledgement messages that could keep invalidating agreement.

Validation

• Final npm run test:ci passed lint, production build, and 192 CI unit tests.
• Complete kernel run: 674 passed. All four kernel smoke scripts passed. Later prompt and preview changes passed 24 collaboration and four preview regressions respectively.
• Seven recorded real-provider scenarios passed with 27 settled turns, including Claude/Codex directed chat, pause/update/resume, threaded goals, and a seven-turn Council with specialist follow-up and revised synthesis.
• Independent code review passed. Browser acceptance and screenshots are recorded in the linked report below.

Workspace members currently support read-only Claude and Codex. Comparisons retain the existing global workflow capacity limit, including idle and archived sessions. Mobile layouts below the Electron minimum width of 1024px are outside this acceptance.

Claude's read-only setting uses native plan permissions with edit tools disabled. The real UI run observed an allowed provider-owned plan file write under ~/.claude/plans/; the project fixture stayed unchanged. This is not an operating-system filesystem sandbox.

Acceptance evidence

The final browser pass used eight real provider turns, leaving five idle sessions and no open requests, queue entries, or active leases. It verified completed mixed-provider Thread agreement, the human-gated comparison, full recommendation draft import, the supported 1024px layout, and capacity-only Run blocking.

Feature guide · UI acceptance and screenshots · Real-provider scenarios · Review and regression record

Completed group Thread with both Agents' assessments:

Supported narrow desktop layout: