* feat(agent): replace hard delete with archive/restore
Replace agent deletion with soft archive pattern. Archived agents
are preserved in the database with all historical references intact
but cannot be assigned, mentioned, or trigger tasks.
Backend:
- Add archived_at/archived_by columns to agent table (migration 031)
- Replace DELETE /api/agents/{id} with POST /api/agents/{id}/archive
- Add POST /api/agents/{id}/restore endpoint
- ListAgents excludes archived by default (?include_archived=true to include)
- Skip archived agents in task triggers (on_assign, on_comment, on_mention)
- Block assignment to archived agents
- Cancel pending tasks on archive
- New events: agent:archived, agent:restored (replacing agent:deleted)
Frontend:
- Agent type includes archived_at/archived_by fields
- Mention autocomplete and assignee picker filter out archived agents
- Agent list shows archived agents with muted styling
- Agent detail shows archive banner with restore button
- Delete button replaced with Archive button and updated confirmation dialog
- API client: archiveAgent/restoreAgent replace deleteAgent
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(agent): self-review fixes for archive feature
- Fix: workspace store now fetches agents with include_archived=true
so archived agents are actually visible in the frontend (the archived
UI was dead code before — ListAgents excludes archived by default)
- Fix: add error logging for CancelAgentTasksByAgent in ArchiveAgent
- Fix: add idempotency guards — return 409 Conflict when archiving
an already-archived agent or restoring a non-archived agent
- Fix: revert unnecessary extra GetAgent query in ReconcileAgentStatus
(archived agents won't have running tasks after CancelAgentTasksByAgent)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>