perf(chat): trim sub-agent tool noise from wire payload#425
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Sessions with heavy sub-agent (Task) use loaded slowly and consumed a lot of bandwidth when opening the Chat panel. The bulk of the payload was sub-agent internal tool_result content (file dumps, command output) and large tool_use inputs (Write/Edit bodies) that the collapsed Agent view never renders — pure dead weight on the wire. Add trimSubAgentForWire: for messages nested under a Task (parent.toolUseId set), empty tool_result content and reduce tool_use input to the single displayed brief field. Apply it at every egress to the frontend — message reads (getBySessionId), the live stream broadcast, and the reconnect catch-up buffer. The DB copy is never touched, so resume, branching/undo, interrupt detection, and the navigation rail/virtual-scroll windowing are all unaffected. Because the trim is display-only, the Debug modal now fetches the full untrimmed sub-agent messages straight from the DB (messages:get-subagents) and rebuilds the complete subActivities, so Debug Information still shows the real, complete data. Trimming is engine-agnostic (keyed on the unified parent.toolUseId and camelCase brief fields). The brief-field whitelist must stay in sync with getToolBrief in the AgentTool variants.
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Sessions with heavy sub-agent (Task) use loaded slowly and consumed a lot of bandwidth when opening the Chat panel. The bulk of the payload was sub-agent internal tool_result content (file dumps, command output) and large tool_use inputs (Write/Edit bodies) that the collapsed Agent view never renders — pure dead weight on the wire.
Add trimSubAgentForWire: for messages nested under a Task (parent.toolUseId set), empty tool_result content and reduce tool_use input to the single displayed brief field. Apply it at every egress to the frontend — message reads (getBySessionId), the live stream broadcast, and the reconnect catch-up buffer. The DB copy is never touched, so resume, branching/undo, interrupt detection, and the navigation rail/virtual-scroll windowing are all unaffected.
Because the trim is display-only, the Debug modal now fetches the full untrimmed sub-agent messages straight from the DB (messages:get-subagents) and rebuilds the complete subActivities, so Debug Information still shows the real, complete data.
Trimming is engine-agnostic (keyed on the unified parent.toolUseId and camelCase brief fields). The brief-field whitelist must stay in sync with getToolBrief in the AgentTool variants.