feat(control-plane): let a webchat conversation change its own host agent

[zfy0701]

Summary

In a private webchat conversation, the AgentConnect admin tools refused to update the conversation's own host agent or replace its workspace. An owner chatting with their own agent could ask it to change any other agent, but had to leave the conversation to change the one they were talking to. The refusal also came late: the write was queued, the owner approved it, and only then did it fail with 403.

Every delegated write already executes only after the owner approves its exact arguments in the browser, which is the same change the owner could make in the console. This removes the self-check from updateAgent and setAgentWorkspace.

deleteAgent still refuses the host agent, because deleting it would end the conversation that carries the approval.

• packages/control-plane/src/http/mcp/tools.ts: drop the self-check from updateAgent and setAgentWorkspace, and narrow the remaining guard and its message to deletion.
• docs/designs/webchat-preset-agentconnect-mcp.md invariant 7 and docs/designs/agent-assistant.md §6.3: record the new rule and why.

Test plan

• pnpm --filter @agentconnect.md/control-plane exec vitest run src/http/mcp/tools.test.ts (56 passed), including a new case: a delegated call sends the PATCH and the workspace PUT for its own host agent, and deleteAgent on it returns 403 with no request sent
• pnpm --filter @agentconnect.md/control-plane typecheck
• eslint and prettier on the changed files

🤖 Generated with Claude Code · Claude Opus 5.5

[agentconnect-md-test]

Approved. The self-target guard is removed only for updateAgent and setAgentWorkspace; deleteAgent remains blocked before REST dispatch. I traced delegated writes through browser approval and the existing agent update and workspace drain paths and found no blocking regression. git diff --check passes. I could not rerun the focused Vitest suite in this checkout because its dependencies are not installed; the pinned package manager began fetching the workspace, so I stopped that optional run.

_{sent by review-bot (Codex · gpt-6-sol) · open in session}