feat(agentex): golden-agent self-posts its Slack reply; gateway skips relay

[michael-chou359]

What

golden-agent is the only agent with Slack write tools (SlackBot, auto-enabled on slack-origin golden-agent turns), so it posts its own reply into the thread. Today the gateway also relays golden-agent's text output → double-write, and the agent's interim posts clear the `thinking…` status. This makes golden-agent the single writer for its own turns.

Change

• _run_turn: when the target is golden-agent, set `thinking…` and fire the turn with collect=False, then return — no reply relay (the agent posts it). Every other agent (registered agents, SYNC agents) has no Slack tools, so the gateway stays the single writer and keeps relay + status.
• _dispatch: collect flag — send the event without polling/relaying a reply.
• _turn_content: for golden-agent, a directive to deliver its reply via post_message, and to keep thinking… alive across multi-message turns via set_status (re-assert after each non-final post; the final post clears it).

The signal is the golden-agent name, not config_id — configs are personas that keep the golden-agent name, so the name is the exact self-posting set.

Paired change (must ship together)

Depends on the SlackBot set_status tool in golden-agent: agentex-agents mc/golden-agent-slackbot-tools. Deploy golden-agent + this gateway change together, or golden-agent replies won't reach Slack.

Behavior after both land

golden-agent posts its own reply; `thinking…` shows the whole turn and clears only on its final message; no double-posting. Non-golden agents unchanged.

Testing

Slack gateway unit suite green (self-post skip, non-golden relay, collect flag, self-post directive); ruff clean.

🤖 Generated with Claude Code

Greptile Summary

This PR makes golden-agent responsible for posting its own Slack replies while retaining gateway relay behavior for other agents.

• Adds self-posting instructions, including multi-message status handling, to golden-agent turn context.
• Adds a non-collecting dispatch mode that sends EVENT_SEND without polling for a reply.
• Updates gateway tests for golden-agent self-posting and non-golden relay behavior.

Confidence Score: 4/5

The PR is not yet safe to merge because a golden-agent failure after EVENT_SEND acceptance can leave the user without a reply or error indication.

The previously reported failure remains: collect=False returns before asynchronous turn completion, so later execution failures bypass the gateway's exception delivery path while the Slack thread may remain marked as thinking.

Files Needing Attention: agentex/src/domain/use_cases/slack_gateway_use_case.py

Important Files Changed

Filename	Overview
agentex/src/domain/use_cases/slack_gateway_use_case.py	Splits Slack delivery ownership by agent name and adds a fire-without-collection dispatch path.
agentex/tests/unit/use_cases/test_slack_gateway_use_case.py	Updates unit coverage for self-post directives, golden-agent relay suppression, and unchanged non-golden relay behavior.

_{Reviews (2): Last reviewed commit: "Merge branch 'main' into mc/slack-golden..." | Re-trigger Greptile}