feat(eve): add ability to unsubscribe eve from Slack threads (v3)

[benpankow]

Summary

This exploratory PR adds durable Slack thread subscriptions using the existing per-session Slack channel state, without introducing another storage method or adding framework-level code (entirely internal to Slack state).

The API progresses from mention-only behavior, to following active threads, to a custom subscription lifecycle.

1. Respond only to explicit mentions

This remains the default:

export default slackChannel({
  credentials: connectSlackCredentials("slack/my-agent"),
});

2. Respond to replies in active threads

export default slackChannel({
  credentials: connectSlackCredentials("slack/my-agent"),
  threadSubscription: true,
});

Messages outside active eve threads remain ignored.

3. Refine when a thread remains subscribed

export default slackChannel({
  credentials: connectSlackCredentials("slack/my-agent"),
  threadSubscription: {
    resolve({ current, isBotMentioned }, message) {
      if (isBotMentioned) return "subscribed";
      if (current === "unsubscribed") return current;

      const mentionsSomeone = /<@[A-Z0-9]+(?:\|[^>]+)?>/.test(message.text);
      return mentionsSomeone ? "unsubscribed" : current;
    },
  },
});

The resolver runs inside the durable session after state is hydrated. Returning "subscribed" dispatches the message; returning "unsubscribed" persists the state and ignores it before model execution. Explicit mentions can resubscribe the same session while preserving its history and state.

Test Plan

• Added unit tests for default, subscribed-thread, unsubscribe, and resubscribe behavior
• Manually verified the handoff behavior with a deployed Slack agent

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Project	Deployment	Actions	Updated (UTC)
eve-docs	Building	Preview, Comment, Open in v0	Jul 24, 2026 5:25pm

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Suggested change

	const current = adapterCtx.state.subscription as SlackSubscriptionState;
	// Durable sessions created before `subscription` was added to
	// `SlackChannelState` have no persisted value here. Default a
	// missing/invalid value to "subscribed" so legacy threads follow
	// (rather than throwing when the default resolver returns `current`).
	const current: SlackSubscriptionState =
	adapterCtx.state.subscription === "unsubscribed" ? "unsubscribed" : "subscribed";

Legacy durable Slack sessions lacking the new subscription state field cause the deliver hook to throw (session.failed) on non-mention messages instead of following/ignoring the thread.