Summary

• Problem: In multi-account Slack setups, sessions_send announce replies use the default bot token instead of the target agent's token because resolveAnnounceTarget() returns the key-parsed fallback (no accountId) for Slack
• Why it matters: Messages appear under the wrong bot identity, breaking multi-agent setups
• What changed: Added preferSessionLookupForAnnounceTarget: true to Slack channel plugin meta, matching the existing WhatsApp pattern
• What did NOT change (scope boundary): No changes to resolveAnnounceTarget() logic or any other channel plugin

Change Type (select all)

• Bug fix
• Feature
• Refactor
• Docs
• Security hardening
• Chore/infra

Scope (select all touched areas)

• Gateway / orchestration
• Skills / tool execution
• Auth / tokens
• Memory / storage
• Integrations
• API / contracts
• UI / DX
• CI/CD / infra

Linked Issue/PR

• Closes [Bug]: sessions_send announce uses wrong Slack accountId in multi-account setups #30956
• Related sessions_send announce step uses wrong Slack accountId in multi-account setups #14854 (original report, auto-closed by stale bot)

User-visible / Behavior Changes

In multi-account Slack setups, sessions_send announce replies now post using the correct bot token for the target agent's Slack account instead of always using the default account's token.

Security Impact (required)

• New permissions/capabilities? No
• Secrets/tokens handling changed? No
• New/changed network calls? No
• Command/tool execution surface changed? No
• Data access scope changed? No

Repro + Verification

Environment

• OS: All
• Runtime/container: Any
• Model/provider: N/A
• Integration/channel (if any): Slack (multi-account)
• Relevant config (redacted): Two Slack accounts with separate bot tokens

Steps

1. Configure two Slack accounts (default + secondary) with separate bot tokens
2. Agent A (default account) sends a message to Agent B (secondary account) via sessions_send
3. Agent B's announce reply posts to the channel

Expected

• Reply is posted using Agent B's bot token

Actual

• Reply is posted using Agent A's (default) bot token

Evidence

• Failing test/log before + passing after
• Trace/log snippets
• Screenshot/recording
• Perf numbers (if relevant)

New test in src/agents/tools/sessions.test.ts verifies resolveAnnounceTarget() hydrates accountId from sessions.list for Slack sessions. Test fails without the flag.

Human Verification (required)

• Verified scenarios: New test confirms session-store lookup path is triggered for Slack
• Edge cases checked: Single-account setups unaffected (accountId absence is harmless when only one account exists)
• What you did not verify: Live multi-account Slack environment

Compatibility / Migration

• Backward compatible? Yes
• Config/env changes? No
• Migration needed? No

Failure Recovery (if this breaks)

• How to disable/revert this change quickly: Remove preferSessionLookupForAnnounceTarget: true from extensions/slack/src/channel.ts
• Files/config to restore: extensions/slack/src/channel.ts
• Known bad symptoms reviewers should watch for: Announce messages failing or timing out due to session-store lookup errors

Risks and Mitigations

• Risk: Session-store lookup adds a sessions.list call to the announce path for Slack
  • Mitigation: WhatsApp has used this exact path since the feature was introduced with no reported issues