test(slack): add peer-agent smoke target

[LeonSGP43]

Summary

• add a dedicated synthetic Slack peer-agent smoke target for strict mention + allow_bots=mentions deployments
• cover the live-routing invariants for human mentions, peer-bot mention gating, and passive ack/status/error suppression
• document the single post-deploy pytest command and failure buckets in the Slack messaging guide

Testing

• uv run --frozen pytest -q tests/gateway/test_slack_peer_agent_smoke.py -o addopts=''
• uv run --frozen ruff check tests/gateway/test_slack_peer_agent_smoke.py
• git diff --check

Closes #51630.

[tonydwb]

Code Review Summary

Verdict: Approved

Well-structured addition of a repeatable smoke test for Slack peer-agent routing invariants. Key positives:

• Uses synthetic in-process Slack events (no live messages or real tokens needed)
• Thorough preflight contract check covering config, connectivity, and bot identity
• Tests all critical routing paths: human mention routing, peer-bot ignore without mention, explicit peer-bot mention routing, passive ack/status/error suppression
• Good documentation of failure buckets in the companion docs update
• Clean mock setup with _ensure_slack_mock() for environments without slack_bolt installed

No security concerns. The test file is self-contained and well-documented.

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Reviewed by Hermes Agent

[teknium1]

Thanks for adding a focused synthetic routing target and documenting an operator command.

Problems

• tests/gateway/test_slack_peer_agent_smoke.py:91 creates the passing configuration, mocked client, and bot identity before _assert_peer_agent_preflight() runs. The preflight cannot therefore produce the config, connectivity, or bot-identity failures that website/docs/user-guide/messaging/slack.md:409 presents as post-deploy checks.
• tests/gateway/test_slack_peer_agent_smoke.py:163 supplies bot_id for peer events. Current main already recognizes that shape at plugins/platforms/slack/adapter.py:2600; this does not cover the ordinary bot-user event shape discussed in linked PR #51627.

Suggested changes

• Either describe this as a deterministic adapter regression test, or add a path that inspects effective runtime configuration and identity state.
• Add the no-bot_id/no-subtype peer bot-user event shape if this target is intended to cover the peer-routing incident class.

Automated hermes-sweeper review.

[teknium1]

This only exercises the already-recognized bot_id event shape. Please add the ordinary peer bot-user event shape (a user ID without bot_id or subtype) if this smoke target is meant to cover the routing incident described by #51627.

[teknium1]

The target constructs its own passing config, mocked client, and bot identity, so it cannot validate a deployed gateway after a restart or distinguish those runtime failure buckets. Please either narrow this wording to an adapter regression test or add a runtime-aware check.

[teknium1]

Merged via #69483 — your commit was cherry-picked/reapplied onto current main with your authorship preserved in git history: your peer-agent smoke test was cherry-picked clean, fixes #51630.

Thanks for the contribution!