Summary

Describe the problem and fix in 2–5 bullets:

• Problem: message:received internal hooks rely on SessionKey; when inbound context ends up with an empty/missing session key, hook dispatch is skipped.
• Why it matters: Discord guild traffic can still process normally while hook automations miss events.
• What changed: added a session-key guard in Discord inbound processing and a fallback in hook dispatch (SessionKey -> CommandTargetSessionKey).
• What did NOT change (scope boundary): no changes to routing policy, mention gating, or reply delivery behavior.

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 message:received hook does not fire for Discord guild channel messages #31212
• Related #

User-visible / Behavior Changes

• Internal message:received hooks now still emit when inbound context has no SessionKey but has CommandTargetSessionKey.
• Discord inbound processing now guarantees a non-empty session key reaches dispatch by falling back to route session key.

Security Impact (required)

• New permissions/capabilities? (Yes/No) No
• Secrets/tokens handling changed? (Yes/No) No
• New/changed network calls? (Yes/No) No
• Command/tool execution surface changed? (Yes/No) No
• Data access scope changed? (Yes/No) No
• If any Yes, explain risk + mitigation:

Repro + Verification

Environment

• OS: macOS
• Runtime/container: Node 22 + Vitest
• Model/provider: n/a
• Integration/channel (if any): Discord + internal hooks
• Relevant config (redacted): n/a

Steps

1. Build inbound context where SessionKey is empty/missing.
2. Dispatch inbound message through dispatchReplyFromConfig.
3. Observe internal hook dispatch behavior.

Expected

• message:received internal hooks emit when a fallback session key exists.

Actual

• Before: skipped when SessionKey absent.
• After: emits using fallback CommandTargetSessionKey.

Evidence

Attach at least one:

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

Human Verification (required)

What you personally verified (not just CI), and how:

• Verified scenarios:
  • pnpm exec vitest run src/auto-reply/reply/dispatch-from-config.test.ts src/discord/monitor/message-handler.process.test.ts
  • pnpm exec oxlint src/auto-reply/reply/dispatch-from-config.ts src/auto-reply/reply/dispatch-from-config.test.ts src/discord/monitor/message-handler.process.ts src/discord/monitor/message-handler.process.test.ts
• Edge cases checked:
  • Missing SessionKey + present CommandTargetSessionKey.
  • Discord derived session key empty fallback to route session key.
• What you did not verify:
  • Live Discord runtime against real gateway credentials.

Compatibility / Migration

• Backward compatible? (Yes/No) Yes
• Config/env changes? (Yes/No) No
• Migration needed? (Yes/No) No
• If yes, exact upgrade steps:

Failure Recovery (if this breaks)

• How to disable/revert this change quickly: revert commit 0d76f9fbb.
• Files/config to restore:
  • src/auto-reply/reply/dispatch-from-config.ts
  • src/discord/monitor/message-handler.process.ts
• Known bad symptoms reviewers should watch for:
  • duplicate/missing message:received internal hook events.

Risks and Mitigations

List only real risks for this PR. Add/remove entries as needed. If none, write None.

• Risk: fallback session-key resolution could emit a hook in cases that previously skipped.
  • Mitigation: added focused regression tests for both fallback paths and left default behavior unchanged when no key is available.