Outbound Session Mirroring Refactor (Issue #1520)

Status

• In progress.
• Core + plugin channel routing updated for outbound mirroring.
• Gateway send now derives target session when sessionKey is omitted.

Context

Outbound sends were mirrored into the current agent session (tool session key) rather than the target channel session. Inbound routing uses channel/peer session keys, so outbound responses landed in the wrong session and first-contact targets often lacked session entries.

Goals

• Mirror outbound messages into the target channel session key.
• Create session entries on outbound when missing.
• Keep thread/topic scoping aligned with inbound session keys.
• Cover core channels plus bundled extensions.

Implementation Summary

• New outbound session routing helper:
  • src/infra/outbound/outbound-session.ts
  • resolveOutboundSessionRoute builds target sessionKey using buildAgentSessionKey (dmScope + identityLinks).
  • ensureOutboundSessionEntry writes minimal MsgContext via recordSessionMetaFromInbound.
• runMessageAction (send) derives target sessionKey and passes it to executeSendAction for mirroring.
• message-tool no longer mirrors directly; it only resolves agentId from the current session key.
• Plugin send path mirrors via appendAssistantMessageToSessionTranscript using the derived sessionKey.
• Gateway send derives a target session key when none is provided (default agent), and ensures a session entry.

Thread/Topic Handling

• Slack: replyTo/threadId -> resolveThreadSessionKeys (suffix).
• Discord: threadId/replyTo -> resolveThreadSessionKeys with useSuffix=false to match inbound (thread channel id already scopes session).
• Telegram: topic IDs map to chatId:topic:<id> via buildTelegramGroupPeerId.

Extensions Covered

• Matrix, MS Teams, Mattermost, BlueBubbles, Nextcloud Talk, Zalo, Zalo Personal, Nostr, Tlon.
• Notes:
  • Mattermost targets now strip @ for DM session key routing.
  • Zalo Personal uses DM peer kind for 1:1 targets (group only when group: is present).
  • BlueBubbles group targets strip chat_* prefixes to match inbound session keys.
  • Slack auto-thread mirroring matches channel ids case-insensitively.
  • Gateway send lowercases provided session keys before mirroring.

Decisions

• Gateway send session derivation: if sessionKey is provided, use it. If omitted, derive a sessionKey from target + default agent and mirror there.
• Session entry creation: always use recordSessionMetaFromInbound with Provider/From/To/ChatType/AccountId/Originating* aligned to inbound formats.
• Target normalization: outbound routing uses resolved targets (post resolveChannelTarget) when available.
• Session key casing: canonicalize session keys to lowercase on write and during migrations.

Tests Added/Updated

• src/infra/outbound/outbound-session.test.ts
  • Slack thread session key.
  • Telegram topic session key.
  • dmScope identityLinks with Discord.
• src/agents/tools/message-tool.test.ts
  • Derives agentId from session key (no sessionKey passed through).
• src/gateway/server-methods/send.test.ts
  • Derives session key when omitted and creates session entry.

Open Items / Follow-ups

• Voice-call plugin uses custom voice:<phone> session keys. Outbound mapping is not standardized here; if message-tool should support voice-call sends, add explicit mapping.
• Confirm if any external plugin uses non-standard From/To formats beyond the bundled set.

Files Touched

• src/infra/outbound/outbound-session.ts
• src/infra/outbound/outbound-send-service.ts
• src/infra/outbound/message-action-runner.ts
• src/agents/tools/message-tool.ts
• src/gateway/server-methods/send.ts
• Tests in:
  • src/infra/outbound/outbound-session.test.ts
  • src/agents/tools/message-tool.test.ts
  • src/gateway/server-methods/send.test.ts