fix: trim repeated slack thread context payloads (#32133) (thanks @sourman)

CHANGELOG.md

@@ -63,6 +63,7 @@ Docs: https://docs.openclaw.ai
 - WhatsApp/inbound self-message context: propagate inbound `fromMe` through the web inbox pipeline and annotate direct self messages as `(self)` in envelopes so agents can distinguish owner-authored turns from contact turns. (#32167) Thanks @scoootscooob.
 - Exec approvals/allowlist matching: escape regex metacharacters in path-pattern literals (while preserving glob wildcards), preventing crashes on allowlisted executables like `/usr/bin/g++` and correctly matching mixed wildcard/literal token paths. (#32162) Thanks @stakeswky.
 - Agents/tool-result guard: always clear pending tool-call state on interruptions even when synthetic tool results are disabled, preventing orphaned tool-use transcripts that cause follow-up provider request failures. (#32120) Thanks @jnMetaCode.
+- Slack/thread context payloads: only inject thread starter/history text on first thread turn for new sessions while preserving thread metadata, reducing repeated context-token bloat on long-lived thread sessions. (#32133) Thanks @sourman.
 - Webchat/stream finalization: persist streamed assistant text when final events omit `message`, while keeping final payload precedence and skipping empty stream buffers to prevent disappearing replies after tool turns. (#31920) Thanks @Sid-Qin.
 - Cron/store migration: normalize legacy cron jobs with string `schedule` and top-level `command`/`timeout` fields into canonical schedule/payload/session-target shape on load, preventing schedule-error loops on old persisted stores. (#31926) Thanks @bmendonca3.
 - Gateway/Heartbeat model reload: treat `models.*` and `agents.defaults.model` config updates as heartbeat hot-reload triggers so heartbeat picks up model changes without a full gateway restart. (#32046) Thanks @stakeswky.

src/slack/monitor/message-handler/prepare.test.ts

@@ -510,6 +510,7 @@ describe("slack prepareSlackMessage inbound contract", () => {
 
     expect(prepared).toBeTruthy();
     expect(prepared!.ctxPayload.IsFirstThreadTurn).toBe(true);
+    expect(prepared!.ctxPayload.ThreadStarterBody).toBe("starter");
     expect(prepared!.ctxPayload.ThreadHistoryBody).toContain("assistant reply");
     expect(prepared!.ctxPayload.ThreadHistoryBody).toContain("follow-up question");
     expect(prepared!.ctxPayload.ThreadHistoryBody).not.toContain("current message");
@@ -558,6 +559,7 @@ describe("slack prepareSlackMessage inbound contract", () => {
     expect(prepared!.ctxPayload.ThreadHistoryBody).toBeUndefined();
     // Thread starter should also be skipped for existing sessions
     expect(prepared!.ctxPayload.ThreadStarterBody).toBeUndefined();
+    expect(prepared!.ctxPayload.ThreadLabel).toContain("Slack thread");
     // Replies API should only be called once (for thread starter lookup, not history)
     expect(replies).toHaveBeenCalledTimes(1);
   });