fix: avoid repeated discord thread starter context

CHANGELOG.md

@@ -48,6 +48,7 @@ Docs: https://docs.openclaw.ai
 - Discord: preserve attachment and sticker filenames when saving inbound media, so agents can see human-readable file names instead of only UUID-based paths. Fixes #59744. Thanks @xela92 and @rockcent.
 - Discord: preserve non-ASCII channel names in session display labels while keeping allowlist matching on the existing ASCII slug contract. Thanks @swjeong9.
 - Discord/PluralKit: canonicalize proxied webhook turns to the original Discord message id for inbound dedupe, while preserving the proxy message id for reply routing. Thanks @acgh213.
+- Discord: only inject thread starter context on the first turn of the effective thread session, so follow-up thread replies do not repeat the starter block. Fixes #41355; supersedes #44447 and #44449. Thanks @p3nchan.
 - Gateway/diagnostics: include a bounded redacted startup error message in stability bundles, so crash-loop reports identify the failing plugin or contract without exposing secrets. Refs #75797. Thanks @ymebosma.
 - Gateway/pricing: abort in-flight model pricing catalog fetches when Gateway shutdown stops the refresh loop, and avoid post-stop cache writes or refresh timers. Fixes #72208. Thanks @rzcq.
 - Codex/app-server: make startup retry cleanup ownership-aware so concurrent Codex lanes cannot close another lane's freshly restarted shared app-server client. Thanks @vincentkoc.

extensions/discord/src/monitor/message-handler.context.ts

@@ -296,6 +296,15 @@ export async function buildDiscordMessageProcessContext(params: {
         }))
       : undefined;
   const originatingTo = autoThreadContext?.OriginatingTo ?? dmConversationTarget ?? replyTarget;
+  const effectiveSessionKey =
+    boundSessionKey ?? autoThreadContext?.SessionKey ?? threadKeys.sessionKey;
+  const effectivePreviousTimestamp =
+    effectiveSessionKey === route.sessionKey
+      ? previousTimestamp
+      : readSessionUpdatedAt({
+          storePath,
+          sessionKey: effectiveSessionKey,
+        });
 
   const ctxPayload = finalizeInboundContext({
     Body: combinedBody,
@@ -306,7 +315,7 @@ export async function buildDiscordMessageProcessContext(params: {
     ...(preflightAudioTranscript !== undefined ? { Transcript: preflightAudioTranscript } : {}),
     From: effectiveFrom,
     To: effectiveTo,
-    SessionKey: boundSessionKey ?? autoThreadContext?.SessionKey ?? threadKeys.sessionKey,
+    SessionKey: effectiveSessionKey,
     AccountId: route.accountId,
     ChatType: isDirectMessage ? "direct" : "channel",
     ConversationLabel: fromLabel,
@@ -335,7 +344,7 @@ export async function buildDiscordMessageProcessContext(params: {
     ModelParentSessionKey:
       autoThreadContext?.ModelParentSessionKey ?? modelParentSessionKey ?? undefined,
     MessageThreadId: threadChannel?.id ?? autoThreadContext?.createdThreadId ?? undefined,
-    ThreadStarterBody: threadStarterBody,
+    ThreadStarterBody: !effectivePreviousTimestamp ? threadStarterBody : undefined,
     ThreadLabel: threadLabel,
     Timestamp: resolveTimestampMs(message.timestamp),
     ...mediaPayload,

extensions/discord/src/monitor/message-handler.process.test.ts

@@ -364,6 +364,7 @@ function getLastDispatchCtx():
       OriginatingTo?: string;
       ParentSessionKey?: string;
       SessionKey?: string;
+      ThreadStarterBody?: string;
       To?: string;
       Transcript?: string;
     }
@@ -384,6 +385,7 @@ function getLastDispatchCtx():
           OriginatingTo?: string;
           ParentSessionKey?: string;
           SessionKey?: string;
+          ThreadStarterBody?: string;
           To?: string;
           Transcript?: string;
         };
@@ -1053,6 +1055,49 @@ describe("processDiscordMessage session routing", () => {
     });
     expect(getLastDispatchCtx()?.ParentSessionKey).toBeUndefined();
   });
+
+  it("omits thread starter context when the effective thread session already exists", async () => {
+    const threadSessionKey = "agent:main:discord:channel:thread-1";
+    readSessionUpdatedAt.mockImplementation((params?: unknown) => {
+      const sessionKey = (params as { sessionKey?: string } | undefined)?.sessionKey;
+      return sessionKey === threadSessionKey ? 1_700_000_000_000 : undefined;
+    });
+    const rest = {
+      get: vi.fn(async () => ({
+        content: "original thread starter",
+        embeds: [],
+        author: { id: "U2", username: "bob", discriminator: "0" },
+        timestamp: new Date().toISOString(),
+      })),
+    };
+    const ctx = await createBaseContext({
+      baseSessionKey: threadSessionKey,
+      route: BASE_CHANNEL_ROUTE,
+      messageChannelId: "thread-1",
+      message: {
+        id: "m1",
+        channelId: "thread-1",
+        content: "follow-up",
+        timestamp: new Date().toISOString(),
+        attachments: [],
+      },
+      messageText: "follow-up",
+      baseText: "follow-up",
+      threadChannel: { id: "thread-1", name: "child-thread" },
+      threadParentId: "parent-1",
+      client: { rest },
+      channelConfig: { allowed: true, users: ["U2"] },
+    });
+
+    await runProcessDiscordMessage(ctx);
+
+    expect(rest.get).toHaveBeenCalled();
+    expect(getLastDispatchCtx()).toMatchObject({
+      SessionKey: threadSessionKey,
+      MessageThreadId: "thread-1",
+    });
+    expect(getLastDispatchCtx()?.ThreadStarterBody).toBeUndefined();
+  });
 });
 
 describe("processDiscordMessage draft streaming", () => {