fix: harden outbound mirroring normalization

src/infra/outbound/message-action-runner.threading.test.ts

@@ -89,4 +89,30 @@ describe("runMessageAction Slack threading", () => {
     const call = mocks.executeSendAction.mock.calls[0]?.[0];
     expect(call?.ctx?.mirror?.sessionKey).toBe("agent:main:slack:channel:c123:thread:111.222");
   });
+
+  it("matches auto-threading when channel ids differ in case", async () => {
+    mocks.executeSendAction.mockResolvedValue({
+      handledBy: "plugin",
+      payload: {},
+    });
+
+    await runMessageAction({
+      cfg: slackConfig,
+      action: "send",
+      params: {
+        channel: "slack",
+        target: "channel:c123",
+        message: "hi",
+      },
+      toolContext: {
+        currentChannelId: "C123",
+        currentThreadTs: "333.444",
+        replyToMode: "all",
+      },
+      agentId: "main",
+    });
+
+    const call = mocks.executeSendAction.mock.calls[0]?.[0];
+    expect(call?.ctx?.mirror?.sessionKey).toBe("agent:main:slack:channel:c123:thread:333.444");
+  });
 });

src/infra/outbound/message-action-runner.ts

@@ -217,7 +217,7 @@ function resolveSlackAutoThreadId(params: {
   if (context.replyToMode !== "all" && context.replyToMode !== "first") return undefined;
   const parsedTarget = parseSlackTarget(params.to, { defaultKind: "channel" });
   if (!parsedTarget || parsedTarget.kind !== "channel") return undefined;
-  if (parsedTarget.id !== context.currentChannelId) return undefined;
+  if (parsedTarget.id.toLowerCase() !== context.currentChannelId.toLowerCase()) return undefined;
   if (context.replyToMode === "first" && context.hasRepliedRef?.value) return undefined;
   return context.currentThreadTs;
 }