From 5391928e2e91fb7a77d0575b9d660ad327c2bedc Mon Sep 17 00:00:00 2001
From: "ScrewTSW (public-projects)" <thescrewcollab@gmail.com>
Date: Tue, 18 Aug 2026 22:48:08 +0200
Subject: [PATCH] fix(gui): don't drop batched messages after a <think> block

The `<think>...</think>` fast-path in the `streamUpdate` reducer ended in
`return` rather than `continue`. Since it sits inside a
`for (const message of action.payload)` loop, returning exits the reducer
entirely and silently discards every remaining message in the batch, not
just the one being handled.

The sibling early-exit for redacted thinking uses `continue`, and nothing
runs after the loop, so `continue` is the intended control flow here.

This went unnoticed because every existing `streamUpdate` test dispatches a
single-element payload, where `return` and `continue` are indistinguishable.
The added test uses a two-message payload and fails on `return`.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
---
 gui/src/redux/slices/sessionSlice.test.ts | 26 +++++++++++++++++++++++
 gui/src/redux/slices/sessionSlice.ts      |  6 +++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/gui/src/redux/slices/sessionSlice.test.ts b/gui/src/redux/slices/sessionSlice.test.ts
index e933d1dd879..a32a2ab5e15 100644
--- a/gui/src/redux/slices/sessionSlice.test.ts
+++ b/gui/src/redux/slices/sessionSlice.test.ts
@@ -133,6 +133,32 @@ describe("sessionSlice streamUpdate", () => {
       );
       expect(newState.history[1].message.id).toBe("mock-uuid-1");
     });
+
+    it("should not drop later messages in a batch after a <think> block", () => {
+      const initialState = createInitialState();
+      const action = {
+        type: "session/streamUpdate",
+        payload: [
+          {
+            role: "assistant" as const,
+            content: "<think>Reasoning here.</think>First part.",
+          },
+          {
+            role: "assistant" as const,
+            content: " Second part.",
+          },
+        ],
+      };
+
+      const newState = sessionSlice.reducer(initialState, action);
+
+      expect(newState.history[0].reasoning?.text).toBe("Reasoning here.");
+
+      // The second message in the same payload must still be appended.
+      expect(newState.history[1].message.content).toBe(
+        "First part. Second part.",
+      );
+    });
   });
 
   describe("Tool Call With Response", () => {
diff --git a/gui/src/redux/slices/sessionSlice.ts b/gui/src/redux/slices/sessionSlice.ts
index 8784d0c41dc..60eccf02145 100644
--- a/gui/src/redux/slices/sessionSlice.ts
+++ b/gui/src/redux/slices/sessionSlice.ts
@@ -580,7 +580,11 @@ export const sessionSlice = createSlice({
 
               handleToolCallsInMessage(message, lastItem);
 
-              return;
+              // `continue`, not `return`: this branch has finished handling
+              // *this* message, but `action.payload` may contain more. A
+              // `return` here exits the reducer entirely and silently drops
+              // every remaining message in the batch.
+              continue;
             }
           }