From 135df948d8f5b9b25ff7d02cf5844e2df82f938b Mon Sep 17 00:00:00 2001
From: Aniruddha Adak <adakaniruddha9@gmail.com>
Date: Thu, 17 Sep 2026 03:46:12 +0530
Subject: [PATCH] fix(agents): emit a single delta when copilot/qwen/bob repeat
 a payload across fields

---
 next/src/lib/agents/__tests__/argv.test.ts | 61 ++++++++++++++++++++++
 next/src/lib/agents/argv.ts                | 29 +++++++---
 2 files changed, 82 insertions(+), 8 deletions(-)

diff --git a/next/src/lib/agents/__tests__/argv.test.ts b/next/src/lib/agents/__tests__/argv.test.ts
index 449277d9..6130c647 100644
--- a/next/src/lib/agents/__tests__/argv.test.ts
+++ b/next/src/lib/agents/__tests__/argv.test.ts
@@ -163,6 +163,39 @@ describe("parseLine opencode", () => {
   });
 });
 
+describe("parseLine copilot", () => {
+  it("emits a single delta when response and text repeat one payload", () => {
+    const line = JSON.stringify({
+      response: "<html><body>Hello</body></html>",
+      text: "<html><body>Hello</body></html>",
+    });
+
+    expect(parseLine("copilot", line)).toEqual([
+      {
+        kind: "delta",
+        text: "<html><body>Hello</body></html>",
+      },
+    ]);
+  });
+});
+
+describe("parseLine qwen", () => {
+  it("emits a single delta when text, content, and message repeat one payload", () => {
+    const line = JSON.stringify({
+      text: "<html><body>Hello</body></html>",
+      content: "<html><body>Hello</body></html>",
+      message: "<html><body>Hello</body></html>",
+    });
+
+    expect(parseLine("qwen", line)).toEqual([
+      {
+        kind: "delta",
+        text: "<html><body>Hello</body></html>",
+      },
+    ]);
+  });
+});
+
 describe("parseLine bob", () => {
   it("extracts text from stream-json output", () => {
     const line = JSON.stringify({
@@ -203,6 +236,34 @@ describe("parseLine bob", () => {
     ]);
   });
 
+  it("emits a single delta when text, content, and message repeat one payload", () => {
+    // Some CLIs echo the turn payload under several keys at once. Emitting
+    // one delta per key appends the same HTML two or three times.
+    const line = JSON.stringify({
+      text: "<html><body>Hello</body></html>",
+      content: "<html><body>Hello</body></html>",
+      message: "<html><body>Hello</body></html>",
+    });
+
+    expect(parseLine("bob", line)).toEqual([
+      {
+        kind: "delta",
+        text: "<html><body>Hello</body></html>",
+      },
+    ]);
+  });
+
+  it("falls back to the next populated field when the first is empty", () => {
+    const line = JSON.stringify({ text: "", content: "<html><body>Hi</body></html>" });
+
+    expect(parseLine("bob", line)).toEqual([
+      {
+        kind: "delta",
+        text: "<html><body>Hi</body></html>",
+      },
+    ]);
+  });
+
   it("handles final answer after thinking when --hide-intermediary-output is used", () => {
     // When --hide-intermediary-output is enabled, Bob only emits the final answer.
     // This test verifies that the parser correctly handles the final completion.
diff --git a/next/src/lib/agents/argv.ts b/next/src/lib/agents/argv.ts
index f92b6b59..380fafd6 100644
--- a/next/src/lib/agents/argv.ts
+++ b/next/src/lib/agents/argv.ts
@@ -372,8 +372,13 @@ function parseLineWithState(agent: string, line: string, state: ParseState): Age
   }
 
   if (agent === "copilot") {
-    if (typeof obj.response === "string") out.push({ kind: "delta", text: obj.response });
-    if (typeof obj.text === "string") out.push({ kind: "delta", text: obj.text });
+    // Copilot can echo the turn payload under both `response` and `text`.
+    // Emit a single delta (first populated field wins), like the opencode
+    // single-pick below — otherwise the same HTML is appended twice.
+    const text = [obj.response, obj.text].find(
+      (value): value is string => typeof value === "string" && value.length > 0,
+    );
+    if (text) out.push({ kind: "delta", text });
   }
 
   if (agent === "opencode") {
@@ -417,15 +422,23 @@ function parseLineWithState(agent: string, line: string, state: ParseState): Age
   }
 
   if (agent === "qwen") {
-    if (typeof obj.text === "string") out.push({ kind: "delta", text: obj.text });
-    if (typeof obj.content === "string") out.push({ kind: "delta", text: obj.content });
-    if (typeof obj.message === "string") out.push({ kind: "delta", text: obj.message });
+    // Qwen can echo the turn payload under `text`, `content`, and `message`
+    // at once. Emit a single delta (first populated field wins), like the
+    // opencode single-pick above — otherwise the same HTML is appended up to
+    // three times.
+    const text = [obj.text, obj.content, obj.message].find(
+      (value): value is string => typeof value === "string" && value.length > 0,
+    );
+    if (text) out.push({ kind: "delta", text });
   }
 
   if (agent === "bob") {
-    if (typeof obj.text === "string") out.push({ kind: "delta", text: obj.text });
-    if (typeof obj.content === "string") out.push({ kind: "delta", text: obj.content });
-    if (typeof obj.message === "string") out.push({ kind: "delta", text: obj.message });
+    // Same single-pick as qwen: Bob repeats the completion across `text`,
+    // `content`, and `message` on some stream-json lines.
+    const text = [obj.text, obj.content, obj.message].find(
+      (value): value is string => typeof value === "string" && value.length > 0,
+    );
+    if (text) out.push({ kind: "delta", text });
   }
 
   if (agent === "qoder") {