diff --git a/next/src/lib/agents/__tests__/argv.test.ts b/next/src/lib/agents/__tests__/argv.test.ts
new file mode 100644
index 0000000..28cefc9
--- /dev/null
+++ b/next/src/lib/agents/__tests__/argv.test.ts
@@ -0,0 +1,106 @@
+import { describe, expect, it } from "vitest";
+import { parseLine, makeParser } from "../argv";
+
+function deltas(result: ReturnType<typeof parseLine>) {
+  return result.filter((r) => r.kind === "delta").map((r) => r.text);
+}
+
+describe("parseLine (opencode)", () => {
+  it("extracts text from singular part.text envelope", () => {
+    const line = JSON.stringify({
+      type: "text",
+      part: { type: "text", text: "hello world" },
+    });
+    expect(deltas(parseLine("opencode", line))).toEqual(["hello world"]);
+  });
+
+  it("extracts text from parts[].text array envelope", () => {
+    const line = JSON.stringify({
+      type: "text",
+      parts: [
+        { type: "text", text: "hello " },
+        { type: "text", text: "world" },
+      ],
+    });
+    expect(deltas(parseLine("opencode", line))).toEqual(["hello ", "world"]);
+  });
+
+  it("extracts text from top-level text field", () => {
+    const line = JSON.stringify({ text: "top-level content" });
+    expect(deltas(parseLine("opencode", line))).toContain("top-level content");
+  });
+
+  it("extracts text from top-level content field", () => {
+    const line = JSON.stringify({ content: "content field" });
+    expect(deltas(parseLine("opencode", line))).toContain("content field");
+  });
+
+  it("extracts text from top-level message field", () => {
+    const line = JSON.stringify({ message: "message field" });
+    expect(deltas(parseLine("opencode", line))).toContain("message field");
+  });
+
+  it("produces no non-empty delta when all text fields are empty", () => {
+    const line = JSON.stringify({
+      type: "text",
+      text: "",
+      content: "",
+      message: "",
+      part: { type: "text", text: "" },
+    });
+    expect(deltas(parseLine("opencode", line)).filter(Boolean)).toEqual([]);
+  });
+
+  it("handles empty top-level fields with content in part.text (regression #67)", () => {
+    const line = JSON.stringify({
+      type: "text",
+      text: "",
+      content: "",
+      message: "",
+      part: {
+        type: "text",
+        text: "# 春之声\n\n三月的风是软的。",
+      },
+    });
+    expect(deltas(parseLine("opencode", line))).toContain(
+      "# 春之声\n\n三月的风是软的。",
+    );
+  });
+});
+
+describe("parseLine (qwen)", () => {
+  it("extracts text from singular part.text envelope", () => {
+    const line = JSON.stringify({
+      type: "text",
+      part: { type: "text", text: "qwen output" },
+    });
+    expect(deltas(parseLine("qwen", line))).toEqual(["qwen output"]);
+  });
+
+  it("extracts text from parts[].text array envelope", () => {
+    const line = JSON.stringify({
+      parts: [{ text: "a" }, { text: "b" }],
+    });
+    expect(deltas(parseLine("qwen", line))).toEqual(["a", "b"]);
+  });
+});
+
+describe("makeParser (opencode) multi-line streaming", () => {
+  it("accumulates deltas across multiple lines", () => {
+    const parse = makeParser("opencode");
+    parse(
+      JSON.stringify({ type: "step_start", part: { type: "step-start" } }),
+    );
+    const r2 = parse(
+      JSON.stringify({ type: "text", part: { type: "text", text: "hello" } }),
+    );
+    const r3 = parse(
+      JSON.stringify({
+        type: "text",
+        part: { type: "text", text: " world" },
+      }),
+    );
+    expect(deltas(r2)).toEqual(["hello"]);
+    expect(deltas(r3)).toEqual([" world"]);
+  });
+});
diff --git a/next/src/lib/agents/argv.ts b/next/src/lib/agents/argv.ts
index c6cc169..21d3b14 100644
--- a/next/src/lib/agents/argv.ts
+++ b/next/src/lib/agents/argv.ts
@@ -366,6 +366,14 @@ function parseLineWithState(agent: string, line: string, state: ParseState): Age
     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 });
+    if (Array.isArray(obj.parts)) {
+      for (const part of obj.parts) {
+        if (typeof part?.text === "string") out.push({ kind: "delta", text: part.text });
+      }
+    }
+    if (obj.type === "text" && typeof obj.part?.text === "string") {
+      out.push({ kind: "delta", text: obj.part.text });
+    }
   }
 
   if (agent === "qoder") {