fix(agent-core): preserve empty prompt arguments (#96405)

lin-hongkuan · web-flow · commit c030b305a444 · 2026-06-25T16:25:52.000+08:00
diff --git a/packages/agent-core/src/harness/prompt-template-arguments.test.ts b/packages/agent-core/src/harness/prompt-template-arguments.test.ts
@@ -0,0 +1,11 @@
+// Agent Core tests cover prompt template argument parsing behavior.
+import { describe, expect, it } from "vitest";
+import { parseCommandArgs, substituteArgs } from "./prompt-template-arguments.js";
+
+describe("prompt template arguments", () => {
+  it("preserves quoted empty arguments so positional placeholders stay aligned", () => {
+    expect(parseCommandArgs('first "" third')).toEqual(["first", "", "third"]);
+    expect(parseCommandArgs("first '' third")).toEqual(["first", "", "third"]);
+    expect(substituteArgs("$1|$2|$3", parseCommandArgs('first "" third'))).toBe("first||third");
+  });
+});
diff --git a/packages/agent-core/src/harness/prompt-template-arguments.ts b/packages/agent-core/src/harness/prompt-template-arguments.ts
@@ -5,26 +5,31 @@ export function parseCommandArgs(argsString: string): string[] {
   const args: string[] = [];
   let current = "";
   let inQuote: string | null = null;
+  let hasToken = false;
 
   for (const char of argsString) {
     if (inQuote) {
       if (char === inQuote) {
         inQuote = null;
       } else {
+        hasToken = true;
         current += char;
       }
     } else if (char === '"' || char === "'") {
+      hasToken = true;
       inQuote = char;
     } else if (/\s/.test(char)) {
-      if (current) {
+      if (hasToken) {
         args.push(current);
         current = "";
+        hasToken = false;
       }
     } else {
+      hasToken = true;
       current += char;
     }
   }
-  if (current) {
+  if (hasToken) {
     args.push(current);
   }
   return args;
