fix(coding-agent): merge piped stdin into initial prompt closes #2315

packages/coding-agent/test/initial-message.test.ts

@@ -0,0 +1,47 @@
+import { describe, expect, test } from "vitest";
+import type { Args } from "../src/cli/args.js";
+import { buildInitialMessage } from "../src/cli/initial-message.js";
+
+function createArgs(messages: string[] = []): Args {
+	return {
+		messages: [...messages],
+		fileArgs: [],
+		unknownFlags: new Map(),
+	};
+}
+
+describe("buildInitialMessage", () => {
+	test("merges piped stdin with the first CLI message into one prompt", () => {
+		const parsed = createArgs(["Summarize the text given"]);
+		const result = buildInitialMessage({
+			parsed,
+			stdinContent: "README contents\n",
+		});
+
+		expect(result.initialMessage).toBe("README contents\nSummarize the text given");
+		expect(parsed.messages).toEqual([]);
+	});
+
+	test("uses stdin as the initial prompt when no CLI message is present", () => {
+		const parsed = createArgs();
+		const result = buildInitialMessage({
+			parsed,
+			stdinContent: "README contents",
+		});
+
+		expect(result.initialMessage).toBe("README contents");
+		expect(parsed.messages).toEqual([]);
+	});
+
+	test("combines stdin, file text, and first CLI message in one prompt", () => {
+		const parsed = createArgs(["Explain it", "Second message"]);
+		const result = buildInitialMessage({
+			parsed,
+			stdinContent: "stdin\n",
+			fileText: "file\n",
+		});
+
+		expect(result.initialMessage).toBe("stdin\nfile\nExplain it");
+		expect(parsed.messages).toEqual(["Second message"]);
+	});
+});