fix(coding-agent): process BMP images from disk

closes #6047

packages/coding-agent/test/block-images.test.ts

@@ -10,6 +10,22 @@ import { createReadTool } from "../src/core/tools/read.ts";
 const TINY_PNG_BASE64 =
 	"iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8DwHwAFBQIAX8jx0gAAAABJRU5ErkJggg==";
 
+function createTinyBmp1x1Red24bpp(): Buffer {
+	const buffer = Buffer.alloc(58);
+	buffer.write("BM", 0, "ascii");
+	buffer.writeUInt32LE(buffer.length, 2);
+	buffer.writeUInt32LE(54, 10);
+	buffer.writeUInt32LE(40, 14);
+	buffer.writeInt32LE(1, 18);
+	buffer.writeInt32LE(1, 22);
+	buffer.writeUInt16LE(1, 26);
+	buffer.writeUInt16LE(24, 28);
+	buffer.writeUInt32LE(0, 30);
+	buffer.writeUInt32LE(4, 34);
+	buffer[56] = 0xff;
+	return buffer;
+}
+
 describe("blockImages setting", () => {
 	describe("SettingsManager", () => {
 		it("should default blockImages to false", () => {
@@ -106,6 +122,18 @@ describe("blockImages setting", () => {
 			expect(result.images[0].type).toBe("image");
 		});
 
+		it("should process BMP images from disk as PNG attachments", async () => {
+			const imagePath = join(testDir, "test.bmp");
+			writeFileSync(imagePath, createTinyBmp1x1Red24bpp());
+
+			const result = await processFileArguments([imagePath]);
+
+			expect(result.images).toHaveLength(1);
+			expect(result.images[0].type).toBe("image");
+			expect(result.images[0].mimeType).toBe("image/png");
+			expect(result.text).toContain("[Image converted from image/bmp to image/png.]");
+		});
+
 		it("should process text files normally", async () => {
 			// Create test text file
 			const textPath = join(testDir, "test.txt");

packages/coding-agent/test/image-process.test.ts

@@ -0,0 +1,53 @@
+import { describe, expect, it } from "vitest";
+import { processImage } from "../src/utils/image-process.ts";
+import { detectSupportedImageMimeType } from "../src/utils/mime.ts";
+
+function createTinyBmp1x1Red24bpp(): Buffer {
+	const buffer = Buffer.alloc(58);
+	buffer.write("BM", 0, "ascii");
+	buffer.writeUInt32LE(buffer.length, 2);
+	buffer.writeUInt32LE(54, 10);
+	buffer.writeUInt32LE(40, 14);
+	buffer.writeInt32LE(1, 18);
+	buffer.writeInt32LE(1, 22);
+	buffer.writeUInt16LE(1, 26);
+	buffer.writeUInt16LE(24, 28);
+	buffer.writeUInt32LE(0, 30);
+	buffer.writeUInt32LE(4, 34);
+	buffer[56] = 0xff;
+	return buffer;
+}
+
+function expectPngMagic(base64Data: string): void {
+	const buffer = Buffer.from(base64Data, "base64");
+	expect(buffer[0]).toBe(0x89);
+	expect(buffer[1]).toBe(0x50);
+	expect(buffer[2]).toBe(0x4e);
+	expect(buffer[3]).toBe(0x47);
+}
+
+describe("image processing pipeline", () => {
+	it("detects BMP files from magic bytes", () => {
+		expect(detectSupportedImageMimeType(createTinyBmp1x1Red24bpp())).toBe("image/bmp");
+	});
+
+	it("converts BMP files to PNG attachments when auto-resize is disabled", async () => {
+		const result = await processImage(createTinyBmp1x1Red24bpp(), "image/bmp", { autoResizeImages: false });
+
+		expect(result.ok).toBe(true);
+		if (!result.ok) return;
+		expect(result.mimeType).toBe("image/png");
+		expect(result.hints).toContain("[Image converted from image/bmp to image/png.]");
+		expectPngMagic(result.data);
+	});
+
+	it("converts BMP files before auto-resizing", async () => {
+		const result = await processImage(createTinyBmp1x1Red24bpp(), "image/bmp");
+
+		expect(result.ok).toBe(true);
+		if (!result.ok) return;
+		expect(result.mimeType).toBe("image/png");
+		expect(result.hints).toContain("[Image converted from image/bmp to image/png.]");
+		expectPngMagic(result.data);
+	});
+});

packages/coding-agent/test/tools.test.ts

@@ -34,6 +34,22 @@ function getTextOutput(result: any): string {
 	);
 }
 
+function createTinyBmp1x1Red24bpp(): Buffer {
+	const buffer = Buffer.alloc(58);
+	buffer.write("BM", 0, "ascii");
+	buffer.writeUInt32LE(buffer.length, 2);
+	buffer.writeUInt32LE(54, 10);
+	buffer.writeUInt32LE(40, 14);
+	buffer.writeInt32LE(1, 18);
+	buffer.writeInt32LE(1, 22);
+	buffer.writeUInt16LE(1, 26);
+	buffer.writeUInt16LE(24, 28);
+	buffer.writeUInt32LE(0, 30);
+	buffer.writeUInt32LE(4, 34);
+	buffer[56] = 0xff;
+	return buffer;
+}
+
 describe("Coding Agent Tools", () => {
 	let testDir: string;
 
@@ -191,6 +207,24 @@ describe("Coding Agent Tools", () => {
 			expect((imageBlock?.data ?? "").length).toBeGreaterThan(0);
 		});
 
+		it("should read BMP files from disk as PNG image attachments", async () => {
+			const testFile = join(testDir, "image.bmp");
+			writeFileSync(testFile, createTinyBmp1x1Red24bpp());
+
+			const result = await readTool.execute("test-call-img-bmp", { path: testFile });
+
+			expect(result.content[0]?.type).toBe("text");
+			expect(getTextOutput(result)).toContain("Read image file [image/png]");
+			expect(getTextOutput(result)).toContain("[Image converted from image/bmp to image/png.]");
+
+			const imageBlock = result.content.find(
+				(c): c is { type: "image"; mimeType: string; data: string } => c.type === "image",
+			);
+			expect(imageBlock).toBeDefined();
+			expect(imageBlock?.mimeType).toBe("image/png");
+			expect(Buffer.from(imageBlock?.data ?? "", "base64")[0]).toBe(0x89);
+		});
+
 		it("should treat files with image extension but non-image content as text", async () => {
 			const testFile = join(testDir, "not-an-image.png");
 			writeFileSync(testFile, "definitely not a png");