Fix non-PNG images not displaying in Kitty protocol terminals

JPEG/GIF/WebP images were not rendering in terminals using the Kitty
graphics protocol (Kitty, Ghostty, WezTerm) because it requires PNG
format (f=100). Non-PNG images are now converted to PNG using sharp
before being sent to the terminal.

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- JPEG/GIF/WebP images not displaying in terminals using Kitty graphics protocol (Kitty, Ghostty, WezTerm). The protocol requires PNG format, so non-PNG images are now converted before display.
+
 ## [0.32.2] - 2026-01-03
 
 ### Added

packages/coding-agent/src/modes/interactive/components/tool-execution.ts

@@ -14,6 +14,7 @@ import stripAnsi from "strip-ansi";
 import type { CustomTool } from "../../../core/custom-tools/types.js";
 import { computeEditDiff, type EditDiffError, type EditDiffResult } from "../../../core/tools/edit-diff.js";
 import { DEFAULT_MAX_BYTES, DEFAULT_MAX_LINES, formatSize } from "../../../core/tools/truncate.js";
+import { convertToPng } from "../../../utils/image-convert.js";
 import { sanitizeBinaryOutput } from "../../../utils/shell.js";
 import { getLanguageFromPath, highlightCode, theme } from "../theme/theme.js";
 import { renderDiff } from "./diff.js";
@@ -68,6 +69,8 @@ export class ToolExecutionComponent extends Container {
 	// Cached edit diff preview (computed when args arrive, before tool executes)
 	private editDiffPreview?: EditDiffResult | EditDiffError;
 	private editDiffArgsKey?: string; // Track which args the preview is for
+	// Cached converted images for Kitty protocol (which requires PNG), keyed by index
+	private convertedImages: Map<number, { data: string; mimeType: string }> = new Map();
 
 	constructor(
 		toolName: string,
@@ -157,6 +160,39 @@ export class ToolExecutionComponent extends Container {
 		this.result = result;
 		this.isPartial = isPartial;
 		this.updateDisplay();
+		// Convert non-PNG images to PNG for Kitty protocol (async)
+		this.maybeConvertImagesForKitty();
+	}
+
+	/**
+	 * Convert non-PNG images to PNG for Kitty graphics protocol.
+	 * Kitty requires PNG format (f=100), so JPEG/GIF/WebP won't display.
+	 */
+	private maybeConvertImagesForKitty(): void {
+		const caps = getCapabilities();
+		// Only needed for Kitty protocol
+		if (caps.images !== "kitty") return;
+		if (!this.result) return;
+
+		const imageBlocks = this.result.content?.filter((c: any) => c.type === "image") || [];
+
+		for (let i = 0; i < imageBlocks.length; i++) {
+			const img = imageBlocks[i];
+			if (!img.data || !img.mimeType) continue;
+			// Skip if already PNG or already converted
+			if (img.mimeType === "image/png") continue;
+			if (this.convertedImages.has(i)) continue;
+
+			// Convert async
+			const index = i;
+			convertToPng(img.data, img.mimeType).then((converted) => {
+				if (converted) {
+					this.convertedImages.set(index, converted);
+					this.updateDisplay();
+					this.ui.requestRender();
+				}
+			});
+		}
 	}
 
 	setExpanded(expanded: boolean): void {
@@ -249,14 +285,25 @@ export class ToolExecutionComponent extends Container {
 			const imageBlocks = this.result.content?.filter((c: any) => c.type === "image") || [];
 			const caps = getCapabilities();
 
-			for (const img of imageBlocks) {
+			for (let i = 0; i < imageBlocks.length; i++) {
+				const img = imageBlocks[i];
 				if (caps.images && this.showImages && img.data && img.mimeType) {
+					// Use converted PNG for Kitty protocol if available
+					const converted = this.convertedImages.get(i);
+					const imageData = converted?.data ?? img.data;
+					const imageMimeType = converted?.mimeType ?? img.mimeType;
+
+					// For Kitty, skip non-PNG images that haven't been converted yet
+					if (caps.images === "kitty" && imageMimeType !== "image/png") {
+						continue;
+					}
+
 					const spacer = new Spacer(1);
 					this.addChild(spacer);
 					this.imageSpacers.push(spacer);
 					const imageComponent = new Image(
-						img.data,
+						imageData,
-						img.mimeType,
+						imageMimeType,
 						{ fallbackColor: (s: string) => theme.fg("toolOutput", s) },
 						{ maxWidthCells: 60 },
 					);

packages/coding-agent/src/utils/image-convert.ts

@@ -0,0 +1,26 @@
+/**
+ * Convert image to PNG format for terminal display.
+ * Kitty graphics protocol requires PNG format (f=100).
+ */
+export async function convertToPng(
+	base64Data: string,
+	mimeType: string,
+): Promise<{ data: string; mimeType: string } | null> {
+	// Already PNG, no conversion needed
+	if (mimeType === "image/png") {
+		return { data: base64Data, mimeType };
+	}
+
+	try {
+		const sharp = (await import("sharp")).default;
+		const buffer = Buffer.from(base64Data, "base64");
+		const pngBuffer = await sharp(buffer).png().toBuffer();
+		return {
+			data: pngBuffer.toString("base64"),
+			mimeType: "image/png",
+		};
+	} catch {
+		// Sharp not available or conversion failed
+		return null;
+	}
+}