diff --git a/packages/coding-agent/examples/extensions/README.md b/packages/coding-agent/examples/extensions/README.md
index fb8f3cc4..4cad773e 100644
--- a/packages/coding-agent/examples/extensions/README.md
+++ b/packages/coding-agent/examples/extensions/README.md
@@ -34,6 +34,7 @@ cp permission-gate.ts ~/.pi/agent/extensions/
 | `questionnaire.ts` | Multi-question input with tab bar navigation between questions |
 | `tool-override.ts` | Override built-in tools (e.g., add logging/access control to `read`) |
 | `truncated-tool.ts` | Wraps ripgrep with proper output truncation (50KB/2000 lines) |
+| `antigravity-image-gen.ts` | Generate images via Google Antigravity with optional save-to-disk modes |
 | `ssh.ts` | Delegate all tools to a remote machine via SSH using pluggable operations |
 | `subagent/` | Delegate tasks to specialized subagents with isolated context windows |
 
diff --git a/packages/coding-agent/examples/extensions/antigravity-image-gen.ts b/packages/coding-agent/examples/extensions/antigravity-image-gen.ts
new file mode 100644
index 00000000..e138178b
--- /dev/null
+++ b/packages/coding-agent/examples/extensions/antigravity-image-gen.ts
@@ -0,0 +1,413 @@
+/**
+ * Antigravity Image Generation
+ *
+ * Generates images via Google Antigravity's image models (gemini-3-pro-image, imagen-3).
+ * Returns images as tool result attachments for inline terminal rendering.
+ * Requires OAuth login via /login for google-antigravity.
+ *
+ * Usage:
+ *   "Generate an image of a sunset over mountains"
+ *   "Create a 16:9 wallpaper of a cyberpunk city"
+ *
+ * Save modes (tool param, env var, or config file):
+ *   save=none     - Don't save to disk (default)
+ *   save=project  - Save to <repo>/.pi/generated-images/
+ *   save=global   - Save to ~/.pi/agent/generated-images/
+ *   save=custom   - Save to saveDir param or PI_IMAGE_SAVE_DIR
+ *
+ * Environment variables:
+ *   PI_IMAGE_SAVE_MODE  - Default save mode (none|project|global|custom)
+ *   PI_IMAGE_SAVE_DIR   - Directory for custom save mode
+ *
+ * Config files (project overrides global):
+ *   ~/.pi/agent/extensions/antigravity-image-gen.json
+ *   <repo>/.pi/extensions/antigravity-image-gen.json
+ *   Example: { "save": "global" }
+ */
+
+import { randomUUID } from "node:crypto";
+import { existsSync, readFileSync } from "node:fs";
+import { mkdir, writeFile } from "node:fs/promises";
+import { homedir } from "node:os";
+import { join } from "node:path";
+import { StringEnum } from "@mariozechner/pi-ai";
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+import { type Static, Type } from "@sinclair/typebox";
+
+const PROVIDER = "google-antigravity";
+
+const ASPECT_RATIOS = ["1:1", "2:3", "3:2", "3:4", "4:3", "4:5", "5:4", "9:16", "16:9", "21:9"] as const;
+
+type AspectRatio = (typeof ASPECT_RATIOS)[number];
+
+const DEFAULT_MODEL = "gemini-3-pro-image";
+const DEFAULT_ASPECT_RATIO: AspectRatio = "1:1";
+const DEFAULT_SAVE_MODE = "none";
+
+const SAVE_MODES = ["none", "project", "global", "custom"] as const;
+type SaveMode = (typeof SAVE_MODES)[number];
+
+const ANTIGRAVITY_ENDPOINT = "https://daily-cloudcode-pa.sandbox.googleapis.com";
+
+const ANTIGRAVITY_HEADERS = {
+	"User-Agent": "antigravity/1.11.5 darwin/arm64",
+	"X-Goog-Api-Client": "google-cloud-sdk vscode_cloudshelleditor/0.1",
+	"Client-Metadata": JSON.stringify({
+		ideType: "IDE_UNSPECIFIED",
+		platform: "PLATFORM_UNSPECIFIED",
+		pluginType: "GEMINI",
+	}),
+};
+
+const IMAGE_SYSTEM_INSTRUCTION =
+	"You are an AI image generator. Generate images based on user descriptions. Focus on creating high-quality, visually appealing images that match the user's request.";
+
+const TOOL_PARAMS = Type.Object({
+	prompt: Type.String({ description: "Image description." }),
+	model: Type.Optional(
+		Type.String({
+			description: "Image model id (e.g., gemini-3-pro-image, imagen-3). Default: gemini-3-pro-image.",
+		}),
+	),
+	aspectRatio: Type.Optional(StringEnum(ASPECT_RATIOS)),
+	save: Type.Optional(StringEnum(SAVE_MODES)),
+	saveDir: Type.Optional(
+		Type.String({
+			description: "Directory to save image when save=custom. Defaults to PI_IMAGE_SAVE_DIR if set.",
+		}),
+	),
+});
+
+type ToolParams = Static<typeof TOOL_PARAMS>;
+
+interface CloudCodeAssistRequest {
+	project: string;
+	model: string;
+	request: {
+		contents: Content[];
+		sessionId?: string;
+		systemInstruction?: { role?: string; parts: { text: string }[] };
+		generationConfig?: {
+			maxOutputTokens?: number;
+			temperature?: number;
+			imageConfig?: { aspectRatio?: string };
+			candidateCount?: number;
+		};
+		safetySettings?: Array<{ category: string; threshold: string }>;
+	};
+	requestType?: string;
+	userAgent?: string;
+	requestId?: string;
+}
+
+interface CloudCodeAssistResponseChunk {
+	response?: {
+		candidates?: Array<{
+			content?: {
+				role: string;
+				parts?: Array<{
+					text?: string;
+					inlineData?: {
+						mimeType?: string;
+						data?: string;
+					};
+				}>;
+			};
+		}>;
+		usageMetadata?: {
+			promptTokenCount?: number;
+			candidatesTokenCount?: number;
+			thoughtsTokenCount?: number;
+			totalTokenCount?: number;
+			cachedContentTokenCount?: number;
+		};
+		modelVersion?: string;
+		responseId?: string;
+	};
+	traceId?: string;
+}
+
+interface Content {
+	role: "user" | "model";
+	parts: Part[];
+}
+
+interface Part {
+	text?: string;
+	inlineData?: {
+		mimeType?: string;
+		data?: string;
+	};
+}
+
+interface ParsedCredentials {
+	accessToken: string;
+	projectId: string;
+}
+
+interface ExtensionConfig {
+	save?: SaveMode;
+	saveDir?: string;
+}
+
+interface SaveConfig {
+	mode: SaveMode;
+	outputDir?: string;
+}
+
+function parseOAuthCredentials(raw: string): ParsedCredentials {
+	let parsed: { token?: string; projectId?: string };
+	try {
+		parsed = JSON.parse(raw) as { token?: string; projectId?: string };
+	} catch {
+		throw new Error("Invalid Google OAuth credentials. Run /login to re-authenticate.");
+	}
+	if (!parsed.token || !parsed.projectId) {
+		throw new Error("Missing token or projectId in Google OAuth credentials. Run /login.");
+	}
+	return { accessToken: parsed.token, projectId: parsed.projectId };
+}
+
+function readConfigFile(path: string): ExtensionConfig {
+	if (!existsSync(path)) {
+		return {};
+	}
+	try {
+		const content = readFileSync(path, "utf-8");
+		const parsed = JSON.parse(content) as ExtensionConfig;
+		return parsed ?? {};
+	} catch {
+		return {};
+	}
+}
+
+function loadConfig(cwd: string): ExtensionConfig {
+	const globalConfig = readConfigFile(join(homedir(), ".pi", "agent", "extensions", "antigravity-image-gen.json"));
+	const projectConfig = readConfigFile(join(cwd, ".pi", "extensions", "antigravity-image-gen.json"));
+	return { ...globalConfig, ...projectConfig };
+}
+
+function resolveSaveConfig(params: ToolParams, cwd: string): SaveConfig {
+	const config = loadConfig(cwd);
+	const envMode = (process.env.PI_IMAGE_SAVE_MODE || "").toLowerCase();
+	const paramMode = params.save;
+	const mode = (paramMode || envMode || config.save || DEFAULT_SAVE_MODE) as SaveMode;
+
+	if (!SAVE_MODES.includes(mode)) {
+		return { mode: DEFAULT_SAVE_MODE as SaveMode };
+	}
+
+	if (mode === "project") {
+		return { mode, outputDir: join(cwd, ".pi", "generated-images") };
+	}
+
+	if (mode === "global") {
+		return { mode, outputDir: join(homedir(), ".pi", "agent", "generated-images") };
+	}
+
+	if (mode === "custom") {
+		const dir = params.saveDir || process.env.PI_IMAGE_SAVE_DIR || config.saveDir;
+		if (!dir || !dir.trim()) {
+			throw new Error("save=custom requires saveDir or PI_IMAGE_SAVE_DIR.");
+		}
+		return { mode, outputDir: dir };
+	}
+
+	return { mode };
+}
+
+function imageExtension(mimeType: string): string {
+	const lower = mimeType.toLowerCase();
+	if (lower.includes("jpeg") || lower.includes("jpg")) return "jpg";
+	if (lower.includes("gif")) return "gif";
+	if (lower.includes("webp")) return "webp";
+	return "png";
+}
+
+async function saveImage(base64Data: string, mimeType: string, outputDir: string): Promise<string> {
+	await mkdir(outputDir, { recursive: true });
+	const timestamp = new Date().toISOString().replace(/[:.]/g, "-");
+	const ext = imageExtension(mimeType);
+	const filename = `image-${timestamp}-${randomUUID().slice(0, 8)}.${ext}`;
+	const filePath = join(outputDir, filename);
+	await writeFile(filePath, Buffer.from(base64Data, "base64"));
+	return filePath;
+}
+
+function buildRequest(prompt: string, model: string, projectId: string, aspectRatio: string): CloudCodeAssistRequest {
+	return {
+		project: projectId,
+		model,
+		request: {
+			contents: [
+				{
+					role: "user",
+					parts: [{ text: prompt }],
+				},
+			],
+			systemInstruction: {
+				parts: [{ text: IMAGE_SYSTEM_INSTRUCTION }],
+			},
+			generationConfig: {
+				imageConfig: { aspectRatio },
+				candidateCount: 1,
+			},
+			safetySettings: [
+				{ category: "HARM_CATEGORY_HARASSMENT", threshold: "BLOCK_ONLY_HIGH" },
+				{ category: "HARM_CATEGORY_HATE_SPEECH", threshold: "BLOCK_ONLY_HIGH" },
+				{ category: "HARM_CATEGORY_SEXUALLY_EXPLICIT", threshold: "BLOCK_ONLY_HIGH" },
+				{ category: "HARM_CATEGORY_DANGEROUS_CONTENT", threshold: "BLOCK_ONLY_HIGH" },
+				{ category: "HARM_CATEGORY_CIVIC_INTEGRITY", threshold: "BLOCK_ONLY_HIGH" },
+			],
+		},
+		requestType: "agent",
+		requestId: `agent-${Date.now()}-${Math.random().toString(36).slice(2, 11)}`,
+		userAgent: "antigravity",
+	};
+}
+
+async function parseSseForImage(
+	response: Response,
+	signal?: AbortSignal,
+): Promise<{ image: { data: string; mimeType: string }; text: string[] }> {
+	if (!response.body) {
+		throw new Error("No response body");
+	}
+
+	const reader = response.body.getReader();
+	const decoder = new TextDecoder();
+	let buffer = "";
+	const textParts: string[] = [];
+
+	try {
+		while (true) {
+			if (signal?.aborted) {
+				throw new Error("Request was aborted");
+			}
+
+			const { done, value } = await reader.read();
+			if (done) break;
+
+			buffer += decoder.decode(value, { stream: true });
+			const lines = buffer.split("\n");
+			buffer = lines.pop() || "";
+
+			for (const line of lines) {
+				if (!line.startsWith("data:")) continue;
+				const jsonStr = line.slice(5).trim();
+				if (!jsonStr) continue;
+
+				let chunk: CloudCodeAssistResponseChunk;
+				try {
+					chunk = JSON.parse(jsonStr) as CloudCodeAssistResponseChunk;
+				} catch {
+					continue;
+				}
+
+				const responseData = chunk.response;
+				if (!responseData?.candidates) continue;
+
+				for (const candidate of responseData.candidates) {
+					const parts = candidate.content?.parts;
+					if (!parts) continue;
+					for (const part of parts) {
+						if (part.text) {
+							textParts.push(part.text);
+						}
+						if (part.inlineData?.data) {
+							await reader.cancel();
+							return {
+								image: {
+									data: part.inlineData.data,
+									mimeType: part.inlineData.mimeType || "image/png",
+								},
+								text: textParts,
+							};
+						}
+					}
+				}
+			}
+		}
+	} finally {
+		reader.releaseLock();
+	}
+
+	throw new Error("No image data returned by the model");
+}
+
+async function getCredentials(ctx: {
+	modelRegistry: { getApiKeyForProvider: (provider: string) => Promise<string | undefined> };
+}): Promise<ParsedCredentials> {
+	const apiKey = await ctx.modelRegistry.getApiKeyForProvider(PROVIDER);
+	if (!apiKey) {
+		throw new Error("Missing Google Antigravity OAuth credentials. Run /login for google-antigravity.");
+	}
+	return parseOAuthCredentials(apiKey);
+}
+
+export default function antigravityImageGen(pi: ExtensionAPI) {
+	pi.registerTool({
+		name: "generate_image",
+		label: "Generate image",
+		description:
+			"Generate an image via Google Antigravity image models. Returns the image as a tool result attachment. Optional saving via save=project|global|custom|none, or PI_IMAGE_SAVE_MODE/PI_IMAGE_SAVE_DIR.",
+		parameters: TOOL_PARAMS,
+		async execute(_toolCallId, params: ToolParams, onUpdate, ctx, signal) {
+			const { accessToken, projectId } = await getCredentials(ctx);
+			const model = params.model || DEFAULT_MODEL;
+			const aspectRatio = params.aspectRatio || DEFAULT_ASPECT_RATIO;
+
+			const requestBody = buildRequest(params.prompt, model, projectId, aspectRatio);
+			onUpdate?.({
+				content: [{ type: "text", text: `Requesting image from ${PROVIDER}/${model}...` }],
+				details: { provider: PROVIDER, model, aspectRatio },
+			});
+
+			const response = await fetch(`${ANTIGRAVITY_ENDPOINT}/v1internal:streamGenerateContent?alt=sse`, {
+				method: "POST",
+				headers: {
+					Authorization: `Bearer ${accessToken}`,
+					"Content-Type": "application/json",
+					Accept: "text/event-stream",
+					...ANTIGRAVITY_HEADERS,
+				},
+				body: JSON.stringify(requestBody),
+				signal,
+			});
+
+			if (!response.ok) {
+				const errorText = await response.text();
+				throw new Error(`Image request failed (${response.status}): ${errorText}`);
+			}
+
+			const parsed = await parseSseForImage(response, signal);
+			const saveConfig = resolveSaveConfig(params, ctx.cwd);
+			let savedPath: string | undefined;
+			let saveError: string | undefined;
+			if (saveConfig.mode !== "none" && saveConfig.outputDir) {
+				try {
+					savedPath = await saveImage(parsed.image.data, parsed.image.mimeType, saveConfig.outputDir);
+				} catch (error) {
+					saveError = error instanceof Error ? error.message : String(error);
+				}
+			}
+			const summaryParts = [`Generated image via ${PROVIDER}/${model}.`, `Aspect ratio: ${aspectRatio}.`];
+			if (savedPath) {
+				summaryParts.push(`Saved image to: ${savedPath}`);
+			} else if (saveError) {
+				summaryParts.push(`Failed to save image: ${saveError}`);
+			}
+			if (parsed.text.length > 0) {
+				summaryParts.push(`Model notes: ${parsed.text.join(" ")}`);
+			}
+
+			return {
+				content: [
+					{ type: "text", text: summaryParts.join(" ") },
+					{ type: "image", data: parsed.image.data, mimeType: parsed.image.mimeType },
+				],
+				details: { provider: PROVIDER, model, aspectRatio, savedPath, saveMode: saveConfig.mode },
+			};
+		},
+	});
+}