From 5f724c59247b723c9880ea4a6025ca3c6a517f32 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 2 Feb 2026 20:17:21 -0800
Subject: [PATCH] Reduce MAX_CONTROL_DATA_SIZE + EINVAL for i and I

---
 .../src/kitty/KittyGraphicsHandler.ts         | 16 +++++++++-
 .../src/kitty/KittyGraphicsTypes.ts           |  4 +++
 addons/addon-image/test/ImageAddon.test.ts    | 30 +++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/addons/addon-image/src/kitty/KittyGraphicsHandler.ts b/addons/addon-image/src/kitty/KittyGraphicsHandler.ts
index 028f58d8..f9843644 100644
--- a/addons/addon-image/src/kitty/KittyGraphicsHandler.ts
+++ b/addons/addon-image/src/kitty/KittyGraphicsHandler.ts
@@ -30,7 +30,7 @@ const BASE64_SHARD_SIZE = 1048576;
 const DECODED_SHARD_SIZE = 786432;
 
 // Maximum control data size
-const MAX_CONTROL_DATA_SIZE = 4096;
+const MAX_CONTROL_DATA_SIZE = 512;
 
 // Semicolon codepoint
 const SEMICOLON = 0x3B;
@@ -211,6 +211,13 @@ export class KittyGraphicsHandler implements IApcHandler, IResetHandler {
 
     // Parse command to check m=1 and get pending key
     const cmd = parseKittyCommand(this._parseControlDataString());
+
+    // Per spec: specifying both i and I is an error
+    if (cmd.id !== undefined && cmd.imageNumber !== undefined) {
+      this._sendResponse(cmd.id, 'EINVAL:cannot specify both i and I keys', cmd.quiet ?? 0);
+      return true;
+    }
+
     const pendingKey = cmd.id ?? 0;
     const isMoreComing = cmd.more === 1;
     const pending = this._pendingTransmissions.get(pendingKey);
@@ -381,6 +388,13 @@ export class KittyGraphicsHandler implements IApcHandler, IResetHandler {
 
   private _handleNoPayloadCommand(): boolean | Promise<boolean> {
     const cmd = parseKittyCommand(this._parseControlDataString());
+
+    // Per spec: specifying both i and I is an error
+    if (cmd.id !== undefined && cmd.imageNumber !== undefined) {
+      this._sendResponse(cmd.id, 'EINVAL:cannot specify both i and I keys', cmd.quiet ?? 0);
+      return true;
+    }
+
     const action = cmd.action ?? 't';
 
     switch (action) {
diff --git a/addons/addon-image/src/kitty/KittyGraphicsTypes.ts b/addons/addon-image/src/kitty/KittyGraphicsTypes.ts
index 17ebefc1..ef91bf57 100644
--- a/addons/addon-image/src/kitty/KittyGraphicsTypes.ts
+++ b/addons/addon-image/src/kitty/KittyGraphicsTypes.ts
@@ -47,6 +47,8 @@ export const enum KittyKey {
   FORMAT = 'f',
   // Image ID for referencing stored images
   ID = 'i',
+  // Image number (alternative to ID, terminal assigns ID)
+  IMAGE_NUMBER = 'I',
   // Source image width in pixels
   WIDTH = 's',
   // Source image height in pixels
@@ -79,6 +81,7 @@ export interface IKittyCommand {
   action?: string;
   format?: number;
   id?: number;
+  imageNumber?: number;
   width?: number;
   height?: number;
   x?: number;
@@ -148,6 +151,7 @@ export function parseKittyCommand(data: string): IKittyCommand {
     switch (key) {
       case KittyKey.FORMAT: cmd.format = numValue; break;
       case KittyKey.ID: cmd.id = numValue; break;
+      case KittyKey.IMAGE_NUMBER: cmd.imageNumber = numValue; break;
       case KittyKey.WIDTH: cmd.width = numValue; break;
       case KittyKey.HEIGHT: cmd.height = numValue; break;
       case KittyKey.X_OFFSET: cmd.x = numValue; break;
diff --git a/addons/addon-image/test/ImageAddon.test.ts b/addons/addon-image/test/ImageAddon.test.ts
index 923da858..d07990dc 100644
--- a/addons/addon-image/test/ImageAddon.test.ts
+++ b/addons/addon-image/test/ImageAddon.test.ts
@@ -504,6 +504,36 @@ test.describe('ImageAddon', () => {
 
       strictEqual(await ctx.page.evaluate('window.kittyGotResponse'), false);
     });
+
+    test('responds with EINVAL when both i and I keys are specified', async () => {
+      let response = '';
+      await ctx.page.evaluate(() => {
+        (window as any).kittyResponse = '';
+        (window as any).term.onData((data: string) => { (window as any).kittyResponse = data; });
+      });
+
+      // Per spec: "Specifying both i and I keys in any command is an error"
+      await ctx.proxy.write(`\x1b_Gi=100,I=200,a=q,f=100;${KITTY_BLACK_1X1_BASE64}\x1b\\`);
+      await timeout(100);
+
+      response = await ctx.page.evaluate('window.kittyResponse');
+      strictEqual(response, '\x1b_Gi=100;EINVAL:cannot specify both i and I keys\x1b\\');
+    });
+
+    test('responds with EINVAL for i+I conflict even without payload', async () => {
+      let response = '';
+      await ctx.page.evaluate(() => {
+        (window as any).kittyResponse = '';
+        (window as any).term.onData((data: string) => { (window as any).kittyResponse = data; });
+      });
+
+      // Delete command with both i and I (no payload case)
+      await ctx.proxy.write('\x1b_Gi=101,I=201,a=d\x1b\\');
+      await timeout(100);
+
+      response = await ctx.page.evaluate('window.kittyResponse');
+      strictEqual(response, '\x1b_Gi=101;EINVAL:cannot specify both i and I keys\x1b\\');
+    });
   });
 
   test.describe('Kitty pixel verification', () => {