[pull] main from microsoft:main

.agents/skills/launch/SKILL.md

@@ -111,6 +111,30 @@ agent-browser snapshot -i
 - Code OSS uses the default user data directory. Unlike VS Code Insiders, you don't typically need `--user-data-dir` since there's usually only one Code OSS instance running.
 - If you see "Sent env to running instance. Terminating..." it means Code OSS is already running and forwarded your args to the existing instance. Quit Code OSS and relaunch with the flag, or use `--user-data-dir=/tmp/code-oss-debug` to force a new instance.
 
+## Launching the Sessions App (Agent Sessions Window)
+
+The Sessions app is a separate workbench mode launched with the `--sessions` flag. It uses a dedicated user data directory to avoid conflicts with the main Code OSS instance.
+
+```bash
+cd <repo-root>  # the root of your VS Code checkout
+./scripts/code.sh --sessions --remote-debugging-port=9224
+```
+
+Wait for the window to fully initialize, then connect:
+
+```bash
+# Wait for Sessions app to start, retry until connected
+for i in 1 2 3 4 5; do agent-browser connect 9224 2>/dev/null && break || sleep 3; done
+
+# Verify you're connected to the right target (not about:blank)
+agent-browser tab
+agent-browser snapshot -i
+```
+
+**Tips:**
+- The `--sessions` flag launches the Agent Sessions workbench instead of the standard VS Code workbench.
+- Set `VSCODE_SKIP_PRELAUNCH=1` to skip the compile step if you've already built.
+
 ## Launching VS Code Extensions for Debugging
 
 To debug a VS Code extension via agent-browser, launch VS Code Insiders with `--extensionDevelopmentPath` and `--remote-debugging-port`. Use `--user-data-dir` to avoid conflicting with an already-running instance.

.github/instructions/agentHostTesting.instructions.md

@@ -0,0 +1,27 @@
+---
+description: Architecture documentation for VS Code AI Customization view. Use when working in `src/vs/workbench/contrib/chat/browser/aiCustomization`
+applyTo: 'src/vs/platform/agentHost/**'
+---
+
+# Agent Host
+
+The agent host communicates via the Agent Host Protocol. The specification for this lives in a directory `../agent-host-protocol` as a sibling of the VS Code directory.
+
+If this directory doesn't exist, you should use the "ask questions" tool to ask the user if they want to clone `git@github.com:microsoft/agent-host-protocol.git` to that directory. After doing so, you should also prompt the user to add `file:///<path/to/agent-host-protocol>/plugins/copilot-plugin` as a plugin in their `chat.pluginLocations` settings.
+
+## Overall Protocol
+
+The sessions process is a portable, standalone server that multiple clients can connect to. Clients see a synchronized view of sessions and can send commands that are reflected back as state-changing actions. The protocol is designed around four requirements:
+
+1. **Synchronized multi-client state** — an immutable, redux-like state tree mutated exclusively by actions flowing through pure reducers. While there is the option to implement functionality via imperative commands, we ALWAYS prefer to model features as pure state and actions.
+2. **Lazy loading** — clients subscribe to state by URI and load data on demand. The session list is fetched imperatively. Large content (images, long tool outputs) is stored by reference and fetched separately.
+3. **Write-ahead with reconciliation** — clients optimistically apply their own actions locally, then reconcile when the server echoes them back alongside any concurrent actions from other clients or the server itself.
+4. **Forward-compatible versioning** — newer clients can connect to older servers. A single protocol version number maps to a capabilities object; clients check capabilities before using features.
+
+See the agent host protocol documentation for more details.
+
+## End to End Testing
+
+You can run `node ./scripts/code-agent-host.js` to start an agent host. If you pass `--enable-mock-agent`, then the `ScriptedMockAgent` will be used.
+
+By default this will listen on `ws://127.0.0.1:8081`. You can then use the `ahp-websocket` client, when available, to connect to and communicate with it.

.vscode/settings.json

@@ -72,6 +72,7 @@
 		"extensions/terminal-suggest/src/completions/upstream/**": true,
 		"test/smoke/out/**": true,
 		"test/automation/out/**": true,
+		"src/vs/platform/agentHost/common/state/protocol/**": true,
 		"test/integration/browser/out/**": true,
 		// "src/vs/sessions/**": true
 	},

.vscode/tasks.json

@@ -409,7 +409,7 @@
 			"type": "shell",
 			"command": "npm ci && npm run watch",
 			"windows": {
-				"command": "cmd /d /c \"npm ci && npm run watch\""
+				"command": "cmd /c \"npm ci && npm run watch\""
 			},
 			"inSessions": true,
 			"runOptions": {

build/npm/postinstall.ts

@@ -292,13 +292,15 @@ async function main() {
 	// Temporary: patch @github/copilot-sdk session.js to fix ESM import
 	// (missing .js extension on vscode-jsonrpc/node). Fixed upstream in v0.1.32.
 	// TODO: Remove once @github/copilot-sdk is updated to >=0.1.32
-	const sessionFile = path.join(root, 'node_modules', '@github', 'copilot-sdk', 'dist', 'session.js');
-	if (fs.existsSync(sessionFile)) {
-		const content = fs.readFileSync(sessionFile, 'utf8');
-		const patched = content.replace(/from "vscode-jsonrpc\/node"/g, 'from "vscode-jsonrpc/node.js"');
-		if (content !== patched) {
-			fs.writeFileSync(sessionFile, patched);
-			log('.', 'Patched @github/copilot-sdk session.js (vscode-jsonrpc ESM import fix)');
+	for (const dir of ['', 'remote']) {
+		const sessionFile = path.join(root, dir, 'node_modules', '@github', 'copilot-sdk', 'dist', 'session.js');
+		if (fs.existsSync(sessionFile)) {
+			const content = fs.readFileSync(sessionFile, 'utf8');
+			const patched = content.replace(/from "vscode-jsonrpc\/node"/g, 'from "vscode-jsonrpc/node.js"');
+			if (content !== patched) {
+				fs.writeFileSync(sessionFile, patched);
+				log(dir || '.', 'Patched @github/copilot-sdk session.js (vscode-jsonrpc ESM import fix)');
+			}
 		}
 	}
 }

cli/src/bin/code/main.rs

@@ -8,7 +8,7 @@ use std::process::Command;
 
 use clap::Parser;
 use cli::{
-	commands::{args, serve_web, tunnels, update, version, CommandContext},
+	commands::{agent_host, args, serve_web, tunnels, update, version, CommandContext},
 	constants::get_default_user_agent,
 	desktop, log,
 	state::LauncherPaths,
@@ -103,6 +103,10 @@ async fn main() -> Result<(), std::convert::Infallible> {
 				serve_web::serve_web(context!(), sw_args).await
 			}
 
+			Some(args::Commands::AgentHost(ah_args)) => {
+				agent_host::agent_host(context!(), ah_args).await
+			}
+
 			Some(args::Commands::Tunnel(mut tunnel_args)) => match tunnel_args.subcommand.take() {
 				Some(args::TunnelSubcommand::Prune) => tunnels::prune(context!()).await,
 				Some(args::TunnelSubcommand::Unregister) => tunnels::unregister(context!()).await,

cli/src/commands.rs

@@ -5,6 +5,7 @@
 
 mod context;
 
+pub mod agent_host;
 pub mod args;
 pub mod serve_web;
 pub mod tunnels;