Skip serializing our internal language kernel terminal processes on shutdown

When we quit Positron, we tear down any language runtime kernel processes (which are now managed by the terminal service host).

These internal terminal processes should not be serialized/replayed on restarting Positron.

This change attempts to detect those internal positron kernel terminal processes without changing the terminal service API.

Issue: #213

Author: petetronic

.vscode/launch.json

@@ -549,6 +549,7 @@
 				"Attach to Main Process",
 				"Attach to Extension Host",
 				"Attach to Shared Process",
+				"Attach to Pty Host Process"
 			],
 			"preLaunchTask": "Ensure Prelaunch Dependencies",
 			"presentation": {

extensions/jupyter-adapter/src/JupyterKernel.ts

@@ -409,7 +409,7 @@ export class JupyterKernel extends EventEmitter implements vscode.Disposable {
 		const command = args.join(' ');
 
 		// Create environment.
-		const env = {};
+		const env = { POSITRON_LANGUAGE: this._spec.language };
 		Object.assign(env, process.env, this._spec.env);
 
 		// We are now starting the kernel

src/vs/platform/terminal/node/ptyService.ts

@@ -134,6 +134,15 @@ export class PtyService extends Disposable implements IPtyService {
 	async serializeTerminalState(ids: number[]): Promise<string> {
 		const promises: Promise<ISerializedTerminalState>[] = [];
 		for (const [persistentProcessId, persistentProcess] of this._ptys.entries()) {
+
+			// --- Start Positron ---
+			// Skip serializing Positron language runtime kernel processes
+			const positronLanguage = persistentProcess.shellLaunchConfig.env?.POSITRON_LANGUAGE;
+			if (positronLanguage) {
+				continue;
+			}
+			// --- End Positron ---
+
 			// Only serialize persistent processes that have had data written or performed a replay
 			if (persistentProcess.hasWrittenData && ids.indexOf(persistentProcessId) !== -1) {
 				promises.push(Promises.withAsyncBody<ISerializedTerminalState>(async r => {