diff --git a/.prettierignore b/.prettierignore
index 41c915fed..e260f6508 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -8,6 +8,9 @@ package-lock.json
 /packages/lit-dev-content/_dev/
 /packages/lit-dev-content/_site/
 /packages/lit-dev-content/rollupout/
+/packages/lit-dev-tutorial-plugin/.vscode-test/
+/packages/lit-dev-tutorial-plugin/.test-bin/
+/packages/lit-dev-tutorial-plugin/out/
 # TODO(aomarks) Would be nice to format samples, but Prettier doesn't always do
 # a great job compared to our manual formatting.
 /packages/lit-dev-content/samples/
diff --git a/packages/lit-dev-tutorial-plugin/.vscode/launch.json b/packages/lit-dev-tutorial-plugin/.vscode/launch.json
index 670d6e66c..1210201da 100644
--- a/packages/lit-dev-tutorial-plugin/.vscode/launch.json
+++ b/packages/lit-dev-tutorial-plugin/.vscode/launch.json
@@ -3,32 +3,26 @@
 // Hover to view descriptions of existing attributes.
 // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
 {
-	"version": "0.2.0",
-	"configurations": [
-		{
-			"name": "Run Extension",
-			"type": "extensionHost",
-			"request": "launch",
-			"args": [
-				"--extensionDevelopmentPath=${workspaceFolder}"
-			],
-			"outFiles": [
-				"${workspaceFolder}/out/**/*.js"
-			],
-			"preLaunchTask": "${defaultBuildTask}"
-		},
-		{
-			"name": "Extension Tests",
-			"type": "extensionHost",
-			"request": "launch",
-			"args": [
-				"--extensionDevelopmentPath=${workspaceFolder}",
-				"--extensionTestsPath=${workspaceFolder}/out/test/suite/index"
-			],
-			"outFiles": [
-				"${workspaceFolder}/out/test/**/*.js"
-			],
-			"preLaunchTask": "${defaultBuildTask}"
-		}
-	]
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Run Extension",
+      "type": "extensionHost",
+      "request": "launch",
+      "args": ["--extensionDevelopmentPath=${workspaceFolder}"],
+      "outFiles": ["${workspaceFolder}/out/**/*.js"],
+      "preLaunchTask": "${defaultBuildTask}"
+    },
+    {
+      "name": "Extension Tests",
+      "type": "extensionHost",
+      "request": "launch",
+      "args": [
+        "--extensionDevelopmentPath=${workspaceFolder}",
+        "--extensionTestsPath=${workspaceFolder}/out/test/suite/index"
+      ],
+      "outFiles": ["${workspaceFolder}/out/test/**/*.js"],
+      "preLaunchTask": "${defaultBuildTask}"
+    }
+  ]
 }
diff --git a/packages/lit-dev-tutorial-plugin/.vscode/settings.json b/packages/lit-dev-tutorial-plugin/.vscode/settings.json
index 30bf8c2d3..ffeaf91cb 100644
--- a/packages/lit-dev-tutorial-plugin/.vscode/settings.json
+++ b/packages/lit-dev-tutorial-plugin/.vscode/settings.json
@@ -1,11 +1,11 @@
 // Place your settings in this file to overwrite default and user settings.
 {
-    "files.exclude": {
-        "out": false // set this to true to hide the "out" folder with the compiled JS files
-    },
-    "search.exclude": {
-        "out": true // set this to false to include "out" folder in search results
-    },
-    // Turn off tsc task auto detection since we have the necessary tasks as npm scripts
-    "typescript.tsc.autoDetect": "off"
-}
\ No newline at end of file
+  "files.exclude": {
+    "out": false // set this to true to hide the "out" folder with the compiled JS files
+  },
+  "search.exclude": {
+    "out": true // set this to false to include "out" folder in search results
+  },
+  // Turn off tsc task auto detection since we have the necessary tasks as npm scripts
+  "typescript.tsc.autoDetect": "off"
+}
diff --git a/packages/lit-dev-tutorial-plugin/.vscode/tasks.json b/packages/lit-dev-tutorial-plugin/.vscode/tasks.json
index 3b17e53b6..078ff7e01 100644
--- a/packages/lit-dev-tutorial-plugin/.vscode/tasks.json
+++ b/packages/lit-dev-tutorial-plugin/.vscode/tasks.json
@@ -1,20 +1,20 @@
 // See https://go.microsoft.com/fwlink/?LinkId=733558
 // for the documentation about the tasks.json format
 {
-	"version": "2.0.0",
-	"tasks": [
-		{
-			"type": "npm",
-			"script": "watch",
-			"problemMatcher": "$tsc-watch",
-			"isBackground": true,
-			"presentation": {
-				"reveal": "never"
-			},
-			"group": {
-				"kind": "build",
-				"isDefault": true
-			}
-		}
-	]
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "type": "npm",
+      "script": "watch",
+      "problemMatcher": "$tsc-watch",
+      "isBackground": true,
+      "presentation": {
+        "reveal": "never"
+      },
+      "group": {
+        "kind": "build",
+        "isDefault": true
+      }
+    }
+  ]
 }
diff --git a/packages/lit-dev-tutorial-plugin/src/extension.ts b/packages/lit-dev-tutorial-plugin/src/extension.ts
index 55b8ba098..82b293b21 100644
--- a/packages/lit-dev-tutorial-plugin/src/extension.ts
+++ b/packages/lit-dev-tutorial-plugin/src/extension.ts
@@ -5,18 +5,19 @@
  */
 
 import * as vscode from 'vscode';
-import { BeforeAfterDir } from './tree-items/before-after-dir.js';
-import { GenericFile } from './tree-items/generic-file.js';
-import { PlaygroundFile } from './tree-items/playground-file.js';
-import { TutorialStep } from './tree-items/tutorial-step.js';
-import { Tutorial } from './tree-items/tutorial.js';
+import {BeforeAfterDir} from './tree-items/before-after-dir.js';
+import {GenericFile} from './tree-items/generic-file.js';
+import {PlaygroundFile} from './tree-items/playground-file.js';
+import {TutorialStep} from './tree-items/tutorial-step.js';
+import {Tutorial} from './tree-items/tutorial.js';
 import {LitDevTutorialTreeProvider, TutorialTreeItem} from './tree-provider.js';
 
 export async function activate() {
   const rootPath =
-  vscode.workspace.workspaceFolders && vscode.workspace.workspaceFolders.length > 0
-    ? vscode.workspace.workspaceFolders[0].uri.fsPath
-    : undefined;
+    vscode.workspace.workspaceFolders &&
+    vscode.workspace.workspaceFolders.length > 0
+      ? vscode.workspace.workspaceFolders[0].uri.fsPath
+      : undefined;
 
   if (!rootPath) {
     return;
@@ -36,38 +37,68 @@ export async function activate() {
   vscode.commands.registerCommand('litDevTutorial.createTutorial', () => {
     provider.createTutorial();
   });
-  vscode.commands.registerCommand('litDevTutorial.addStep', (tutorial: Tutorial) => {
-    TutorialStep.create(tutorial);
-	});
-  vscode.commands.registerCommand('litDevTutorial.moveStepUp', (step: TutorialStep) => {
-    step.moveUp();
-	});
-  vscode.commands.registerCommand('litDevTutorial.moveStepDown', (step: TutorialStep) => {
-    step.moveDown();
-	});
-  vscode.commands.registerCommand('litDevTutorial.addAfterStep', (step: TutorialStep) => {
-    BeforeAfterDir.create(step, 'after');
-	});
-  vscode.commands.registerCommand('litDevTutorial.delete', (item: TutorialTreeItem) => {
-    item.delete();
-  });
-  vscode.commands.registerCommand('litDevTutorial.makeSolvable', (item: TutorialStep) => {
-    item.solvable = true;
-  item.provider.refresh();
-  });
-  vscode.commands.registerCommand('litDevTutorial.makeUnsolvable', (item: TutorialStep) => {
-    item.solvable = false;
-    item.provider.refresh();
-  });
-  vscode.commands.registerCommand('litDevTutorial.createPlaygroundFile', (dir: BeforeAfterDir) => {
-    PlaygroundFile.create(dir);
-  });
-  vscode.commands.registerCommand('litDevTutorial.revealInSidebar', (item: GenericFile | PlaygroundFile) => {
-    item.revealInSidebar();
-  });
-  vscode.commands.registerCommand('litDevTutorial.renameStep', (item: TutorialStep) => {
-    item.rename();
-  });
+  vscode.commands.registerCommand(
+    'litDevTutorial.addStep',
+    (tutorial: Tutorial) => {
+      TutorialStep.create(tutorial);
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.moveStepUp',
+    (step: TutorialStep) => {
+      step.moveUp();
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.moveStepDown',
+    (step: TutorialStep) => {
+      step.moveDown();
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.addAfterStep',
+    (step: TutorialStep) => {
+      BeforeAfterDir.create(step, 'after');
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.delete',
+    (item: TutorialTreeItem) => {
+      item.delete();
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.makeSolvable',
+    (item: TutorialStep) => {
+      item.solvable = true;
+      item.provider.refresh();
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.makeUnsolvable',
+    (item: TutorialStep) => {
+      item.solvable = false;
+      item.provider.refresh();
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.createPlaygroundFile',
+    (dir: BeforeAfterDir) => {
+      PlaygroundFile.create(dir);
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.revealInSidebar',
+    (item: GenericFile | PlaygroundFile) => {
+      item.revealInSidebar();
+    }
+  );
+  vscode.commands.registerCommand(
+    'litDevTutorial.renameStep',
+    (item: TutorialStep) => {
+      item.rename();
+    }
+  );
 }
 
 // this method is called when your extension is deactivated
diff --git a/packages/lit-dev-tutorial-plugin/src/test/runTest.ts b/packages/lit-dev-tutorial-plugin/src/test/runTest.ts
index 72d334a3e..d3bb4d710 100644
--- a/packages/lit-dev-tutorial-plugin/src/test/runTest.ts
+++ b/packages/lit-dev-tutorial-plugin/src/test/runTest.ts
@@ -6,24 +6,24 @@
 
 import * as path from 'path';
 
-import { runTests } from '@vscode/test-electron';
+import {runTests} from '@vscode/test-electron';
 
 async function main() {
-	try {
-		// The folder containing the Extension Manifest package.json
-		// Passed to `--extensionDevelopmentPath`
-		const extensionDevelopmentPath = path.resolve(__dirname, '../../');
+  try {
+    // The folder containing the Extension Manifest package.json
+    // Passed to `--extensionDevelopmentPath`
+    const extensionDevelopmentPath = path.resolve(__dirname, '../../');
 
-		// The path to test runner
-		// Passed to --extensionTestsPath
-		const extensionTestsPath = path.resolve(__dirname, './suite/index');
+    // The path to test runner
+    // Passed to --extensionTestsPath
+    const extensionTestsPath = path.resolve(__dirname, './suite/index');
 
-		// Download VS Code, unzip it and run the integration test
-		await runTests({ extensionDevelopmentPath, extensionTestsPath });
-	} catch (err) {
-		console.error('Failed to run tests');
-		process.exit(1);
-	}
+    // Download VS Code, unzip it and run the integration test
+    await runTests({extensionDevelopmentPath, extensionTestsPath});
+  } catch (err) {
+    console.error('Failed to run tests');
+    process.exit(1);
+  }
 }
 
 main();
diff --git a/packages/lit-dev-tutorial-plugin/src/test/suite/extension.test.ts b/packages/lit-dev-tutorial-plugin/src/test/suite/extension.test.ts
index 217eef725..bbe9b6043 100644
--- a/packages/lit-dev-tutorial-plugin/src/test/suite/extension.test.ts
+++ b/packages/lit-dev-tutorial-plugin/src/test/suite/extension.test.ts
@@ -30,7 +30,10 @@ suite('Tutorial Extension', () => {
 
   suite('startup', () => {
     test('recognizes lit.dev repo', async () => {
-      await vscode.commands.executeCommand('vscode.openFolder', vscode.Uri.file(litDevPath));
+      await vscode.commands.executeCommand(
+        'vscode.openFolder',
+        vscode.Uri.file(litDevPath)
+      );
       console.log('opened!');
     });
   });
diff --git a/packages/lit-dev-tutorial-plugin/src/test/util.ts b/packages/lit-dev-tutorial-plugin/src/test/util.ts
index 40c2c9232..ed1614cfd 100644
--- a/packages/lit-dev-tutorial-plugin/src/test/util.ts
+++ b/packages/lit-dev-tutorial-plugin/src/test/util.ts
@@ -198,7 +198,9 @@ export const prepopulateTutorial = async (
 
   for (let i = options.tutorials.length - 1; i >= 0; i--) {
     const tutorial = options.tutorials[i];
-    const tutorialSection = (tutorial as typeof tutorial & {category ?: 'Learn'|'Build'}).category ?? 'Learn';
+    const tutorialSection =
+      (tutorial as typeof tutorial & {category?: 'Learn' | 'Build'}).category ??
+      'Learn';
     const tutorialIndex = dataFileLines.findIndex((line) =>
       line.includes(`// ${tutorialSection}`)
     );
diff --git a/packages/lit-dev-tutorial-plugin/src/tree-items/generic-file.ts b/packages/lit-dev-tutorial-plugin/src/tree-items/generic-file.ts
index ea70ae277..354af39e7 100644
--- a/packages/lit-dev-tutorial-plugin/src/tree-items/generic-file.ts
+++ b/packages/lit-dev-tutorial-plugin/src/tree-items/generic-file.ts
@@ -72,6 +72,8 @@ export class GenericFile extends vscode.TreeItem {
 
   revealInSidebar() {
     vscode.commands.executeCommand('vscode.open', vscode.Uri.file(this.path));
-    vscode.commands.executeCommand('workbench.files.action.showActiveFileInExplorer');
+    vscode.commands.executeCommand(
+      'workbench.files.action.showActiveFileInExplorer'
+    );
   }
 }
diff --git a/packages/lit-dev-tutorial-plugin/src/tree-items/playground-file.ts b/packages/lit-dev-tutorial-plugin/src/tree-items/playground-file.ts
index 67529981c..49a200d67 100644
--- a/packages/lit-dev-tutorial-plugin/src/tree-items/playground-file.ts
+++ b/packages/lit-dev-tutorial-plugin/src/tree-items/playground-file.ts
@@ -127,6 +127,8 @@ export class PlaygroundFile extends vscode.TreeItem {
 
   revealInSidebar() {
     vscode.commands.executeCommand('vscode.open', vscode.Uri.file(this.path));
-    vscode.commands.executeCommand('workbench.files.action.showActiveFileInExplorer');
+    vscode.commands.executeCommand(
+      'workbench.files.action.showActiveFileInExplorer'
+    );
   }
 }
diff --git a/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial-step.ts b/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial-step.ts
index e59c521b1..50f912cac 100644
--- a/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial-step.ts
+++ b/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial-step.ts
@@ -18,7 +18,7 @@ export class TutorialStep extends vscode.TreeItem {
   private _hasAfter = false;
   checkable = false;
   beforeDir!: BeforeAfterDir;
-  afterDir: BeforeAfterDir|undefined = undefined;
+  afterDir: BeforeAfterDir | undefined = undefined;
 
   get dirName() {
     return `${this.step}`.padStart(2, '0');
@@ -68,10 +68,7 @@ export class TutorialStep extends vscode.TreeItem {
 
     this._hasAfter = value;
 
-    const tutorialJsonPath = path.join(
-      this.tutorial.path,
-      'tutorial.json'
-    );
+    const tutorialJsonPath = path.join(this.tutorial.path, 'tutorial.json');
     let tutorialJson = getJson<TutorialJson>(tutorialJsonPath)!;
 
     if (value) {
@@ -97,15 +94,11 @@ export class TutorialStep extends vscode.TreeItem {
     }
 
     this._solvable = solvable;
-    const tutorialJsonPath = path.join(
-      this.tutorial.path,
-      'tutorial.json'
-    );
+    const tutorialJsonPath = path.join(this.tutorial.path, 'tutorial.json');
     let tutorialJson = getJson<TutorialJson>(tutorialJsonPath)!;
 
     if (solvable) {
       delete tutorialJson.steps[this.step].noSolve;
-
     } else {
       this.hasAfter = false;
       tutorialJson = getJson<TutorialJson>(tutorialJsonPath)!;
@@ -219,7 +212,7 @@ export class TutorialStep extends vscode.TreeItem {
       return;
     }
 
-    const isSolvableStr = await vscode.window.showQuickPick(['Yes', 'No'],{
+    const isSolvableStr = await vscode.window.showQuickPick(['Yes', 'No'], {
       title: 'Should this step have a "solve" button?',
     });
 
@@ -231,7 +224,7 @@ export class TutorialStep extends vscode.TreeItem {
     let hasAfter = false;
 
     if (!hideSolve) {
-      const hasAfterStr = await vscode.window.showQuickPick(['Yes', 'No'],{
+      const hasAfterStr = await vscode.window.showQuickPick(['Yes', 'No'], {
         title: 'Is "after" step the "before" of the next step?',
       });
 
diff --git a/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial.ts b/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial.ts
index a4303adb5..c8292ee35 100644
--- a/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial.ts
+++ b/packages/lit-dev-tutorial-plugin/src/tree-items/tutorial.ts
@@ -171,7 +171,9 @@ export class Tutorial extends vscode.TreeItem {
     } catch (_e) {}
 
     const dateObj = new Date();
-    const date = `${dateObj.getFullYear()}-${dateObj.getMonth() + 1}-${dateObj.getDate()}`;
+    const date = `${dateObj.getFullYear()}-${
+      dateObj.getMonth() + 1
+    }-${dateObj.getDate()}`;
 
     const tutorialJson: TutorialJson = {
       header: name,
diff --git a/packages/lit-dev-tutorial-plugin/src/tree-provider.ts b/packages/lit-dev-tutorial-plugin/src/tree-provider.ts
index 7e152bfff..f20ab719b 100644
--- a/packages/lit-dev-tutorial-plugin/src/tree-provider.ts
+++ b/packages/lit-dev-tutorial-plugin/src/tree-provider.ts
@@ -13,7 +13,7 @@ import {TutorialStep} from './tree-items/tutorial-step';
 import {getJson} from './fs-helpers';
 import {BeforeAfterDir} from './tree-items/before-after-dir';
 import {PlaygroundFile} from './tree-items/playground-file';
-import { TutorialJson } from './types';
+import {TutorialJson} from './types';
 
 interface PackageJson {
   name?: string;
@@ -140,15 +140,15 @@ export class LitDevTutorialTreeProvider
       file.isFile()
     );
 
-    const tutorialJson = getJson<TutorialJson>(path.join(element.path, 'tutorial.json'))!;
+    const tutorialJson = getJson<TutorialJson>(
+      path.join(element.path, 'tutorial.json')
+    )!;
     const jsonSteps = tutorialJson.steps;
 
-    const steps = tutorialStepEntries.map(
-      (step, index) => {
-        const jsonStep = jsonSteps[index];
-        return new TutorialStep(this, element, step.name, !jsonStep.noSolve)
-      }
-    );
+    const steps = tutorialStepEntries.map((step, index) => {
+      const jsonStep = jsonSteps[index];
+      return new TutorialStep(this, element, step.name, !jsonStep.noSolve);
+    });
     const files = tutorialFileEntries.map(
       (file) => new GenericFile(this, path.join(tutorialPath, file.name))
     );
@@ -158,23 +158,28 @@ export class LitDevTutorialTreeProvider
   private onTutorialStep(element: TutorialStep) {
     const tutorialPath = element.path;
     const tutorialEntries = fs.readdirSync(tutorialPath, {withFileTypes: true});
-    const tutorialDirEntries = tutorialEntries.filter(
-      (file) =>
-        (file.isDirectory() && file.name === 'before') || file.name === 'after'
-    ).reverse();
-
-    const beforeAfterDirs = tutorialDirEntries.map(
-      (entry) => {
-        const dir = new BeforeAfterDir(this, element, entry.name as 'before' | 'after')
-        if (entry.name === 'before') {
-          element.beforeDir = dir;
-        } else if (entry.name === 'after') {
-          element.afterDir = dir;
-        }
-
-        return dir;
+    const tutorialDirEntries = tutorialEntries
+      .filter(
+        (file) =>
+          (file.isDirectory() && file.name === 'before') ||
+          file.name === 'after'
+      )
+      .reverse();
+
+    const beforeAfterDirs = tutorialDirEntries.map((entry) => {
+      const dir = new BeforeAfterDir(
+        this,
+        element,
+        entry.name as 'before' | 'after'
+      );
+      if (entry.name === 'before') {
+        element.beforeDir = dir;
+      } else if (entry.name === 'after') {
+        element.afterDir = dir;
       }
-    );
+
+      return dir;
+    });
 
     const stepInstructionsMdFile = new GenericFile(
       this,
@@ -206,7 +211,9 @@ export class LitDevTutorialTreeProvider
     });
 
     const projectJsonFile = files.find((file) => file instanceof GenericFile)!;
-    const playgroundFiles = files.filter((file) => !(file instanceof GenericFile));
+    const playgroundFiles = files.filter(
+      (file) => !(file instanceof GenericFile)
+    );
 
     return [...playgroundFiles, projectJsonFile];
   }
diff --git a/packages/lit-dev-tutorial-plugin/tsconfig.json b/packages/lit-dev-tutorial-plugin/tsconfig.json
index fe565bea9..fb305d5e8 100644
--- a/packages/lit-dev-tutorial-plugin/tsconfig.json
+++ b/packages/lit-dev-tutorial-plugin/tsconfig.json
@@ -1,18 +1,16 @@
 {
-	"compilerOptions": {
-		"module": "commonjs",
-		"target": "ES2020",
-		"outDir": "out",
-		"lib": [
-			"ES2020"
-		],
-		"sourceMap": true,
-		"rootDir": "src",
-		"strict": true,   /* enable all strict type-checking options */
-		"skipLibCheck": true
-		/* Additional Checks */
-		// "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
-		// "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
-		// "noUnusedParameters": true,  /* Report errors on unused parameters. */
-	}
+  "compilerOptions": {
+    "module": "commonjs",
+    "target": "ES2020",
+    "outDir": "out",
+    "lib": ["ES2020"],
+    "sourceMap": true,
+    "rootDir": "src",
+    "strict": true /* enable all strict type-checking options */,
+    "skipLibCheck": true
+    /* Additional Checks */
+    // "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
+    // "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
+    // "noUnusedParameters": true,  /* Report errors on unused parameters. */
+  }
 }