feat(cli): Add templates to celest init

- Adds two templates to `celest init`: the exiting `hello` template and a `data` template which is a slim version of the `tasks` example project.
- Fixes some false-positive errors when running `celest start` from a generated template where codegen is required.

Author: dnys1

apps/cli/lib/src/analyzer/celest_analyzer.dart

@@ -8,6 +8,7 @@ import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/analysis/analysis_context_collection.dart';
 import 'package:analyzer/src/dart/analysis/driver_based_analysis_context.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:celest_ast/celest_ast.dart' as ast;
 import 'package:celest_cli/src/analyzer/analysis_error.dart';
 import 'package:celest_cli/src/analyzer/analysis_result.dart';
@@ -112,6 +113,29 @@ const project = Project(name: 'cache_warmup');
   CelestProjectResolver? _resolver;
   CelestProjectResolver get resolver => _resolver!;
 
+  /// Whether [code] and [message] represent a possible false-positive for
+  /// missing code generation.
+  bool _missingCodegenError(AnalysisError error) {
+    switch (error.errorCode) {
+      case CompileTimeErrorCode.URI_DOES_NOT_EXIST:
+        final regex = RegExp(r'''Target of URI doesn't exist: '(.+?)'\.''');
+        final match = regex.firstMatch(error.message);
+        final uri = match?.group(1);
+        if (uri == null) {
+          return false;
+        }
+        final path =
+            context.currentSession.uriConverter.uriToPath(Uri.parse(uri));
+        if (path == null) {
+          _logger.fine('Failed to convert URI to path: $uri');
+          return false;
+        }
+        return p.isWithin(projectPaths.generatedDir, path);
+    }
+
+    return false;
+  }
+
   @override
   void reportError(
     String error, {
@@ -497,7 +521,15 @@ const project = Project(name: 'cache_warmup');
           .expand((unit) => unit.errors)
           .where((error) => error.severity == Severity.error)
           .toList();
-      if (apiErrors.isNotEmpty) {
+
+      // If there's a false positive from missing generated code, which can
+      // happen for example when starting from a template proejct, then skip
+      // reporting errors since they may be resolved through generation, and if
+      // not, they'll be caught by the frontend compiler.
+      final falsePositiveForGeneratedCode =
+          apiErrors.isNotEmpty && apiErrors.any(_missingCodegenError);
+
+      if (apiErrors.isNotEmpty && !falsePositiveForGeneratedCode) {
         for (final apiError in apiErrors) {
           reportError(
             apiError.message,

apps/cli/lib/src/commands/init_command.dart

@@ -15,6 +15,17 @@ final class InitCommand extends CelestCommand with Configure, ProjectCreator {
       hide: true,
       defaultsTo: true,
     );
+    argParser.addOption(
+      'template',
+      abbr: 't',
+      help: 'The project template to use.',
+      allowed: ['hello', 'data'],
+      allowedHelp: {
+        'hello': 'A simple greeting API.',
+        'data': 'A project with a database and cloud functions.',
+      },
+      defaultsTo: 'hello',
+    );
   }
 
   @override
@@ -29,6 +40,9 @@ final class InitCommand extends CelestCommand with Configure, ProjectCreator {
   @override
   Progress? currentProgress;
 
+  @override
+  late final String template = argResults!.option('template')!;
+
   /// Precache assets in the background.
   Future<void> _precacheInBackground() async {
     final command = switch (CliRuntime.current) {
@@ -97,9 +111,9 @@ final class InitCommand extends CelestCommand with Configure, ProjectCreator {
     stdout.writeln();
     cliLogger.success('🚀 To start a local development server, run:');
     cliLogger
-      ..info(Platform.lineTerminator)
-      ..info('      $command${Platform.lineTerminator}')
-      ..info(Platform.lineTerminator);
+      ..info('')
+      ..info('      $command')
+      ..info('');
 
     return 0;
   }

apps/cli/lib/src/commands/start_command.dart

@@ -8,7 +8,20 @@ import 'package:mason_logger/mason_logger.dart';
 
 final class StartCommand extends CelestCommand
     with Configure, Migrate, ProjectCreator {
-  StartCommand();
+  StartCommand() {
+    argParser.addOption(
+      'template',
+      abbr: 't',
+      help: 'The project template to use.',
+      allowed: ['hello', 'data'],
+      allowedHelp: {
+        'hello': 'A simple greeting API.',
+        'data': 'A project with a database and cloud functions.',
+      },
+      defaultsTo: 'hello',
+      hide: true,
+    );
+  }
 
   @override
   String get description => 'Starts a local Celest environment.';
@@ -22,6 +35,9 @@ final class StartCommand extends CelestCommand
   @override
   Progress? currentProgress;
 
+  @override
+  late final String template = argResults!.option('template')!;
+
   @override
   Future<int> run() async {
     await super.run();

apps/cli/lib/src/init/project_generator.dart

@@ -1,20 +1,32 @@
 import 'package:celest_cli/src/init/migrations/add_analyzer_plugin.dart';
 import 'package:celest_cli/src/init/migrations/macos_entitlements.dart';
 import 'package:celest_cli/src/init/project_migration.dart';
+import 'package:celest_cli/src/init/templates/project_template.dart';
 import 'package:celest_cli/src/project/celest_project.dart';
 import 'package:celest_cli/src/sdk/dart_sdk.dart';
 
+typedef ProjectTemplateFactory = ProjectTemplate Function(
+  String projectRoot,
+  String projectName,
+  String projectDisplayName,
+);
+
 /// Manages the generation of a new Celest project.
 class ProjectGenerator {
   ProjectGenerator({
     required this.projectName,
+    required this.projectDisplayName,
     required this.parentProject,
+    this.projectTemplate = HelloProject.new,
     required this.projectRoot,
   });
 
+  /// The sanitized name of the project.
+  final String projectName;
+
   /// The name of the project to initialize, as chosen by the user
   /// when running `celest start` for the first time.
-  final String projectName;
+  final String projectDisplayName;
 
   /// The root directory of the enclosing Flutter project.
   ///
@@ -23,17 +35,32 @@ class ProjectGenerator {
   /// Flutter code.
   final ParentProject? parentProject;
 
+  /// The project template to use for the migration.
+  final ProjectTemplateFactory projectTemplate;
+
   /// The root directory of the initialized Celest project.
   final String projectRoot;
 
   /// Generates a new Celest project.
   Future<void> generate() async {
+    final template = projectTemplate(
+      projectRoot,
+      projectName,
+      projectDisplayName,
+    );
     await Future.wait(
       [
         ProjectFile.gitIgnore(projectRoot),
         ProjectFile.analysisOptions(projectRoot),
-        ProjectFile.pubspec(projectRoot, projectName, parentProject),
-        ProjectTemplate.hello(projectRoot, projectName),
+        ProjectFile.pubspec(
+          projectRoot,
+          projectName: projectName,
+          projectDisplayName: projectDisplayName,
+          parentProject: parentProject,
+          additionalDependencies: template.additionalDependencies,
+        ),
+        ProjectFile.client(projectRoot, projectName),
+        template,
         if (parentProject
             case ParentProject(
               path: final appRoot,

apps/cli/lib/src/init/project_init.dart

@@ -8,6 +8,7 @@ import 'package:celest_cli/src/context.dart';
 import 'package:celest_cli/src/exceptions.dart';
 import 'package:celest_cli/src/init/project_generator.dart';
 import 'package:celest_cli/src/init/project_migrate.dart';
+import 'package:celest_cli/src/init/templates/project_template.dart';
 import 'package:celest_cli/src/project/celest_project.dart';
 import 'package:celest_cli/src/pub/pub_action.dart';
 import 'package:celest_cli/src/sdk/dart_sdk.dart';
@@ -18,8 +19,12 @@ import 'package:dcli/dcli.dart' as dcli;
 import 'package:mason_logger/mason_logger.dart';
 
 base mixin ProjectCreator on Configure {
+  /// The project template to use when creating a project.
+  String get template;
+
   Future<String> createProject({
     required String projectName,
+    required String projectDisplayName,
     required ParentProject? parentProject,
   }) async {
     logger.finest(
@@ -31,6 +36,12 @@ base mixin ProjectCreator on Configure {
         parentProject: parentProject,
         projectRoot: projectPaths.projectRoot,
         projectName: projectName,
+        projectDisplayName: projectDisplayName,
+        projectTemplate: switch (template) {
+          'hello' => HelloProject.new,
+          'data' => DataProject.new,
+          _ => unreachable('Invalid project template: $template'),
+        },
       ).generate();
       logger.fine('Project generated successfully');
     });
@@ -74,13 +85,15 @@ base mixin Configure on CelestCommand {
         'To create a new project, run `celest init`.',
       );
 
-  String newProjectName({String? defaultName}) {
+  ({
+    String projectNameInput,
+    String projectName,
+  }) newProjectName({String? defaultName}) {
     if (defaultName != null && defaultName.startsWith('celest')) {
       defaultName = null;
     }
-    defaultName ??= 'my_project';
-    String? projectName;
-    while (projectName == null) {
+    defaultName ??= 'My Project';
+    for (;;) {
       final input = dcli
           .ask('Enter a name for your project', defaultValue: defaultName)
           .trim();
@@ -90,13 +103,12 @@ base mixin Configure on CelestCommand {
       }
       final words = input.groupIntoWords();
       for (final (index, word) in List.of(words).indexed) {
-        if (word == 'celest') {
+        if (word.toLowerCase() == 'celest') {
           words.removeAt(index);
         }
       }
-      projectName = words.snakeCase;
+      return (projectNameInput: input, projectName: words.snakeCase);
     }
-    return projectName;
   }
 
   Future<bool> configure() async {
@@ -128,8 +140,13 @@ base mixin Configure on CelestCommand {
 
   /// Returns true if the project needs to be migrated.
   Stream<ConfigureState> _configure() async* {
-    final (projectName, projectRoot, isExistingProject, parentProject) =
-        await _locateProject();
+    final (
+      projectNameInput,
+      projectName,
+      projectRoot,
+      isExistingProject,
+      parentProject
+    ) = await _locateProject();
 
     yield const Initializing();
     await init(projectRoot: projectRoot, parentProject: parentProject);
@@ -141,6 +158,7 @@ base mixin Configure on CelestCommand {
         yield const CreatingProject();
         await projectCreator.createProject(
           projectName: projectName!,
+          projectDisplayName: projectNameInput!,
           parentProject: parentProject,
         );
         yield const CreatedProject();
@@ -169,7 +187,7 @@ base mixin Configure on CelestCommand {
     yield Initialized(needsAnalyzerMigration: needsAnalyzerMigration);
   }
 
-  Future<(String? name, String root, bool, ParentProject?)>
+  Future<(String? nameInput, String? name, String root, bool, ParentProject?)>
       _locateProject() async {
     var currentDir = fileSystem.currentDirectory;
     final currentDirIsEmpty = await currentDir.list().isEmpty;
@@ -228,6 +246,7 @@ base mixin Configure on CelestCommand {
 
     String projectRoot;
     String? projectName;
+    String? projectNameInput;
     if (isExistingProject) {
       if (this is InitCommand) {
         cliLogger.success(
@@ -259,7 +278,8 @@ base mixin Configure on CelestCommand {
       if (currentDirIsEmpty) {
         defaultProjectName ??= p.basename(currentDir.path);
       }
-      projectName = newProjectName(defaultName: defaultProjectName);
+      (:projectNameInput, :projectName) =
+          newProjectName(defaultName: defaultProjectName);
 
       // Choose where to store the project based on the current directory.
       projectRoot = switch (celestDir) {
@@ -269,11 +289,12 @@ base mixin Configure on CelestCommand {
         // for the project which is unattached to any parent project, named
         // after the project.
         null when !currentDirIsEmpty => await run(() async {
-            final projectRoot = p.join(currentDir.path, projectName);
+            final directoryName = projectName!.snakeCase;
+            final projectRoot = p.join(currentDir.path, directoryName);
             final projectDir = fileSystem.directory(projectRoot);
             if (projectDir.existsSync() && !await projectDir.list().isEmpty) {
               throw CliException(
-                'A directory named "$projectName" already exists. '
+                'A directory named "$directoryName" already exists. '
                 'Please choose a different name, or run this command from a '
                 'different directory.',
               );
@@ -286,7 +307,13 @@ base mixin Configure on CelestCommand {
       };
     }
 
-    return (projectName, projectRoot, isExistingProject, parentProject);
+    return (
+      projectNameInput,
+      projectName,
+      projectRoot,
+      isExistingProject,
+      parentProject
+    );
   }
 
   // TODO(dnys1): Improve logic here so that we don't run pub upgrade if