refactoring: Implement resource fetching service, add new skill definitions, and introduce prompts file.

tool/lib/src/commands/generate_skill_command.dart

@@ -9,6 +9,7 @@ import 'package:path/path.dart' as p;
 
 import '../models/skill_params.dart';
 import '../services/gemini_service.dart';
+import '../services/resource_fetcher_service.dart';
 import 'base_skill_command.dart';
 
 /// Command to generate skills from a configuration file.
@@ -46,10 +47,12 @@ class GenerateSkillCommand extends BaseSkillCommand {
     }
 
     try {
-      final combinedMarkdown = await fetchAndConvertContent(
+      final fetcher = ResourceFetcherService(
+        httpClient: httpClient,
+        logger: logger,
+      );
+      final combinedMarkdown = await fetcher.fetchAndConvertContent(
         skill.resources,
-        httpClient,
-        logger,
         configDir: configDir,
       );
 

tool/lib/src/commands/validate_skill_command.dart

@@ -9,6 +9,7 @@ import 'package:path/path.dart' as p;
 
 import '../models/skill_params.dart';
 import '../services/gemini_service.dart';
+import '../services/resource_fetcher_service.dart';
 import 'base_skill_command.dart';
 
 /// Command to validate skills by re-generating and comparing with existing skills.
@@ -52,10 +53,12 @@ class ValidateSkillCommand extends BaseSkillCommand {
 
     try {
       // Re-generate markdown content
-      final markdown = await fetchAndConvertContent(
+      final fetcher = ResourceFetcherService(
+        httpClient: httpClient,
+        logger: logger,
+      );
+      final markdown = await fetcher.fetchAndConvertContent(
         skill.resources,
-        httpClient,
-        logger,
         configDir: configDir,
       );
 

tool/lib/src/services/gemini_service.dart

@@ -8,11 +8,10 @@ import 'package:google_cloud_ai_generativelanguage_v1beta/generativelanguage.dar
 import 'package:http/http.dart' as http;
 import 'package:logging/logging.dart';
 import 'package:meta/meta.dart';
-import 'package:path/path.dart' as p;
 import 'package:retry/retry.dart';
 import 'package:yaml_writer/yaml_writer.dart';
 
-import 'markdown_converter.dart';
+import 'prompts.dart';
 import 'skill_instructions.dart';
 
 /// Service for interacting with the Gemini API to generate and validate skills.
@@ -71,7 +70,7 @@ class GeminiService {
   }) async {
     final service = GenerativeService(client: _client);
     final lastModified = io.HttpDate.format(DateTime.now());
-    final prompt = _createSkillPrompt(rawMarkdown, instructions);
+    final prompt = Prompts.createSkillPrompt(rawMarkdown, instructions);
 
     final request = _createRequest(
       prompt,
@@ -128,32 +127,13 @@ class GeminiService {
     int thinkingBudget = defaultThinkingBudget,
   }) async {
     final service = GenerativeService(client: _client);
-    final validationPrompt =
-        '''
-Validate the following skill document against the provided source material and verify if it is valid.
-Focus on:
-1. Accuracy: Does the skill capture the technical details correctly based on the Source Material?
-2. Structure: Is the skill well-structured according to skill best practices?
-3. Completeness: Is any critical information missing in the skill that is present in the Source Material?
-
-Context:
-- The skill was originally generated on: $generationDate
-- The current evaluation is using model: $modelName
-- The instructions used to generate the skill were:
-$instructions
-
-Source Material:
-$markdown
-
-Current Skill Content:
-  "$currentSkillContent"
----
-
-Grade the current output based on the instructions and the comparison to current website content and instructions today.
-Establish a conclusion on whether the new skill is valid or not.
-Reasons for a good or bad quality grade should be provided including concepts such as missing content, different model used, more than a few months old, etc.
-On the very last line, output "Grade: [0-100]" representing overall quality of the skill compared to the assumed value if it were generated again today.
-''';
+    final validationPrompt = Prompts.validateExistingSkillContentPrompt(
+      markdown,
+      instructions,
+      generationDate,
+      modelName,
+      currentSkillContent,
+    );
 
     final request = _createRequest(
       validationPrompt,
@@ -223,24 +203,6 @@ On the very last line, output "Grade: [0-100]" representing overall quality of t
     return '${cleaned.trim()}\n';
   }
 
-  String _createSkillPrompt(String markdown, String? instructions) {
-    return '''
-Rewrite the following technical documentation into a high-quality "SKILL.md" file.
-
-DO NOT include any YAML frontmatter. Start immediately with the markdown content (e.g. headers).
-
-**Guidelines:**
-1. **Ignore Noise**: Exclude navigation bars, footers, "Edit this page" links, and other non-technical content.
-2. **Decision Trees**: If the content describes a process with multiple choices or steps, YOU MUST create a "Decision Logic" or "Flowchart" section to guide the agent.
-3. **Clarity**: Use clear headings, bullet points, and code blocks.
-4. **Format**: Do NOT wrap the entire output in a markdown code block (like ```markdown ... ```). Return raw markdown text.
-${instructions != null && instructions.isNotEmpty ? '5. **Special Instructions**: $instructions' : ''}
-
-Raw Content:
-$markdown
-''';
-  }
-
   GenerateContentRequest _createRequest(
     String prompt, {
     String? systemInstruction,
@@ -282,65 +244,3 @@ class _ApiKeyClient extends http.BaseClient {
     return _inner.send(request);
   }
 }
-
-/// Fetches and converts content from a list of resources.
-///
-/// Throws an [Exception] if fetching any resource fails. This strict behavior
-/// prevents wasting Gemini tokens on generating low-quality skills when
-/// source material is missing.
-Future<String> fetchAndConvertContent(
-  List<String> resources,
-  http.Client httpClient,
-  Logger logger, {
-  io.Directory? configDir,
-}) async {
-  final converter = MarkdownConverter();
-  final sb = StringBuffer();
-  for (final resource in resources) {
-    logger.info('  Fetching $resource...');
-
-    if (resource.startsWith('http://')) {
-      throw Exception(
-        'Insecure HTTP URL found: $resource. '
-        'Only HTTPS URLs or relative file paths are allowed.',
-      );
-    }
-
-    if (resource.startsWith('https://')) {
-      final response = await httpClient.get(Uri.parse(resource));
-      if (response.statusCode == 200) {
-        sb
-          ..writeln('--- Raw content from $resource ---')
-          ..writeln(converter.convert(response.body));
-      } else {
-        throw Exception(
-          'Failed to fetch $resource: HTTP ${response.statusCode}. '
-          'Failing fast to save Gemini tokens.',
-        );
-      }
-    } else {
-      if (configDir == null) {
-        throw Exception(
-          'Relative resource "$resource" found, but no configuration '
-          'directory was provided to resolve it.',
-        );
-      }
-      final file = io.File(p.join(configDir.path, resource));
-      if (!file.existsSync()) {
-        throw Exception('Local resource file not found: ${file.path}');
-      }
-
-      final String content;
-      try {
-        content = file.readAsStringSync();
-      } on io.FileSystemException {
-        throw Exception('Local resource file is not readable: ${file.path}');
-      }
-
-      sb
-        ..writeln('--- Raw content from $resource ---')
-        ..writeln(content);
-    }
-  }
-  return sb.toString();
-}

tool/lib/src/services/prompts.dart

@@ -0,0 +1,62 @@
+// Copyright (c) 2026, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// ignore_for_file: avoid_classes_with_only_static_members
+
+/// Manages prompts used by the GeminiService.
+class Prompts {
+  /// Creates the prompt for generating a new skill.
+  static String createSkillPrompt(String markdown, String? instructions) {
+    return '''
+Rewrite the following technical documentation into a high-quality "SKILL.md" file.
+
+DO NOT include any YAML frontmatter. Start immediately with the markdown content (e.g. headers).
+
+**Guidelines:**
+1. **Ignore Noise**: Exclude navigation bars, footers, "Edit this page" links, and other non-technical content.
+2. **Decision Trees**: If the content describes a process with multiple choices or steps, YOU MUST create a "Decision Logic" or "Flowchart" section to guide the agent.
+3. **Clarity**: Use clear headings, bullet points, and code blocks.
+4. **Format**: Do NOT wrap the entire output in a markdown code block (like ```markdown ... ```). Return raw markdown text.
+${instructions != null && instructions.isNotEmpty ? '5. **Special Instructions**: $instructions' : ''}
+
+Raw Content:
+$markdown
+''';
+  }
+
+  /// Creates the prompt for validating an existing skill.
+  static String validateExistingSkillContentPrompt(
+    String markdown,
+    String instructions,
+    String generationDate,
+    String modelName,
+    String currentSkillContent,
+  ) {
+    return '''
+Validate the following skill document against the provided source material and verify if it is valid.
+Focus on:
+1. Accuracy: Does the skill capture the technical details correctly based on the Source Material?
+2. Structure: Is the skill well-structured according to skill best practices?
+3. Completeness: Is any critical information missing in the skill that is present in the Source Material?
+
+Context:
+- The skill was originally generated on: $generationDate
+- The current evaluation is using model: $modelName
+- The instructions used to generate the skill were:
+$instructions
+
+Source Material:
+$markdown
+
+Current Skill Content:
+  "$currentSkillContent"
+---
+
+Grade the current output based on the instructions and the comparison to current website content and instructions today.
+Establish a conclusion on whether the new skill is valid or not.
+Reasons for a good or bad quality grade should be provided including concepts such as missing content, different model used, more than a few months old, etc.
+On the very last line, output "Grade: [0-100]" representing overall quality of the skill compared to the assumed value if it were generated again today.
+''';
+  }
+}

tool/lib/src/services/resource_fetcher_service.dart

@@ -0,0 +1,84 @@
+// Copyright (c) 2026, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io' as io;
+
+import 'package:http/http.dart' as http;
+import 'package:logging/logging.dart';
+import 'package:path/path.dart' as p;
+
+import 'markdown_converter.dart';
+
+/// Fetches and converts content from diverse resources.
+class ResourceFetcherService {
+  /// Creates a new [ResourceFetcherService].
+  ResourceFetcherService({
+    required http.Client httpClient,
+    required Logger logger,
+  }) : _httpClient = httpClient,
+       _logger = logger;
+
+  final http.Client _httpClient;
+  final Logger _logger;
+
+  /// Fetches and converts content from a list of resources.
+  ///
+  /// Throws an [Exception] if fetching any resource fails. This strict behavior
+  /// prevents wasting tokens on generating low-quality skills when
+  /// source material is missing.
+  Future<String> fetchAndConvertContent(
+    List<String> resources, {
+    io.Directory? configDir,
+  }) async {
+    final converter = MarkdownConverter();
+    final sb = StringBuffer();
+    for (final resource in resources) {
+      _logger.info('  Fetching $resource...');
+
+      if (resource.startsWith('http://')) {
+        throw Exception(
+          'Insecure HTTP URL found: $resource. '
+          'Only HTTPS URLs or relative file paths are allowed.',
+        );
+      }
+
+      if (resource.startsWith('https://')) {
+        final response = await _httpClient.get(Uri.parse(resource));
+        if (response.statusCode == 200) {
+          sb
+            ..writeln('--- Raw content from $resource ---')
+            ..writeln(converter.convert(response.body));
+        } else {
+          throw Exception(
+            'Failed to fetch $resource: HTTP ${response.statusCode}. '
+            'Failing fast to save Gemini tokens.',
+          );
+        }
+      } else {
+        if (configDir == null) {
+          throw Exception(
+            'Relative resource "$resource" found, but no configuration '
+            'directory was provided to resolve it.',
+          );
+        }
+        final file = io.File(p.join(configDir.path, resource));
+        if (!file.existsSync()) {
+          throw Exception('Local resource file not found: ${file.path}');
+        }
+
+        final String content;
+        try {
+          content = file.readAsStringSync();
+        } on io.FileSystemException {
+          throw Exception('Local resource file is not readable: ${file.path}');
+        }
+
+        sb
+          ..writeln('--- Raw content from $resource ---')
+          ..writeln(content);
+      }
+    }
+    return sb.toString();
+  }
+}