diff --git a/Sources/AiSTKit/AnalyzerConfiguration.swift b/Sources/AiSTKit/AnalyzerConfiguration.swift
new file mode 100644
index 0000000..d0b635f
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+++ b/Sources/AiSTKit/AnalyzerConfiguration.swift
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+//
+//  AnalyzerConfiguration.swift
+//  SyntaxKit
+//
+//  Created by Leo Dion.
+//  Copyright © 2026 BrightDigit.
+//
+//  Permission is hereby granted, free of charge, to any person
+//  obtaining a copy of this software and associated documentation
+//  files (the “Software”), to deal in the Software without
+//  restriction, including without limitation the rights to use,
+//  copy, modify, merge, publish, distribute, sublicense, and/or
+//  sell copies of the Software, and to permit persons to whom the
+//  Software is furnished to do so, subject to the following
+//  conditions:
+//
+//  The above copyright notice and this permission notice shall be
+//  included in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND,
+//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+//  OTHER DEALINGS IN THE SOFTWARE.
+//
+
+/// Configuration for the SyntaxKit analyzer, assembled by the `skit analyze`
+/// subcommand from parsed command-line arguments and handed to
+/// `SyntaxKitAnalyzer`.
+public struct AnalyzerConfiguration: Sendable {
+  /// Folder containing `dsl.swift` and `expected.swift`.
+  public let inputFolderPath: String
+  /// Path to the existing SyntaxKit library sources.
+  public let syntaxKitPath: String
+  /// Where to write the updated library.
+  public let outputFolderPath: String
+  /// Claude API key.
+  public let apiKey: String
+  /// Claude model identifier.
+  public let model: String
+  /// Enables verbose progress output.
+  public let verbose: Bool
+
+  /// Creates an analyzer configuration.
+  ///
+  /// - Parameters:
+  ///   - inputFolderPath: Folder containing `dsl.swift` and `expected.swift`.
+  ///   - syntaxKitPath: Path to the existing SyntaxKit library sources.
+  ///   - outputFolderPath: Where to write the updated library.
+  ///   - apiKey: Claude API key.
+  ///   - model: Claude model identifier.
+  ///   - verbose: Enables verbose progress output.
+  public init(
+    inputFolderPath: String,
+    syntaxKitPath: String,
+    outputFolderPath: String,
+    apiKey: String,
+    model: String,
+    verbose: Bool
+  ) {
+    self.inputFolderPath = inputFolderPath
+    self.syntaxKitPath = syntaxKitPath
+    self.outputFolderPath = outputFolderPath
+    self.apiKey = apiKey
+    self.model = model
+    self.verbose = verbose
+  }
+}
diff --git a/Sources/AiSTKit/AnalyzerError.swift b/Sources/AiSTKit/AnalyzerError.swift
new file mode 100644
index 0000000..808204f
--- /dev/null
+++ b/Sources/AiSTKit/AnalyzerError.swift
@@ -0,0 +1,49 @@
+//
+//  AnalyzerError.swift
+//  SyntaxKit
+//
+//  Created by Leo Dion.
+//  Copyright © 2026 BrightDigit.
+//
+//  Permission is hereby granted, free of charge, to any person
+//  obtaining a copy of this software and associated documentation
+//  files (the “Software”), to deal in the Software without
+//  restriction, including without limitation the rights to use,
+//  copy, modify, merge, publish, distribute, sublicense, and/or
+//  sell copies of the Software, and to permit persons to whom the
+//  Software is furnished to do so, subject to the following
+//  conditions:
+//
+//  The above copyright notice and this permission notice shall be
+//  included in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND,
+//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+//  OTHER DEALINGS IN THE SOFTWARE.
+//
+
+/// Errors thrown by the `skit analyze` pipeline. Each case carries a
+/// human-readable message; the subcommand decides how to present it.
+public enum AnalyzerError: Error {
+  /// Required command-line arguments were not provided.
+  case missingRequiredArguments(String)
+  /// No API key was provided via flag or the `ANTHROPIC_API_KEY`
+  /// environment variable.
+  case missingAPIKey(String)
+  /// The input or SyntaxKit path does not exist.
+  case invalidPath(String)
+  /// A required input file (`dsl.swift`, `expected.swift`) was not found
+  /// in the input folder.
+  case missingInputFile(String)
+  /// Generating the AST from the input sources failed.
+  case astGenerationError(String)
+  /// The Claude API call failed (network, authentication, rate limit, …).
+  case apiError(String)
+  /// Parsing the generated code out of Claude's response failed.
+  case codeGenerationError(String)
+}