refactor: improve thinking logic

internal/thinking/errors.go

@@ -0,0 +1,71 @@
+// Package thinking provides unified thinking configuration processing logic.
+package thinking
+
+// ErrorCode represents the type of thinking configuration error.
+type ErrorCode string
+
+// Error codes for thinking configuration processing.
+const (
+	// ErrInvalidSuffix indicates the suffix format cannot be parsed.
+	// Example: "model(abc" (missing closing parenthesis)
+	ErrInvalidSuffix ErrorCode = "INVALID_SUFFIX"
+
+	// ErrUnknownLevel indicates the level value is not in the valid list.
+	// Example: "model(ultra)" where "ultra" is not a valid level
+	ErrUnknownLevel ErrorCode = "UNKNOWN_LEVEL"
+
+	// ErrThinkingNotSupported indicates the model does not support thinking.
+	// Example: claude-haiku-4-5 does not have thinking capability
+	ErrThinkingNotSupported ErrorCode = "THINKING_NOT_SUPPORTED"
+
+	// ErrLevelNotSupported indicates the model does not support level mode.
+	// Example: using level with a budget-only model
+	ErrLevelNotSupported ErrorCode = "LEVEL_NOT_SUPPORTED"
+
+	// ErrProviderMismatch indicates the provider does not match the model.
+	// Example: applying Claude format to a Gemini model
+	ErrProviderMismatch ErrorCode = "PROVIDER_MISMATCH"
+)
+
+// ThinkingError represents an error that occurred during thinking configuration processing.
+//
+// This error type provides structured information about the error, including:
+//   - Code: A machine-readable error code for programmatic handling
+//   - Message: A human-readable description of the error
+//   - Model: The model name related to the error (optional)
+//   - Details: Additional context information (optional)
+type ThinkingError struct {
+	// Code is the machine-readable error code
+	Code ErrorCode
+	// Message is the human-readable error description.
+	// Should be lowercase, no trailing period, with context if applicable.
+	Message string
+	// Model is the model name related to this error (optional)
+	Model string
+	// Details contains additional context information (optional)
+	Details map[string]interface{}
+}
+
+// Error implements the error interface.
+// Returns the message directly without code prefix.
+// Use Code field for programmatic error handling.
+func (e *ThinkingError) Error() string {
+	return e.Message
+}
+
+// NewThinkingError creates a new ThinkingError with the given code and message.
+func NewThinkingError(code ErrorCode, message string) *ThinkingError {
+	return &ThinkingError{
+		Code:    code,
+		Message: message,
+	}
+}
+
+// NewThinkingErrorWithModel creates a new ThinkingError with model context.
+func NewThinkingErrorWithModel(code ErrorCode, message, model string) *ThinkingError {
+	return &ThinkingError{
+		Code:    code,
+		Message: message,
+		Model:   model,
+	}
+}