Enforce Go style rules across codebase

Apply five style rules: convert iota string enums to typed
string constants, replace errors.As with errors.AsType,
merge three-group imports into two groups, fix multiline
parameter/argument formatting, and replace fmt.Sprintf URL
construction with net/url.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/llm/anthropic/provider.go

@@ -396,8 +396,8 @@ func mapError(err error) error {
 		return &llm.ErrStreamingRequired{Err: err}
 	}
 
-	var apiErr *anthropic.Error
-	if !errors.As(err, &apiErr) {
+	apiErr, ok := errors.AsType[*anthropic.Error](err)
+	if !ok {
 		return err
 	}
 

pkg/llm/bedrock/provider.go

@@ -329,9 +329,8 @@ func mapStopReason(reason types.StopReason) llm.FinishReason {
 }
 
 func mapError(err error) error {
-	var respErr *smithyhttp.ResponseError
-	if !errors.As(err, &respErr) {
-		// Check for common error types by message content.
+	respErr, ok := errors.AsType[*smithyhttp.ResponseError](err)
+	if !ok {
 		msg := err.Error()
 		if strings.Contains(msg, "throttling") || strings.Contains(msg, "ThrottlingException") {
 			return &llm.ErrRateLimit{Err: err}

pkg/llm/chat.go

@@ -206,10 +206,13 @@ func (a *StreamAccumulator) Response() *ChatCompletionResponse {
 
 	var parts []Part
 	if thinking := a.thinking.String(); thinking != "" {
-		parts = append(parts, ThinkingPart{
-			Text:      thinking,
-			Signature: a.thinkingSignature,
-		})
+		parts = append(
+			parts,
+			ThinkingPart{
+				Text:      thinking,
+				Signature: a.thinkingSignature,
+			},
+		)
 	}
 
 	parts = append(parts, TextPart{Text: a.content.String()})

pkg/llm/openai/provider.go

@@ -213,9 +213,10 @@ func buildMessages(messages []llm.Message) []openai.ChatCompletionMessageParamUn
 				case llm.ImagePart:
 					parts = append(
 						parts,
-						openai.ImageContentPart(openai.ChatCompletionContentPartImageImageURLParam{
-							URL: p.URL,
-						},
+						openai.ImageContentPart(
+							openai.ChatCompletionContentPartImageImageURLParam{
+								URL: p.URL,
+							},
 						),
 					)
 				case llm.FilePart:
@@ -381,8 +382,8 @@ func mapFinishReason(reason string) llm.FinishReason {
 }
 
 func mapError(err error) error {
-	var apiErr *openai.Error
-	if !errors.As(err, &apiErr) {
+	apiErr, ok := errors.AsType[*openai.Error](err)
+	if !ok {
 		return err
 	}
 
@@ -513,9 +514,11 @@ func isReasoningModel(model string) bool {
 func buildFilePart(p llm.FilePart) openai.ChatCompletionContentPartUnionParam {
 	switch {
 	case strings.HasPrefix(p.MimeType, "image/"):
-		return openai.ImageContentPart(openai.ChatCompletionContentPartImageImageURLParam{
-			URL: fmt.Sprintf("data:%s;base64,%s", p.MimeType, p.Data),
-		})
+		return openai.ImageContentPart(
+			openai.ChatCompletionContentPartImageImageURLParam{
+				URL: fmt.Sprintf("data:%s;base64,%s", p.MimeType, p.Data),
+			},
+		)
 	case strings.HasPrefix(p.MimeType, "text/"):
 		decoded, err := base64.StdEncoding.DecodeString(p.Data)
 		if err != nil {
@@ -524,9 +527,11 @@ func buildFilePart(p llm.FilePart) openai.ChatCompletionContentPartUnionParam {
 
 		return openai.TextContentPart(fmt.Sprintf("File: %s\n\n%s", p.Filename, string(decoded)))
 	default:
-		return openai.FileContentPart(openai.ChatCompletionContentPartFileFileParam{
-			FileData: param.NewOpt(fmt.Sprintf("data:%s;base64,%s", p.MimeType, p.Data)),
-			Filename: param.NewOpt(p.Filename),
-		})
+		return openai.FileContentPart(
+			openai.ChatCompletionContentPartFileFileParam{
+				FileData: param.NewOpt(fmt.Sprintf("data:%s;base64,%s", p.MimeType, p.Data)),
+				Filename: param.NewOpt(p.Filename),
+			},
+		)
 	}
 }