error reporting fixes

pkg/sidekick/llm.go

@@ -5,12 +5,21 @@ import (
   "bytes"
   "context"
   "encoding/json"
+  "errors"
   "fmt"
   "io"
   "net/http"
   "strings"
 )
 
+var (
+  ErrLLMTimeout         = errors.New("the request to the AI model timed out. Please try again later")
+  ErrLLMRateLimit       = errors.New("rate limit exceeded. Please wait a moment and try again")
+  ErrLLMAuth            = errors.New("authentication failed. Please check your API key")
+  ErrLLMServer          = errors.New("the AI provider's server encountered an error. Please try again later")
+  ErrLLMInvalidResponse = errors.New("the AI model returned an invalid response structure")
+)
+
 // LLMClient represents an abstraction over the LLM provider
 type LLMClient interface {
   Call(ctx context.Context, model ModelConfig, messages []Message,
@@ -63,11 +72,22 @@ func (s *standardLLMClient) Call(ctx context.Context, model ModelConfig, msgs []
 
   resp, err := client.Do(req)
   if err != nil {
+    if errors.Is(err, context.DeadlineExceeded) || strings.Contains(err.Error(), "timeout") {
+      return Message{}, ErrLLMTimeout
+    }
     return Message{}, fmt.Errorf("HTTP request failed: %w", err)
   }
   defer resp.Body.Close()
 
   if resp.StatusCode != http.StatusOK {
+    switch resp.StatusCode {
+    case http.StatusUnauthorized, http.StatusForbidden:
+      return Message{}, ErrLLMAuth
+    case http.StatusTooManyRequests:
+      return Message{}, ErrLLMRateLimit
+    case http.StatusInternalServerError, http.StatusBadGateway, http.StatusServiceUnavailable:
+      return Message{}, ErrLLMServer
+    }
     body, _ := io.ReadAll(resp.Body)
     return Message{}, fmt.Errorf("API returned error (%d): %s", resp.StatusCode, string(body))
   }
@@ -91,7 +111,7 @@ func (s *standardLLMClient) Call(ctx context.Context, model ModelConfig, msgs []
   }
 
   if err := json.Unmarshal(body, &openAIResp); err != nil {
-    return Message{}, fmt.Errorf("failed to unmarshal response: %w", err)
+    return Message{}, fmt.Errorf("%w: failed to parse API response: %v", ErrLLMInvalidResponse, err)
   }
 
   if openAIResp.Error != nil {
@@ -99,7 +119,7 @@ func (s *standardLLMClient) Call(ctx context.Context, model ModelConfig, msgs []
   }
 
   if len(openAIResp.Choices) == 0 {
-    return Message{}, fmt.Errorf("API returned no choices")
+    return Message{}, fmt.Errorf("%w: API returned no choices", ErrLLMInvalidResponse)
   }
 
   return openAIResp.Choices[0].Message, nil