feat(pierre): sanity check

internal/pierre/review.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"fmt"
 	"log"
+
+	"git.schreifuchs.ch/schreifuchs/pierre-bot/internal/chatter"
 )
 
 func (s *Service) MakeReview(ctx context.Context, organisation string, repo string, prID int) error {
@@ -20,6 +22,46 @@ func (s *Service) MakeReview(ctx context.Context, organisation string, repo stri
 		return fmt.Errorf("error judging PR: %w", err)
 	}
 
+	// ---------- Sanity‑check step (always enabled) ----------
+	headSHA, err := s.git.GetPRHeadSHA(ctx, organisation, repo, prID)
+	if err != nil {
+		log.Printf("warning: could not fetch PR head SHA (%v); skipping sanity check", err)
+	} else {
+		filtered := []Comment{}
+		for _, c := range comments {
+			// Retrieve full file content at the PR head
+			fileContent, fErr := s.git.GetFileContent(ctx, organisation, repo, c.File, headSHA)
+			if fErr != nil {
+				log.Printf("failed to fetch file %s: %v – keeping original comment", c.File, fErr)
+				filtered = append(filtered, c)
+				continue
+			}
+
+			// Build a simple sanity‑check prompt
+			systemPrompt := `You are a senior software architect. Given the full source code of a file and a review comment that refers to it, decide whether the comment is useful. Return JSON with fields "useful" (bool) and "reason" (short explanation, ≤2 sentences).`
+			userPrompt := fmt.Sprintf("File content:\n%s\n\nComment:\n%s", fileContent, c.Message)
+
+			type sanityResult struct {
+				Useful bool   `json:"useful"`
+				Reason string `json:"reason"`
+			}
+			var res sanityResult
+			if err := s.chat.GenerateStructured(ctx, []chatter.Message{{Role: chatter.RoleSystem, Content: systemPrompt}, {Role: chatter.RoleUser, Content: userPrompt}}, &res); err != nil {
+				log.Printf("sanity check error for %s:%d: %v – keeping comment", c.File, c.Line, err)
+				filtered = append(filtered, c)
+				continue
+			}
+			if res.Useful {
+				// Optionally annotate the comment with the reason for debugging
+				c.Message = fmt.Sprintf("%s (Reason: %s)", c.Message, res.Reason)
+				filtered = append(filtered, c)
+			} else {
+				log.Printf("comment on %s:%d discarded: %s", c.File, c.Line, res.Reason)
+			}
+		}
+		comments = filtered
+	}
+
 	fmt.Printf("Analysis complete. Found %d issues.\n---\n", len(comments))
 
 	model := s.chat.GetProviderName()