Fix pagination loop termination with Since filter

pkg/github/client.go

@@ -28,16 +28,29 @@ func (f *IssueFetcher) FetchIssues(ctx context.Context, owner, repo string, sinc
 	}
 
 	var allIssues []*github.Issue
+	seen := make(map[int64]bool)
 	for {
 		issues, resp, err := f.client.Issues.ListByRepository(ctx, owner, repo, opt)
 		if err != nil {
 			return nil, fmt.Errorf("failed to list issues: %w", err)
 		}
-		allIssues = append(allIssues, issues...)
-		if resp.NextPage == 0 {
+
+		for _, issue := range issues {
+			id := issue.GetID()
+			if !seen[id] {
+				seen[id] = true
+				allIssues = append(allIssues, issue)
+			}
+		}
+
+		if resp == nil || resp.NextPage == 0 {
 			break
 		}
 		opt.Page = resp.NextPage
+
+		if err := ctx.Err(); err != nil {
+			return nil, fmt.Errorf("context cancelled: %w", err)
+		}
 	}
 	return allIssues, nil
 }

pkg/github/client_test.go

@@ -176,6 +176,80 @@ func TestFetchIssues_EmptyPageWithNext(t *testing.T) {
 	}
 }
 
+func TestFetchIssues_DuplicatePrevention(t *testing.T) {
+	sinceTime := time.Now().Add(-24 * time.Hour).Truncate(time.Second)
+	sinceStr := sinceTime.Format(time.RFC3339)
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		q := r.URL.Query()
+		if q.Get("since") != sinceStr {
+			t.Errorf("expected since parameter %q, got %q", sinceStr, q.Get("since"))
+		}
+
+		pageStr := q.Get("page")
+		page := 1
+		if pageStr != "" {
+			var err error
+			page, err = strconv.Atoi(pageStr)
+			if err != nil {
+				t.Fatalf("invalid page parameter: %v", err)
+			}
+		}
+
+		var issues []*github.Issue
+		var nextPage int
+
+		switch page {
+		case 1:
+			issues = []*github.Issue{
+				{ID: github.Int64(1), Title: github.String("Issue 1")},
+				{ID: github.Int64(2), Title: github.String("Issue 2")},
+			}
+			nextPage = 2
+		case 2:
+			// Page 2 returns issue 2 again (duplicate) plus a new one
+			issues = []*github.Issue{
+				{ID: github.Int64(2), Title: github.String("Issue 2")},
+				{ID: github.Int64(3), Title: github.String("Issue 3")},
+			}
+			nextPage = 0
+		default:
+			t.Fatalf("unexpected page request: %d", page)
+		}
+
+		if nextPage != 0 {
+			linkHeader := fmt.Sprintf("<%s?page=%d&since=%s>; rel=\"next\"", server.URL+r.URL.Path, nextPage, url.QueryEscape(sinceStr))
+			w.Header().Set("Link", linkHeader)
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(issues)
+	}))
+	defer server.Close()
+
+	httpClient := server.Client()
+	client := github.NewClient(httpClient)
+	baseURL, _ := url.Parse(server.URL + "/")
+	client.BaseURL = baseURL
+
+	fetcher := NewIssueFetcher(client)
+	issues, err := fetcher.FetchIssues(context.Background(), "owner", "repo", sinceTime, 2)
+	if err != nil {
+		t.Fatalf("FetchIssues failed: %v", err)
+	}
+
+	if len(issues) != 3 {
+		t.Errorf("expected 3 unique issues, got %d", len(issues))
+	}
+
+	expectedIDs := []int64{1, 2, 3}
+	for i, issue := range issues {
+		if issue.GetID() != expectedIDs[i] {
+			t.Errorf("at index %d: expected ID %d, got %d", i, expectedIDs[i], issue.GetID())
+		}
+	}
+}
+
 func TestFetchIssues_Integration(t *testing.T) {
 	token := os.Getenv("GITHUB_TOKEN")
 	repoFullName := os.Getenv("GITHUB_REPOSITORY")