fix: server-side task ID injection for plan tools and UI polish (#431)

apps/backend/internal/github/client_helpers.go

@@ -195,21 +195,30 @@ func convertRawStatusContexts(raw []ghStatusContext) []CheckRun {
 	return checks
 }
 
-// mergeChecks deduplicates check runs and commit statuses by normalized name/url.
-// If both sources refer to the same item, check-run data wins.
+// mergeChecks deduplicates check runs and commit statuses by normalized name.
+// Check-run source wins over status-context; among same-source duplicates the
+// most recent entry (by StartedAt) is kept.
 func mergeChecks(checkRuns, statusChecks []CheckRun) []CheckRun {
 	merged := make([]CheckRun, 0, len(checkRuns)+len(statusChecks))
 	byKey := make(map[string]int)
 
 	for _, check := range statusChecks {
 		key := checkMergeKey(check)
+		if idx, ok := byKey[key]; ok {
+			if isNewerCheck(check, merged[idx]) {
+				merged[idx] = check
+			}
+			continue
+		}
 		byKey[key] = len(merged)
 		merged = append(merged, check)
 	}
 	for _, check := range checkRuns {
 		key := checkMergeKey(check)
 		if idx, ok := byKey[key]; ok {
-			merged[idx] = check
+			if merged[idx].Source == checkSourceStatusContext || isNewerCheck(check, merged[idx]) {
+				merged[idx] = check
+			}
 			continue
 		}
 		byKey[key] = len(merged)
@@ -219,9 +228,18 @@ func mergeChecks(checkRuns, statusChecks []CheckRun) []CheckRun {
 }
 
 func checkMergeKey(check CheckRun) string {
-	name := strings.ToLower(strings.TrimSpace(check.Name))
-	url := strings.ToLower(strings.TrimSpace(check.HTMLURL))
-	return name + "|" + url
+	return strings.ToLower(strings.TrimSpace(check.Name))
+}
+
+// isNewerCheck reports whether a started more recently than b.
+func isNewerCheck(a, b CheckRun) bool {
+	if a.StartedAt == nil {
+		return false
+	}
+	if b.StartedAt == nil {
+		return true
+	}
+	return a.StartedAt.After(*b.StartedAt)
 }
 
 // convertSearchItemToPR converts common search result fields into a PR struct.

apps/backend/internal/github/client_helpers_test.go

@@ -264,6 +264,60 @@ func TestConvertRawStatusContextsAndMergeChecks(t *testing.T) {
 	}
 }
 
+func TestMergeChecksDuplicateCheckRunsByName(t *testing.T) {
+	t1 := time.Date(2025, 6, 1, 10, 0, 0, 0, time.UTC)
+	t2 := time.Date(2025, 6, 1, 11, 0, 0, 0, time.UTC)
+
+	// Two check-runs with the same name but different URLs (different check suites).
+	checkRuns := []CheckRun{
+		{Name: "Analyze (go)", Source: checkSourceCheckRun, Status: "in_progress", HTMLURL: "https://github.com/o/r/runs/1", StartedAt: &t1},
+		{Name: "Analyze (go)", Source: checkSourceCheckRun, Status: "in_progress", HTMLURL: "https://github.com/o/r/runs/2", StartedAt: &t2},
+	}
+	merged := mergeChecks(checkRuns, nil)
+	if len(merged) != 1 {
+		t.Fatalf("expected 1 check after dedupe, got %d", len(merged))
+	}
+	if merged[0].HTMLURL != "https://github.com/o/r/runs/2" {
+		t.Errorf("expected newer check-run to win, got URL %s", merged[0].HTMLURL)
+	}
+}
+
+func TestMergeChecksCheckRunWinsOverStatusDifferentURL(t *testing.T) {
+	t1 := time.Date(2025, 6, 1, 10, 0, 0, 0, time.UTC)
+
+	checkRuns := []CheckRun{
+		{Name: "ci/test", Source: checkSourceCheckRun, Status: "completed", Conclusion: "success", HTMLURL: "https://github.com/o/r/runs/1", StartedAt: &t1},
+	}
+	statuses := []CheckRun{
+		{Name: "ci/test", Source: checkSourceStatusContext, Status: "in_progress", HTMLURL: "https://other-url.com/status/1", StartedAt: &t1},
+	}
+	merged := mergeChecks(checkRuns, statuses)
+	if len(merged) != 1 {
+		t.Fatalf("expected 1 check after dedupe, got %d", len(merged))
+	}
+	if merged[0].Source != checkSourceCheckRun {
+		t.Errorf("expected check_run to win over status_context, got source %s", merged[0].Source)
+	}
+}
+
+func TestIsNewerCheck(t *testing.T) {
+	t1 := time.Date(2025, 6, 1, 10, 0, 0, 0, time.UTC)
+	t2 := time.Date(2025, 6, 1, 11, 0, 0, 0, time.UTC)
+
+	if isNewerCheck(CheckRun{StartedAt: &t1}, CheckRun{StartedAt: &t2}) {
+		t.Error("older should not be newer")
+	}
+	if !isNewerCheck(CheckRun{StartedAt: &t2}, CheckRun{StartedAt: &t1}) {
+		t.Error("newer should be newer")
+	}
+	if isNewerCheck(CheckRun{StartedAt: nil}, CheckRun{StartedAt: &t1}) {
+		t.Error("nil StartedAt should not be newer")
+	}
+	if !isNewerCheck(CheckRun{StartedAt: &t1}, CheckRun{StartedAt: nil}) {
+		t.Error("non-nil should be newer than nil")
+	}
+}
+
 func TestConvertSearchItemToPR(t *testing.T) {
 	now := time.Now()
 	pr := convertSearchItemToPR(