Address round 2 feedback from #178 (items 13-16)

- Rule 3 (Serial Plan): Suppress for TRIVIAL plans and 0ms actual elapsed;
  demote to Info unless user explicitly forced serial (MAXDOP 1 / hint)
- Statement tab warning count: Use total (statement + node) warnings to
  match the main warnings strip count
- Parameters card: Span 2 columns when populated for more horizontal space

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata

src/PlanViewer.Core/Services/PlanAnalyzer.cs

@@ -124,9 +124,12 @@ private static void TryOverrideSeverity(PlanWarning warning, AnalyzerConfig cfg)
     private static void AnalyzeStatement(PlanStatement stmt, AnalyzerConfig cfg)
     {
         // Rule 3: Serial plan with reason
-        // Skip trivial statements (e.g., variable assignments, constant scans) — not worth warning about
+        // Skip: trivial cost (< 0.01), TRIVIAL optimization (can't go parallel anyway),
+        // and 0ms actual elapsed time (not worth flagging).
         if (!cfg.IsRuleDisabled(3) && !string.IsNullOrEmpty(stmt.NonParallelPlanReason)
-            && stmt.StatementSubTreeCost >= 0.01)
+            && stmt.StatementSubTreeCost >= 0.01
+            && stmt.StatementOptmLevel != "TRIVIAL"
+            && !(stmt.QueryTimeStats != null && stmt.QueryTimeStats.ElapsedTimeMs == 0))
         {
             var reason = stmt.NonParallelPlanReason switch
             {
@@ -138,11 +141,14 @@ private static void AnalyzeStatement(PlanStatement stmt, AnalyzerConfig cfg)
                 _ => stmt.NonParallelPlanReason
             };
 
+            // Only warn (not info) when the user explicitly forced serial execution
+            var isExplicit = stmt.NonParallelPlanReason is "MaxDOPSetToOne" or "QueryHintNoParallelSet";
+
             stmt.PlanWarnings.Add(new PlanWarning
             {
                 WarningType = "Serial Plan",
                 Message = $"Query running serially: {reason}.",
-                Severity = PlanWarningSeverity.Warning
+                Severity = isExplicit ? PlanWarningSeverity.Warning : PlanWarningSeverity.Info
             });
         }
 

src/PlanViewer.Web/Pages/Index.razor

@@ -74,9 +74,9 @@ else
                     {
                         <span class="stmt-tab-cost">@s.EstimatedCost.ToString("N2")</span>
                     }
-                    @if (s.Warnings.Count > 0)
+                    @if (GetAllWarnings(s).Count > 0)
                     {
-                        <span class="stmt-tab-warns">@s.Warnings.Count</span>
+                        <span class="stmt-tab-warns">@GetAllWarnings(s).Count</span>
                     }
                 </button>
             }

src/PlanViewer.Web/wwwroot/css/app.css

@@ -373,7 +373,8 @@ textarea::placeholder {
     margin-bottom: 0.75rem;
 }
 
-/* Wait stats card gets extra width when present */
+/* Give params and waits cards extra width when populated */
+.insight-card.params.has-items,
 .insight-card.waits.has-items {
     grid-column: span 2;
 }