perf(deployment): staleness/comparison paths no longer Roslyn-compile every script — deploy gate remains the authoritative compile

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

src/ZB.MOM.WW.ScadaBridge.DeploymentManager/FlatteningPipeline.cs

@@ -54,7 +54,8 @@ public class FlatteningPipeline : IFlatteningPipeline
     /// <inheritdoc />
     public async Task<Result<FlatteningPipelineResult>> FlattenAndValidateAsync(
         int instanceId,
-        CancellationToken cancellationToken = default)
+        CancellationToken cancellationToken = default,
+        bool validateScripts = true)
     {
         // Load instance with full graph
         var instance = await _templateRepo.GetInstanceByIdAsync(instanceId, cancellationToken);
@@ -158,13 +159,19 @@ public class FlatteningPipeline : IFlatteningPipeline
         // on the site — blocks the deployment. (The template DESIGN-TIME validate path in
         // ManagementActor leaves this non-blocking by NOT enforcing, since bindings are
         // set later at instance/deploy time.)
+        // validateScripts == false is the read-only staleness/comparison path: skip
+        // only the expensive Roslyn ValidateScriptCompilation (which loads a
+        // non-collectible InteractiveAssemblyLoader assembly per script). Structural
+        // and semantic validation still run so a genuinely broken flatten is surfaced;
+        // the deploy path (validateScripts: true) remains the authoritative compile gate.
         var validation = _validationService.Validate(
             config,
             resolvedSharedScripts,
             alarmCapableConnectionNames,
             enforceConnectionBindings: true,
             siteConnectionNames: siteConnectionNames,
-            resolveSchemaRef: resolveSchemaRef);
+            resolveSchemaRef: resolveSchemaRef,
+            validateScriptCompilation: validateScripts);
 
         // Compute revision hash
         var hash = _revisionHashService.ComputeHash(config);