Refactored Merge-DatumArray for performance optimization

CHANGELOG.md

@@ -39,6 +39,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   evaluate to `$null` or empty strings are now silently skipped
   instead of causing lookup errors.
 - Added knockout support for hashtable array items.
+- Added private function `Get-DatumTupleKeyValueString` for consistent composite key generation
+- Added private function `Test-DatumKnockout` for efficient knockout matching
 
 ### Changed
 
@@ -52,6 +54,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   using an InvokeCommand expression that returns a path for some nodes
   and nothing for others.
 - Updated build pipeline to also test against Linux and MacOS
+- Refactored `Merge-DatumArray` for performance optimization:
+  - Replaced O(n²) nested loop comparisons using `Compare-Hashtable` with O(n+m) hash-based indexing
+  - Pre-computed knockout reference items to avoid repeated checks during merge
+  - Changed output type from `[System.Collections.ArrayList]` to `[System.Collections.Generic.List[object]]`
+  - Updated RsopWithInvokCommandHandler integration tests to ensure also
+    node specific Datum handler values from lower layers are merged
+    correctly.
 
 ### Fixed
 
@@ -75,6 +84,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   property separator under `ResolutionPrecedence` and
   `lookup_options`.
 - Fixed issues running integration tests with PowerShell on Linux.
+- Fixed build issue with latest ModuleBuilder version by pinning to v3.1.8
+
+### Removed
+
+- Removed private function `Compare-Hashtable.ps1` (no longer needed)
 
 ## [0.41.0] - 2026-02-03
 

RequiredModules.psd1

@@ -14,7 +14,7 @@
     'DscResource.AnalyzerRules' = 'latest'
     #'DscResource.Common'        = 'latest'
     Plaster                     = 'latest'
-    ModuleBuilder               = 'latest'
+    ModuleBuilder               = '3.1.8'
     ChangelogManagement         = 'latest'
     Sampler                     = 'latest'
     'Sampler.GitHubTasks'       = 'latest'

memory-bank/systemPatterns.md

@@ -133,12 +133,6 @@ tests/
 - **DscWorkshopConfigData**: Full hierarchy with ProtectedData credentials + domain join
 - **Demo3**: Node1, Node2, Node3 — simple role merge + `$false` value test
 
-### Known Skipped Tests (3 tests)
-All in `RsopWithInvokCommandHandler.tests.ps1`, tagged with "There is a bug in the merge logic":
-- Ethernet 3 Gateway for DSCFile01
-- Ethernet 3 DnsServer for DSCFile01
-- Interface Count for DSCFile01
-
 ## Build System
 - **Sampler-based**: Uses the Sampler module for build/test/publish pipeline
 - **ModuleBuilder**: Merges source files into single module output

source/Private/Get-DatumTupleKeyValueString.ps1

@@ -0,0 +1,20 @@
+function Get-DatumTupleKeyValueString
+{
+    [OutputType([string])]
+    [CmdletBinding()]
+    param(
+        [hashtable]$Item,
+        [string[]]$Keys
+    )
+    if (-not $Keys)
+    {
+        $Keys = $Item.Keys
+    }
+
+    $sep = '#'
+    $values = foreach ($k in $Keys)
+    {
+        $Item[$k]
+    }
+    return ($values -join $sep)
+}