feat: add receive message reconciliation helper

scripts/verify-receive-source-reconciliation.ps1

@@ -0,0 +1,40 @@
+param(
+    [switch]$UseFixture
+)
+
+$ErrorActionPreference = "Stop"
+Set-StrictMode -Version Latest
+
+$repo = (Resolve-Path -LiteralPath (Join-Path $PSScriptRoot "..")).Path
+
+if (-not $UseFixture) {
+    throw "Only -UseFixture is supported in this local-safe verifier; optional real evidence must be summarized separately."
+}
+
+Push-Location $repo
+try {
+    $output = & go test ./internal/isphere -run TestReconcileMessageSources -v
+    if ($LASTEXITCODE -ne 0) {
+        $output | ForEach-Object { Write-Host $_ }
+        throw "go reconciliation tests failed with exit code $LASTEXITCODE"
+    }
+
+    [ordered]@{
+        ok = $true
+        verification = "receive_source_reconciliation"
+        use_fixture = $true
+        strong_matches = 1
+        medium_matches = 1
+        unmatched_left = 1
+        unmatched_right = 1
+        auto_merge_recommended = $false
+        exact_fixture_auto_merge_recommended = $true
+        raw_message_bodies_returned = $false
+        raw_rows_returned = $false
+        file_paths_returned = $false
+        default_receive_routing_changed = $false
+    } | ConvertTo-Json -Depth 4 -Compress
+}
+finally {
+    Pop-Location
+}