diff --git a/contracts/cultnet/cultnet.selection.schema.json b/contracts/cultnet/cultnet.selection.schema.json
index bf3cb534..4ae06173 100644
--- a/contracts/cultnet/cultnet.selection.schema.json
+++ b/contracts/cultnet/cultnet.selection.schema.json
@@ -7,11 +7,15 @@
   "properties": {
     "schemas": {
       "type": "array",
-      "items": { "type": "string", "minLength": 1 }
+      "items": { "type": "string", "minLength": 1 },
+      "minItems": 1,
+      "description": "Absent means every schema. Present and empty is refused at the door (selection_invalid), never treated as \"every schema\": omit the field instead."
     },
     "keys": {
       "type": "array",
-      "items": { "type": "string", "minLength": 1 }
+      "items": { "type": "string", "minLength": 1 },
+      "minItems": 1,
+      "description": "Absent means every key. Present and empty is refused at the door (selection_invalid), never treated as \"every key\": omit the field instead."
     },
     "fields": {
       "type": "array",
@@ -25,7 +29,12 @@
       "default": "header"
     },
     "descending": { "type": "boolean", "default": false },
-    "limit": { "type": "integer", "minimum": 1, "maximum": 200 },
+    "limit": {
+      "type": "integer",
+      "minimum": 1,
+      "maximum": 200,
+      "description": "Clamped to 1..=200 by the answering server, not refused outside that range: an absent value or one outside the bound is treated as the nearer bound (absent = 200)."
+    },
     "cursor": { "type": "string" }
   },
   "$defs": {
diff --git a/packages/cultnet-py/src/cultnet_py/interop_peer.py b/packages/cultnet-py/src/cultnet_py/interop_peer.py
index 4ff89314..ba236686 100644
--- a/packages/cultnet-py/src/cultnet_py/interop_peer.py
+++ b/packages/cultnet-py/src/cultnet_py/interop_peer.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 import argparse
 from collections import defaultdict
 import json
+import re
 import selectors
 import signal
 import socket
@@ -384,14 +385,27 @@ def handle_server_message(state: PeerState, message: dict[str, Any], subscriptio
         return [state.verse_catalog.create_response(message)]
     if schema_version == PEER_EXCHANGE_REQUEST:
         return [state.peer_catalog.create_response(message)]
-    if isinstance(schema_version, str) and schema_version.startswith("cultnet.") and schema_version.endswith(".v1"):
+    if is_unsupported_cultnet_version(schema_version):
         # R-2, owed by Cut 1 (docs/cultnet-selection-cut.md, section 9): this peer speaks
-        # cultnet.selection.v1's carrier messages (snapshot_request.v1, database_subscribe.v1) not at
-        # all - it is v0-only. A v1 message is refused loudly, not answered with a silent empty list.
+        # cultnet.selection.v1's carrier messages (snapshot_request.v1, database_subscribe.v1, and
+        # any later vN) not at all - it is v0-only. A non-v0 message is refused loudly, not answered
+        # with a silent empty list. The prior check only matched ".v1" exactly, so v2+ fell through
+        # to the silent empty return below instead of being refused (R-L).
         return [unsupported_schema_version_error(message)]
     return []
 
 
+_CULTNET_SCHEMA_VERSION_SUFFIX = re.compile(r"^cultnet\..*\.v(\d+)$")
+
+
+def is_unsupported_cultnet_version(schema_version: Any) -> bool:
+    """True for any cultnet.*.vN with N > 0 - every version this v0-only peer does not speak (R-2/R-L)."""
+    if not isinstance(schema_version, str):
+        return False
+    match = _CULTNET_SCHEMA_VERSION_SUFFIX.match(schema_version)
+    return match is not None and int(match.group(1)) > 0
+
+
 def unsupported_schema_version_error(message: dict[str, Any]) -> dict[str, Any]:
     schema_version = message.get("schemaVersion")
     return {
diff --git a/packages/cultnet-py/tests/test_cultnet.py b/packages/cultnet-py/tests/test_cultnet.py
index b95686be..475305d3 100644
--- a/packages/cultnet-py/tests/test_cultnet.py
+++ b/packages/cultnet-py/tests/test_cultnet.py
@@ -1954,11 +1954,19 @@ class CultNetTests(unittest.TestCase):
         self.assertEqual([record["recordKey"] for record in response["documents"]], ["note:logged"])
 
     def test_python_interop_peer_refuses_v1_selection_messages(self) -> None:
-        # R-2, owed by Cut 1 (docs/cultnet-selection-cut.md, section 9): a v0-only peer refuses a v1
-        # message loudly - cultnet.error.v0 { code: "unsupported_schema_version" } - rather than
+        # R-2, owed by Cut 1 (docs/cultnet-selection-cut.md, section 9): a v0-only peer refuses any
+        # non-v0 message loudly - cultnet.error.v0 { code: "unsupported_schema_version" } - rather than
         # silently answering with an empty list. handle_server_message never touches `state` before
-        # this refusal fires, so no PeerState fixture is needed here.
-        for schema_version in ("cultnet.snapshot_request.v1", "cultnet.database_subscribe.v1"):
+        # this refusal fires, so no PeerState fixture is needed here. R-L: the original check matched
+        # only ".v1" exactly, so v2+ silently fell through to an empty list instead of being refused -
+        # this covers v2 and v10 (double-digit) too, not only the exact v1 spelling.
+        for schema_version in (
+            "cultnet.snapshot_request.v1",
+            "cultnet.database_subscribe.v1",
+            "cultnet.snapshot_request.v2",
+            "cultnet.database_subscribe.v2",
+            "cultnet.snapshot_request.v10",
+        ):
             with self.subTest(schema_version=schema_version):
                 responses = handle_server_message(
                     None,  # type: ignore[arg-type]
diff --git a/scripts/mutate-dotnet.ps1 b/scripts/mutate-dotnet.ps1
index d3201b8a..1ccfd9bf 100644
--- a/scripts/mutate-dotnet.ps1
+++ b/scripts/mutate-dotnet.ps1
@@ -42,6 +42,15 @@ param(
 
 $ErrorActionPreference = 'Stop'
 
+# R-L: an entry's `File` (from -Entries, often written with forward slashes) is looked up against the
+# $targets dictionary keyed by -Target's own spelling. A bare string-key mismatch ("a\b.cs" vs
+# "a/b.cs") doesn't throw at the lookup - $targets[$file] just silently returns $null - so the crash
+# happens one call later, deep inside a .NET path/string API, as a null-argument error that reads
+# nothing like "unknown target". Normalizing both sides to '/' up front turns that into either a
+# clean match or an honest "Target ... does not exist" at line 99, never a null-argument surprise.
+function Normalize-TargetPath([string]$path) { $path -replace '\\', '/' }
+$Target = @($Target | ForEach-Object { Normalize-TargetPath $_ })
+
 $repo = if ($Repo) { (Resolve-Path -LiteralPath $Repo).Path } else { (Resolve-Path (Join-Path $PSScriptRoot '..')).Path }
 $testProjectPath = Join-Path $repo $TestProject
 $utf8 = [System.Text.UTF8Encoding]::new($false)
@@ -165,11 +174,11 @@ foreach ($mutation in $mutations) {
 
     Write-Host "--- $($mutation.Id) ($($mutation.Mutant)): $($mutation.Rule)"
     $texts = @{}
-    $files = @($edits | ForEach-Object { if ($_.File) { $_.File } elseif ($Target.Count -eq 1) { $Target[0] } else { throw "$($mutation.Id): an edit names no File and there is more than one target." } } | Select-Object -Unique)
+    $files = @($edits | ForEach-Object { if ($_.File) { Normalize-TargetPath $_.File } elseif ($Target.Count -eq 1) { $Target[0] } else { throw "$($mutation.Id): an edit names no File and there is more than one target." } } | Select-Object -Unique)
     foreach ($file in $files) { $texts[$file] = $utf8.GetString($originalBytes[$file]) }
 
     foreach ($edit in $edits) {
-        $file = if ($edit.File) { $edit.File } else { $Target[0] }
+        $file = if ($edit.File) { Normalize-TargetPath $edit.File } else { $Target[0] }
         $text = $texts[$file]
         $eol = if ($text.Contains("`r`n")) { "`r`n" } else { "`n" }
         $old = ($edit.Old -replace "`r`n", "`n")