diff --git a/biome.jsonc b/biome.jsonc
index a437355f..7afbd8a7 100644
--- a/biome.jsonc
+++ b/biome.jsonc
@@ -60,7 +60,11 @@
     },
     {
       "path": "./scripts/grit/import-boundaries/no-app-server-protocol-boundary-imports.grit",
-      "includes": ["**/src/**/*.{ts,tsx}", "!**/src/app-server/**"]
+      "includes": ["**/src/**/*.{ts,tsx}", "!**/src/app-server/**", "!**/src/features/chat/app-server/mappers/message-stream/turn-items.ts"]
+    },
+    {
+      "path": "./scripts/grit/import-boundaries/no-chat-turn-item-non-turn-protocol-imports.grit",
+      "includes": ["**/src/features/chat/app-server/mappers/message-stream/turn-items.ts"]
     },
     {
       "path": "./scripts/grit/import-boundaries/no-generated-app-server-boundary-imports.grit",
diff --git a/scripts/grit/import-boundaries/no-app-server-protocol-boundary-imports.grit b/scripts/grit/import-boundaries/no-app-server-protocol-boundary-imports.grit
index f85aeaaf..b71e2a25 100644
--- a/scripts/grit/import-boundaries/no-app-server-protocol-boundary-imports.grit
+++ b/scripts/grit/import-boundaries/no-app-server-protocol-boundary-imports.grit
@@ -9,12 +9,7 @@ private pattern js_module_reference() {
 
 private pattern app_server_protocol_source() { r"^[\"'](?:(?:\.\./)+app-server/protocol|src/app-server/protocol)/[^/\"']+(?:/.*)?[\"']$" }
 
-private pattern turn_protocol_source() { r"^[\"'](?:(?:\.\./)+app-server/protocol/turn|src/app-server/protocol/turn)(?:/.*)?[\"']$" }
-
 js_module_reference() as $stmt where {
-  $stmt <: contains `$source` where {
-    $source <: app_server_protocol_source(),
-    not { $filename <: r".*/src/features/chat/app-server/mappers/message-stream/turn-items\.ts$", $source <: turn_protocol_source() }
-  },
+  $stmt <: contains `$source` where { $source <: app_server_protocol_source() },
   register_diagnostic(span=$stmt, message="Source modules outside root src/app-server must use domain models and app-server services instead of app-server protocol modules. Chat turn-item conversion may consume turn protocol at its app-server boundary; feature state and UI must use Panel-owned models.", severity="error")
 }
diff --git a/scripts/grit/import-boundaries/no-chat-turn-item-non-turn-protocol-imports.grit b/scripts/grit/import-boundaries/no-chat-turn-item-non-turn-protocol-imports.grit
new file mode 100644
index 00000000..8e6dce98
--- /dev/null
+++ b/scripts/grit/import-boundaries/no-chat-turn-item-non-turn-protocol-imports.grit
@@ -0,0 +1,17 @@
+language js
+
+private pattern js_module_reference() {
+  or {
+    JsImport(),
+    JsImportCallExpression()
+  }
+}
+
+private pattern app_server_protocol_source() { r"^[\"'](?:(?:\.\./)+app-server/protocol|src/app-server/protocol)/[^/\"']+(?:/.*)?[\"']$" }
+
+private pattern turn_protocol_source() { r"^[\"'](?:(?:\.\./)+app-server/protocol/turn|src/app-server/protocol/turn)(?:/.*)?[\"']$" }
+
+js_module_reference() as $stmt where {
+  $stmt <: contains `$source` where { $source <: app_server_protocol_source(), not { $source <: turn_protocol_source() } },
+  register_diagnostic(span=$stmt, message="Source modules outside root src/app-server must use domain models and app-server services instead of app-server protocol modules. Chat turn-item conversion may consume turn protocol at its app-server boundary; feature state and UI must use Panel-owned models.", severity="error")
+}
diff --git a/tests/scripts/grit-policy.test.mjs b/tests/scripts/grit-policy.test.mjs
index c2748d19..0eb02a33 100644
--- a/tests/scripts/grit-policy.test.mjs
+++ b/tests/scripts/grit-policy.test.mjs
@@ -1156,6 +1156,7 @@ async function createAppServerBoundaryPolicyReport() {
   const cwd = await tempBiomeWorkspace([
     "no-generated-app-server-boundary-imports.grit",
     "no-app-server-protocol-boundary-imports.grit",
+    "no-chat-turn-item-non-turn-protocol-imports.grit",
     "no-domain-outer-layer-imports.grit",
     "no-lower-level-feature-imports.grit",
     "no-app-server-connection-boundary-imports.grit",