Allow default apply_patch environment

Let multi-environment apply_patch calls without an explicit environment_id fall through to the primary turn environment, matching the optional parser contract and existing resolve_tool_environment(None) behavior.

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/tools/handlers/apply_patch.rs

@@ -589,10 +589,6 @@ fn require_environment_id(
             "apply_patch environment selection is unavailable for this turn".to_string(),
         )),
         Some(environment_id) => Ok(Some(environment_id.to_string())),
-        None if allow_environment_id => Err(FunctionCallError::RespondToModel(
-            "apply_patch environment_id is required when multiple environments are available"
-                .to_string(),
-        )),
         None => Ok(None),
     }
 }

codex-rs/core/src/tools/handlers/apply_patch_tests.rs

@@ -207,10 +207,7 @@ fn reconcile_environment_id_requires_selection_when_enabled() {
         require_environment_id(
             /*parsed_environment_id*/ None, /*allow_environment_id*/ true
         ),
-        Err(FunctionCallError::RespondToModel(
-            "apply_patch environment_id is required when multiple environments are available"
-                .to_string(),
-        ))
+        Ok(None)
     );
 }