fix: retain structured Workdir refusal diagnostics across provider boundaries

crates/tools/src/checkout_tests.rs

@@ -421,6 +421,13 @@ fn checkout_known_refusals_have_typed_codes_without_changing_normal_tools() {
     use workdir::{WorkdirError, WorkdirSessionCapability};
     let cases = [
         (WorkdirError::Denied("denied".into()), "checkout_denied"),
+        (
+            WorkdirError::DenialContext {
+                reason: workdir::WorkdirDenialReason::OsPermissionDenied,
+                source: Box::new(WorkdirError::OutOfScope("outside".into())),
+            },
+            "checkout_denied",
+        ),
         (
             WorkdirError::OutOfScope("outside".into()),
             "checkout_denied",

crates/tools/src/file_target.rs

@@ -139,7 +139,12 @@ impl FileTarget {
 
 pub(crate) fn checked_error(error: workdir::WorkdirError) -> ToolError {
     use workdir::WorkdirError;
+    if let WorkdirError::DenialContext { source, .. } = error {
+        // Diagnostic enrichment must not change the established tool classification.
+        return checked_error(*source);
+    }
     let code = match &error {
+        WorkdirError::DenialContext { .. } => unreachable!("unwrapped above"),
         WorkdirError::Conflict(_) | WorkdirError::NotFound(_) => "checkout_stale",
         WorkdirError::Denied { .. }
         | WorkdirError::OutOfScope { .. }