diff --git a/codex-rs/windows-sandbox-rs/src/allow.rs b/codex-rs/windows-sandbox-rs/src/allow.rs
index de6215999..7a879df4a 100644
--- a/codex-rs/windows-sandbox-rs/src/allow.rs
+++ b/codex-rs/windows-sandbox-rs/src/allow.rs
@@ -18,6 +18,13 @@ pub fn compute_allow_paths(
             allow.push(p);
         }
     };
+    let include_tmp_env_vars = matches!(
+        policy,
+        SandboxPolicy::WorkspaceWrite {
+            exclude_tmpdir_env_var: false,
+            ..
+        }
+    );
 
     if matches!(policy, SandboxPolicy::WorkspaceWrite { .. }) {
         add_path(command_cwd.to_path_buf());
@@ -33,7 +40,7 @@ pub fn compute_allow_paths(
             }
         }
     }
-    if !matches!(policy, SandboxPolicy::ReadOnly) {
+    if include_tmp_env_vars {
         for key in ["TEMP", "TMP"] {
             if let Some(v) = env_map.get(key) {
                 let abs = PathBuf::from(v);
@@ -80,4 +87,32 @@ mod tests {
             "additional writable root should be allowed"
         );
     }
+
+    #[test]
+    fn excludes_tmp_env_vars_when_requested() {
+        let command_cwd = PathBuf::from(r"C:\Workspace");
+        let temp_dir = PathBuf::from(r"C:\TempDir");
+        let _ = fs::create_dir_all(&command_cwd);
+        let _ = fs::create_dir_all(&temp_dir);
+
+        let policy = SandboxPolicy::WorkspaceWrite {
+            writable_roots: vec![],
+            network_access: false,
+            exclude_tmpdir_env_var: true,
+            exclude_slash_tmp: false,
+        };
+        let mut env_map = HashMap::new();
+        env_map.insert("TEMP".into(), temp_dir.to_string_lossy().to_string());
+
+        let allow = compute_allow_paths(&policy, &command_cwd, &command_cwd, &env_map);
+
+        assert!(
+            allow.iter().any(|p| p == &command_cwd),
+            "command cwd should be allowed"
+        );
+        assert!(
+            !allow.iter().any(|p| p == &temp_dir),
+            "TEMP should be excluded when exclude_tmpdir_env_var is true"
+        );
+    }
 }
diff --git a/codex-rs/windows-sandbox-rs/src/lib.rs b/codex-rs/windows-sandbox-rs/src/lib.rs
index 1720294f2..e2277daad 100644
--- a/codex-rs/windows-sandbox-rs/src/lib.rs
+++ b/codex-rs/windows-sandbox-rs/src/lib.rs
@@ -71,6 +71,10 @@ mod windows_impl {
 
     type PipeHandles = ((HANDLE, HANDLE), (HANDLE, HANDLE), (HANDLE, HANDLE));
 
+    fn should_apply_network_block(policy: &SandboxPolicy) -> bool {
+        !policy.has_full_network_access()
+    }
+
     fn ensure_dir(p: &Path) -> Result<()> {
         if let Some(d) = p.parent() {
             std::fs::create_dir_all(d)?;
@@ -214,9 +218,12 @@ mod windows_impl {
         timeout_ms: Option<u64>,
     ) -> Result<CaptureResult> {
         let policy = parse_policy(policy_json_or_preset)?;
+        let apply_network_block = should_apply_network_block(&policy);
         normalize_null_device_env(&mut env_map);
         ensure_non_interactive_pager(&mut env_map);
-        apply_no_network_to_env(&mut env_map)?;
+        if apply_network_block {
+            apply_no_network_to_env(&mut env_map)?;
+        }
         ensure_codex_home_exists(codex_home)?;
 
         let current_dir = cwd.to_path_buf();
@@ -447,6 +454,36 @@ mod windows_impl {
             timed_out,
         })
     }
+
+    #[cfg(test)]
+    mod tests {
+        use super::should_apply_network_block;
+        use crate::policy::SandboxPolicy;
+
+        fn workspace_policy(network_access: bool) -> SandboxPolicy {
+            SandboxPolicy::WorkspaceWrite {
+                writable_roots: Vec::new(),
+                network_access,
+                exclude_tmpdir_env_var: false,
+                exclude_slash_tmp: false,
+            }
+        }
+
+        #[test]
+        fn applies_network_block_when_access_is_disabled() {
+            assert!(should_apply_network_block(&workspace_policy(false)));
+        }
+
+        #[test]
+        fn skips_network_block_when_access_is_allowed() {
+            assert!(!should_apply_network_block(&workspace_policy(true)));
+        }
+
+        #[test]
+        fn applies_network_block_for_read_only() {
+            assert!(should_apply_network_block(&SandboxPolicy::ReadOnly));
+        }
+    }
 }
 
 #[cfg(not(target_os = "windows"))]