fix(core): require exact outer argv authority

codex-rs/core/src/exec_policy.rs

@@ -365,7 +365,7 @@ impl ExecPolicyManager {
                         matched_prefix,
                         decision: Decision::Allow,
                         ..
-                    } if matched_prefix.len() == outer.len()
+                    } if matched_prefix.as_slice() == outer
                 )
             })
         });

codex-rs/core/src/exec_policy_windows_tests.rs

@@ -146,7 +146,11 @@ async fn only_exact_outer_rules_can_bypass_runtime_resolution() {
                 "host_executable(name = \"powershell\", paths = [\"{executable}\"])\n\
              prefix_rule(pattern=[\"powershell\", {rest}], decision=\"allow\")"
             ),
-            Some(true),
+            Some(false),
+        ),
+        (
+            format!("prefix_rule(pattern=[\"powershell\", {rest}], decision=\"allow\")"),
+            Some(false),
         ),
         (
             format!(