diff --git a/codex-rs/code-mode/src/description.rs b/codex-rs/code-mode/src/description.rs
index 73f5536c09..cfa9d67e23 100644
--- a/codex-rs/code-mode/src/description.rs
+++ b/codex-rs/code-mode/src/description.rs
@@ -568,6 +568,11 @@ mod tests {
 
     #[test]
     fn preview_failed_log_from_code_mode() {
-        panic!("intentional preview failure: code-mode test log");
+        let actual = "code-mode actual preview value";
+        let expected = "code-mode expected preview value";
+        assert_eq!(
+            actual, expected,
+            "intentional preview failure: code-mode assertion diff"
+        );
     }
 }
diff --git a/codex-rs/config/src/types_tests.rs b/codex-rs/config/src/types_tests.rs
index ab34d9addc..2ab65daaba 100644
--- a/codex-rs/config/src/types_tests.rs
+++ b/codex-rs/config/src/types_tests.rs
@@ -44,5 +44,6 @@ fn deserialize_skill_config_with_path_selector() {
 
 #[test]
 fn preview_failed_log_from_config() {
-    panic!("intentional preview failure: config test log");
+    eprintln!("intentional preview stderr: config before panic");
+    panic!("intentional preview failure: config panic after stderr");
 }
diff --git a/codex-rs/protocol/src/exec_output_tests.rs b/codex-rs/protocol/src/exec_output_tests.rs
index fc71db9ac7..5f2127cd08 100644
--- a/codex-rs/protocol/src/exec_output_tests.rs
+++ b/codex-rs/protocol/src/exec_output_tests.rs
@@ -68,8 +68,8 @@ fn test_invalid_bytes_still_fall_back_to_lossy() {
 }
 
 #[test]
-fn preview_failed_log_from_protocol() {
-    panic!("intentional preview failure: protocol test log");
+fn preview_failed_log_from_protocol() -> Result<(), String> {
+    Err("intentional preview failure: protocol returned Result::Err".to_string())
 }
 
 fn decode_shell_output(bytes: &[u8]) -> String {
diff --git a/codex-rs/utils/output-truncation/src/truncate_tests.rs b/codex-rs/utils/output-truncation/src/truncate_tests.rs
index 43f5e251a8..1d5494a8bd 100644
--- a/codex-rs/utils/output-truncation/src/truncate_tests.rs
+++ b/codex-rs/utils/output-truncation/src/truncate_tests.rs
@@ -282,5 +282,9 @@ fn byte_count_conversion_clamps_non_positive_values() {
 
 #[test]
 fn preview_failed_log_from_output_truncation() {
-    panic!("intentional preview failure: output-truncation test log");
+    let output = "output-truncation preview value";
+    assert!(
+        output.contains("truncated marker"),
+        "intentional preview failure: output-truncation predicate assertion"
+    );
 }