diff --git a/openless-all/app/crates/openless-core/src/coding_agent.rs b/openless-all/app/crates/openless-core/src/coding_agent.rs
index b1283e8ff..6227b2018 100644
--- a/openless-all/app/crates/openless-core/src/coding_agent.rs
+++ b/openless-all/app/crates/openless-core/src/coding_agent.rs
@@ -604,14 +604,20 @@ pub fn build_dsh_patch_yaml(patch_path: &Path, prompt: &str) -> Result<String, B
         .map_err(|error| BackendError::new(BackendErrorCode::Internal, error.to_string()))?;
     let task = serde_json::to_string(prompt)
         .map_err(|error| BackendError::new(BackendErrorCode::Internal, error.to_string()))?;
+    // Not `\` line continuations: they strip the next line's leading spaces, which
+    // flattened this document into invalid YAML that dsh refused to parse.
     Ok(format!(
-        "# Generated by OpenLess. Applied as the last patch layer for one headless run.\n\
-- insert:\n\
-    - id: dsh-events\n\
-      name: {path}\n\
-- id: headless-runner\n\
-  config:\n\
-    task: {task}\n"
+        concat!(
+            "# Generated by OpenLess. Applied as the last patch layer for one headless run.\n",
+            "- insert:\n",
+            "    - id: dsh-events\n",
+            "      name: {path}\n",
+            "- id: headless-runner\n",
+            "  config:\n",
+            "    task: {task}\n",
+        ),
+        path = path,
+        task = task,
     ))
 }
 
@@ -1300,9 +1306,11 @@ fn summarize_stderr(stderr: &str) -> Option<String> {
         .lines()
         .map(str::trim)
         .filter(|line| !line.is_empty());
+    // A crashing Node CLI prints "Error: <cause>" and a stack, then ends with
+    // "Node.js vX" — taking only the last line would show just the version.
     lines
         .clone()
-        .find(|line| line.starts_with("dsh:") || line.contains("error:"))
+        .find(|line| line.starts_with("dsh:") || line.to_ascii_lowercase().contains("error:"))
         .or_else(|| lines.next_back())
         .map(str::to_string)
 }
@@ -2386,6 +2394,54 @@ mod tests {
         }
     }
 
+    #[test]
+    fn summarize_stderr_picks_the_node_crash_message_not_the_version_footer() {
+        let stderr = "file:///D:/dsh/lib/index.js:3564\n\
+\t\tthrow new Error(`${binName}: failed to parse ${label} ${file}: ${String(error)}`);\n\
+\t\t      ^\n\
+\n\
+Error: dsh: failed to parse overlay C:\\Temp\\openless.patch.yml: YAMLException: bad indentation\n\
+    at parsePatchList (file:///D:/dsh/lib/index.js:3564:9)\n\
+\n\
+Node.js v24.18.1\n";
+
+        assert_eq!(
+            summarize_stderr(stderr).as_deref(),
+            Some("Error: dsh: failed to parse overlay C:\\Temp\\openless.patch.yml: YAMLException: bad indentation")
+        );
+    }
+
+    #[test]
+    fn summarize_stderr_falls_back_to_the_last_line() {
+        assert_eq!(
+            summarize_stderr("starting\nsomething odd happened\n").as_deref(),
+            Some("something odd happened")
+        );
+        assert_eq!(summarize_stderr("\n  \n"), None);
+    }
+
+    #[test]
+    fn dsh_patch_yaml_keeps_its_indentation() {
+        let yaml = build_dsh_patch_yaml(
+            Path::new(r"C:\Users\me\AppData\Local\Temp\dsh-events.mjs"),
+            "第一行\n\"第二行\"",
+        )
+        .unwrap();
+
+        assert_eq!(
+            yaml,
+            concat!(
+                "# Generated by OpenLess. Applied as the last patch layer for one headless run.\n",
+                "- insert:\n",
+                "    - id: dsh-events\n",
+                "      name: \"C:\\\\Users\\\\me\\\\AppData\\\\Local\\\\Temp\\\\dsh-events.mjs\"\n",
+                "- id: headless-runner\n",
+                "  config:\n",
+                "    task: \"第一行\\n\\\"第二行\\\"\"\n",
+            )
+        );
+    }
+
     #[test]
     fn materialization_plan_substitutes_plain_and_json_paths() {
         let directory = std::env::temp_dir().join("openless-agent-plan");