diff --git a/evalharness/agent/envs/swe_agentic.py b/evalharness/agent/envs/swe_agentic.py
index 3700ecd..5ee0245 100644
--- a/evalharness/agent/envs/swe_agentic.py
+++ b/evalharness/agent/envs/swe_agentic.py
@@ -189,11 +189,17 @@ class SWEAgenticEnvironment(Environment):
                 total_usage = total_usage + out.usage
                 text = out.text or ''
                 if SENTINEL in text:
-                    # payload after the sentinel echo = `cat patch.txt` output.
-                    # A unified diff must end with a newline; a stripped
-                    # payload fails git apply with 'corrupt patch at line N'
-                    patch = text.split(SENTINEL, 1)[1].strip() + '\n'
-                    break
+                    # the model MENTIONED the sentinel in prose OR ran it.
+                    # Never split on the mention -- the model discusses the
+                    # command and that chatter became the "patch" (145B of
+                    # conversational English). Read the ACTUAL file the agent
+                    # created in the container.
+                    r3 = await asyncio.to_thread(
+                        self._exec, 'cat /testbed/patch.txt')
+                    if r3['exit'] == 0 and r3['out'].strip():
+                        patch = r3['out'].strip() + '\n'
+                        break
+                    # patch.txt empty/missing: keep looping, git-diff at end
                 if out.tool_calls:
                     messages.append(ChatMessage(role='assistant', content=text))
                     for tc in out.tool_calls:
@@ -203,8 +209,12 @@ class SWEAgenticEnvironment(Environment):
                             role='user',
                             content=f"exit={res['exit']}\n{res['out']}"))
                         if SENTINEL in res['out']:
-                            # sentinel appeared in command output: capture patch
-                            patch = res['out'].split(SENTINEL, 1)[1].strip() + '\n'
+                            # sentinel in command output: the `cat patch.txt`
+                            # already ran -- read the actual file
+                            r2 = await asyncio.to_thread(
+                                self._exec, 'cat /testbed/patch.txt')
+                            if r2['exit'] == 0 and r2['out'].strip():
+                                patch = r2['out'].strip() + '\n'
                 else:
                     # no tool call: nudge per protocol
                     messages.append(ChatMessage(role='assistant', content=text))