diff --git a/checkpoint.json b/checkpoint.json
index 5bc60201a..9e0bc7634 100644
--- a/checkpoint.json
+++ b/checkpoint.json
@@ -1,41 +1,49 @@
 {
-  "timestamp": "2026-03-16T11:59:09.646073Z",
-  "current_node": "solve",
+  "timestamp": "2026-03-16T11:59:13.164019Z",
+  "current_node": "extract_patch",
   "completed_nodes": [
     "start",
     "setup",
-    "solve"
+    "solve",
+    "extract_patch"
   ],
   "node_retries": {
     "start": 1,
-    "solve": 1,
-    "setup": 1
+    "extract_patch": 1,
+    "setup": 1,
+    "solve": 1
   },
   "context_values": {
     "command.stderr": "",
     "graph.rankdir": "LR",
     "internal.fidelity": "compact",
-    "internal.thread_id": "setup",
+    "internal.thread_id": "solve",
     "internal.retry_count.start": 1,
     "thread.start.current_node": "setup",
     "failure_signature": "",
-    "current_node": "solve",
+    "current_node": "extract_patch",
     "internal.retry_count.setup": 1,
     "internal.retry_count.solve": 1,
     "last_stage": "solve",
-    "current.preamble": "Goal: UsernameValidator allows trailing newline in usernames\nDescription\n\t\nASCIIUsernameValidator and UnicodeUsernameValidator use the regex \nr'^[\\w.@+-]+$'\nThe intent is to only allow alphanumeric characters as well as ., @, +, and -. However, a little known quirk of Python regexes is that $ will also match a trailing newline. Therefore, the user name validators will accept usernames which end with a newline. You can avoid this behavior by instead using \\A and \\Z to terminate regexes. For example, the validator regex could be changed to\nr'\\A[\\w.@+-]+\\Z'\nin order to reject usernames that end with a newline.\nI am not sure how to officially post a patch, but the required change is trivial - using the regex above in the two validators in contrib.auth.validators.\n\n\n## Completed stages\n- **setup**: fail\n  - Script: `git clone https://github.com/django/django.git . && git checkout d26b2424437dabeeca94d7900b37d2df4410da0c && python -m pip install -e .`\n  - Stdout:\n    ```\n    fatal: destination path '.' already exists and is not an empty directory.\n    ```\n  - Stderr: (empty)\n\n## Context\n- failure_class: deterministic\n- failure_signature: setup|deterministic|script failed with exit code: <n> ## stdout fatal: destination path '.' already exists and is not an empty directory.\n",
+    "current.preamble": "Goal: UsernameValidator allows trailing newline in usernames\nDescription\n\t\nASCIIUsernameValidator and UnicodeUsernameValidator use the regex \nr'^[\\w.@+-]+$'\nThe intent is to only allow alphanumeric characters as well as ., @, +, and -. However, a little known quirk of Python regexes is that $ will also match a trailing newline. Therefore, the user name validators will accept usernames which end with a newline. You can avoid this behavior by instead using \\A and \\Z to terminate regexes. For example, the validator regex could be changed to\nr'\\A[\\w.@+-]+\\Z'\nin order to reject usernames that end with a newline.\nI am not sure how to officially post a patch, but the required change is trivial - using the regex above in the two validators in contrib.auth.validators.\n\n\n## Completed stages\n- **setup**: fail\n  - Script: `git clone https://github.com/django/django.git . && git checkout d26b2424437dabeeca94d7900b37d2df4410da0c && python -m pip install -e .`\n  - Stdout:\n    ```\n    fatal: destination path '.' already exists and is not an empty directory.\n    ```\n  - Stderr: (empty)\n- **solve**: success\n  - Model: claude-haiku-4-5, 8.1k tokens in / 3.5k out\n  - Files: /tmp/django/django/contrib/auth/validators.py, /tmp/django/test_validators.py\n",
     "last_response": "Perfect! The changes are complete and verified. Let me create a summary of the fix:\n\n## Summary\n\nI successfully fixed the Django username validator issue in `/tmp/django/django/contrib/auth/validators",
     "thread.setup.current_node": "solve",
     "response.solve": "Perfect! The changes are complete and verified. Let me create a summary of the fix:\n\n## Summary\n\nI successfully fixed the Django username validator issue in `/tmp/django/django/contrib/auth/validators.py`.\n\n### The Problem\nBoth `ASCIIUsernameValidator` and `UnicodeUsernameValidator` used the regex pattern `r'^[\\w.@+-]+$'`, which has a subtle Python regex quirk: the `$` anchor matches before a trailing newline, not just at the end of the string. This allowed usernames ending with a newline to be incorrectly accepted.\n\n### The Solution\nChanged both validators' regex patterns from `r'^[\\w.@+-]+$'` to `r'\\A[\\w.@+-]+\\Z'`:\n- Line 10: `ASCIIUsernameValidator.regex = r'\\A[\\w.@+-]+\\Z'`\n- Line 20: `UnicodeUsernameValidator.regex = r'\\A[\\w.@+-]+\\Z'`\n\nThe `\\A` and `\\Z` anchors have stricter semantics:\n- `\\A` matches only at the absolute start of the string (never at newlines)\n- `\\Z` matches only at the absolute end of the string (never before newlines)\n\n### Verification\nThe fix was tested with both validators and confirmed to:\n- ✅ Accept valid usernames: `validuser`, `user.name`, `user@example.com`, `user+tag`, `user-name`, `user_name`\n- ✅ Reject usernames with trailing newlines: `validuser\\n`\n- ✅ Reject usernames with embedded newlines: `user\\nname`\n\nThis is a minimal, targeted fix that directly addresses the issue without any side effects.",
     "internal.run_id": "01KKV8571T7NZ32CMPW5ZWCCC7",
     "internal.node_visit_count": 1,
+    "internal.retry_count.extract_patch": 1,
     "outcome": "success",
-    "command.output": "fatal: destination path '.' already exists and is not an empty directory.\n",
+    "command.output": "",
+    "thread.solve.current_node": "extract_patch",
     "graph.goal": "UsernameValidator allows trailing newline in usernames\nDescription\n\t\nASCIIUsernameValidator and UnicodeUsernameValidator use the regex \nr'^[\\w.@+-]+$'\nThe intent is to only allow alphanumeric characters as well as ., @, +, and -. However, a little known quirk of Python regexes is that $ will also match a trailing newline. Therefore, the user name validators will accept usernames which end with a newline. You can avoid this behavior by instead using \\A and \\Z to terminate regexes. For example, the validator regex could be changed to\nr'\\A[\\w.@+-]+\\Z'\nin order to reject usernames that end with a newline.\nI am not sure how to officially post a patch, but the required change is trivial - using the regex above in the two validators in contrib.auth.validators.\n",
     "failure_class": ""
   },
   "logs": [],
   "node_outcomes": {
+    "start": {
+      "status": "success",
+      "duration_ms": 0
+    },
     "solve": {
       "status": "success",
       "context_updates": {
@@ -58,9 +66,14 @@
       ],
       "duration_ms": 55810
     },
-    "start": {
+    "extract_patch": {
       "status": "success",
-      "duration_ms": 0
+      "context_updates": {
+        "command.stderr": "",
+        "command.output": ""
+      },
+      "notes": "Script completed: git diff",
+      "duration_ms": 231
     },
     "setup": {
       "status": "fail",
@@ -75,13 +88,14 @@
       "duration_ms": 86
     }
   },
-  "next_node_id": "extract_patch",
+  "next_node_id": "exit",
   "loop_failure_signatures": {
     "setup|deterministic|script failed with exit code: <n> ## stdout fatal: destination path '.' already exists and is not an empty directory.": 1
   },
   "node_visits": {
     "setup": 1,
-    "start": 1,
-    "solve": 1
+    "solve": 1,
+    "extract_patch": 1,
+    "start": 1
   }
 }
\ No newline at end of file
diff --git a/nodes/extract_patch/script_invocation.json b/nodes/extract_patch/script_invocation.json
new file mode 100644
index 000000000..6d29afc80
--- /dev/null
+++ b/nodes/extract_patch/script_invocation.json
@@ -0,0 +1,5 @@
+{
+  "command": "git diff",
+  "language": "shell",
+  "timeout_ms": null
+}
\ No newline at end of file
diff --git a/nodes/extract_patch/script_timing.json b/nodes/extract_patch/script_timing.json
new file mode 100644
index 000000000..3dd24d261
--- /dev/null
+++ b/nodes/extract_patch/script_timing.json
@@ -0,0 +1,5 @@
+{
+  "duration_ms": 228,
+  "exit_code": 0,
+  "timed_out": false
+}
\ No newline at end of file
diff --git a/nodes/extract_patch/status.json b/nodes/extract_patch/status.json
new file mode 100644
index 000000000..edb5c2c5d
--- /dev/null
+++ b/nodes/extract_patch/status.json
@@ -0,0 +1,6 @@
+{
+  "status": "success",
+  "notes": "Script completed: git diff",
+  "failure_reason": null,
+  "timestamp": "2026-03-16T11:59:13.162224+00:00"
+}
\ No newline at end of file