diff --git a/checkpoint.json b/checkpoint.json
index c53041ffe..1ccd36e22 100644
--- a/checkpoint.json
+++ b/checkpoint.json
@@ -1,25 +1,28 @@
 {
-  "timestamp": "2026-03-16T12:07:13.890515Z",
-  "current_node": "solve",
+  "timestamp": "2026-03-16T12:07:16.209911Z",
+  "current_node": "extract_patch",
   "completed_nodes": [
     "start",
     "setup",
-    "solve"
+    "solve",
+    "extract_patch"
   ],
   "node_retries": {
     "setup": 1,
     "start": 1,
-    "solve": 1
+    "solve": 1,
+    "extract_patch": 1
   },
   "context_values": {
     "thread.start.current_node": "setup",
-    "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-opus-4-6, 5.1k tokens in / 1.8k out\n  - Files: /tmp/django-fix/django/contrib/auth/validators.py\n",
+    "internal.retry_count.extract_patch": 1,
     "internal.fidelity": "compact",
-    "command.output": "fatal: destination path '.' already exists and is not an empty directory.\n",
+    "command.output": "",
     "thread.setup.current_node": "solve",
     "response.solve": "The fix works correctly. Both validators now:\n- ✅ Accept valid usernames (e.g., `validuser`)\n- ✅ Reject usernames with trailing newlines (e.g., `validuser\\n`)\n\n**Summary of changes:** In `django/contrib/auth/validators.py`, changed the regex in both `ASCIIUsernameValidator` and `UnicodeUsernameValidator` from `r'^[\\w.@+-]+$'` to `r'\\A[\\w.@+-]+\\Z'`. \n\nThe issue was that Python's `$` in regex matches both end-of-string and just before a trailing newline, while `\\Z` matches only the absolute end of the string. Similarly, `\\A` is used instead of `^` for consistency (matching only the absolute start of the string).",
-    "internal.thread_id": "setup",
-    "current_node": "solve",
+    "internal.thread_id": "solve",
+    "current_node": "extract_patch",
     "failure_signature": "",
     "last_stage": "solve",
     "command.stderr": "",
@@ -32,14 +35,11 @@
     "failure_class": "",
     "internal.retry_count.setup": 1,
     "internal.run_id": "01KKV8M223JTFVZ853MV9PGXVD",
-    "internal.retry_count.start": 1
+    "internal.retry_count.start": 1,
+    "thread.solve.current_node": "extract_patch"
   },
   "logs": [],
   "node_outcomes": {
-    "start": {
-      "status": "success",
-      "duration_ms": 0
-    },
     "setup": {
       "status": "fail",
       "context_updates": {
@@ -52,6 +52,19 @@
       },
       "duration_ms": 26
     },
+    "extract_patch": {
+      "status": "success",
+      "context_updates": {
+        "command.output": "",
+        "command.stderr": ""
+      },
+      "notes": "Script completed: git diff",
+      "duration_ms": 30
+    },
+    "start": {
+      "status": "success",
+      "duration_ms": 0
+    },
     "solve": {
       "status": "success",
       "context_updates": {
@@ -75,13 +88,14 @@
       "duration_ms": 57355
     }
   },
-  "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,
+    "extract_patch": 1,
     "solve": 1,
-    "start": 1
+    "start": 1,
+    "setup": 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..4176f16cf
--- /dev/null
+++ b/nodes/extract_patch/script_timing.json
@@ -0,0 +1,5 @@
+{
+  "duration_ms": 26,
+  "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..f1803e3a8
--- /dev/null
+++ b/nodes/extract_patch/status.json
@@ -0,0 +1,6 @@
+{
+  "status": "success",
+  "notes": "Script completed: git diff",
+  "failure_reason": null,
+  "timestamp": "2026-03-16T12:07:16.209471+00:00"
+}
\ No newline at end of file
diff --git a/nodes/solve/diff.patch b/nodes/solve/diff.patch
new file mode 100644
index 000000000..aa0cbdf78
--- /dev/null
+++ b/nodes/solve/diff.patch
@@ -0,0 +1,32 @@
+diff --git a/django/contrib/auth/validators.py b/django/contrib/auth/validators.py
+new file mode 100644
+index 0000000..74e31f5
+--- /dev/null
++++ b/django/contrib/auth/validators.py
+@@ -0,0 +1,25 @@
++import re
++
++from django.core import validators
++from django.utils.deconstruct import deconstructible
++from django.utils.translation import gettext_lazy as _
++
++
++@deconstructible
++class ASCIIUsernameValidator(validators.RegexValidator):
++    regex = r'\A[\w.@+-]+\Z'
++    message = _(
++        'Enter a valid username. This value may contain only English letters, '
++        'numbers, and @/./+/-/_ characters.'
++    )
++    flags = re.ASCII
++
++
++@deconstructible
++class UnicodeUsernameValidator(validators.RegexValidator):
++    regex = r'\A[\w.@+-]+\Z'
++    message = _(
++        'Enter a valid username. This value may contain only letters, '
++        'numbers, and @/./+/-/_ characters.'
++    )
++    flags = 0
+\ No newline at end of file