Add custom instructions for AI

home/home.nix

@@ -82,6 +82,42 @@ in
     };
     codex = {
       enable = true;
+      custom-instructions = ''
+## 10. Applying Patch Files with patch
+
+When the built-in `apply_patch` tool or `git apply` fails to apply a diff/patch file (especially if the file being patched contains special characters that might confuse simpler patch tools), the standard `patch` utility can be a more robust alternative.
+
+- **Patch File Format**: Ensure your patch file is in a standard unified diff format. Typically, these patches are generated with `git diff > my_feature.patch` or manually crafted. If the patch refers to files with `a/` and `b/` prefixes (e.g., `--- a/file.txt`, `+++ b/file.txt`), you'll use the `-p1` option.
+
+- **Creating the Patch File**: You can create a patch file using shell redirection, for example:
+
+```bash`
+cat <<'EOF' > fix_descriptive_name.patch
+--- a/path/to/your/file.ext
++++ b/path/to/your/file.ext
+@@ -line_num,num_lines +line_num,num_lines @@ context_or_change
+-old_line_content
++new_line_content
+EOF
+```
+
+*Important*: Ensure the `EOF` marker is on its own line with no trailing spaces.
+
+- **Applying the Patch**: Use the `patch` command via the `shell` tool. The `-p1` option strips the leading component from file paths in the patch file (`a/`, `b/`).
+
+```
+# Example: Apply a patch file
+default_api.shell(command=["sh", "-c", "patch -p1 < fix_descriptive_name.patch"])
+```
+
+- **Verification**: After applying, always verify that the target file has been changed as expected (e.g., using `cat` or `git diff`).
+
+- **Cleanup**: Remove the patch file if it's no longer needed:
+
+```
+default_api.shell(command=["rm", "fix_descriptive_name.patch"])
+```
+'';
       settings = {
         model = "${localFastModel}";
         provider = "ollama";