Add git lfs pre-commit check

Author: rtibbles

.pre-commit-config.yaml

@@ -1,4 +1,4 @@
-exclude: (\.git/|\.tox/|\.venv/|build/|static/|dist/|node_modules/|kolibripip\.pex)
+exclude: (\.git/|\.tox/|\.venv/|build/|static/(?!assets/fonts)|dist/|node_modules/|kolibripip\.pex)
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v4.6.0
@@ -90,6 +90,11 @@ repos:
     language: pygrep
     exclude: (^packages/kolibri-common/|moduleMapping\.js|(__tests__|__fixtures__))
     files: ^packages/.*\.(js|vue)$
+  - id: check-lfs-pointers
+    name: Check LFS files are pointers not binary data
+    description: Prevents accidentally committing binary files that should be LFS pointers (issue #7099)
+    entry: python .pre-commit-hooks/check_lfs_pointers.py
+    language: python
 -   repo: https://github.com/isidentical/teyit
     rev: 0.4.3
     hooks:

.pre-commit-hooks/check_lfs_pointers.py

@@ -0,0 +1,121 @@
+#!/usr/bin/env python3
+"""
+Pre-commit hook to ensure files designated for Git LFS are actually LFS pointers.
+
+This prevents accidentally committing binary files that should be managed by Git LFS.
+See: https://github.com/learningequality/kolibri/issues/7099
+
+Checks staged content (what will be committed) to verify it's an LFS pointer,
+not binary data. This works whether or not Git LFS is installed in the environment
+running the check.
+"""
+import logging
+import subprocess
+import sys
+
+
+LFS_POINTER_HEADER = b"version https://git-lfs.github.com/spec/v1"
+
+
+def has_lfs_filter(filepath):
+    """
+    Check if a file has the LFS filter attribute set.
+
+    Args:
+        filepath: Path to the file to check
+
+    Returns:
+        bool: True if file has filter=lfs attribute
+    """
+    try:
+        result = subprocess.run(
+            ["git", "check-attr", "filter", filepath],
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+        return "filter: lfs" in result.stdout
+    except subprocess.CalledProcessError:
+        return False
+
+
+def is_lfs_pointer(filepath):
+    """
+    Check if the staged content for a file is an LFS pointer.
+
+    Reads the staged content (what will be committed) to verify it starts
+    with the LFS pointer header.
+
+    Args:
+        filepath: Path to the file to check
+
+    Returns:
+        bool: True if staged content is an LFS pointer, False otherwise
+    """
+    try:
+        result = subprocess.run(
+            ["git", "show", f":{filepath}"],
+            capture_output=True,
+            check=True,
+        )
+        first_line = result.stdout.split(b"\n")[0].strip()
+        return first_line.startswith(LFS_POINTER_HEADER)
+    except subprocess.CalledProcessError:
+        return False
+
+
+def main(filenames):
+    """
+    Main function to check staged files against LFS patterns.
+
+    Args:
+        filenames: List of filenames to check (passed by pre-commit)
+
+    Returns:
+        int: Exit code (0 for success, 1 for failure)
+    """
+    # Configure logging to write to stderr
+    logging.basicConfig(level=logging.ERROR, format="%(message)s", stream=sys.stderr)
+    logger = logging.getLogger(__name__)
+
+    failed_files = []
+
+    for filepath in filenames:
+        if has_lfs_filter(filepath):
+            if not is_lfs_pointer(filepath):
+                failed_files.append(filepath)
+
+    if failed_files:
+        logger.error("\n" + "=" * 80)
+        logger.error("ERROR: LFS Pointer Check Failed")
+        logger.error("=" * 80)
+        logger.error("")
+        logger.error(
+            "The following files should be LFS pointers but contain binary data:"
+        )
+        logger.error("")
+
+        for filepath in failed_files:
+            logger.error("  \033[31m✗\033[0m %s", filepath)
+
+        logger.error("")
+        logger.error("-" * 80)
+        logger.error("These files match LFS patterns in .gitattributes but were not")
+        logger.error("committed through Git LFS.")
+        logger.error("")
+        logger.error("To fix this issue:")
+        logger.error("  1. Ensure Git LFS is installed: git lfs install")
+        logger.error(
+            "  2. Remove the binary files from staging: git rm --cached <file>"
+        )
+        logger.error("  3. Re-add the files (Git LFS will handle them): git add <file>")
+        logger.error("=" * 80)
+        logger.error("")
+
+        return 1
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv[1:]))