feat: add pre-commit hook to collapse extra blank lines

Add collapse_blank_lines.py script and pre-commit hook that
automatically collapses 2+ consecutive blank lines into a single
blank line. Preserves blank lines inside code blocks.

Applies to .md and .py files in the TinyTorch repository.

tinytorch/.pre-commit-config.yaml

@@ -7,6 +7,20 @@
 # =============================================================================
 
 repos:
+  # ===========================================================================
+  # MARKDOWN FORMATTING
+  # ===========================================================================
+
+  - repo: local
+    hooks:
+      - id: collapse-blank-lines
+        name: "TinyTorch: Collapse extra blank lines"
+        description: "Replace 2+ consecutive blank lines with single blank line"
+        entry: python3 tools/dev/collapse_blank_lines.py
+        language: python
+        files: \.(md|py)$
+        pass_filenames: true
+
   # ===========================================================================
   # CLI DOCUMENTATION VALIDATORS
   # ===========================================================================
@@ -14,7 +28,7 @@ repos:
   - repo: local
     hooks:
       - id: validate-cli-docs
-        name: "Validate CLI documentation"
+        name: "TinyTorch: Validate CLI documentation"
         description: "Ensure tito commands in docs match actual CLI"
         entry: python3 tools/dev/validate_cli_docs.py
         language: python

tinytorch/tools/dev/collapse_blank_lines.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+"""
+Collapse multiple consecutive blank lines into single blank lines.
+
+For markdown files, this preserves content inside code blocks (```...```)
+to avoid interfering with language-specific formatting.
+"""
+
+import sys
+
+
+def collapse_blank_lines(content):
+    """Replace multiple consecutive blank lines with a single blank line.
+
+    Preserves content inside code blocks (```...```) to avoid interfering
+    with language-specific formatters.
+    """
+    lines = content.split('\n')
+    result = []
+    in_code_block = False
+    blank_count = 0
+
+    for line in lines:
+        # Detect code block boundaries
+        if line.strip().startswith('```'):
+            in_code_block = not in_code_block
+            # Flush accumulated blank lines before code block
+            if blank_count > 0:
+                result.append('')  # Add single blank line
+                blank_count = 0
+            result.append(line)
+            continue
+
+        # Inside code blocks, preserve all content including blank lines
+        if in_code_block:
+            result.append(line)
+            continue
+
+        # Outside code blocks, collapse excessive blank lines
+        if line.strip() == '':
+            blank_count += 1
+        else:
+            # Add at most one blank line
+            if blank_count > 0:
+                result.append('')
+                blank_count = 0
+            result.append(line)
+
+    # Handle trailing blank lines
+    if blank_count > 0:
+        result.append('')
+
+    return '\n'.join(result)
+
+
+def main():
+    """Process files and collapse extra blank lines."""
+    if len(sys.argv) < 2:
+        print("Usage: python collapse_blank_lines.py <file1> [file2] ...")
+        sys.exit(1)
+
+    modified_files = []
+
+    for filename in sys.argv[1:]:
+        try:
+            with open(filename, 'r', encoding='utf-8') as f:
+                content = f.read()
+
+            new_content = collapse_blank_lines(content)
+
+            if new_content != content:
+                with open(filename, 'w', encoding='utf-8') as f:
+                    f.write(new_content)
+                modified_files.append(filename)
+                print(f"Collapsed blank lines: {filename}")
+
+        except Exception as e:
+            print(f"Error processing {filename}: {e}", file=sys.stderr)
+            sys.exit(1)
+
+    # Exit with code 1 if files were modified (pre-commit convention)
+    if modified_files:
+        sys.exit(1)
+    sys.exit(0)
+
+
+if __name__ == "__main__":
+    main()