docs: add utility function docstrings

utils/paths.py

@@ -2,6 +2,16 @@
 
 
 def resolve_path(base: str | Path, path: str | Path):
+    """Resolve a path relative to a base directory.
+
+    Args:
+        base: Base directory used when ``path`` is relative.
+        path: Absolute or relative path to resolve.
+
+    Returns:
+        The resolved absolute path when ``path`` is absolute, otherwise the
+        resolved base directory joined with ``path``.
+    """
     path = Path(path)
     if path.is_absolute():
         return path.resolve()
@@ -10,6 +20,16 @@ def resolve_path(base: str | Path, path: str | Path):
 
 
 def display_path_rel_to_cwd(path: str, cwd: Path | None) -> str:
+    """Return a path display string relative to the current working directory.
+
+    Args:
+        path: Path to display.
+        cwd: Current working directory to make ``path`` relative to, if possible.
+
+    Returns:
+        ``path`` relative to ``cwd`` when possible; otherwise, the original path
+        string or normalized path string.
+    """
     try:
         p = Path(path)
     except Exception:
@@ -25,13 +45,30 @@ def display_path_rel_to_cwd(path: str, cwd: Path | None) -> str:
 
 
 def ensure_parent_directory(path: str | Path) -> Path:
+    """Ensure the parent directory for a path exists.
+
+    Args:
+        path: File path whose parent directory should be created.
+
+    Returns:
+        The input path converted to a ``Path`` instance.
+    """
     path = Path(path)
 
     path.parent.mkdir(parents=True, exist_ok=True)
     return path
 
 
 def is_binary_file(path: str | Path) -> bool:
+    """Check whether a file appears to contain binary data.
+
+    Args:
+        path: File path to inspect.
+
+    Returns:
+        True if the first bytes of the file contain a null byte; otherwise False.
+        Returns False if the file cannot be read.
+    """
     try:
         with open(path, "rb") as f:
             chunk = f.read(8192)

utils/text.py

@@ -2,6 +2,15 @@
 
 
 def get_tokenizer(model: str):
+    """Get a tokenization function for a model.
+
+    Args:
+        model: Model name used to select a tiktoken encoding.
+
+    Returns:
+        A callable that encodes text into token IDs. Falls back to the
+        ``cl100k_base`` encoding when the model-specific encoding is unavailable.
+    """
     try:
         encoding = tiktoken.encoding_for_model(model)
         return encoding.encode
@@ -11,6 +20,15 @@ def get_tokenizer(model: str):
 
 
 def count_tokens(text: str, model: str = "gemini-2.0-flash-exp") -> int:
+    """Count the number of tokens in text for a model.
+
+    Args:
+        text: Text to count tokens for.
+        model: Model name used to select a tokenizer.
+
+    Returns:
+        Number of tokens in ``text``.
+    """
     tokenizer = get_tokenizer(model)
 
     if tokenizer:
@@ -20,6 +38,14 @@ def count_tokens(text: str, model: str = "gemini-2.0-flash-exp") -> int:
 
 
 def estimate_tokens(text: str) -> int:
+    """Estimate the number of tokens in text using character count.
+
+    Args:
+        text: Text to estimate token count for.
+
+    Returns:
+        Estimated token count, with a minimum of 1.
+    """
     return max(1, len(text) // 4)
 
 
@@ -30,6 +56,19 @@ def truncate_text(
     suffix: str = "\n... [truncated]",
     preserve_lines: bool = True,
 ):
+    """Truncate text to fit within a maximum token count.
+
+    Args:
+        text: Text to truncate.
+        model: Model name used to count tokens.
+        max_tokens: Maximum number of tokens allowed in the returned text.
+        suffix: Text appended when truncation occurs.
+        preserve_lines: Whether to truncate only at line boundaries when possible.
+
+    Returns:
+        The original text when it fits within ``max_tokens``; otherwise, a
+        truncated version with ``suffix`` appended.
+    """
     current_tokens = count_tokens(text, model)
     if current_tokens <= max_tokens:
         return text