Read long files by range
A partial result may reflect the reader's limit rather than the end of the file. Note the last line number returned, then continue from the following offset or narrow the range to the passage you need.
For structured files, inspect the surrounding context as well. A function, configuration block, or data row can depend on definitions and settings elsewhere in the document.
Keep the inspection focused and complete
When investigating a specific behavior, search for its symbol or setting first, then read enough adjacent lines to understand how it is used. This reduces noise while preserving the relevant control flow.
If the tool reports an unsupported format or a read error, use a compatible export or conversion and keep the original file intact. A successful partial read should be treated as one segment of the source, not as a summary of the entire file.