Problem: get_repo_root() shells out on every call, causing 4-6
redundant subprocesses per gdiff_file() invocation.
highlight_vim_syntax() leaks a scratch buffer if nvim_buf_call errors.
lib.ensure() silently drops callbacks during download, permanently
missing intra-line highlights. The debounce timer callback can operate
on an invalid buffer.
Solution: Cache get_repo_root() results by parent directory. Wrap
nvim_buf_call and nvim_buf_delete in pcall so the scratch buffer is
always cleaned up. Queue pending callbacks in lib.ensure() so all
callers receive the handle once the download completes. Guard the
debounce timer callback with nvim_buf_is_valid.
Adds functions for accessing git index content and working tree files:
- get_index_content() retrieves file from staging area via :0:path
- get_working_content() reads file directly from disk
- file_exists_in_index() checks if file is staged
- file_exists_at_revision() checks if file exists at given revision
Compares current buffer against any git revision (default HEAD), opens result
with full diffs.nvim syntax highlighting. Follows fugitive convention:
:Gdiff/:Gvdiff open vertical split, :Ghdiff opens horizontal split.