- Walks every commit across branches, tags, remote-tracking refs, and stash
- Deduplicates blob scans by OID (seenBlobs map) so identical content
across commits/files is scanned exactly once
- Emits chunks with source format git:<short-sha>:<path>
- Honors --since filter via GitSource.Since (commit author date)
- Resolves annotated tag objects down to their commit hash
- Skips binary blobs via go-git IsBinary plus null-byte sniff
- 8 subtests cover history walk, dedup, modified-file, multi-branch,
tag reachability, since filter, source format, missing repo
