All four paths in the sources list -- compact_deletes.go, compaction_watermark.go, internal/tombstone/, segment/rewrite.go -- are upstream's, and none exist in this repo. internal/tombstone/ is the trap: it is indistinguishable from Stream's own src/internal/ convention, so a reader goes looking for it here. Marked the whole section as upstream and listed Stream's actual counterparts (storage/tombstone.zig, storage/segment_rewrite.zig, compact/watermark.zig, compact/pass.zig, compact/steady.zig) so the two can be read side by side. Also names the two references that are not committed anywhere: the 2026-07-09 agent study in the title, and the "2026-06-12 cache-invalidation design note". Same dangling-reference problem fixed in upstream-bootstrap-spec.md last pass; this closes the second of the two. "docs/README.md 3.3" is upstream's docs/README.md -- there is no docs/README.md here, so the citation silently pointed at our own docs/. Defines pebble, consistent with the other upstream spec. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>