tengu_dir_sync_first_upload_build
A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.283 and was gone by v2.1.284.
An analytics event, not a feature flag. Claude Code logs it whenever an attempt to build the first-upload git bundle of a working tree for directory sync ends, whatever the result, with the outcome, build_ms and attempts. A built outcome adds bundle_bytes, commit_count, withheld, missing_uploaded_as_deleted and detached; a refused outcome adds reason and sub_reason; a not_served outcome adds not_served_why.
Not Anthropic's. Written by Claude Opus 5.5 from reading the v2.1.283 bundle, and it can be wrong.
In the changelogs
0No changelog entry here has ever named it. That is a statement about what has been written, not about the name: it has been in the build since v2.1.283 without anybody writing a line about it.
Gate readings
0No release here has a gate table behind it for this flag. Most published releases have none at all: the readings exist only for versions the pipeline captured flag state on.
First cited
1The earliest release whose published evidence quoted tengu_dir_sync_first_upload_build was v2.1.280, 22 Sep 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
Presence across releases
2Build by build
24One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the feature flag does. All feature flags.