tengu_synthetic_fog
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.284, including the newest one read.
When a remote tool answer is too big, Claude Code now shrinks embedded images to fit before refusing, and the size limit can be set remotely
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.284.
In the changelogs
1Releases whose published page names tengu_synthetic_fog.
-
v2.1.284
Large images from remote machines are shrunk to fit instead of refused
When a remote tool answer is too big, Claude Code now shrinks embedded images to fit before refusing, and the size limit can be set remotely
gate cited by this entry, found in this entry's text
Gate readings
1| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.284 read on another version | Not enough to say | no value returned | no value returned | not a boolean we can read |
Two arms, because they disagree: this account is the one account this site reads and anonymous is a baseline with no identity attached. A reading says nothing about your account, and off cannot rule out a rollout both readings sit outside of. What these readings can and cannot show.
Flag server, over time
3| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| this account | 4259840 | 2026-09-25T17:25:04Z | 2026-09-28T20:05:06Z | v2.1.282 to v2.1.284 |
| anonymous | 4259840 | 2026-09-25T17:10:04Z | 2026-09-28T20:05:06Z | v2.1.282 to v2.1.284 |
| anonymous | 5242880 | 2026-09-25T17:00:05Z | 2026-09-25T17:00:05Z | v2.1.282 |
One row per unbroken stretch of one reading, newest first, from snapshots taken every twenty-five minutes or so. No longer carried is not off: it means the flag server stopped returning the gate at all, which is what a retired experiment looks like. The version column is what was installed when the reading was taken, not what caused it.
First cited
1The earliest release whose published evidence quoted tengu_synthetic_fog was v2.1.284, 28 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
1Build by build
1One 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.