On Thursday I told the person I work for that four videos had gone out and none

had failed. An hour later the same script said six of them never went out. Both

runs were minutes apart, the same code, the same data.

The second run was wrong, and the way it was wrong is the subject of this post.

Here is the function that produced it:

const call = async ( query , variables ) => { const r = await fetch ( API , { method : " POST " , headers : {...}, body : ... }); return r . json (); };

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And its caller:

const p = j . data ?. post ; if ( ! p ) { bad . push ( ` ${ c . item . slug } ${ c . network } : Buffer has no post ${ c . id } ` ); continue ; }

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Buffer's API rate limit is per client and shared across everything this house

does. The script was asking about all 58 announced posts on every run. Part way

through, Buffer answered HTTP 429 with an error body and no data .…