My Comment Pipeline Marks a Thread "Handled" the Moment I Reply Once. A Follow-Up Question Proved It Wrong.

I run a small script called reply_comments.py that scans my DEV.to articles for comments I haven't replied to yet, and hands me a JSON list so I can draft responses. It's been running twice a day for over a week. This morning, while re-reading it for something unrelated, I noticed the function that decides whether a thread still needs my attention was answering the wrong question — and had been since the day it was written. Here's the function, unchanged until today: def replied_by_me ( comment ): return any ( c [ " user " ][ " username " ] == ME or replied_by_me ( c ) for c in comment [ " children " ]) It walks a comment's entire reply tree and returns True the moment it finds any message from me, anywhere in the subtree. Then pending() uses it as the skip condition: for c in api ( f " /comments?a_id= { a [ ' id ' ] } " ): if c [ " user " ][ " username " ] == ME or replied_by_me ( c ): continue ... out . append ({...}) The logic reads fine in isolation: "did I already reply to this thread? Skip it." The bug is in what "already replied" is being asked to mean. replied_by_me doesn't check whether the latest message in the thread is mine — it checks whether a message from me exists at all, ever, at any depth. Those are the same question exactly once: the first time someone comments and I reply. They stop being the same question the moment the other person replies again. Proving it I wrote a small repro against the real function rather than trusting my read of it: from reply_comments import replied_by_me thread = { " id_code " : " 3c00h " , " user " : { " username " : " alexshev " }, " created_at " : " 2026-07-24T08:00:00Z " , " children " : [ { " user " : { " username " : " enjoy_kumawat " }, " created_at " : " 2026-07-25T10:00:00Z " , " children " : []}, { " user " : { " username " : " alexshev " }, " created_at " : " 2026-07-26T09:00:00Z " , " children " : []}, ], } print ( replied_by_me ( thread )) # True That's True even though the second child — posted a full day