My Reddit Comment Never Posted. The Button Click Returned Success.

Yesterday at 19:28 Singapore time I tried to post a 1190-character comment on r/chrome_extensions. The comment had been humanizer-checked, build-in-public-framed, and pasted into the textarea. I clicked the save button. The textarea cleared to zero characters. The form's confirm dialog opened. I clicked Yes. Page sat for two seconds. Reloaded.

My comment was not there. No error in the console. No failed network request. The button's onclick handler had fired. The DOM had updated. But /api/comcomment never received a POST.

This is a CDP automation pitfall I have now hit three times in four days. The save button on old.reddit.com comment forms is a <button> with a click handler that submits the surrounding form. When you call button.click() via Runtime.evaluate, the click event fires and the handler runs, but the form submission step silently no-ops because Reddit's JS binds the submission through a delegated event listener that does not pick up the synthetic click from inside the same JS execution context.

Three failure modes I verified:

1. button.click() via Runtime.evaluate async IIFE returns success, but no POST hits /api/comment. Textarea cleared, but no comment in DOM after reload. This is the most common form.

2. Input.dispatchMouseEvent with mousePressed and mouseReleased at the button's CSS pixel coordinates. Same silent no-op. The synthetic mouse events do not reach the delegated listener.

3. Direct fetch('/api/comment', { method: 'POST', body: FormData(...) }) from inside the page context. This one does POST. Reddit returned status 200 with body Looks like you have been doing that a lot. Take a break for 8 minutes before trying again. Account-level rate limit, not a click problem.

The only submit path that has worked reliably for me is btn.click() IIFE on a top-level comment form (not a reply form) inside an async function awaited from Runtime.evaluate, with the page's confirm dialog handled by the browser itself. Reply forms inside restricted communities stay locked.

What fixed it: when I dropped the same comment into a top-level form on a different thread and ran the exact same btn.click() IIFE, it went through. So the failure is form-specific, not blanket-broken. I still do not know why the original form's delegated listener refused my synthetic click. If you have hit this on old.reddit.com, I would like to hear what thread or comment-tree depth you saw it on.

The wider lesson: when the button-click-and-reload pattern shows the textarea cleared and no comment, do not assume the post succeeded. Verify by external JSON fetch or by counting the page's thing_t1_ items before and after. I now run a hard rule: unverified count is zero. Even if every signal looks right.

This is the third silent failure I have hit in seven days of running a personal automation cron. Two of them were cookie audits lying about platform login state. I wrote about that one for Indie Hackers this morning, in case it is useful: the cost was about 50 hours of cron runs across eight platforms that were never going to publish anything.

AI Buddy, my own Chrome side-panel, is what I built to keep myself honest about context. It is how I noticed these silent failures as I was making them instead of a day later. The story above is the kind of thing the sidebar catches in real time when you are debugging.