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fix: renew the ALTCHA proof when its challenge expires - #5
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The widget solves its proof once, on load, and the challenge the server issues is only valid for DEFAULT_EXPIRES_SECONDS (600). When that window closes the widget moves to the `expired` state and clears the solution -- it does not re-solve on its own. On a long form that is easily reached before the visitor is done. The Snellman consumer-service forms pair a 400+ option product dropdown with two date pickers, an address block and a file upload; ten minutes is an ordinary amount of time to spend there. Submitting past that point fails validation with a form-level message that highlights no field, and the visitor loses everything they typed. Re-solve on `expired` so the payload stays fresh for as long as the form is open. Renewal is parked while the tab is hidden and resumes on visibilitychange, so backgrounded tabs don't grind proof-of-work for nothing. A MutationObserver picks up widgets that appear later, since Gravity Forms replaces the form markup after AJAX submissions and on multi-page navigation. Verified in a browser against a build with a shortened window: the widget expires, renews, and returns to `verified` with a fresh payload -- and keeps doing so on each subsequent expiry. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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The problem
The widget solves its proof once, on load. The challenge the server issues is valid for
Challenge::DEFAULT_EXPIRES_SECONDS(600s). When that window closes the widget moves to theexpiredstate and clears the solution — it does not re-solve on its own.On a long form, ten minutes is an ordinary amount of time. The Snellman consumer-service forms (43 fi / 45 sv) pair a 400+ option product dropdown with two date pickers, an address block and a file upload. Past the window, submitting fails validation with a form-level message that highlights no field, and the visitor loses everything they typed.
This surfaced as a bug report against the sv form that was initially attributed to the product field. It isn't — with ALTCHA bypassed, every branch of that form validates cleanly, including the one reported as broken.
The fix
Re-solve on the widget's
expiredevent.verify()re-reads thechallengeattribute (a URL), so this fetches a fresh challenge rather than re-solving the dead one.visibilitychange— a backgrounded tab can't be submitting, so there's no reason to grind proof-of-work there.MutationObserverbinds widgets that appear later, since Gravity Forms replaces the form markup after AJAX submissions and on multi-page navigation.expiredevent doesn't bubble, so listeners are bound per element.display="invisible"means none of this is visible to the visitor.Verification
Against a local build with the window shortened to 25s, watching the real event and network timeline:
verified(552-char payload)verified, payload restoredIt recovers repeatedly, not just once.
Test suite: 63/63 pass.
pint --testclean.Tradeoff
A form left open now re-solves every 10 minutes while it's on screen. At the standard cost (200k, ~4s) that's cheap, and nothing happens at all while the tab is hidden.
Note
Carries the
0.6.0version bump. #2 (feat/classify-verification-failures) should ship in the same release.🤖 Generated with Claude Code