fix(runtime): consume date tails and spec-split fancy regexes

changelog.d/9438-fancy-regex-split.md

@@ -0,0 +1,14 @@
+### Fixed
+
+- **Regex separators that require fancy-regex now run the same
+  `RegExp.prototype[Symbol.split]` cursor algorithm as ordinary patterns.** The
+  old `find_iter` fallback emitted a trailing `""` after a zero-width match at
+  the end and discarded separator captures. The fancy lane now uses
+  `captures_from_pos` on the complete subject, performs the spec's sticky
+  `q`/`p` walk bounded by `q < size`, splices matched and unmatched captures,
+  and stops as soon as `limit` is reached.
+
+  Coverage includes lookbehind and lookahead separators, captures, start/end
+  matches, empty subjects, limits, and the multiline `^` / `$` forms rewritten
+  onto the fancy lane by #9427. The pre-existing runtime test that pinned the
+  incorrect trailing element now asserts Node's result.

changelog.d/9509-date-parse-tail.md

@@ -0,0 +1,17 @@
+### Fixed
+
+- **ISO-shaped date parsing now consumes the complete clock tail instead of
+  silently discarding it.** Space-separated `AM` / `PM`, the GMT family, and
+  V8's fixed `EST` / `EDT` / `CST` / `CDT` / `MST` / `MDT` / `PST` / `PDT`
+  table are applied to the parsed instant; the same zone words work on
+  date-only and partial `YYYY` / `YYYY-MM` forms. Missing day/month components,
+  repeated whitespace, numeric offsets, and parenthesized comments retain
+  Node's measured behavior.
+
+  Every other suffix must now make the parse fail. In particular,
+  `"2026-09-01 10:30GMT"`, `"...10:30EST"` and `"...10:30PM"` are Invalid
+  Date, matching Node, rather than plausible but wrong local instants produced
+  from the `HH:MM` prefix. The expanded #9449 parity fixture and focused
+  runtime tests cover both 12-hour boundaries, zone-plus-meridiem, all eight US
+  abbreviations, partial dates, date-only zone words, and invalid attached or
+  unknown tails with host-zone-independent assertions.