The incident timeline editor is built, verified and committed.

What was delivered (commit 537f121, bundle 165 KB):

• Vite + React + TypeScript source in src/, lockfile, and the static export in dist/ with relative asset URLs.
• Events with timestamp, severity, status and notes. The list is always ordered by real instant, equal timestamps are marked and reorderable within their tie, and shifting a timestamp reorders the row.
• UTC or local display with the offset always printed. Typed times are read in the chosen zone unless they carry an offset. Impossible dates are refused with the valid range, skipped DST hours are refused with both offsets, and repeated DST hours ask which occurrence is meant.
• Search, severity and status filters, sort direction, JSON export, and import with field-by-field validation before Replace or Merge.
• Autosave to local storage with a live status pill covering saved, unsaved, storage unavailable, storage full and corrupt-data states. Refresh keeps events and the zone preference.
• A clearly labelled synthetic sample incident. No accounts, no wallet or transaction code.
• README.md (install, preview, rebuild, publish, data format, test summary), DESIGN.md (tokens, typography, layout, components from the final source), LICENSE, and scripts/browser-check.mjs for repeatable browser verification.
• artifacts/validation.md plus 18 screenshots, delivered as artifacts since the harness excludes that folder from git.

Verification results on the final build

Check	Result
Typecheck	passed
Unit tests	27 passed
Production build	passed
Scripted browser checks	45 of 45 passed

The browser run covered keyboard navigation with visible focus rings, empty and error states, DST cases, ties, export and import, refresh, storage failure paths, reduced motion, rendered contrast, and no horizontal overflow at 1280, 820, 390 and 320 px.

Better Interface review produced seven findings, all fixed and rechecked. The two medium ones were a toolbar that overflowed the timeline column at intermediate widths, now solved with container queries, and a sticky header that consumed a quarter of a phone viewport, now sticky only above 640 px.

Limitations recorded in the report: no screen-reader session, no physical device, no native browser zoom, and the interactive MCP browser could not reach the export because it blocks file: URLs and no preview launcher exists here. The same Chromium was driven by a bounded script instead, and its screenshots were inspected.