diff --git a/sfm/event_browser.html b/sfm/event_browser.html
index 9f5fd31..30542af 100644
--- a/sfm/event_browser.html
+++ b/sfm/event_browser.html
@@ -356,6 +356,16 @@ function _psiToDbl(psi) {
return 20 * Math.log10(psi / DBL_REF);
}
+// Format an ISO timestamp in the browser's local timezone — UTC values
+// (with 'Z' suffix) convert; naive values are interpreted as local clock.
+// Returns '—' for null/empty/unparseable.
+function _fmtTsLocal(iso) {
+ if (!iso) return '—';
+ const d = new Date(iso);
+ if (isNaN(d)) return iso;
+ return d.toLocaleString();
+}
+
// Adaptive decimal formatter — scientific notation only for truly extreme
// values. Normal-range peaks render as plain decimals with sensible
// precision (was previously forcing toExponential(3) which produced ugly
@@ -458,7 +468,7 @@ function renderEventList() {
const row = document.createElement('div');
row.className = 'event-row' + (ev.false_trigger ? ' false_trigger' : '');
if (ev.id === currentEventId) row.className += ' active';
- const ts = (ev.timestamp || '').replace('T', ' ').replace('Z', '');
+ const ts = _fmtTsLocal(ev.timestamp);
const pvs = ev.peak_vector_sum != null ? `${ev.peak_vector_sum.toFixed(3)} in/s` : '—';
row.innerHTML = `
@@ -510,7 +520,7 @@ function renderMeta(data, ev) {
const metaDiv = document.getElementById('event-meta');
const fields = [
['Serial', data.serial || ev?.serial || '—'],
- ['Timestamp', (data.timestamp || ev?.timestamp || '—').replace('T', ' ').replace('Z', '')],
+ ['Timestamp', _fmtTsLocal(data.timestamp || ev?.timestamp)],
['Record', data.record_type || ev?.record_type || '—'],
['Sample rate', data.sample_rate ? `${data.sample_rate} sps` : '—'],
['Geo range', data.geo_range ? `${data.geo_range} (${data.geo_full_scale_ips} in/s FS)` : '—'],
diff --git a/sfm/sfm_webapp.html b/sfm/sfm_webapp.html
index 9b0f862..856c8f5 100644
--- a/sfm/sfm_webapp.html
+++ b/sfm/sfm_webapp.html
@@ -2864,7 +2864,9 @@ function _renderSidecar(data) {
};
document.getElementById('sc-f-serial').textContent = ev.serial || '—';
- document.getElementById('sc-f-ts').textContent = ev.timestamp || '—';
+ // Route through _fmtTs so the unit-local naive timestamp shows as
+ // "5/27/2026, 6:00:13 AM" instead of "2026-05-27T06:00:13".
+ document.getElementById('sc-f-ts').textContent = _fmtTs(ev.timestamp);
document.getElementById('sc-f-rt').textContent = ev.record_type || '—';
document.getElementById('sc-f-sr').textContent = (ev.sample_rate ?? '—') + (ev.sample_rate ? ' sps' : '');
document.getElementById('sc-f-key').textContent = ev.waveform_key || '—';
@@ -2884,7 +2886,10 @@ function _renderSidecar(data) {
document.getElementById('sc-f-bwsize').textContent = bw.filesize != null ? `${bw.filesize} bytes` : '—';
document.getElementById('sc-f-sha').textContent = bw.sha256 || '—';
document.getElementById('sc-f-src').textContent = src.kind || '—';
- document.getElementById('sc-f-cap').textContent = src.captured_at || '—';
+ // captured_at has a "Z" suffix (UTC); _fmtTs converts to browser local
+ // — matches the BW-reported recorded-at, no more "21:59:57 vs it's 6 PM"
+ // confusion from operators reading the raw UTC value.
+ document.getElementById('sc-f-cap').textContent = _fmtTs(src.captured_at);
document.getElementById('sc-edit-ft').checked = !!rev.false_trigger;
document.getElementById('sc-edit-reviewer').value = rev.reviewer || '';