feat(operator): expandable audit row reveals event metadata

Rows with a non-empty metadata object now show a chevron and become
clickable. Clicking expands a detail row underneath that lists every
metadata field — partner.updated/tenant.updated render their 'changes'
array as a row of mono chips, everything else falls back to a generic
key/value layout. Toggling is per-row, so the operator can open
several at once when comparing actions.

apps/operator/pages/audit.vue

@@ -72,6 +72,26 @@ function shortIp(ip?: string) {
   return ip.replace(/^::ffff:/, '')
 }
 
+// Row expansion — reveals metadata.changes + any other metadata keys for the
+// row. Kept as a plain Set so toggling stays O(1) and the operator can have
+// multiple rows open at once.
+const expanded = ref(new Set<string>())
+function toggleRow(id: string) {
+  if (expanded.value.has(id)) expanded.value.delete(id)
+  else expanded.value.add(id)
+  // Force reactivity — Set mutations aren't tracked by Vue directly.
+  expanded.value = new Set(expanded.value)
+}
+function hasDetails(e: AuditEvent): boolean {
+  return !!e.metadata && Object.keys(e.metadata).length > 0
+}
+function formatMetaValue(v: unknown): string {
+  if (v === null || v === undefined) return '—'
+  if (Array.isArray(v)) return v.join(', ')
+  if (typeof v === 'object') return JSON.stringify(v)
+  return String(v)
+}
+
 // ── Tamper-evidence (Phase 3) + cold-storage archives (Phase 4) ────────
 interface VerifyReport {
   ok: boolean
@@ -205,6 +225,7 @@ function fmtRelative(iso: string | null | undefined): string {
         <table v-if="allEvents.length">
           <thead>
             <tr>
+              <th class="caret-col"></th>
               <th>Time</th>
               <th>Actor</th>
               <th>Action</th>
@@ -215,7 +236,18 @@ function fmtRelative(iso: string | null | undefined): string {
             </tr>
           </thead>
           <tbody>
-            <tr v-for="e in allEvents" :key="e._id">
+            <template v-for="e in allEvents" :key="e._id">
+              <tr
+                :class="['row', { expandable: hasDetails(e), open: expanded.has(e._id) }]"
+                @click="hasDetails(e) && toggleRow(e._id)"
+              >
+                <td class="caret-col">
+                  <UiIcon
+                    v-if="hasDetails(e)"
+                    :name="expanded.has(e._id) ? 'chevDown' : 'chevRight'"
+                    :size="12"
+                  />
+                </td>
                 <td><Mono>{{ fmtAbs(e.at) }}</Mono></td>
                 <td class="actor">
                   <div v-if="e.actorType === 'system'" class="sys">sys</div>
@@ -238,6 +270,25 @@ function fmtRelative(iso: string | null | undefined): string {
                   </Badge>
                 </td>
               </tr>
+              <tr v-if="expanded.has(e._id) && hasDetails(e)" class="detail-row">
+                <td></td>
+                <td colspan="7">
+                  <dl class="meta">
+                    <template v-for="(value, key) in e.metadata" :key="key">
+                      <dt><Mono dim>{{ key }}</Mono></dt>
+                      <dd>
+                        <span v-if="key === 'changes' && Array.isArray(value)" class="changes">
+                          <Mono v-for="field in value as string[]" :key="field" class="change-chip">
+                            {{ field }}
+                          </Mono>
+                        </span>
+                        <Mono v-else>{{ formatMetaValue(value) }}</Mono>
+                      </dd>
+                    </template>
+                  </dl>
+                </td>
+              </tr>
+            </template>
           </tbody>
         </table>
         <div v-else class="empty"><Mono dim>// no events match the current filters</Mono></div>
@@ -414,6 +465,36 @@ th {
 th.r, td.r { text-align: right; }
 td { padding: 10px 16px; font-size: 12px; border-top: 1px solid var(--border); vertical-align: middle; }
 td.actor { display: flex; align-items: center; gap: 10px; }
+
+/* Expandable row: rows with metadata show a caret + become clickable. */
+.caret-col { width: 28px; padding-left: 12px; padding-right: 0; color: var(--text-mute); }
+tr.row.expandable { cursor: pointer; }
+tr.row.expandable:hover { background: var(--surface); }
+tr.row.open .caret-col { color: var(--text); }
+
+tr.detail-row td {
+  background: var(--surface);
+  border-top: 0;
+  padding: 10px 16px 14px 16px;
+}
+.meta {
+  margin: 0;
+  display: grid;
+  grid-template-columns: max-content 1fr;
+  gap: 6px 14px;
+  align-items: baseline;
+}
+.meta dt { font-size: 10px; letter-spacing: 0.06em; text-transform: uppercase; }
+.meta dd { margin: 0; font-size: 12px; color: var(--text-dim); }
+.changes { display: inline-flex; flex-wrap: wrap; gap: 6px; }
+.change-chip {
+  padding: 2px 8px;
+  border: 1px solid var(--border);
+  border-radius: 999px;
+  background: var(--bg);
+  font-size: 11px;
+  color: var(--text);
+}
 .name { font-size: 12px; font-weight: 500; }
 .action { font-weight: 500; }
 .target { font-size: 12px; color: var(--text-dim); }