dashboard: per-container journald viewer

new GET /api/journal/{name}?unit=&lines= shells out journalctl -M
<container> -b --no-pager --output=short-iso --lines=<N> (cap 5000).
optional unit filter, restricted to hive-ag3nt.service /
hive-m1nd.service so the shell-out can't be coerced into reading
unrelated units. validates the container name against the live list
before invoking journalctl.

frontend renders a collapsed '↳ logs · <container>' details block
on each container row. expanding triggers a lazy fetch; refresh
button re-fetches; unit dropdown switches between the harness
service (default) and the full machine journal. output sits in a
24em-tall monospace pre, auto-scrolled to the bottom on fresh
fetch.

hive-c0re's systemd unit already runs as root, so journalctl has
the access it needs.

hive-c0re/assets/app.js

@@ -161,11 +161,66 @@
       }
       li.append(actions);
 
+      // Per-container journald viewer. Expand to fetch + render the
+      // last N lines; refresh button re-fetches; unit selector
+      // narrows to the harness service (or empty = full machine).
+      const journalUnit = c.is_manager ? 'hive-m1nd.service' : 'hive-ag3nt.service';
+      li.append(buildJournalDetails(c.container, journalUnit));
+
       ul.append(li);
     }
     root.append(ul);
   }
 
+  // Build the per-container journald <details>. Lazy-fetches when the
+  // operator expands; refresh re-fetches; unit toggle switches
+  // between the harness service and the full machine journal.
+  function buildJournalDetails(containerName, defaultUnit) {
+    const details = el('details', { class: 'journal' });
+    const summary = el('summary', {}, '↳ logs · ' + containerName);
+    const body = el('div', { class: 'journal-body' });
+    const controls = el('div', { class: 'journal-controls' });
+    const unitSelect = el('select', { class: 'journal-unit' });
+    unitSelect.append(
+      el('option', { value: defaultUnit }, defaultUnit),
+      el('option', { value: '' }, '(full machine journal)'),
+    );
+    const refresh = el('button', { type: 'button', class: 'btn btn-restart journal-refresh' },
+      '↻ refresh');
+    const pre = el('pre', { class: 'journal-output' }, 'fetching…');
+    let fetching = false;
+    async function fetchLogs() {
+      if (fetching) return;
+      fetching = true;
+      pre.textContent = 'fetching…';
+      const unit = unitSelect.value;
+      const params = new URLSearchParams({ lines: '500' });
+      if (unit) params.set('unit', unit);
+      try {
+        const resp = await fetch('/api/journal/' + containerName + '?' + params);
+        const text = await resp.text();
+        if (!resp.ok) {
+          pre.textContent = 'error: ' + resp.status + '\n' + text;
+        } else {
+          pre.textContent = text || '(empty)';
+          // Auto-scroll to bottom on fresh fetch.
+          pre.scrollTop = pre.scrollHeight;
+        }
+      } catch (err) {
+        pre.textContent = 'fetch failed: ' + err;
+      } finally {
+        fetching = false;
+      }
+    }
+    details.addEventListener('toggle', () => { if (details.open) fetchLogs(); });
+    refresh.addEventListener('click', (e) => { e.preventDefault(); fetchLogs(); });
+    unitSelect.addEventListener('change', fetchLogs);
+    controls.append(unitSelect, refresh);
+    body.append(controls, pre);
+    details.append(summary, body);
+    return details;
+  }
+
   function renderTombstones(s) {
     const root = $('tombstones-section');
     root.innerHTML = '';

hive-c0re/assets/dashboard.css

@@ -143,6 +143,53 @@ a:hover {
   opacity: 0.85;
 }
 .container-row.tombstone .name { color: var(--muted); }
+/* Per-container journald viewer: collapsed by default, fetches
+   lazily on expand. The output is in monospace inside a bordered
+   <pre>; controls (unit select + refresh) sit above. */
+.journal {
+  margin-top: 0.5em;
+  font-size: 0.85em;
+}
+.journal > summary {
+  cursor: pointer;
+  color: var(--muted);
+  letter-spacing: 0.05em;
+}
+.journal > summary:hover { color: var(--cyan); }
+.journal .journal-body {
+  margin-top: 0.4em;
+  padding-top: 0.4em;
+  border-top: 1px dashed var(--border);
+}
+.journal-controls {
+  display: flex;
+  gap: 0.5em;
+  margin-bottom: 0.4em;
+  align-items: center;
+}
+.journal-unit {
+  font-family: inherit;
+  font-size: 0.9em;
+  background: var(--bg-elev);
+  color: var(--fg);
+  border: 1px solid var(--border);
+  padding: 0.2em 0.4em;
+}
+.journal-refresh { font-size: 0.75em; padding: 0.15em 0.5em; }
+.journal-output {
+  margin: 0;
+  background: #11111b;
+  color: var(--fg);
+  border: 1px solid var(--purple-dim);
+  padding: 0.5em 0.7em;
+  max-height: 24em;
+  overflow: auto;
+  font-size: 0.85em;
+  line-height: 1.4;
+  white-space: pre;
+  word-break: normal;
+}
+
 .pending-state {
   color: var(--amber);
   font-size: 0.85em;