feat(logs): URL deep-link + fetched-age chip for AGENT/SYSTEM tabs

Adds ?agent=name and ?unit=svc URL params to pre-select the agent on
the AGENT tab (used by the per-agent overflow menu journal logs link).
Last-fetched timestamp chip shows how stale the output is.

Agent selection is NOT persisted to localStorage — URL params only.

docs/web-ui/dashboard.md

@@ -410,14 +410,12 @@ immediate re-fetch.
 name (populated from `GET /api/state`) and unit filter
 (`hive-ag3nt.service` / `(full machine journal)`). Fetches
 `GET /api/journal/{name}?unit=<unit>&lines=500` on selection change
-or `↻ refresh`. Output rendered as a `<pre>` block. The last-selected
+or `↻ refresh`. Output rendered as a `<pre>` block. A `?agent=<name>`
-agent name and unit are persisted to `localStorage` (`logs-agent` /
+and/or `?unit=<svc>` URL param pre-selects the agent + unit on page
-`logs-unit`) and restored on page load. A `?agent=<name>` and/or
+load — the per-agent `⋮` menu's **journal logs →** entry uses this to
-`?unit=<svc>` URL param overrides the stored values — the per-agent
+deep-link directly to a specific agent's journal. A "fetched N ago"
-`⋮` menu's **journal logs →** entry uses this to deep-link directly
+chip appears after the `↻ refresh` button following each successful
-to a specific agent's journal. A "fetched N ago" chip appears after
+fetch and ticks every 30 s.
-the `↻ refresh` button following each successful fetch and ticks
-every 30 s.
 
 **SYSTEM sub-tab** — host-side service logs. Unit selector (currently
 only `hive-c0re.service`). Fetches

frontend/packages/dashboard/src/logs.css

@@ -71,6 +71,8 @@ body.logs-shell {
   font-size: 0.85em;
 }
 .journal-refresh { font-size: 0.75em; padding: 0.15em 0.5em; }
+/* "fetched N ago" chip next to the refresh button on AGENT + SYSTEM tabs. */
+.logs-fetch-ts { font-size: 0.8em; color: var(--muted); }
 .journal-output {
   margin: 0;
   background: var(--crust);

frontend/packages/dashboard/src/logs.html

@@ -56,6 +56,7 @@
           <option value="">(full machine journal)</option>
         </select>
         <button type="button" class="btn btn-restart" id="agent-refresh">↻ refresh</button>
+        <span id="agent-fetch-ts" class="meta logs-fetch-ts" hidden></span>
       </div>
       <pre id="agent-output" class="journal-output">select an agent above</pre>
     </section>
@@ -69,6 +70,7 @@
           <option value="hive-c0re.service">hive-c0re.service</option>
         </select>
         <button type="button" class="btn btn-restart" id="system-refresh">↻ refresh</button>
+        <span id="system-fetch-ts" class="meta logs-fetch-ts" hidden></span>
       </div>
       <pre id="system-output" class="journal-output">loading…</pre>
     </section>

frontend/packages/dashboard/src/logs.js

@@ -13,6 +13,11 @@
 //   - The build list auto-refreshes (debounced 2s) when rebuild_queue_changed
 //     fires from the dashboard SSE stream, so new log entries appear without
 //     a manual page refresh.
+//
+// URL params `?agent=name` and `?unit=svc` pre-select the agent + unit on
+// the AGENT tab (deep-link from other pages, e.g. the per-agent ⋮ menu).
+// Last-fetched timestamp is shown next to the refresh button on AGENT +
+// SYSTEM tabs so the operator knows how stale the output is.
 
 import {
   $, el, fmtAgeSecs, openStream,
@@ -265,8 +270,16 @@ import {
   const agentUnitSelect = $('agent-unit-select');
   const agentRefresh    = $('agent-refresh');
   const agentOutput     = $('agent-output');
+  const agentFetchTs    = $('agent-fetch-ts');
 
-  // Populate agent selector from /api/state
+  // Format a last-fetched timestamp: "fetched just now" / "fetched 3m ago".
+  function fmtFetchTs(fetchedAt) {
+    const ageSecs = Math.floor((Date.now() - fetchedAt) / 1000);
+    return 'fetched ' + (ageSecs < 5 ? 'just now' : fmtAgeSecs(ageSecs) + ' ago');
+  }
+
+  // Populate agent selector from /api/state, then honour any `?agent=` /
+  // `?unit=` URL params (used by the per-agent ⋮ menu's deep-link).
   async function loadAgentList() {
     try {
       const resp = await fetch('/api/state');
@@ -278,10 +291,26 @@ import {
       for (const c of (state.containers || [])) {
         agentSelect.append(el('option', { value: c.name }, c.name));
       }
+      // Deep-link: honour ?agent= and ?unit= URL params.
+      const urlAgent = new URLSearchParams(location.search).get('agent');
+      const urlUnit  = new URLSearchParams(location.search).get('unit');
+      if (urlAgent) {
+        const found = Array.from(agentSelect.options).some((o) => o.value === urlAgent);
+        if (found) {
+          agentSelect.value = urlAgent;
+          if (urlUnit && agentUnitSelect) {
+            const unitFound = Array.from(agentUnitSelect.options)
+              .some((o) => o.value === urlUnit);
+            if (unitFound) agentUnitSelect.value = urlUnit;
+          }
+          fetchAgent();
+        }
+      }
     } catch { /**/ }
   }
 
   let agentFetching = false;
+  let agentLastFetch = 0;
   async function fetchAgent() {
     if (!agentSelect || !agentOutput) return;
     const name = agentSelect.value;
@@ -289,6 +318,7 @@ import {
     if (agentFetching) return;
     agentFetching = true;
     agentOutput.textContent = 'fetching…';
+    if (agentFetchTs) agentFetchTs.hidden = true;
     const unit = agentUnitSelect ? agentUnitSelect.value : '';
     const params = new URLSearchParams({ lines: '500' });
     if (unit) params.set('unit', unit);
@@ -297,6 +327,13 @@ import {
       const text = await resp.text();
       agentOutput.textContent = resp.ok ? (text || '(empty)') : 'error ' + resp.status + '\n' + text;
       agentOutput.scrollTop = agentOutput.scrollHeight;
+      if (resp.ok) {
+        agentLastFetch = Date.now();
+        if (agentFetchTs) {
+          agentFetchTs.textContent = fmtFetchTs(agentLastFetch);
+          agentFetchTs.hidden = false;
+        }
+      }
     } catch (err) {
       agentOutput.textContent = 'fetch failed: ' + err;
     } finally {
@@ -313,13 +350,16 @@ import {
   const systemUnitSelect = $('system-unit-select');
   const systemRefresh    = $('system-refresh');
   const systemOutput     = $('system-output');
+  const systemFetchTs    = $('system-fetch-ts');
 
   let systemFetching = false;
+  let systemLastFetch = 0;
   async function fetchSystem() {
     if (!systemOutput) return;
     if (systemFetching) return;
     systemFetching = true;
     systemOutput.textContent = 'fetching…';
+    if (systemFetchTs) systemFetchTs.hidden = true;
     const unit = systemUnitSelect ? systemUnitSelect.value : 'hive-c0re.service';
     const params = new URLSearchParams({ lines: '500' });
     if (unit) params.set('unit', unit);
@@ -328,6 +368,13 @@ import {
       const text = await resp.text();
       systemOutput.textContent = resp.ok ? (text || '(empty)') : 'error ' + resp.status + '\n' + text;
       systemOutput.scrollTop = systemOutput.scrollHeight;
+      if (resp.ok) {
+        systemLastFetch = Date.now();
+        if (systemFetchTs) {
+          systemFetchTs.textContent = fmtFetchTs(systemLastFetch);
+          systemFetchTs.hidden = false;
+        }
+      }
     } catch (err) {
       systemOutput.textContent = 'fetch failed: ' + err;
     } finally {
@@ -346,4 +393,15 @@ import {
   fetchBuild();
   if (tab === 'system') fetchSystem();
 
+  // Tick the last-fetched timestamps every 30s so "fetched 1m ago" stays
+  // accurate without a manual refresh.
+  setInterval(() => {
+    if (agentLastFetch && agentFetchTs && !agentFetchTs.hidden) {
+      agentFetchTs.textContent = fmtFetchTs(agentLastFetch);
+    }
+    if (systemLastFetch && systemFetchTs && !systemFetchTs.hidden) {
+      systemFetchTs.textContent = fmtFetchTs(systemLastFetch);
+    }
+  }, 30_000);
+
 })();