tabs.js: scrub #262/#486/#163 cookies from agent links + topology move + SSE resync (#712 batch 6)

Three small clusters of cookies removed:

- #262 (×2): agent-declared dashboard links via /api/agent/<name>/links.
  Both comment blocks describe the same architectural decision
  (agent backend = source of truth, DOM-built so link strings can't
  reach the HTML parser). The cookies just attributed the decision
  to a PR; the prose stands without them.
- #486 (×2): M0V3 topology affordances + addBulkButton perAgentBodyFor
  hook. Substantive prose moved to docs/web-ui.md::Selection bar in
  #695 already; in-code comments now reference the docs.
- #163 (×3): snapshot re-sync + SSE catchup idempotence. The cookies
  flagged 'this is why the guard exists'; replaced with the present-
  tense 'post-disconnect SSE catchup can carry duplicate rows' which
  reads as the actual reason without needing the issue context.

tabs.js: 31 → 24 #NNN refs (-7). Net +1 line (the rewrites are
sometimes slightly longer when 'issue #N' is replaced with the
substantive description; net is still ahead). 67% reduction since
milestone start.

refs #712

frontend/packages/dashboard/src/tabs.js

@@ -579,8 +579,8 @@ window.marked = marked;
       // a same-origin proxy that forwards the agent backend's own link list
       // (stats / screen-if-gui / forge profile / agent-configs / extras).
       // The agent backend is the single source of truth; no hardcoded link
-      // list here (issue #262). DOM-built — link strings come from the
-      // agent's process and must never reach the HTML parser.
+      // list here. DOM-built — link strings come from the agent's process
+      // and must never reach the HTML parser.
       const navStrip = el('span', { class: 'nav-strip' });
       head.append(navStrip);
       const forgeBase = `http://${hostname}:3000`;
@@ -709,9 +709,8 @@ window.marked = marked;
       // The hardcoded config-repo trigger and the agent-declared
       // extras block both moved into the unified nav strip in the
       // head row above (sourced from the agent backend via
-      // `/api/agent/{name}/links` — issue #262). Only the journald
-      // trigger stays here since it opens the side panel rather
-      // than a link.
+      // `/api/agent/{name}/links`). Only the journald trigger stays
+      // here since it opens the side panel rather than a link.
       body.append(drill);
 
       li.append(icon, body);
@@ -806,7 +805,8 @@ window.marked = marked;
       disabledTitle: why('PURG3', managerNames.map((n) => `\`${n}\` is the manager`)),
     });
 
-    // #486 — move agent(s) in the topology tree. Two affordances:
+    // Move agent(s) in the topology tree — see
+    // docs/web-ui.md::Selection bar for the two affordances:
     //
     //   ⇡ M0V3 → ROOT   promote selected agent(s) to top-level (parent=null)
     //   ⇢ M0V3 → [sel]  reparent the single selected agent under a picked
@@ -973,9 +973,8 @@ window.marked = marked;
       //    `opts.body` is a static object applied to every POST.
       //  - `opts.perAgentBodyFor(name)` is set: `opts.action` is the
       //    full URL (no name appended) and the per-agent body comes
-      //    from the callback. Used by /api/topology/set-parent (#486),
-      //    where the agent name is a body field rather than a URL
-      //    component.
+      //    from the callback. Used by /api/topology/set-parent, where
+      //    the agent name is a body field rather than a URL component.
       for (const name of names) {
         const body = opts.perAgentBodyFor
           ? new URLSearchParams(opts.perAgentBodyFor(name))
@@ -1161,9 +1160,10 @@ window.marked = marked;
     const idx = questionsState.pending.findIndex((q) => q.id === ev.id);
     const existing = idx >= 0 ? questionsState.pending[idx] : null;
     if (idx >= 0) questionsState.pending.splice(idx, 1);
-    // Idempotent: a snapshot re-sync (issue #163) can carry this same
-    // answered row in `question_history` while a live event also
-    // delivers it — guard the unshift so history can't double a row.
+    // Idempotent: a snapshot re-sync (post-disconnect SSE catchup) can
+    // carry this same answered row in `question_history` while a live
+    // event also delivers it — guard the unshift so history can't
+    // double a row.
     if (!questionsState.history.some((h) => h.id === ev.id)) {
       questionsState.history.unshift({
         id: ev.id,
@@ -1461,9 +1461,10 @@ window.marked = marked;
   function applyApprovalResolved(ev) {
     // Drop from pending; prepend to history (newest-first), cap at 30.
     approvalsState.pending = approvalsState.pending.filter((a) => a.id !== ev.id);
-    // Idempotent: a snapshot re-sync (issue #163) can carry this same
-    // resolved row in `approval_history` while a live event also
-    // delivers it — guard the unshift so history can't double a row.
+    // Idempotent: a snapshot re-sync (post-disconnect SSE catchup) can
+    // carry this same resolved row in `approval_history` while a live
+    // event also delivers it — guard the unshift so history can't
+    // double a row.
     if (!approvalsState.history.some((h) => h.id === ev.id)) {
       approvalsState.history.unshift({
         id: ev.id,
@@ -3216,10 +3217,10 @@ window.marked = marked;
       catch (err) { console.error('dashboard SSE handler', ev.kind, err); }
     };
     es.onopen = () => {
-      // Re-sync to recover events that fired during a disconnect
-      // window (issue #163). Initial connect also fires onopen — the
-      // first refreshState() above and this one race, but refreshState
-      // is idempotent so the second call just overwrites with the
+      // Re-sync to recover events that fired during the SSE disconnect
+      // window. Initial connect also fires onopen — the first
+      // refreshState() above and this one race, but refreshState is
+      // idempotent so the second call just overwrites with the
       // freshest snapshot. Cheap on a quiescent server, fine to repeat.
       refreshState();
     };