feat: auto-load new namespaces when PromotionStrategies are added

[Copilot]

The namespace dropdown fetched namespaces only once on mount, requiring a page refresh to discover namespaces added after initial load.

Changes

• NamespaceStore.ts: Added an addNamespace(ns: string) action that appends a namespace to the list only if it's not already present (no-op otherwise).

• NamespaceDropdown.tsx: Subscribes to the existing SSE /watch?kind=PromotionStrategy endpoint (no namespace filter = all namespaces). On each event, the namespace is extracted directly from the event payload (metadata.namespace) and added to the store via addNamespace — no extra API calls are made. The /list?kind=namespace call happens only once on mount for the initial list. EventSource is closed on unmount.

fetch('/list?kind=namespace')
  .then(data => setNamespaces(...));  // initial load only

const eventSource = new EventSource('/watch?kind=PromotionStrategy');
eventSource.addEventListener('PromotionStrategy', (evt) => {
  const ns = JSON.parse(evt.data)?.metadata?.namespace;
  if (typeof ns === 'string' && ns) addNamespace(ns);  // no extra API calls
});
return () => eventSource.close();

Reuses the existing SSE infrastructure already in place for PromotionStrategy real-time updates — no backend changes required. New namespaces are discovered purely from the event stream regardless of how many PromotionStrategy events are received.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Auto-load new namespaces when PromotionStrategies are added</issue_title>
<issue_description>The dashboard currently requires a page refresh to load new namespaces when PromotionStrategies are added to those namespaces.

The list should auto-refresh as PromotionStragegies are added.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Auto-load new namespaces when PromotionStrategies are added #1141

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.29%. Comparing base (eb875ff) to head (06e37af).
⚠️ Report is 5 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1142      +/-   ##
==========================================
+ Coverage   50.60%   51.29%   +0.69%     
==========================================
  Files          51       51              
  Lines        5501     5501              
==========================================
+ Hits         2784     2822      +38     
+ Misses       2417     2392      -25     
+ Partials      300      287      -13     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[crenshaw-dev]

@copilot if I have 100 PromotionStrategies that are fairly active (updating often), that'll be a lot of list operations on the namespaces. Can we just watch the namespaces instead of listing them?

[Copilot]

@copilot if I have 100 PromotionStrategies that are fairly active (updating often), that'll be a lot of list operations on the namespaces. Can we just watch the namespaces instead of...

Done in ec3c924. Instead of re-calling /list?kind=namespace on every event, I now extract metadata.namespace directly from the SSE event payload and append it to the store via a new addNamespace action (no-op if already present). The /list?kind=namespace call only happens once on mount for the initial list — no extra API calls regardless of how many PromotionStrategy events are received.