perf: audit EmbeddingGemma 2 and reuse measured query embeddings

apps/desktop/tests/search-state.test.mjs

@@ -1,6 +1,6 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
-import { LatestLane, AutomaticIndexGate, emptySearchState } from '../src/search-state.ts';
+import { LatestLane, AutomaticIndexGate, emptySearchState, semanticAvailable, SEMANTIC_SETTLE_MS } from '../src/search-state.ts';
 const settle = () => new Promise(resolve => setImmediate(resolve));
 
 test('coalesces queued keystrokes and discards stale responses', async () => {
@@ -67,3 +67,14 @@ test('no document content and unavailable semantics have actionable distinct gui
   assert.match(emptySearchState('lexical', 'no-content').detail, /readable documents/);
   assert.match(emptySearchState('lexical', 'unavailable').detail, /retry the search/);
 });
+
+
+test('old committed semantic generation stays available during rebuild, activation readiness gates replacement', () => {
+  assert.equal(semanticAvailable(null), false);
+  assert.equal(semanticAvailable({ready: true, generation: null, embedding: true}), false);
+  assert.equal(semanticAvailable({ready: true, generation: 1, embedding: false}), true);
+  assert.equal(semanticAvailable({ready: true, generation: 1, embedding: true}), true);
+  assert.equal(semanticAvailable({ready: false, generation: 2, embedding: true}), false);
+  assert.equal(semanticAvailable({ready: true, generation: 2, embedding: false}), true);
+  assert.equal(SEMANTIC_SETTLE_MS, 120);
+});