Make fixed mode's index list completely static

In fixed mode, refreshIndexList() is now a no-op. The index list is
completely static and never changes, even if indexes are deleted from
the store.

This fixes the issue where:
1. Fixed mode starts with [-i pytorch -i react]
2. User deletes pytorch from the store
3. Agent calls list_indexes → triggers refreshIndexList()
4. Previously: indexNames would shrink to ["react"]
5. Now: indexNames remains ["pytorch", "react"]

In discovery mode, refreshIndexList() still refreshes from the store
to pick up new/deleted indexes.

Changes:
- src/clients/multi-index-runner.ts: Make refreshIndexList() a no-op in fixed mode
- src/clients/multi-index-runner.test.ts: Update test to expect static list in fixed mode

All tests pass, build succeeds.

Agent-Id: agent-0ac871dd-5181-4ed9-84d1-446aa4b19c81

Author: richhankins

src/clients/multi-index-runner.test.ts

@@ -203,10 +203,10 @@ describe("MultiIndexRunner.refreshIndexList", () => {
     expect(runner.indexNames).toEqual(["pytorch", "react"]);
   });
 
-  it("in fixed mode, refreshIndexList handles missing indexes gracefully", async () => {
+  it("in fixed mode, refreshIndexList is a no-op even when indexes are deleted", async () => {
     const store = createMockStoreWithIndexes(["pytorch", "react"]);
 
-    // Create runner in fixed mode with pytorch, react, and a missing index
+    // Create runner in fixed mode with pytorch and react
     const runner = await MultiIndexRunner.create({
       store,
       indexNames: ["pytorch", "react"],
@@ -233,7 +233,7 @@ describe("MultiIndexRunner.refreshIndexList", () => {
 
     await runner.refreshIndexList();
 
-    // Should only include react (pytorch is gone from store)
-    expect(runner.indexNames).toEqual(["react"]);
+    // In fixed mode, the list should remain unchanged even though pytorch was deleted
+    expect(runner.indexNames).toEqual(["pytorch", "react"]);
   });
 });

src/clients/multi-index-runner.ts

@@ -207,21 +207,24 @@ export class MultiIndexRunner {
    * Refresh the list of available indexes from the store.
    * Call after adding or removing indexes.
    *
-   * In fixed mode (when originalIndexNames is set), only includes indexes
-   * from the original allowlist, even if other indexes exist in the store.
+   * In fixed mode (when originalIndexNames is set), this is a no-op.
+   * The list is completely static and never changes.
+   *
+   * In discovery mode, refreshes from the store to pick up new/deleted indexes.
    */
   async refreshIndexList(): Promise<void> {
-    const allIndexNames = await this.store.list();
+    // In fixed mode, the list is static - don't refresh
+    if (this.originalIndexNames) {
+      return;
+    }
 
-    // In fixed mode, filter to only the original allowlist
-    const indexNamesToLoad = this.originalIndexNames
-      ? allIndexNames.filter(name => this.originalIndexNames!.includes(name))
-      : allIndexNames;
+    // Discovery mode: refresh from store
+    const allIndexNames = await this.store.list();
 
     const newIndexes: IndexInfo[] = [];
     const newIndexNames: string[] = [];
 
-    for (const name of indexNamesToLoad) {
+    for (const name of allIndexNames) {
       try {
         const state = await this.store.loadSearch(name);
         if (state) {