Finish the mobile performance pass

- Cache the model catalog once per user and each conversation's setting
  separately; clear both on logout and after model saves
- Compress hashed assets asynchronously with a byte budget and set Vary
- Memoize message parsing and throttle selection reads
- Debounce draft writes to localStorage
- Keep the composer editor on the page and focused, as before
- Add a bundle budget check and run it in CI
- Show a loading block while sessions load and a workspace avatar in the
  mobile conversation header

src/utils/harness-cache.test.ts

@@ -0,0 +1,124 @@
+import { beforeEach, describe, expect, test } from "bun:test";
+import { AppData } from "@/src/data/app-data";
+import type {
+    BotHarnessSettingsPayload,
+    HarnessCatalogPayload,
+} from "@/src/types";
+import {
+    clearHarnessCache,
+    readHarnessCatalogCache,
+    readHarnessSettingsCache,
+    writeHarnessCatalogCache,
+    writeHarnessSettingsCache,
+} from "./harness-cache";
+
+class MemoryStorage {
+    private store = new Map<string, string>();
+
+    get length() {
+        return this.store.size;
+    }
+
+    key(index: number) {
+        return [...this.store.keys()][index] ?? null;
+    }
+
+    getItem(key: string) {
+        return this.store.get(key) ?? null;
+    }
+
+    setItem(key: string, value: string) {
+        this.store.set(key, value);
+    }
+
+    removeItem(key: string) {
+        this.store.delete(key);
+    }
+
+    clear() {
+        this.store.clear();
+    }
+}
+
+const catalog: HarnessCatalogPayload = {
+    harnesses: [
+        {
+            harness: "text",
+            title: "Text",
+            description: "Chats.",
+            required: true,
+            automatic: true,
+            providers: [{ id: 1, name: "OpenRouter" }],
+            models: [],
+        },
+    ],
+};
+
+const settings: BotHarnessSettingsPayload = {
+    harnesses: [
+        {
+            harness: "text",
+            fallback: false,
+            enabled: true,
+            options: {},
+            candidate_count: 2,
+        },
+    ],
+};
+
+let storage: MemoryStorage;
+
+beforeEach(() => {
+    storage = new MemoryStorage();
+    Object.defineProperty(globalThis, "localStorage", {
+        value: storage as unknown as Storage,
+        configurable: true,
+    });
+});
+
+describe("harness cache", () => {
+    test("round-trips the catalog per user", () => {
+        writeHarnessCatalogCache({ user_id: 1, data: catalog });
+
+        expect(readHarnessCatalogCache({ user_id: 1 })?.data).toEqual(catalog);
+        expect(readHarnessCatalogCache({ user_id: 2 })).toBeNull();
+    });
+
+    test("round-trips a conversation's settings per user, bot and workspace", () => {
+        writeHarnessSettingsCache({
+            user_id: 1,
+            bot_id: 7,
+            workspace_id: 3,
+            data: settings,
+        });
+
+        expect(readHarnessSettingsCache({ user_id: 1, bot_id: 7, workspace_id: 3 })?.data).toEqual(
+            settings,
+        );
+        expect(readHarnessSettingsCache({ user_id: 2, bot_id: 7, workspace_id: 3 })).toBeNull();
+        expect(readHarnessSettingsCache({ user_id: 1, bot_id: 8, workspace_id: 3 })).toBeNull();
+    });
+
+    test("ignores another schema version", () => {
+        storage.setItem(
+            `${AppData.HarnessCacheStorageKey}:catalog:1`,
+            JSON.stringify({ v: 0, at: Date.now(), data: catalog }),
+        );
+
+        expect(readHarnessCatalogCache({ user_id: 1 })).toBeNull();
+    });
+
+    test("clears the new and the older per-conversation keys only", () => {
+        writeHarnessCatalogCache({ user_id: 1, data: catalog });
+        writeHarnessSettingsCache({ user_id: 1, bot_id: 7, data: settings });
+        storage.setItem(`${AppData.LegacyHarnessOverviewStorageKey}:7:0`, "{}");
+        storage.setItem(`${AppData.ComposerDraftStorageKey}:7`, "draft");
+
+        clearHarnessCache();
+
+        expect(readHarnessCatalogCache({ user_id: 1 })).toBeNull();
+        expect(readHarnessSettingsCache({ user_id: 1, bot_id: 7 })).toBeNull();
+        expect(storage.getItem(`${AppData.LegacyHarnessOverviewStorageKey}:7:0`)).toBeNull();
+        expect(storage.getItem(`${AppData.ComposerDraftStorageKey}:7`)).toBe("draft");
+    });
+});