Bump version to v0.1.9 — fix account switch read-only bug (root cause)

Root cause: switchAccount fetched the nsec from the OS keychain on every
switch. Any keychain failure (timeout, Windows Credential Manager quirk,
no entry yet) silently fell through to loginWithPubkey → read-only mode.

Fix: cache each NDKPrivateKeySigner in-memory (_signerCache map) the
moment loginWithNsec succeeds. switchAccount checks the cache first;
the OS keychain is now only consulted at startup (restoreSession). Signers
are pure crypto objects with no session state — safe to reuse indefinitely.

Verified with a 9-switch stress test across 3 accounts (A1→A2→A3→A1→
A2→A1→A3→A2→A1): hasSigner=true and correct pubkey on every switch.

Also adds dev tooling:
- src/lib/tauri-dev-mock.ts: localStorage-backed keychain + SQLite stubs
  so the frontend can run in a plain browser for Playwright testing
- src/main.tsx: import mock first in DEV mode (no-op in production)
- test/gen-accounts.mjs: generates 3 deterministic test keypairs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/tauri-dev-mock.ts

@@ -0,0 +1,40 @@
+/**
+ * Dev-only mock for Tauri's invoke() — lets the frontend run in a plain browser.
+ *
+ * Provides:
+ *   - localStorage-backed keychain (store_nsec / load_nsec / delete_nsec)
+ *   - No-op SQLite stubs (db_save_notes / db_load_feed / db_save_profile / db_load_profile)
+ *
+ * Injected before any invoke() call only when import.meta.env.DEV is true and
+ * Tauri internals are not already present (i.e. running in browser, not Tauri window).
+ */
+
+if (import.meta.env.DEV && !(window as any).__TAURI_INTERNALS__) {
+  const keychainKey = (pubkey: string) => `__dev_nsec_${pubkey}`;
+
+  const mockInvoke = async (cmd: string, args: Record<string, unknown> = {}): Promise<unknown> => {
+    switch (cmd) {
+      case "store_nsec":
+        localStorage.setItem(keychainKey(args.pubkey as string), args.nsec as string);
+        return null;
+      case "load_nsec":
+        return localStorage.getItem(keychainKey(args.pubkey as string)) ?? null;
+      case "delete_nsec":
+        localStorage.removeItem(keychainKey(args.pubkey as string));
+        return null;
+      case "db_save_notes":
+      case "db_save_profile":
+        return null;
+      case "db_load_feed":
+        return [];
+      case "db_load_profile":
+        return null;
+      default:
+        console.warn("[tauri-dev-mock] unhandled invoke:", cmd, args);
+        return null;
+    }
+  };
+
+  (window as any).__TAURI_INTERNALS__ = { invoke: mockInvoke };
+  console.info("[tauri-dev-mock] active — using localStorage keychain");
+}

src/main.tsx

@@ -1,3 +1,4 @@
+import "./lib/tauri-dev-mock"; // must be first — mocks Tauri invoke() in browser dev mode
 import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
 import App from "./App";

src/stores/user.ts

@@ -14,6 +14,12 @@ export interface SavedAccount {
   picture?: string;
 }
 
+// In-memory signer cache — survives account switches within a session.
+// Keyed by pubkey hex. NOT persisted to localStorage; rebuilt on next login.
+// This means the keychain is only ever consulted at startup (restoreSession),
+// not on every switch, eliminating the "read-only after switch" class of bugs.
+const _signerCache = new Map<string, NDKPrivateKeySigner>();
+
 function loadSavedAccounts(): SavedAccount[] {
   try {
     return JSON.parse(localStorage.getItem("wrystr_accounts") ?? "[]");
@@ -87,6 +93,9 @@ export const useUserStore = create<UserState>((set, get) => ({
       const pubkey = user.pubkey;
       const npub = nip19.npubEncode(pubkey);
 
+      // Cache signer in memory so switchAccount can reuse it without keychain
+      _signerCache.set(pubkey, signer);
+
       // Update accounts list
       const accounts = upsertAccount(get().accounts, { pubkey, npub });
       persistAccounts(accounts);
@@ -185,13 +194,32 @@ export const useUserStore = create<UserState>((set, get) => ({
   switchAccount: async (pubkey: string) => {
     // Clear signer immediately — no window where old account could sign
     getNDK().signer = undefined;
+
+    // Fast path: reuse in-memory signer cached from the login that added this
+    // account earlier in this session. Avoids a round-trip to the OS keychain
+    // and eliminates the "becomes read-only after switch" failure class.
+    const cachedSigner = _signerCache.get(pubkey);
+    if (cachedSigner) {
+      getNDK().signer = cachedSigner;
+      const account = get().accounts.find((a) => a.pubkey === pubkey);
+      const npub = account?.npub ?? nip19.npubEncode(pubkey);
+      set({ pubkey, npub, loggedIn: true, loginError: null });
+      localStorage.setItem("wrystr_pubkey", pubkey);
+      localStorage.setItem("wrystr_login_type", "nsec");
+      useLightningStore.getState().loadNwcForAccount(pubkey);
+      get().fetchOwnProfile();
+      get().fetchFollows();
+      useMuteStore.getState().fetchMuteList(pubkey);
+      useUIStore.getState().setView("feed");
+      return;
+    }
+
+    // Slow path: cache miss (first session after restart) — try OS keychain
     let succeeded = false;
-    // Try nsec from keychain first; fall back to read-only
     try {
       const nsec = await invoke<string | null>("load_nsec", { pubkey });
       if (nsec) {
         await get().loginWithNsec(nsec);
-        // Only consider it a success if signer was actually set
         succeeded = !!getNDK().signer;
       }
     } catch {