feat: Implement Prompt Builder functionality in Popup and Options

- Added a new "Prompt Builder" tab in the Popup for generating AI prompts with customizable parameters.
- Introduced new state variables for managing prompt styles, personas, formats, and models.
- Enhanced the Options page to fetch and display models based on the provided API key.
- Updated the actions and types to include the new 'prompt' action and its associated parameters.
- Implemented migration logic for legacy plaintext API keys to encrypted storage.
- Updated the getSystemPrompt function to incorporate prompt parameters for better instruction generation.
- Added tests for the new functionality, including context menu entries and prompt generation logic.

entrypoints/background.ts

@@ -1,7 +1,7 @@
 import { defineBackground } from 'wxt/utils/define-background';
 import type { AnalyzePayload, LexAIConfig, LexAIResponse } from '@lib/types';
-import { CONTEXT_MENU_ENTRIES, findContextMenuEntry } from '@lib/actions';
-import { decryptApiKey } from '@lib/crypto';
+import { CONTEXT_MENU_ENTRIES, findContextMenuEntry, resolvePromptPersona } from '@lib/actions';
+import { decryptApiKey, migratePlaintextApiKey } from '@lib/crypto';
 import { callProvider, getSystemPrompt, listModels } from '@lib/providers';
 
 // Resolve the usable API key from stored config: prefer the encrypted path,
@@ -22,13 +22,35 @@ async function handleAnalyzeText(payload: AnalyzePayload): Promise<LexAIResponse
   const stored = await chrome.storage.local.get(['provider', 'apiKey', 'apiKeyEnc', 'encKey', 'model']);
   const config = stored as LexAIConfig;
 
+  // Prompt requests from the toolbar/context menu carry no explicit params —
+  // apply the Prompt Builder settings saved from the popup so all entry
+  // points behave the same. The popup still overrides by sending its own.
+  if (payload.action === 'prompt' && !payload.promptParams) {
+    const saved = (await chrome.storage.local.get([
+      'promptStyle', 'promptPersona', 'customPersona', 'promptFormat', 'promptModel',
+    ])) as Record<string, string | undefined>;
+    payload = {
+      ...payload,
+      promptParams: {
+        promptStyle: saved.promptStyle,
+        persona: resolvePromptPersona(saved.promptPersona, saved.customPersona),
+        format: saved.promptFormat,
+      },
+      model: payload.model ?? (saved.promptModel || undefined),
+    };
+  }
+
   const apiKey = await resolveApiKey(config);
   if (!apiKey) {
     return { error: 'No API key configured. Please open LexAI settings (click the extension icon).' };
   }
 
-  const resolvedConfig: LexAIConfig = { ...config, apiKey };
-  const systemPrompt = getSystemPrompt(payload.action, payload.style);
+  const resolvedConfig: LexAIConfig = {
+    ...config,
+    apiKey,
+    ...(payload.model ? { model: payload.model } : {}),
+  };
+  const systemPrompt = getSystemPrompt(payload.action, payload.style, payload.promptParams);
   return callProvider(resolvedConfig, payload.text, systemPrompt);
 }
 
@@ -37,6 +59,10 @@ async function handleAnalyzeText(payload: AnalyzePayload): Promise<LexAIResponse
 export default defineBackground(() => {
   console.log('LexAI background service worker started');
 
+  // Encrypt any legacy plaintext apiKey left by older builds (no-op otherwise).
+  // The read path keeps its plaintext fallback, so a failed migration is safe.
+  migratePlaintextApiKey().catch(() => {});
+
   // ─── Context menus ───────────────────────────────────────────────────────
   chrome.runtime.onInstalled.addListener(() => {
     chrome.contextMenus.removeAll(() => {
@@ -64,7 +90,11 @@ export default defineBackground(() => {
   });
 
   // ─── Message handler ─────────────────────────────────────────────────────
-  chrome.runtime.onMessage.addListener((message, _sender, sendResponse) => {
+  chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
+    // Only our own contexts (content scripts, popup, options) may drive the
+    // key-bearing call path — ignore anything from another extension.
+    if (sender.id !== chrome.runtime.id) return;
+
     if (message.type === 'ANALYZE_TEXT') {
       // Support both { payload: { text, action, style } } (content.ts) and
       // { text, action, style } (popup) formats
@@ -72,6 +102,8 @@ export default defineBackground(() => {
         text: message.text as string,
         action: message.action as string,
         style: message.style as string | undefined,
+        promptParams: message.promptParams,
+        model: message.model as string | undefined,
       };
       handleAnalyzeText(payload)
         .then(sendResponse)
@@ -99,10 +131,16 @@ export default defineBackground(() => {
     }
 
     if (message.type === 'LIST_MODELS') {
-      const provider = (message.provider as string) || 'openai';
       // Prefer an inline key (freshly typed, not yet saved); else use the stored key.
       const inlineKey = (message.apiKey as string | undefined)?.trim() || undefined;
       (async () => {
+        // Callers that don't know the provider (content script) omit it —
+        // fall back to the configured one.
+        let provider = message.provider as string | undefined;
+        if (!provider) {
+          const stored = await chrome.storage.local.get('provider');
+          provider = (stored.provider as string) || 'openai';
+        }
         let apiKey = inlineKey;
         if (!apiKey) {
           const stored = await chrome.storage.local.get(['apiKey', 'apiKeyEnc', 'encKey']);