feat: supporto ai Focus Modes di Perplexity (parametro 'focus')

- Aggiunto il parametro 'focus' al tool perplexity_search per selezionare la
  fonte di conoscenza (Focus Mode).
- FOCUS_MAP: mappa focus -> search_focus + sources usati dall'endpoint
  perplexity_ask (internet/web, academic/scholar, writing, wolfram, youtube,
  reddit, math, social, finance).
- default: internet (comportamento invariato).
- README aggiornato.

README.md

@@ -74,8 +74,12 @@ Once installed, the agent automatically calls `perplexity_search` whenever it ne
 |---|---|---|---|
 | `query` | string | ✅ | The search query |
 | `recency` | string | — | Filter by age: `hour` · `day` · `week` · `month` · `year` |
+| `focus` | string | — | Perplexity **Focus Mode** (source domain): `internet` · `academic` · `writing` · `wolfram` · `youtube` · `reddit` · `math` · `social` · `finance` (default `internet`) |
 | `limit` | number | — | Max sources to include (1–50) |
 
+**Focus Modes** let the agent route the search to a specific knowledge source:
+`academic` → peer-reviewed/scholarly (PubMed, arXiv, Semantic Scholar), `youtube` → video transcripts, `reddit` → community/opinions, `wolfram`/`math` → computations, `social` → social platforms, `finance` → financial/SEC data, `writing` → model-only (no live search).
+
 Model selection is configured globally with `/perplexity-config` or `PI_PERPLEXITY_MODEL`; it is not exposed as a tool parameter, so agent-generated tool calls cannot accidentally override your configured model.
 
 ### Output format

src/index.ts

@@ -27,6 +27,15 @@ export default function (pi: ExtensionAPI) {
           description: "Filter results by recency",
         }),
       ),
+      focus: Type.Optional(
+        StringEnum(
+          ["internet", "academic", "writing", "wolfram", "youtube", "reddit", "math", "social", "finance"] as const,
+          {
+            description:
+              "Perplexity Focus Mode: source domain to search (internet=web, academic, writing, wolfram/math, youtube, reddit, social, finance)",
+          },
+        ),
+      ),
       limit: Type.Optional(
         Type.Number({ description: "Max sources to return", minimum: 1, maximum: 50 }),
       ),
@@ -77,6 +86,7 @@ export default function (pi: ExtensionAPI) {
             query: params.query,
             model,
             ...(params.recency !== undefined ? { recency: params.recency } : {}),
+            ...(params.focus !== undefined ? { focus: params.focus } : {}),
           },
           auth,
           signal,

src/search/client.ts

@@ -8,10 +8,35 @@ import { PERPLEXITY_USER_AGENT, PERPLEXITY_API_VERSION } from "../constants.js";
 
 const PERPLEXITY_ENDPOINT = "https://www.perplexity.ai/rest/sse/perplexity_ask";
 
+export type FocusMode =
+	| "internet"
+	| "academic"
+	| "writing"
+	| "wolfram"
+	| "youtube"
+	| "reddit"
+	| "math"
+	| "social"
+	| "finance";
+
+// Mappa Focus Mode → search_focus + sources usati dall'endpoint perplexity_ask
+const FOCUS_MAP: Record<FocusMode, { focus: string; sources: string[] }> = {
+	internet: { focus: "internet", sources: ["web"] },
+	academic: { focus: "academic", sources: ["scholar"] },
+	writing: { focus: "writing", sources: [] },
+	wolfram: { focus: "wolfram", sources: ["wolfram"] },
+	youtube: { focus: "youtube", sources: ["youtube"] },
+	reddit: { focus: "reddit", sources: ["reddit"] },
+	math: { focus: "math", sources: ["wolfram"] },
+	social: { focus: "social", sources: ["social"] },
+	finance: { focus: "finance", sources: ["finance"] },
+};
+
 export interface SearchParams {
-  query: string;
-  recency?: "hour" | "day" | "week" | "month" | "year";
-  model: string;
+	query: string;
+	recency?: "hour" | "day" | "week" | "month" | "year";
+	focus?: FocusMode;
+	model: string;
 }
 
 function normalizeUrl(url: string): string {
@@ -120,10 +145,10 @@ function buildRequestBody(params: SearchParams): Record<string, unknown> {
     query_str: query,
     params: {
       query_str: query,
-      search_focus: "internet",
+      search_focus: FOCUS_MAP[params.focus ?? "internet"].focus,
       mode: "copilot",
       model_preference: params.model,
-      sources: ["web"],
+      sources: FOCUS_MAP[params.focus ?? "internet"].sources,
       attachments: [],
       frontend_uuid: randomUUID(),
       frontend_context_uuid: randomUUID(),