feat: Pi Text-Agent — initialer Commit (sauberes Repo)

Vollständiges Multi-Agenten-System für Fact-Checking, Artikelschreiben
und Argumentationsanalyse. Zwei Backends: llama.cpp (★ bevorzugt) und Ollama.

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

lib/perplexity.ts

@@ -0,0 +1,175 @@
+/**
+ * lib/perplexity.ts
+ * Gemeinsamer Perplexity-Sonar-Wrapper für alle Agenten.
+ * Wird von verifier.ts und verify-article.ts genutzt.
+ */
+
+const PRICING = {
+	sonar: { inputPerM: 1, outputPerM: 1 },
+	"sonar-pro": { inputPerM: 3, outputPerM: 15 },
+} as const;
+
+const SEARCH_COST_PER_CALL = 0.005;
+
+export type PerplexitySource = {
+	url: string;
+	title: string | undefined;
+	snippet: string | undefined;
+};
+
+export type PerplexityResult = {
+	summary: string;
+	sources: PerplexitySource[];
+	model: string;
+	promptTokens: number;
+	completionTokens: number;
+	searchQueries: number;
+	estimatedCostUSD: number;
+};
+
+type PerplexityApiResponse = {
+	model?: string;
+	citations?: string[];
+	search_results?: Array<{ url?: string; title?: string; snippet?: string }>;
+	choices?: Array<{ message?: { content?: string } }>;
+	usage?: {
+		prompt_tokens?: number;
+		completion_tokens?: number;
+		total_tokens?: number;
+		search_queries?: number;
+	};
+};
+
+class RetryableError extends Error {}
+
+async function sleep(ms: number) {
+	await new Promise((r) => setTimeout(r, ms));
+}
+
+function estimateCost(model: string, promptTokens: number, completionTokens: number, searchQueries: number): number {
+	const p = PRICING[model as keyof typeof PRICING] ?? PRICING["sonar"];
+	return (promptTokens / 1_000_000) * p.inputPerM +
+		(completionTokens / 1_000_000) * p.outputPerM +
+		searchQueries * SEARCH_COST_PER_CALL;
+}
+
+function parseSources(data: PerplexityApiResponse): PerplexitySource[] {
+	const seen = new Set<string>();
+
+	const fromSearch = data.search_results
+		?.filter((r) => !!r?.url)
+		.map((r) => ({ url: r.url!, title: r.title, snippet: r.snippet }))
+		.filter((s) => !seen.has(s.url) && seen.add(s.url))
+		?? [];
+
+	if (fromSearch.length > 0) return fromSearch.slice(0, 8);
+
+	return (data.citations ?? [])
+		.filter((u): u is string => typeof u === "string" && /^https?:\/\//.test(u) && !seen.has(u) && !!seen.add(u))
+		.slice(0, 8)
+		.map((url) => ({ url, title: undefined, snippet: undefined }));
+}
+
+/**
+ * Ruft die Perplexity Sonar API auf und gibt ein normiertes Ergebnis zurück.
+ * Wirft einen Error wenn PERPLEXITY_API_KEY fehlt oder der Aufruf fehlschlägt.
+ */
+export async function searchPerplexity(
+	query: string,
+	options?: {
+		mode?: "fast" | "deep";
+		recency?: string;
+		signal?: AbortSignal;
+		maxTokens?: number;
+	}
+): Promise<PerplexityResult> {
+	const apiKey = process.env.PERPLEXITY_API_KEY;
+	if (!apiKey) throw new Error("PERPLEXITY_API_KEY ist nicht gesetzt");
+
+	const mode = options?.mode ?? "fast";
+	const model: "sonar" | "sonar-pro" = mode === "deep" ? "sonar-pro" : "sonar";
+	const contextSize = mode === "deep" ? "high" : "low";
+	const maxTokens = options?.maxTokens ?? (mode === "deep" ? 600 : 350);
+
+	const body: Record<string, unknown> = {
+		model,
+		messages: [
+			{
+				role: "system",
+				content:
+					"Du bist ein Recherche-Tool für Fact-Checking. " +
+					"Recherchiere präzise und faktisch. " +
+					"Setze Inline-Zitierungen [1][2][3] direkt nach jedem belegten Satz. " +
+					"Fokussiere auf überprüfbare Fakten und Primärquellen.",
+			},
+			{
+				role: "user",
+				content: `Recherchefrage zum Fact-Checking:\n\n${query}`,
+			},
+		],
+		max_tokens: maxTokens,
+		temperature: 0.1,
+		web_search_options: { search_context_size: contextSize },
+	};
+
+	if (options?.recency) body.search_recency_filter = options.recency;
+
+	let lastError: unknown;
+	for (let attempt = 1; attempt <= 3; attempt++) {
+		try {
+			const resp = await fetch("https://api.perplexity.ai/chat/completions", {
+				method: "POST",
+				headers: { Authorization: `Bearer ${apiKey}`, "Content-Type": "application/json" },
+				body: JSON.stringify(body),
+				signal: options?.signal,
+			});
+
+			if (!resp.ok) {
+				const text = await resp.text().catch(() => "");
+				if (resp.status === 429 || resp.status >= 500) throw new RetryableError(`Perplexity ${resp.status}: ${text}`);
+				throw new Error(`Perplexity ${resp.status}: ${text}`);
+			}
+
+			const data = (await resp.json()) as PerplexityApiResponse;
+			const summary = data.choices?.[0]?.message?.content?.trim() ?? "";
+			if (!summary) throw new RetryableError("Leere Antwort von Perplexity");
+
+			const sources = parseSources(data);
+			const usage = data.usage ?? {};
+			const promptTokens = usage.prompt_tokens ?? 0;
+			const completionTokens = usage.completion_tokens ?? 0;
+			const searchQueries = usage.search_queries ?? 1;
+			const finalModel = data.model ?? model;
+
+			return {
+				summary,
+				sources,
+				model: finalModel,
+				promptTokens,
+				completionTokens,
+				searchQueries,
+				estimatedCostUSD: estimateCost(finalModel, promptTokens, completionTokens, searchQueries),
+			};
+		} catch (err) {
+			lastError = err;
+			if (err instanceof RetryableError && attempt < 3) {
+				await sleep(400 * 2 ** (attempt - 1));
+			} else {
+				break;
+			}
+		}
+	}
+
+	throw lastError instanceof Error ? lastError : new Error("Perplexity-Fehler");
+}
+
+/** Formatiert Quellen als kompakte Inline-Liste für Prompts */
+export function formatSourcesForPrompt(sources: PerplexitySource[], maxSnippetLen = 250): string {
+	return sources
+		.map((s, i) => {
+			const title = s.title ?? s.url;
+			const snippet = s.snippet ? `\n   "${s.snippet.slice(0, maxSnippetLen)}${s.snippet.length > maxSnippetLen ? "…" : ""}"` : "";
+			return `[${i + 1}] ${title} (${s.url})${snippet}`;
+		})
+		.join("\n");
+}