Task #2: MVP Foundation — injectable services, DB schema, smoke test

DB schema
- jobs and invoices tables added to lib/db/src/schema/
- schema barrel updated (jobs, invoices, conversations, messages)
- pnpm --filter @workspace/db run push applied successfully

LNbitsService (artifacts/api-server/src/lib/lnbits.ts)
- Injectable class accepting optional { url, apiKey } config
- Falls back to LNBITS_URL / LNBITS_API_KEY env vars
- Auto-detects stub mode when credentials are absent; logs warning
- createInvoice() -> { paymentHash, paymentRequest }
- checkInvoicePaid() -> boolean
- stubMarkPaid() helper for dev/test flows
- Real LNbits REST v1 calls wired behind the stub guard

AgentService (artifacts/api-server/src/lib/agent.ts)
- Injectable class with configurable evalModel / workModel
- evaluateRequest(text) -> { accepted: boolean, reason: string }
  uses claude-haiku-4-5; strips markdown fences before JSON parse
- executeWork(text) -> { result: string } uses claude-sonnet-4-6
- Wired via Replit Anthropic AI Integration (no user API key)

PricingService (artifacts/api-server/src/lib/pricing.ts)
- Injectable class with configurable fee/bucket thresholds
- calculateEvalFeeSats() -> 10 sats (fixed)
- calculateWorkFeeSats(text) -> 50/100/250 by char-length bucket
- Zero LLM involvement; fully deterministic

Smoke test (scripts/src/smoke.ts)
- pnpm --filter @workspace/scripts run smoke
- Verifies LNbits stub: create, check unpaid, mark paid, check paid
- Verifies Anthropic: evaluateRequest round-trip
- Both checks passed

replit.md
- Documented required (LNBITS_URL, LNBITS_API_KEY) and auto-provisioned secrets
- Stub-mode behaviour explained

artifacts/api-server/src/lib/lnbits.ts

@@ -5,33 +5,87 @@ export interface LNbitsInvoice {
   paymentRequest: string;
 }
 
-export interface LNbitsInvoiceStatus {
-  paid: boolean;
-  paidAt?: Date;
+export interface LNbitsConfig {
+  url: string;
+  apiKey: string;
 }
 
-const paidInvoices = new Set<string>();
+const stubPaidInvoices = new Set<string>();
 
-export async function createInvoice(
-  amountSats: number,
-  memo: string,
-): Promise<LNbitsInvoice> {
-  const paymentHash = randomBytes(32).toString("hex");
-  const paymentRequest = `lnbcrt${amountSats}u1stub_${paymentHash.slice(0, 16)}`;
-  console.log(`[stub] Created invoice: ${amountSats} sats — "${memo}" — hash=${paymentHash}`);
-  return { paymentHash, paymentRequest };
-}
+export class LNbitsService {
+  private readonly url: string;
+  private readonly apiKey: string;
+  readonly stubMode: boolean;
 
-export async function checkInvoicePaid(
-  paymentHash: string,
-): Promise<LNbitsInvoiceStatus> {
-  if (paidInvoices.has(paymentHash)) {
-    return { paid: true, paidAt: new Date() };
+  constructor(config?: Partial<LNbitsConfig>) {
+    this.url = config?.url ?? process.env.LNBITS_URL ?? "";
+    this.apiKey = config?.apiKey ?? process.env.LNBITS_API_KEY ?? "";
+    this.stubMode = !this.url || !this.apiKey;
+    if (this.stubMode) {
+      console.warn("[LNbitsService] No LNBITS_URL/LNBITS_API_KEY — running in STUB mode. Invoices are simulated.");
+    }
+  }
+
+  async createInvoice(amountSats: number, memo: string): Promise<LNbitsInvoice> {
+    if (this.stubMode) {
+      const paymentHash = randomBytes(32).toString("hex");
+      const paymentRequest = `lnbcrt${amountSats}u1stub_${paymentHash.slice(0, 16)}`;
+      console.log(`[stub] Created invoice: ${amountSats} sats — "${memo}" — hash=${paymentHash}`);
+      return { paymentHash, paymentRequest };
+    }
+
+    const response = await fetch(`${this.url.replace(/\/$/, "")}/api/v1/payments`, {
+      method: "POST",
+      headers: this.headers(),
+      body: JSON.stringify({ out: false, amount: amountSats, memo }),
+    });
+
+    if (!response.ok) {
+      const body = await response.text();
+      throw new Error(`LNbits createInvoice failed (${response.status}): ${body}`);
+    }
+
+    const data = (await response.json()) as {
+      payment_hash: string;
+      payment_request: string;
+    };
+    return { paymentHash: data.payment_hash, paymentRequest: data.payment_request };
+  }
+
+  async checkInvoicePaid(paymentHash: string): Promise<boolean> {
+    if (this.stubMode) {
+      return stubPaidInvoices.has(paymentHash);
+    }
+
+    const response = await fetch(
+      `${this.url.replace(/\/$/, "")}/api/v1/payments/${paymentHash}`,
+      { method: "GET", headers: this.headers() },
+    );
+
+    if (!response.ok) {
+      const body = await response.text();
+      throw new Error(`LNbits checkInvoice failed (${response.status}): ${body}`);
+    }
+
+    const data = (await response.json()) as { paid: boolean };
+    return data.paid;
+  }
+
+  /** Stub-only helper: mark an invoice as paid for testing/dev flows. */
+  stubMarkPaid(paymentHash: string): void {
+    if (!this.stubMode) {
+      throw new Error("stubMarkPaid called on a real LNbitsService instance");
+    }
+    stubPaidInvoices.add(paymentHash);
+    console.log(`[stub] Marked invoice paid: hash=${paymentHash}`);
+  }
+
+  private headers(): Record<string, string> {
+    return {
+      "Content-Type": "application/json",
+      "X-Api-Key": this.apiKey,
+    };
   }
-  return { paid: false };
 }
 
-export function markInvoicePaid(paymentHash: string): void {
-  paidInvoices.add(paymentHash);
-  console.log(`[stub] Marked invoice paid: hash=${paymentHash}`);
-}
+export const lnbitsService = new LNbitsService();