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/pricing.ts

@@ -1,8 +1,39 @@
-export const EVAL_FEE_SATS = 10;
-
-export function computeWorkFeeSats(request: string): number {
-  const len = request.trim().length;
-  if (len <= 100) return 50;
-  if (len <= 300) return 100;
-  return 250;
+export interface PricingConfig {
+  evalFeeSats?: number;
+  workFeeShortSats?: number;
+  workFeeMediumSats?: number;
+  workFeeLongSats?: number;
+  shortMaxChars?: number;
+  mediumMaxChars?: number;
 }
+
+export class PricingService {
+  private readonly evalFee: number;
+  private readonly workFeeShort: number;
+  private readonly workFeeMedium: number;
+  private readonly workFeeLong: number;
+  private readonly shortMax: number;
+  private readonly mediumMax: number;
+
+  constructor(config?: PricingConfig) {
+    this.evalFee = config?.evalFeeSats ?? 10;
+    this.workFeeShort = config?.workFeeShortSats ?? 50;
+    this.workFeeMedium = config?.workFeeMediumSats ?? 100;
+    this.workFeeLong = config?.workFeeLongSats ?? 250;
+    this.shortMax = config?.shortMaxChars ?? 100;
+    this.mediumMax = config?.mediumMaxChars ?? 300;
+  }
+
+  calculateEvalFeeSats(): number {
+    return this.evalFee;
+  }
+
+  calculateWorkFeeSats(requestText: string): number {
+    const len = requestText.trim().length;
+    if (len <= this.shortMax) return this.workFeeShort;
+    if (len <= this.mediumMax) return this.workFeeMedium;
+    return this.workFeeLong;
+  }
+}
+
+export const pricingService = new PricingService();