feat(gemini): Skiva 1 – Gemini 2.5 Flash som lärar-tier för kylskåpsskanning

- Gemini-adapter bakom AamosClient-interface (AAMOS_MODE=gemini)
- Serversida/worker: hämtar bild, anropar Gemini, mappar mot canonical_ingredients
- Kostnad/tokens bokförs i ai_usage_counters; global dagsbudget via BudgetStore
- Redis-backed budget i worker, in-memory i tester
- Migration 0019: ai_cost_usd_microcents
- Hermetiska tester med inspelad fixture; separat pnpm eval:scan
- docs/09 uppdaterad ärligt: AAMOS-status, Gemini-flöde, säkerhet/kostnad
- REQUIRE_REAL=1 stödjer AAMOS_MODE=gemini; deploy-grind uppdaterad

apps/worker/src/context.ts

@@ -12,7 +12,8 @@ for (const candidate of [".env", "../.env", "../../.env"]) {
 }
 import { createHmac } from "node:crypto";
 import { createDatabase, type Database } from "@app/database";
-import { createAamosClient, type AamosClient } from "@app/ai-contracts";
+import { createAamosClient, type AamosClient, type BudgetStore } from "@app/ai-contracts";
+import type { Redis } from "ioredis";
 
 export interface WorkerContext {
   db: Database;
@@ -23,13 +24,40 @@ export interface WorkerContext {
   close: () => Promise<void>;
 }
 
-export function createContext(): WorkerContext {
+class RedisBudgetStore implements BudgetStore {
+  constructor(
+    private readonly redis: Redis,
+    private readonly key: string,
+  ) {}
+
+  async getDailySpendUsd(): Promise<number> {
+    const val = await this.redis.get(this.key);
+    return val ? Number(val) : 0;
+  }
+
+  async incrementDailySpendUsd(amountUsd: number): Promise<number> {
+    const newVal = await this.redis.incrbyfloat(this.key, amountUsd);
+    // Expire at next midnight UTC to keep daily window.
+    const ttl = this.secondsUntilMidnightUtc();
+    await this.redis.expire(this.key, ttl);
+    return Number(newVal);
+  }
+
+  private secondsUntilMidnightUtc(): number {
+    const now = new Date();
+    const midnight = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate() + 1));
+    return Math.max(1, Math.floor((midnight.getTime() - now.getTime()) / 1000));
+  }
+}
+
+export function createContext(redis?: Redis): WorkerContext {
   const databaseUrl = process.env.DATABASE_URL;
   if (!databaseUrl) {
     throw new Error("Missing DATABASE_URL. Worker must connect explicitly to the app database.");
   }
   const { db, pool } = createDatabase(databaseUrl);
-  const aamos = createAamosClient();
+  const budgetStore = redis ? new RedisBudgetStore(redis, `gemini:daily:budget:${new Date().toISOString().slice(0, 10)}`) : undefined;
+  const aamos = createAamosClient(undefined, { budgetStore });
   const apiBaseUrl = process.env.API_BASE_URL ?? "http://localhost:4000";
   const secret = process.env.ENTITLEMENT_SIGNING_SECRET ?? "dev-only-change-me-three";