feat(webapp): reload LLM pricing registry on Redis pub/sub

Subscribe to LLM_PRICING_RELOAD_CHANNEL on the worker Redis. Any
process that publishes on the channel triggers an immediate reload
of the in-memory model registry. The 5-minute periodic reload stays
as a backstop.

Lets pricing and model changes propagate to the live registry within
seconds instead of up to 5 minutes.

Author: ericallam

.server-changes/llm-pricing-registry-reload-channel.md

@@ -0,0 +1,6 @@
+---
+area: webapp
+type: improvement
+---
+
+The LLM pricing registry now reloads from the database whenever a publish lands on `LLM_PRICING_RELOAD_CHANNEL` on the worker Redis, instead of waiting for the next 5-minute interval. LLM model and pricing changes reflect in cost enrichment within seconds.

apps/webapp/app/env.server.ts

@@ -1424,6 +1424,7 @@ const EnvironmentSchema = z
     // LLM cost tracking
     LLM_COST_TRACKING_ENABLED: BoolEnv.default(true),
     LLM_PRICING_RELOAD_INTERVAL_MS: z.coerce.number().int().default(5 * 60 * 1000), // 5 minutes
+    LLM_PRICING_RELOAD_CHANNEL: z.string().default("llm-registry:reload"),
     LLM_PRICING_SEED_ON_STARTUP: BoolEnv.default(false),
     LLM_PRICING_READY_TIMEOUT_MS: z.coerce.number().int().default(500),
     LLM_METRICS_BATCH_SIZE: z.coerce.number().int().default(5000),

apps/webapp/app/v3/llmPricingRegistry.server.ts

@@ -1,7 +1,9 @@
 import { ModelPricingRegistry, seedLlmPricing } from "@internal/llm-model-catalog";
 import { prisma, $replica } from "~/db.server";
 import { env } from "~/env.server";
+import { logger } from "~/services/logger.server";
 import { signalsEmitter } from "~/services/signals.server";
+import { createRedisClient } from "~/redis.server";
 import { singleton } from "~/utils/singleton";
 import { setLlmPricingRegistry } from "./utils/enrichCreatableEvents.server";
 
@@ -27,19 +29,50 @@ export const llmPricingRegistry = singleton("llmPricingRegistry", () => {
     console.error("Failed to initialize LLM pricing registry", err);
   });
 
-  // Periodic reload
+  // Periodic reload (backstop for the pub/sub path below)
   const reloadInterval = env.LLM_PRICING_RELOAD_INTERVAL_MS;
   const interval = setInterval(() => {
     registry.reload().catch((err) => {
       console.error("Failed to reload LLM pricing registry", err);
     });
   }, reloadInterval);
 
+  // Pub/sub reload — billing's LLM registry worker publishes on this channel
+  // immediately after writing new/changed model rows, so all webapp pods see
+  // updates within ~1s instead of waiting for the next interval tick.
+  const subscriber = createRedisClient("llm-pricing:subscriber", {
+    keyPrefix: "llm-pricing:subscriber:",
+    host: env.COMMON_WORKER_REDIS_HOST,
+    port: env.COMMON_WORKER_REDIS_PORT,
+    username: env.COMMON_WORKER_REDIS_USERNAME,
+    password: env.COMMON_WORKER_REDIS_PASSWORD,
+    tlsDisabled: env.COMMON_WORKER_REDIS_TLS_DISABLED === "true",
+    clusterMode: env.COMMON_WORKER_REDIS_CLUSTER_MODE_ENABLED === "1",
+  });
+
+  subscriber.subscribe(env.LLM_PRICING_RELOAD_CHANNEL).catch((err) => {
+    logger.warn("Failed to subscribe to LLM pricing reload channel", {
+      channel: env.LLM_PRICING_RELOAD_CHANNEL,
+      error: err instanceof Error ? err.message : String(err),
+    });
+  });
+
+  subscriber.on("message", (channel) => {
+    if (channel !== env.LLM_PRICING_RELOAD_CHANNEL) return;
+    registry.reload().catch((err) => {
+      logger.warn("Failed to reload LLM pricing registry from pub/sub", {
+        error: err instanceof Error ? err.message : String(err),
+      });
+    });
+  });
+
   signalsEmitter.on("SIGTERM", () => {
     clearInterval(interval);
+    void subscriber.quit().catch(() => {});
   });
   signalsEmitter.on("SIGINT", () => {
     clearInterval(interval);
+    void subscriber.quit().catch(() => {});
   });
 
   return registry;