feat: add per-request store API (getRequestStore)

[JamesbbBriz]

Summary

Adds a user-accessible per-request key-value store backed by vinext's existing AsyncLocalStorage-based unified request context.

Primary use case: per-request database clients on Cloudflare Workers. Global DB singletons cause alternating request failures (#537) because Workers isolates reuse across requests but I/O contexts are per-request.

getRequestStore() gives each request its own Map that's automatically garbage-collected when the request completes — no manual cleanup, no TTL hacks.

API

import { getRequestStore } from "vinext/request-store";

// Per-request Prisma client (solves #537):
export function getPrisma(connectionString: string): PrismaClient {
  const store = getRequestStore();
  let prisma = store.get("prisma") as PrismaClient | undefined;
  if (!prisma) {
    const pool = new Pool({ connectionString });
    prisma = new PrismaClient({ adapter: new PrismaPg(pool) });
    store.set("prisma", prisma);
  }
  return prisma;
}

// Works with Drizzle too:
export function getDb(connectionString: string) {
  const store = getRequestStore();
  let db = store.get("db");
  if (!db) {
    db = drizzle(connectionString);
    store.set("db", db);
  }
  return db;
}

Motivation

We're running a production SaaS (OptiTalent) on vinext + Cloudflare Workers with Prisma v7 + Hyperdrive + R2. We hit the exact alternating-failure pattern described in #537 and initially worked around it with a 50ms TTL heuristic. It works, but it's fragile — the correct solution is framework-level per-request scoping.

vinext already has the infrastructure for this via UnifiedRequestContext + AsyncLocalStorage. This PR simply exposes it to users via a clean public API, similar to:

• SvelteKit event.locals
• Hono c.set() / c.get()
• Remix context

Scope & Limitations

getRequestStore() works in any code path wrapped by runWithRequestContext() (the unified ALS scope):

Code path	Supported	Notes
App Router route handlers (app/api/*/route.ts)	✅	Wrapped by RSC entry
App Router server components	✅	Wrapped by RSC entry
App Router server actions	✅	Wrapped by RSC entry
Pages Router API routes (pages/api/*)	✅	Wrapped in 985e6ec (both dev + prod)
Middleware (middleware.ts)	✅	Has runWithExecutionContext, inherits into unified scope

Changes

File	Change
packages/vinext/src/shims/unified-request-context.ts	Add userStore: Map<string, unknown> to UnifiedRequestContext
packages/vinext/src/shims/request-store.ts	New — getRequestStore() public API
packages/vinext/package.json	Add "./request-store" export

Test plan

• Verified in production with Prisma v7 + Hyperdrive (per-request client, zero alternating failures)
• Unit test: getRequestStore() returns isolated Maps across concurrent runWithRequestContext() calls
• Unit test: getRequestStore() returns fallback Map outside request scope

Closes #537

[chatgpt-codex-connector]

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Reviewed commit: f7cdddfc4a

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[chatgpt-codex-connector]

Return a fresh fallback store outside request scope

getRequestStore() is documented as non-persistent outside unified scope, but _fallbackStore is a module-global Map, so every out-of-scope call shares and retains the same data. In practice this can leak request-specific objects (for example DB clients keyed by dynamic values) across unrelated calls/tests and grow unbounded over process lifetime, which defeats the isolation guarantees this API is meant to provide when context propagation is missing.

Useful? React with 👍 / 👎.

[JamesbbBriz]

Local verification

Tested with our production app (Prisma v7 + Hyperdrive + Cloudflare Workers Free plan):

• npm run build:vinext passes with the new request-store.ts in the bundle
• Per-request Prisma client via getRequestStore() — zero alternating failures across 500+ requests
• Outside-scope fallback returns fresh Map each call (addressed review feedback in 371d00d)

Happy to add unit tests if needed — let me know the preferred test framework/location.

[JamesbbBriz]

Superseded by a cleaner PR — squashed commits and addressed all review feedback.