fix(next-js): set local dev drain grace period

[NathanFlurry]

Summary

• Sets drainGracePeriod: 30 in the Next.js local dev auto-config alongside the existing requestLifespan: 300.
• Prevents the engine from rejecting the runner config because its default drain grace is 1800s, which is longer than Next's 300s request lifespan.

Validation

• pnpm --filter @rivetkit/framework-base build
• pnpm --filter @rivetkit/react build
• pnpm --filter @rivetkit/next-js check-types
• pnpm --filter @rivetkit/next-js build

[claude]

PR Review: set dev drain grace period for Next.js auto-config

The PR scope changed significantly since my last review (previously touched serverless/configure.ts with a generic resolveServerlessDrainGracePeriod clamp; that code no longer exists on this branch). Reviewing the current diff: a single line in rivetkit-typescript/packages/next-js/src/mod.ts adding drainGracePeriod: 30 next to the existing requestLifespan: 300 in the dev-mode configurePool block.

Root cause check confirms the fix is correct. In engine/packages/pegboard/src/ops/runner_config/upsert.rs:85-88, the engine rejects drain_grace_period >= request_lifespan, and if drain_grace_period is omitted it defaults to 1800s server-side (engine/packages/api-types/src/namespaces/runner_configs.rs:103). Since Next.js dev mode hardcodes requestLifespan: 300, omitting drainGracePeriod would always fail that upsert. Setting it to 30 (well under 300, and well under the actor_stop_threshold cap checked at upsert.rs:96) fixes it correctly.

Scope is appropriately narrow. I checked other rivetkit-typescript/packages/*/src callers of requestLifespan and next-js/src/mod.ts is the only place that hardcodes it outside of configure.ts's own default (60 * 60, which is far larger than any reasonable drainGracePeriod). So this one-line fix fully resolves the bug without leaving other frameworks exposed to the same failure mode.

Minor / non-blocking:

• No magic-number comment on 30. A short comment (e.g. "must be less than requestLifespan per engine validation") would help a future reader who bumps requestLifespan avoid silently re-breaking this, since the two values are coupled but not derived from each other.
• No test coverage for this package (there's no existing test infra under next-js/src), consistent with the tiny, config-literal nature of the change.

Overall a clean, minimal, correctly-scoped fix.

[railway-app]

🚅 Deployed to the rivet-pr-5355 environment in rivet-frontend

Service	Status	Web	Updated (UTC)
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