Move production builds back to Turbopack on Next.js 16.3.1 - #3645
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Bump Next.js 16.2.6 -> 16.3.1, which fixes the Turbopack scope-hoisting bug that miscompiles the Dynamic-labs SDK and hard-crashed every page of any dynamic-auth instance in production. That crash was the whole reason ADR 0001 forced `next build --webpack`; verified fixed on the rootstock (dynamic) preset. Production builds now use Turbopack (the Next default), which on 16.3.1 is both ~2x faster to bundle and faster at runtime (median FCP 2047ms -> 1049ms, blocking 1444ms -> 453ms), at the cost of ~15% more JS before FCP that no longer hurts load. Full A/B in ADR 0003. - package.json: next -> 16.3.1; drop --webpack from `build` / `build:next` - next.config.js: experimental.useTypeScriptCli = false. Next 16.3 defaults the build type-check to the tsc CLI, which needs typescript/bin/tsc; this repo's native-TS alias (@typescript/typescript6) ships bin/tsc6 only, so the CLI path aborts the build claiming typescript is missing. The compiler-API path uses lib/typescript.js, which the alias provides. - pnpm-workspace.yaml: temporary minimumReleaseAge exceptions for next and its @next/env + @next/swc-* internals (16.3.1 is under the 1-week gate) - tools/dev-server/prod.preset.sh: default build -> Turbopack; --profile stays on webpack (react-dom/profiling alias is webpack-only) - build:analyze stays on webpack (@next/bundle-analyzer is a webpack plugin) - docs: new ADR 0003; ADR 0001 marked superseded; connect-wallet CONTEXT and AGENTS.md updated Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Turbopack's `output: standalone` tracer copies only @swc/helpers/cjs and drops the esm/ entry points that Next's require-hook loads at runtime, so the shipped image's `node server.js` crashed on boot with `Cannot find module '@swc/helpers/esm/_interop_require_default.js'`. webpack traced the package fully, so this only surfaced after the bundler switch — and only on the standalone path, not under `next start`, so it slipped past local checks until a review-env deploy crashlooped the frontend pod. `outputFileTracingIncludes` force-includes the whole package until the Turbopack tracer is fixed upstream. Verified: `node .next/standalone/server.js` now boots and serves 200. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
tom2drum
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Aug 18, 2026
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| Reviewed | 9897b3743b75ffb375add4b7170bd156862f9038 → 895d6bcd01f5c7a6124d8f29838ce0a4534ea55c |
| Round | 1 of 3 |
| Findings | 1 blocker · 1 major · 1 nit |
| By axis | Spec 0 (no task spec) · Standards 1 · Correctness 2 |
| Outcome | blocked |
Not anchorable
major · Correctness — .agents/tasks/3566-main-page-loading-perf/tools/README.md:62-63
Claim. ``prod:preset builds with the same bundler as the shipped image (webpack, per that ADR) — this change switched both to Turbopack; the README still points at ADR 0001 and will mislead anyone re-running the perf tools.
Suggested fix. Point at ADR 0003 and say Turbopack; drop the webpack claim.
— Reviewed by Cursor Grok 4.5
The dynamic-mode verify rule restated the Turbopack crash detail already owned by ADR 0003. Keep the "verify in a production build" rule and the ADR pointer; drop the restatement. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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What & why
Bumps Next.js 16.2.6 → 16.3.1 and switches production builds from webpack back to Turbopack (the Next default).
Next 16.3.1 fixes the Turbopack scope-hoisting bug that miscompiled the Dynamic-labs SDK and hard-crashed every page of any
NEXT_PUBLIC_ACCOUNT_AUTH_PROVIDER=dynamicinstance in production — the crash that forcednext build --webpackin ADR 0001. Verified fixed by building + serving on therootstock(dynamic) preset: home page renders, Dynamic login modal opens, zeroDynamicContextProvidererrors.The main motivation is CI build time. On 16.3.1 the old webpack-vs-Turbopack trade-off is gone — Turbopack is faster to build and faster at runtime.
Perf A/B (rootstock, medians of 3 headless runs, same machine — within-method deltas only)
next build)Turbopack ships ~15% more JS before FCP but halves FCP and cuts blocking time ~2/3 — the cost that used to live in execution is gone. Rationale + full context in the new ADR 0003.
Changes
next→ 16.3.1; drop--webpackfrombuildandbuild:next.experimental.useTypeScriptCli: false(required — see gotcha below).minimumReleaseAgeexceptions fornext+ its@next/env/@next/swc-*internals (16.3.1 is < 1 week old; entries tagged "remove after 20.08.2026").--profilestays on webpack.connect-wallet/CONTEXT.md+AGENTS.mdupdated.Kept on webpack deliberately:
build:analyze(@next/bundle-analyzeris a webpack plugin) andprod:preset --profile(Reactreact-dom/profilingalias is guaranteed on webpack, undocumented on Turbopack).Reviewer note — the
useTypeScriptCligotchaNext 16.3 defaults its build-time type-check to the
tscCLI, which needs atypescript/bin/tscbinary. This repo runs the native TS compiler via the@typescript/typescript6alias, which shipsbin/tsc6only — so the CLI path aborts the build claimingtypescriptis missing, on both bundlers (the check runs before bundling).useTypeScriptCli: falseswitches to the compiler-API path (lib/typescript.js, which the alias does provide); type-checking still runs and passes.Verification
pnpm build) now uses Turbopack.🤖 Generated with Claude Code