chore(deps): upgrade next to 16.3.0 and clean up the TypeScript toolchain

[waleedlatif1]

Summary

• Bumps next, @next/env and the @next/swc-* optional deps to 16.3.0 across the root overrides, apps/sim, apps/docs and packages/emcn
• Pins experimental.useTypeScriptCli: true — TypeScript 7 ships no JavaScript compiler API until 7.1, so Next's default checker can't run and needs the project-local tsc CLI. 16.2.12 was silently skipping build-time type checking entirely: it detected @typescript/native-preview and short-circuited the stage (Finished TypeScript in 138ms). Builds now actually type-check, so a build can fail where it previously passed
• Records that experimental.turbopackFileSystemCacheForBuild's default flipped false -> true for stable in 16.3.0, which makes our explicit false load-bearing rather than defensive — without it this bump would have silently re-enabled a build cache measured 3.2x slower on this codebase ([EXPERIMENT — do not merge] Is the Turbopack FS build cache a net win? #6078)
• Drops @typescript/native-preview from apps/sim and apps/docs. It was the pre-release channel for TS 7, is superseded by typescript@7 (nightlies now ship as typescript@next), and its presence is what suppressed build type checks
• Aligns packages/browser-protocol and packages/terminal-protocol from typescript ^5.7.3 to ^7.0.2 so every workspace is on one compiler version

apps/sim deliberately keeps @typescript/typescript6 as a production dependency: the function sandbox at app/api/function/execute dynamically imports the TS 6 compiler API to transpile user code, and TS 7 has no API to replace it yet.

Type of Change

• Chore / dependency upgrade

Testing

• 23/23 packages type-check; next build succeeds
• 18366/18367 tests pass. The single failure (cloud-review-tools.test.ts, FileNotFoundError: 'rg') is environmental and reproduces identically on a 16.2.12 baseline — CI installs ripgrep explicitly for it
• bun run check:api-validation passes, biome clean
• Benchmarked build and dev:full 3x per version on a byte-identical tree: performance-neutral (build median 100s -> 99s, dev:full warm 10s -> 9s)

Two things reviewers should know:

1. Nine experimental defaults turn on in 16.3.0 that we don't pin. validateRSCRequestHeaders (a CDN cache-poisoning fix) and varyParams both change RSC Vary/caching behavior — worth watching on staging since we sit behind an ALB. cacheComponents is off, so the cacheComponents-gated defaults don't apply
2. next dev in 16.3.0 now writes a managed agent-rules block into AGENTS.md/CLAUDE.md, with no env or config opt-out. It's kept out of this PR, so expect an uncommitted change locally after running dev

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview	Aug 4, 2026 1:20am

[cursor]

PR Summary

Medium Risk
Build-time type checking behavior changes (failures may surface where 16.2.12 passed silently), and Next 16.3.0 enables several experimental defaults and RSC caching header changes worth watching on staging behind the ALB.

Overview
Upgrades Next.js from 16.2.12 to 16.3.0 across the monorepo (next, @next/env, @next/swc-* overrides and lockfile).

In apps/sim/next.config.ts, pins experimental.useTypeScriptCli: true so next build runs the project tsc instead of Next’s in-process checker, which cannot load TypeScript 7 until 7.1—on 16.2.12 the type-check stage was effectively skipped. turbopackFileSystemCacheForBuild: false stays explicit because 16.3.0 flipped that default to true on stable, which would re-enable a build cache measured as much slower on this app.

Removes @typescript/native-preview from apps/sim and apps/docs (superseded by typescript@^7.0.2) and aligns packages/browser-protocol and packages/terminal-protocol to the same TS 7 devDependency. apps/sim still keeps @typescript/typescript6 for the function sandbox transpiler.

^{Reviewed by Cursor Bugbot for commit 676acd2. Configure here.}

[greptile-apps]

Greptile Summary

The PR upgrades Next.js and its associated environment and SWC packages to 16.3.0 while consolidating workspaces on TypeScript 7.

• Enables Next’s project-local TypeScript CLI checker in the Sim app.
• Removes the superseded TypeScript native-preview package.
• Aligns the browser and terminal protocol packages with the repository’s TypeScript version.
• Preserves the explicit disabled build-cache setting after its upstream default changed.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
apps/sim/next.config.ts	Enables Next’s TypeScript CLI checker and documents why the build filesystem cache must remain disabled.
apps/sim/package.json	Upgrades Next to 16.3.0 and removes the obsolete TypeScript native-preview dependency while retaining the separate TypeScript 6 runtime compiler.
apps/docs/package.json	Upgrades Next and removes the obsolete TypeScript native-preview development dependency.
package.json	Aligns root Next environment, framework, and platform-specific SWC dependency versions at 16.3.0.
packages/browser-protocol/package.json	Aligns the package’s development compiler with the repository-wide TypeScript 7 toolchain.
packages/terminal-protocol/package.json	Aligns the package’s development compiler with the repository-wide TypeScript 7 toolchain.
packages/emcn/package.json	Upgrades the component package’s Next development dependency to 16.3.0.
bun.lock	Records dependency resolutions consistent with the changed manifests and removes obsolete native-preview resolutions.

_{Reviews (2): Last reviewed commit: "chore(deps): upgrade next to 16.3.0 and ..." | Re-trigger Greptile}

[waleedlatif1]

@greptile

[waleedlatif1]

@cursor review

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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^{Reviewed by Cursor Bugbot for commit 676acd2. Configure here.}