[chore] Modernize tsconfig + add native TS7 type-check

[ardaerzin]

Context

TypeScript 7 (the Go-native compiler) went GA on 2026-07-08, ~8-12x faster on large codebases with unchanged type semantics. This PR modernizes the tsconfig so the native compiler runs cleanly, types the CSS side-effect imports it (correctly) requires, and adds an opt-in native type-check script. Both apps stay at 0 errors throughout.

Two of the three parts are production-ready changes that stand on their own; the third is an opt-in dev tool. None of it touches the enforced toolchain.

Changes

1. tsconfig modernization (oss/tsconfig.json, ee/tsconfig.json). Switched to the relative-paths, no-baseUrl form:

"baseUrl": ".",
"paths": { "@/oss/*": ["src/*", ...] }        // before
"paths": { "@/oss/*": ["./src/*", ...] }       // after (baseUrl removed)

This is the modern standard form. Classic TS 5.9 accepts it (paths resolve relative to the tsconfig dir when there's no baseUrl), and it is also what TS7 requires — 7.0 removed baseUrl (TS5102) and rejects non-relative path values (TS5090). So one change satisfies both compilers.

2. CSS side-effect import typing (oss/css-modules.d.ts, ee/css-modules.d.ts). Added ambient *.css declarations per app, mirroring the existing packages/css-modules.d.ts. TS7 requires a declaration for import "x.css" (TS2882); classic tolerated it under moduleResolution: bundler. Additive and harmless to classic.

3. Opt-in native type-check. Added @typescript/native-preview (pinned) — the isolated tsgo binary. It does NOT replace the typescript@5.9 package, so typescript-eslint and next build resolve the classic compiler exactly as before. New scripts: type-check:native (tsgo) and type-check (classic — there wasn't a standalone one; type-checking only ran via next build).

The measurement

OSS, full check to zero errors: 18.1s classic → 3.7s native (~4.9x). EE native 4.3s. Less than Microsoft's headline 12x, which is on very large codebases; this is a mid-size app.

Verification (all green)

Check	OSS	EE
native tsgo	0	0
classic tsc	0	0
next build	exit 0, types validated	—
lint (typescript-eslint)	exit 0	—

The next build and lint passes are the important ones: they prove removing baseUrl does not disturb Next's own module resolver or typescript-eslint's parser, both of which read this tsconfig.

Deferred (not in this PR)

Making native the enforced gate — CI, pre-commit, and next build's internal type-check.

The hard blocker is typescript-eslint: TS7.0 shipped without a stable programmatic API (7.1 will add a new one), and npm refuses to install typescript-eslint alongside typescript@7 at all (ERESOLVE — its peer range caps below 6.1.0). So the lint job cannot move to native until 7.1. Microsoft's bridge for this transition is @typescript/typescript6 (a tsc6 binary re-exporting the 6.0 API) — see Announcing TypeScript 7.0 and typescript-eslint#12518.

Whether next build's internal type-check is also blocked is unverified — it depends on whether Next consumes the programmatic API or shells out to the tsc binary, which I did not confirm. Either way, typescript-eslint alone is sufficient reason to keep native off the enforced gate for now. This PR makes the later flip a small change; it does not attempt it.

One preview caveat: the isolated tsgo binary is currently only distributed via the nightly @typescript/native-preview channel (post-GA, the stable native compiler ships as typescript@7, whose tsc bin would collide with typescript@5.9). It's pinned to an exact version, and it sits outside every build path, so the blast radius is a local script.

Tests / notes

• Stacked on [refactor] Delete duplicate InfiniteVirtualTable, migrate to @agenta/ui #5471. Review the stack bottom-up.
• Nothing here changes runtime or the enforced build; the tsconfig and CSS changes are safe to keep even if the native tool is later dropped.

What to QA

Nothing user-facing. For a reviewer: cd web && pnpm type-check (classic, 0 errors) and pnpm type-check:native (tsgo, 0 errors) both pass; pnpm build-oss still succeeds.

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Project	Deployment	Actions	Updated (UTC)
agenta-documentation	Ready	Preview, Comment	Jul 23, 2026 7:42pm

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