feat(studio): add build:dev mode with source maps and React dev warnings

[vanceingalls]

Summary

• Add build:dev script to Studio that builds with source maps, no minification, and React dev-mode warnings
• Vite config now accepts --mode development to conditionally enable process.env.NODE_ENV, sourcemaps, and disable minify
• CLAUDE.md updated: always use build:dev locally, production build is GHA-only

Test plan

• bun run --cwd packages/studio build:dev produces unminified output with .map files
• bun run --cwd packages/studio build still produces minified output without maps
• React dev-mode warnings appear in browser console with dev build

🤖 Generated with Claude Code

[miguel-heygen]

Clean approach — converting defineConfig to the function form for mode-conditional behavior is the right call. Source maps + no minification + React dev warnings for local builds will make debugging significantly easier.

One note: process.env.NODE_ENV define is only set for dev mode, which is correct — Vite already handles this for production builds via its default behavior.

File size check / Windows CI failures are pre-existing and unrelated to this change.

LGTM.

— Magi

[jrusso1020]

Verdict: COMMENT — clean dev-build addition; gated on hf#750 for CI green

Per Rule 5: pulled check_runs at 2f7fcbf3 — File size check is RED, same pre-existing 11-grandfathered-studio-files issue hf#750 is solving. None of this PR's 3 changed files are >500 LOC. Windows tests also red (pre-existing on main per the prior hf#750 review trail). All other required Linux checks green (Lint, Build, Test, Typecheck, CLI smoke, regression, preview-regression, Smoke: global install, Format, CodeQL).

Same disposition as hf#755 earlier today: code-level approvable, practically blocked behind hf#750.

Audited

All 3 files end-to-end. Mechanic checks out:

• vite.config.ts — refactor from object-form defineConfig({...}) to function-form defineConfig(({ mode }) => ({...})). Conditional spread ...(isDev && { define: {...} }) cleanly avoids leaking the define block into production. Production build retains default sourcemap: false + minify: true (the minify: !isDev evaluates to true in non-dev mode). No sourceMappingURL leak risk in deployed assets. ✓

• package.json — adds "build:dev": "vite build --mode development". Single line. ✓

• CLAUDE.md — adds a "Studio Build" subsection with build:dev as the local default, production build as GHA-only, plus a post-build copy command. Reasonable workflow guidance.

One observation (non-blocking)

The dev build's process.env.NODE_ENV = "development" is set via define, which means React picks up dev-mode warnings at runtime. Worth verifying that the studio code doesn't have any branches keyed off process.env.NODE_ENV that change behavior beyond "show extra warnings" — e.g., enabling expensive dev-only invariant checks. Probably fine but worth a quick grep "process.env.NODE_ENV" packages/studio/src to confirm no surprises hidden behind dev-mode conditionals.

Why COMMENT, not APPROVE

The File size check is failing because the studio package still has 11 pre-existing >500 LOC files (the hf#750 allowlist hasn't merged yet). This PR doesn't touch any of those files — the failure is environmental, not introduced here. Once hf#750 lands → rebase → File size check goes green → clean APPROVE.

If hf#750 doesn't merge soon, the alternative is a cherry-pick of its .filesize-allowlist onto this branch. But the cleaner path is just to wait.

Review by Rames Jusso (pr-review)