fix(cli): hide console window for detached child processes on Windows

[dajiaohuang]

What

Add windowsHide: true to the three detached: true spawns in packages/cli that were missing it, so they stop opening a console window on Windows.

File	Spawn
src/telemetry/transport.ts (flushSync)	exit-time telemetry flush → PostHog
src/utils/openBrowser.ts (openBrowser)	--browser-path browser launch
src/commands/previewLifecycle.ts (spawnDetachedPreview)	background preview server

Why

Closes #3476. child_process.spawn() defaults windowsHide to false, and Node's docs state that on Windows a detached: true child has its own console window. So all three sites flash a console window at the user on every invocation.

flushSync() is the worst of the three: it is the process-exit flush path, so it fires on nearly every short-lived command (check, lint, keyframes, capture, snapshot, preview) that exits with queued events — not just renders.

src/utils/autoUpdate.ts already passes windowsHide: true, so the intent was clearly there and the other three were oversights rather than a deliberate difference.

How

Three one-line option additions. windowsHide is a documented no-op on macOS and Linux, so this is inert off Windows — same rationale as the #3379 ffmpeg fix.

One supporting type change: spawnDetachedPreview builds its options object as an object literal and passes it to the SpawnPreview-typed dependencies.spawn. TypeScript's excess-property check rejects a key that is not on that type, so SpawnPreview's options parameter gains windowsHide: boolean.

Not in scope, deliberately:

• [Windows] chrome-headless-shell.exe opens a visible console window on every render #3430 (chrome-headless-shell) and the non-CLI spawns — different class of defect (console-subsystem binaries), tracked separately.
• The shared spawn helper + lint rule suggested at the end of [Windows] Three detached: true spawns missing windowsHide — telemetry flushSync opens a console window on nearly every CLI exit #3476. That is an architecture change and belongs in its own PR.

Tests: the two existing spawn-asserting tests are extended (telemetry/client.test.ts, commands/previewLifecycle.test.ts), and utils/openBrowser.windowsHide.test.ts is added. That last one goes in its own file rather than into openBrowser.test.ts to follow the repo's existing *.windowsHide.test.ts convention (7 such files, incl. orphanCleanup.windowsHide.test.ts next door) — openBrowser.test.ts otherwise holds only pure-function tests and never mocks spawn.

Test plan

• Unit tests added/updated
• Manual testing performed
• Documentation updated (if applicable)

The three touched test files pass in full (36/36):

bunx vitest run src/telemetry/client.test.ts \
  src/commands/previewLifecycle.test.ts \
  src/utils/openBrowser.windowsHide.test.ts

Reverting the three one-line changes makes exactly the three new assertions fail and nothing else, so the tests genuinely pin the fix rather than passing vacuously.

Also run on the changed files: oxlint (0 warnings, 0 errors), oxfmt --check (clean), git diff --check (clean), and the repo's own pre-commit suite (tracked-artifacts, largefiles, lint, format, fallow, typecheck) via git commit.

Two caveats, stated plainly:

• No manual Windows verification. I have no Windows desktop session to watch for the flashing window, so the fix rests on the documented windowsHide/detached semantics quoted in the issue — which is also how the issue itself was diagnosed. Someone on Windows confirming the window is gone would be worth more than my static reasoning.
• bun run --filter @hyperframes/cli test is not green, but not because of this change: 28 tests in 8 unrelated files (commands/init*, commands/cloud/render, registry/publication, tts/synthesize.cache, utils/projectConfig.create, utils/skillsMirror, capture/scaffolding) fail identically with and without this patch — I checked out the base commit and reproduced the same 28 failures. They look environment-related rather than code-related.

One note on the branch: it is based on e5d89f77 rather than the current tip of main. The patch is byte-identical either way (none of these six files changed in between) and it merges cleanly, but I am happy to rebase if you would rather review it against the tip.

🤖 Generated with Claude Code

[miguel-heygen]

@dajiaohuang sign the commits pls