@remotion/studio: Reload config changes in Studio

[JonnyBurger]

Summary

• Watch the loaded Remotion config file from Studio.
• Reset config option state before reloading the config file.
• Trigger a Studio page reload after config reload and add reset coverage.

Stack

• Depends on @remotion/studio: Use runtime Studio config #9022.

Test plan

• bunx turbo run make --filter='@remotion/renderer' --filter='@remotion/studio-shared' --filter='@remotion/studio' --filter='@remotion/studio-server' --filter='@remotion/cli'
• bunx turbo run formatting --filter='@remotion/renderer' --filter='@remotion/studio-shared' --filter='@remotion/studio' --filter='@remotion/studio-server' --filter='@remotion/cli'
• bunx turbo run lint --filter='@remotion/renderer' --filter='@remotion/studio-shared' --filter='@remotion/studio' --filter='@remotion/studio-server' --filter='@remotion/cli'
• bun test packages/cli/src/test/config-reset.test.ts

Closes #9011

Public dir hot-reload remains tracked separately in #9015.

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Project	Deployment	Actions	Updated (UTC)
bugs	Ready	Preview, Comment	Jul 20, 2026 10:34am
remotion	Ready	Preview, Comment	Jul 20, 2026 10:34am

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Important

Two issues to address before merging: the reset defaults are duplicated from each option module and will drift, and a failed config reload currently resets live state before failing.

Reviewed changes — Adds a file watcher for the loaded Remotion config file, resets all mutable config options to defaults before re-evaluating the config, and triggers a Studio page reload via a new config-file-changed event.

• Reset helpers for CLI-only option stores plus a reset() method on the four override options.
• Centralized config reset in ConfigInternals.resetConfigOptions() that restores every BrowserSafeApis.options value to its default before reloading.
• Watcher wiring in studioCommand that listens to the resolved config path and re-runs loadConfig on change.
• Studio client reload by adding config-file-changed to the EventSourceEvent union.
• Test coverage in packages/cli/src/test/config-reset.test.ts.

---

⚠️ Hardcoded reset defaults will drift

packages/cli/src/config/index.ts:155-230 — resetBrowserSafeConfigOptions() maintains a second copy of every option default. Future options or default changes can drift, leaving stale config across reloads.

Consider adding a defaultValue or reset() to RemotionOption and using it from each option module, or add a test asserting every BrowserSafeApis.options entry is covered.

⚠️ Reset happens before the reloaded config is known to be valid

packages/cli/src/studio.ts:98-100 — resetConfigOptions() runs before await loadConfig(remotionRoot). If loadConfig fails, Studio is left in a half-reset state. Also, loadConfigFile calls process.exit(1) for esbuild / missing-tsconfig / missing-output errors, so a typo in remotion.config.ts can terminate the long-running Studio process.

Consider snapshotting option state before resetting and restoring on failure, or validating/bundling the config first and only resetting once it is known to be evaluable.

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