flue dev needs configurable watcher ignores for generated project directories

[kalepail]

Summary

flue dev recursively watches the project root and filters only a small built-in set of paths after events arrive:

• build output directory (dist by default);
• node_modules;
• dotfiles / dot-directories, except selected .flue;
• editor backup/swap files.

There does not appear to be a documented way to add project-specific ignored directories, and the watcher does not appear to consult .gitignore.

That means generated non-dot directories such as evals/results, local benchmark output, snapshots, reports, coverage-like custom folders, or tool-generated artifacts can be tracked by flue dev even when they are intentionally ignored by Git.

Why this matters

In downstream testing, an eval harness writes result files under:

evals/results/

That directory is ignored in .gitignore, but it is still under the Flue project root. Because flue dev watches the root recursively, writes under that directory can be seen as project changes and can trigger rebuild/restart churn.

This is a separate issue from #314:

• flue dev crashes with EMFILE when system hits file watcher limits #314 is about flue dev failing to start when the parent config watcher hits EMFILE / ENOSPC.
• This issue is about normal project watching having no user-configurable ignore mechanism for generated directories that should not trigger rebuilds.

Expected behavior

Flue should let projects exclude generated paths from the dev watcher.

Possible approaches:

1. Add a watch.ignore / dev.ignore config option with glob patterns.
2. Honor .gitignore for root-relative paths, perhaps with Flue’s required internal paths re-included.
3. Add a documented CLI flag such as --ignore <glob> that can be repeated.

Any of these would be better than requiring app-specific patching of Flue's generated CLI bundle.

Current downstream workaround

We patched the installed CLI to ignore one project-specific path:

const EVAL_RESULTS_WATCH_IGNORE = "evals/results";
if (normalized === EVAL_RESULTS_WATCH_IGNORE || normalized.startsWith(`${EVAL_RESULTS_WATCH_IGNORE}/`)) return true;

That solved local rebuild churn for the eval harness, but it is not a general solution and should not be necessary for every project with generated output under the repo root.

Suggested scope

A focused upstream fix could live in packages/cli/src/lib/dev.ts around createWatcher() / isIgnoredPath():

• extend WatcherOptions with additional ignore globs or paths;
• derive those from flue.config.*, CLI args, and/or .gitignore;
• add tests that writing under an ignored generated directory does not call onChange.

This should be independent from the config watcher fallback in #314.

[FredKSchott]

Resolved with a Vite-native approach: flue dev now uses its existing Vite server watchers instead of a separate recursive project watcher, and flue.config.* accepts an optional named export for native configuration. Thanks @kalepail for identifying the generated-directory rebuild churn.

[FredKSchott]

Correction: flue dev now uses its existing Vite server watchers instead of a separate recursive project watcher, and flue.config.* accepts an optional named vite export for native server.watch.ignored configuration.