feat: lazy declaration watchers and single-process workspace watch

[praveenpuglia]

Problem

lerna run build:watch in sc-fe-components starts one bite process per package (54), and each one eagerly built a full TypeScript watch program. Each program loads and watches every imported file, every auto-included @types/* package and sibling packages' dist/*.d.ts. For example, Accordion has 2 source files but its program loaded 646 files and 214 MB.

Change

On watch startup bite now:

1. Re-transpiles only sources whose output is missing or older than the source.
2. Starts the TypeScript watch program only when the package's declarations are stale or one of its files changes.

Idle packages cost only a chokidar watcher on src.

Measured on sc-fe-components (all packages, after a full build)

	Before	After
Memory (RSS)	~19 GB	~7 GB
inotify watches	~265k (machine limit 275k)	~25k
CPU time to start up	742 s	48 s

The first edit in a package pays for starting its program: ~2.9 s in components. After that, edits take ~0.4 s, the same as before.

Notes

• Outputs that look up to date aren't rebuilt when watch mode starts. After changing Babel or TS config, run a normal build. The README says so.
• CreateSmallcases and services use tsx-transform --clean --watch, which wipes dist and so always starts TypeScript at startup. Dropping --clean from those scripts lets them start lazily too.

Workspace mode (--watch --workspace)

Running all 57 per-package watchers with lerna run build:watch --parallel hit EMFILE: too many open files. Each Node process takes one inotify instance, and Linux allows 128 per user by default.

bite-tsx-transform --watch --workspace at the repo root watches every package whose build:watch runs bite, using that script's own arguments (e.g. --src=theming --dist=dist), from a single process. Stale declarations at startup are now generated once instead of keeping a TypeScript watch program alive, so dozens of packages can share the process. A package's watch program still starts on its first edit.

Measured on sc-fe-components with all 55 bite packages, idle:

	Process per package	--workspace
Processes	55	1
Memory (RSS)	~7 GB	~560 MB
inotify instances	55	1
Startup	n/a	4.3 s

Edit latency is unchanged: ~2.3 s for the first .d.ts in components, ~0.3 s after that. Each package edited stays loaded; with two edited it was ~1.1 GB.

Suggested root script in sc-fe-components: "build:watch": "bite-tsx-transform --watch --workspace".

Testing

• Existing suite passes (8 tests).
• New test: workspace mode watches two packages with different layouts in one process, skips a package whose build:watch isn't bite, and updates declarations in a --src=lib --dist=out package.
• New test: watch mode leaves an up-to-date output untouched, doesn't start TypeScript before an edit, and still updates the .d.ts after one. It fails on the previous code.

🤖 Generated with Claude Code

[Daggron]

LGTM!