Slow directory watcher detection and ask/auto add to file_scan_exclusions

[glaudiston]

Body

What are you proposing?

I was having a bad time while using zed in a project repo that contains subrepo dependencies, between then the linux kernel cloned in a subdirectory. seems that the file watcher almost freezes my host that have 32 cores and 128G and a RTX-4090 GPU...

I found out that after excluding some big substructure folder tree the performance went back to normal.

Describe the feature, improvement, or change at a high level.

Why does this matter?

What problem does this solve?
High CPU usage slowing zed performance; and logs like

2026-04-10T08:54:28-03:00 ERROR [crates/fs/src/fs_watcher.rs:303] Error { kind: Io(Os { code: 22, kind: InvalidInput, message: "Invalid argument" }), paths: ["...some path .../linux/scripts/dtc/include-prefixes/riscv/andes"] }

What becomes easier or possible?
performe benchmark on the directory watch costs and if bypass a threshold considered acceptable, ask the user and create or add the ${project dir}/.zed/settings.json adding entries to the file_scan_exclusions

Are there any examples or context?

here my project .zed/settings.json

{
	"file_scan_exclusions": [
		"**/.git",
		"**/node_modules",
		"/os/linux",
		"/os/busybox",
		"**/*.gz",
		"**/*.qcow2",
	],
}

Screenshots, mockups, workflows, or examples from other tools.

Possible approach

If you have ideas about how this could work, share them here.