fix(cloudflare): ignore unchanged env watch events

[shawnsw]

Summary

• ignore fs.watch() events in varlock-wrangler dev when the resolved env graph is unchanged
• prevent restart loops caused by spurious env file watch events on macOS
• keep Wrangler restarts limited to real env changes

Repro

On macOS, varlock-wrangler dev can receive repeated fs.watch() events for env source files even when their contents have not changed.

In our case this showed up under portless as repeated events for apps/api/.env.schema, causing varlock-wrangler to restart Wrangler in a loop.

Root cause

varlock-wrangler dev currently restarts Wrangler on every watched env file event after re-resolving env.

That assumes every watch event represents a semantic env change, which is not always true on macOS.

Fix

Cache the last resolved serialized env graph and compare it after each watch event.

Only restart Wrangler when the newly resolved env graph differs from the previous one.

Why this is safe

This does not change how env is resolved.

It only skips restarts when the resolved env output is identical, so real env changes still trigger the existing restart path.

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[theoephraim]

Thanks!

[theoephraim]

@shawnsw - I am having a hard time recreating the issue locally. Can you give repro steps?

[shawnsw]

@theoephraim On macOS, fs.watch() can emit repeated events for watched env files even when the resolved env graph is unchanged. If varlock-wrangler dev restarts on every watch event, it can loop.

That also explains why you may not reproduce it locally: if your machine does not emit those extra events, the loop does not happen.

The fix is harmless: re-resolve env on each watch event, compare the serialized resolved graph, and only restart when it actually changed. Real env changes still restart Wrangler.

Repro:

1. Run varlock-wrangler dev on macOS.
2. Watch env inputs like .env.schema / .env.local.
3. Trigger repeated watch events without a semantic env change. (see script below)
4. Observe repeated restarts

for i in {1..5}; do
  python3 - <<'PY'
from pathlib import Path
p = Path(".env.schema")
data = p.read_text()
p.write_text(data)
PY
  sleep 1
done

[theoephraim]

Rolled this into #635 - should be out shortly.

Thanks!!