fix(node): count event bytes correctly so the size limits are enforced

[sarmah-rup]

What I hit

Sending server-side events with @segment/analytics-node, oversized events weren't being caught by the client's size guard, so they'd ship and the API would reject the whole batch. It turned out the 32 KB per-event and 480 KB batch limits were not being enforced at all.

Root cause

ContextBatch.calculateSize (packages/node/src/plugins/segmentio/context-batch.ts) is a broken copy of the well-known "count UTF-8 bytes" idiom encodeURI(str).split(/%..|./).length - 1:

encodeURI(JSON.stringify(ctx.event)).split(/%..|i/).length

The . (match any character) was mistyped as a literal i, and the trailing - 1 was dropped. So instead of counting bytes it counts %XX escapes plus the letter "i". A ~39 KB event measures as ~21, passes the 32 KB guard, and gets sent. This has been the case since batching was added in #640.

Fix

Restore the correct byte count:

-    return encodeURI(JSON.stringify(ctx.event)).split(/%..|i/).length
+    return encodeURI(JSON.stringify(ctx.event)).split(/%..|./).length - 1

After the fix, calculateSize equals Buffer.byteLength(json, 'utf8') across ASCII, multibyte, and URL-reserved inputs.

Test

Added packages/node/src/plugins/segmentio/__tests__/context-batch.test.ts: a ~39 KB event is now rejected ("Event exceeds maximum event size of 32 KB"), a small event is still accepted. Verified fail before / pass after (revert the regex and the size test fails). The existing 500 KB test is unaffected. Included a patch changeset for @segment/analytics-node.

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🦋 Changeset detected

Latest commit: a876f56

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@segment/analytics-node	Patch

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