perf(terminal): avoid rescanning cold restore payloads

src/main/daemon/cold-restore-payload-cache.test.ts

@@ -10,6 +10,15 @@ function payload(scrollback: string): ColdRestorePayload {
 }
 
 describe('ColdRestorePayloadCache', () => {
+  it('counts retained strings by UTF-16 code units', () => {
+    expect(
+      getColdRestorePayloadBytes({
+        ...payload('😀'),
+        oscLinks: [{ row: 0, startCol: 0, endCol: 1, uri: 'é' }]
+      })
+    ).toBe(54)
+  })
+
   it('evicts least-recently-used payloads to stay under its byte bound', () => {
     const first = payload('a'.repeat(100))
     const second = payload('b'.repeat(100))

src/main/daemon/cold-restore-payload-cache.ts

@@ -13,8 +13,9 @@ export const MAX_COLD_RESTORE_CACHE_BYTES = 16 * 1024 * 1024
 
 export function getColdRestorePayloadBytes(payload: ColdRestorePayload): number {
   const oscLinkBytes =
-    payload.oscLinks?.reduce((bytes, link) => bytes + Buffer.byteLength(link.uri) + 24, 0) ?? 0
-  return Buffer.byteLength(payload.scrollback) + Buffer.byteLength(payload.cwd) + oscLinkBytes + 16
+    payload.oscLinks?.reduce((bytes, link) => bytes + link.uri.length * 2 + 24, 0) ?? 0
+  // Why: code-unit sizing bounds V8 string storage without rescanning or flattening multi-MB ropes.
+  return payload.scrollback.length * 2 + payload.cwd.length * 2 + oscLinkBytes + 16
 }
 
 export class ColdRestorePayloadCache {