node:v8: modern diagnostics and profiler helper exports are missing from the ESM surface #3904

Summary

Perry's current node:v8 manifest omits several named exports that Node exposes in the ESM namespace. Code that imports modern V8 diagnostics/profiling helpers works in Node but fails Perry check before runtime.

Baseline: 22824ba90abf Expose globalThis.EventTarget (#3628).

This complements the existing focused issues for heap snapshot output (#3140), startup snapshots (#3141), and promise hooks (#3139). This issue is specifically about the missing public named exports and parity coverage for the remaining modern helper surface.

Current manifest gap

target/release/perry --print-api-manifest reports these node:v8 module exports today:

serialize
deserialize
getHeapStatistics
getHeapCodeStatistics
getHeapSpaceStatistics
cachedDataVersionTag
GCProfiler
Serializer
DefaultSerializer
Deserializer
DefaultDeserializer
startupSnapshot
promiseHooks
setFlagsFromString
takeCoverage
stopCoverage
setHeapSnapshotNearHeapLimit

Node v25.9.0 exposes additional named exports:

getCppHeapStatistics
getHeapSnapshot
isStringOneByteRepresentation
queryObjects
startCpuProfile
writeHeapSnapshot
default

getHeapSnapshot and writeHeapSnapshot overlap with #3140. The other helpers are not covered by the existing node:v8 issues found during triage.

Probe

import {
  getCppHeapStatistics,
  getHeapSnapshot,
  isStringOneByteRepresentation,
  queryObjects,
  startCpuProfile,
  writeHeapSnapshot,
} from "node:v8";

for (const [name, value] of [
  ["getCppHeapStatistics", getCppHeapStatistics],
  ["getHeapSnapshot", getHeapSnapshot],
  ["isStringOneByteRepresentation", isStringOneByteRepresentation],
  ["queryObjects", queryObjects],
  ["startCpuProfile", startCpuProfile],
  ["writeHeapSnapshot", writeHeapSnapshot],
] as const) {
  console.log(name, typeof value);
}

Node behavior

Node v25.9.0:

getCppHeapStatistics function
getHeapSnapshot function
isStringOneByteRepresentation function
queryObjects function
startCpuProfile function
writeHeapSnapshot function

Perry behavior

target/release/perry check tmp-v8-modern-export-probe.ts:

Checking 1 file(s)...
error[U006]: The requested module 'node:v8' does not provide an export named 'getCppHeapStatistics'
  --> /private/tmp/perry-node-compat-main/tmp-v8-modern-export-probe.ts:2:4
  |
2 |   getCppHeapStatistics,

Check failed: 1 error(s), 0 warning(s)
  |    ^^^^^^^^^^^^^^^^^^^^

Error: Check failed with errors

Suggested scope

• Add/track getCppHeapStatistics().
• Add/track isStringOneByteRepresentation(value).
• Add/track queryObjects(constructor[, options]).
• Add/track startCpuProfile([title]).
• Ensure the heap snapshot named exports are included in the manifest/export shape as part of node:v8: implement heap snapshot output #3140 or this cut.
• Add Node-vs-Perry parity fixtures that at minimum prove these names are importable and function-valued.

Acceptance

• Perry accepts named ESM imports for Node's current node:v8 helper tail listed above.
• Namespace shape matches Node for the covered names, including typeof and basic presence checks.
• For helpers implemented as stubs initially, the thrown error shape is intentionally tracked and does not masquerade as a missing export.
• getHeapSnapshot / writeHeapSnapshot export-shape work is coordinated with node:v8: implement heap snapshot output #3140 so the public names and runtime contracts converge together.
• Generated manifest/docs/DTS include the same supported public node:v8 exports.

No Test262 scope; this is Node API compatibility.