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Nathan Colosimo d813fb8ee8 feat(core): deterministic sandbox hardening (#3045)
* feat(core): deterministic sandbox hardening

- crypto.subtle.digest computes synchronously via node:crypto:
  byte-identical values, promise settles on a deterministic microtask,
  full BufferSource validation (internal-slot view reads, SAB rejection)
- Atomics.waitAsync (a wall-clock timer), async WebAssembly compilation,
  WeakRef, and FinalizationRegistry are removed from the sandbox — wall
  clock and GC observation are unreplayable; sync WebAssembly
  constructors remain
- freezeSerializationIntrinsics pins the universal dispatch surfaces:
  Object.prototype/Array.prototype/Function.prototype are frozen (every
  missed property read and hasInstance lookup terminates there) and
  serialization-referenced global bindings are non-writable. Value-type
  prototypes and constructor statics stay patchable so polyfills
  (Temporal's Date.prototype.toTemporalInstant, core-js Set.prototype
  .union / Object.groupBy) keep working — the retained-input gate
  verifies the members serialization executes per boundary instead.

Groundwork for retained-VM replay (#2990).

* Drop serialization intrinsic freezing from the sandbox

The retained-VM passivity design moved from pinning/verifying the
sandbox surfaces serialization dispatches on to injecting hardened
operations into devalue itself (with taint-based de-opt), so freezing
Object/Array/Function prototypes and pinning global bindings is no
longer needed. Keep only the determinism hardening (sync digest,
removal of wall-clock/GC-observing APIs).

* Document and lock in why async crypto.subtle methods cannot break quiescence

The remaining async subtle methods reject immediately through the crypto
proxy (brand check — the receiver is not a real SubtleCrypto), so they can
never mint a host-timing promise. Narrow the quiescence comment to what the
code actually enforces and add a test so the unreachability is not silently
"fixed" later.

* simplify sandbox hardening: lean digest input conversion, async digest, explicit subtle throwers

* mark sandbox API removals as a major change

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Co-authored-by: Nathan Rajlich <n@n8.io>
2026-07-27 09:23:16 -07:00
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