PointInTimeAccessor

In one line: a thread-safe, frozen current snapshot fanned across worker threads — a lock-free read engine far lighter than a Transaction.

Built for concurrent reads. One call allocates a single TSN; each worker thread then gets its own EntityAccessor from a flat per-worker array (GetWorkerAccessor(workerId)) — no dictionary, no per-entity locking — and every worker reads the same consistent moment. N threads scan the snapshot in parallel with zero coordination between them; the shared snapshot is immutable, so there is nothing to lock.

Lighter than a Transaction because it carries only the mechanics to read, not to mutate. A Transaction must haul write-staging, a local write cache, commit-time conflict detection, an undo log for Rollback, and the WAL/commit path. A PointInTimeAccessor holds none of that — just a TSN plus one read cursor per worker, reused across ticks with zero allocation after warmup (warm page caches preserved). It reads every storage mode (walking the revision chain for Versioned) and can still store SingleVersion/Transient in place, but it cannot Spawn, Destroy, Commit, Rollback, or write Versioned (throws). For anything structural or transactional, use a Transaction.

⚠️ The name is about parallelism, not time travel. "Point in time" = one fixed current snapshot shared by all workers — it does not read historical/past versions (Typhon has no user-facing as-of-past read API). It is snapshot isolation, fanned across threads.

How it relates

• Snapshot isolation — it is a snapshot; every worker shares one TSN.
• Transaction — the heavier alternative when you need structural changes or Versioned writes; it carries the full staging/commit/rollback machinery this accessor omits.
• The tick — the runtime creates one per parallel system, reused each tick.
• Storage mode — reads all three; writes only the non-Versioned ones.

In the API

• PointInTimeAccessor — Create(dbe, workerCount), GetWorkerAccessor(i), TSN.
• EntityRef — Read<T> / Write<T> through a worker accessor.

Learn & use

• Narrative: Guide ch.5 — parallel reads · ch.4 §5
• Reference: Isolation & durability cheat sheet — naming traps