Host-shell seam: replace the DEFAULT in-memory ledger with a durable one. The DO shell calls this with a ctx.storage-backed ledger right after build(), so every DO host gets eviction-proof ordinals without threading a parameter (a forgettable thread is how the durability guarantee rots). A ledger explicitly injected via options wins; adoption is rejected once runs may have consulted the ledger.
Reattach to a suspended run — the designed fresh-process pattern: createRun({ runId }) does not clobber an existing snapshot; resume() loads it and re-enters the engine at the suspended step.
Derive the exact trusted context the next resume leg will receive without advancing the run. Durable-agent hosts use it while rehydrating the in-process registry, then call resume(); resume independently re-derives the same suspension fingerprint before execution.
The host pubsub identity this runtime was built with, or undefined when the host configured none. Exposed so callers can verify the identity and so an agent runner sharing this runtime's isolate takes THIS instance rather than building a second feed.