# eredu-core
`eredu-core` provides backend-neutral contracts and orchestration for
language-model runtimes. It has no dependency on a concrete accelerator
runtime.
Most applications should use [`eredu`](https://github.com/jbg/eredu/tree/main/eredu). Use this crate
directly when implementing an execution backend or reusing its portable
planning and scheduling components.
## What the crate provides
- The canonical in-memory content-exact artifact identity and logical-member
combining algorithm, plus artifact inspection, resolved model configuration,
tensor catalogs, and preparation plans for SafeTensors and GGUF checkpoints.
- Whole-model backend, session, prefill, decode, completion, capability, and
optional distributed contracts.
- Generation, cancellation, speculative decoding, realtime scheduling, and
transactional request state machines.
- Attention schedules, parallel topology, execution plans, mechanism-capability
admission, reusable inspection reports, and telemetry schemas.
- Weight and cache residency policy, budgets, accounting schemas, eviction
rules, and transfer contracts.
- Portable decoded media descriptions and ordered multimodal requests.
Backend contracts operate on associated opaque types. Implementations retain
their own tensors, queues, executables, caches, samplers, and completion
objects; core coordinates complete model/session operations rather than
defining a tensor algebra.
## Execution model
A backend prepares a model and consumes it to create one stateful session.
`ModelRuntime<B>` owns that backend and session, and submits prefill and decode
work through the same interface for every implementation. Exact completion
objects keep outputs and transactional resources alive until the submitted work
is safe to observe or release.
`SessionAuthority` issues move-only leases for unresolved submissions. Backends
retain them until exact completion or safe teardown; idle guards protect every
state mutation. `SessionAdmission` validates the complete realized capability
report against the report admitted before materialization.
`ModelRuntime` retains that admission and revalidates generic operations after
backend-specific mutable access. Unrestricted session mutation invalidates any
retained execution-plan target proof, preventing stale drafting attachment.
Capabilities fail closed. Optional facilities such as multimodal preparation,
speculative decoding, realtime execution, transfers, and collectives are
separate contracts attached to the selected backend or session.
See the [backend architecture guide](https://github.com/jbg/eredu/blob/main/doc/backend-architecture.md) for the
ownership rules and backend implementation checklist.
## License
Licensed under either Apache-2.0 or MIT.