# L2 backend registry

This directory registers external knowledge backends that may seed or support `L2`.

It is not a canonical object family.
It is an internal bridge surface for:
- human note libraries,
- software repositories,
- local docs stores,
- result stores.

Use:
- `backend_index.jsonl` as the compact registry
- one `*.json` file per backend as the detailed card
- `backend.template.json` as the generic authoring template
- `examples/` for public example cards that demonstrate recommended patterns

Public starter pack for formal-theory backends:
- `FORMAL_THEORY_BACKEND_STARTER.md`
- `examples/formal-theory-note-library.example.json`
- `../../runtime/scripts/run_formal_theory_backend_smoke.sh`

Public paired-backend docs for the theoretical-physics knowledge network:
- `THEORETICAL_PHYSICS_BACKEND_PAIRING.md`
- `THEORETICAL_PHYSICS_PAIRED_BACKEND_CONTRACT.md`
- `theoretical-physics-brain.json`
- `theoretical-physics-knowledge-network.json`

When both backend cards are active in a clone, treat them as two governed
downstream implementations of the same formal-theory knowledge network:
- `theoretical-physics-brain.json`: operator-facing human-readable notes
- `theoretical-physics-knowledge-network.json`: machine-primary typed
  structured companion

Public starter pack for toy-model numeric backends:
- `TOY_MODEL_NUMERIC_BACKEND_STARTER.md`
- `examples/toy-model-numeric-workspace.example.json`
- `../../validation/tools/tfim_exact_diagonalization.py`
- `../../runtime/scripts/run_toy_model_numeric_backend_smoke.sh`

Do not store promoted canonical units here.
Store only backend descriptions and routing rules.
