Core Concepts
A Modality contract is three artifacts:
contract/
├── state/ # posted data (identities, evidence)
├── model/ # possible moves (labeled transition system)
└── rules/ # who / when / under what predicates
A commit is accepted only if it is signed as required, is a valid model transition, and satisfies every accumulated rule. No valid witness means the commit is rejected.
The rest of this guide names the pieces that make that check possible.
The Five Pillars
| Concept | Purpose |
|---|---|
| Append-only log | Immutable, ordered history |
| State machines | Finite, verifiable behaviors |
| Modal logic | Express temporal constraints |
| Predicates | Bind identity to logic |
| Potentialism | Safe accumulation of rules |
How They Fit Together
- A contract is an append-only log of signed commits
- Commits can add state, rules, or perform actions
- A model (labeled transition system) defines what actions are possible
- Rules (temporal formulas) constrain which evolutions are valid
- Predicates bind real-world identity (signatures) to logical constraints
- Potentialism ensures rules can only shrink the space of valid futures
On a network with a hash lane, a commit's hash can be ordered before its body is sent. The body is checked when it is revealed. See Hash Commitments.
A network's MOD can be the asset of one genesis contract, whose rules let only its emission program pay it out. See The MOD Contract.
Dive into each concept: