Capkin State Machine Principle

Capkin is not generic prose and not just a test notation. It is a Gherkin-compatible protocol DSL where every accepted phrase maps into CAP primitives.

Machine
Principal
Capability
State
Input
Guard
Transition
Output
Commitment
Trace

The core shape:

State + Input + Capability + GuardSet -> State' + Output

Capkin adds readable declarations:

Background:
  Given machine ComplianceGatedSwap
  And principal DEX
  And principal Compliance
  And capability DEX may commit SwapInput
  And capability Compliance may evaluate SwapInput

Scenario: CAPKIN-PROTOCOL-001
  Given DEX commits SwapInput
  When Compliance evaluates guard KycAndRiskPolicy
  Then the machine transitions from Requested to Approved

Compiler validation is the boundary between documentation and executable contract. If a line cannot be validated, it is not Capkin.

The principle:

Gherkin gives the scenario shell.
Capkin gives typed protocol meaning.
CAP gives deterministic execution and proof.

This lets non-crypto teams describe behavior without knowing protobuf, Rust, chains, commitments or verifier internals. Domain extensions can add DEX, compliance, DAO, payment or VASP vocabulary without changing the CAP core.

Capkin State Machine Principle

Capkin State Machine Principle

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