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/specify Command

specify

Create formal specification for a component or behavior using TLA+, SysML, or state machines. Use for safety-critical systems.

SKILL.md

Full skill instructions

/​specify Command

Create formal specifications for system components, behaviors, and algorithms.

Usage

/​specify "distributed lock protocol"
/​specify "order lifecycle" format=state-machine
/​specify "vehicle control system" format=sysml
/​specify "consensus algorithm" format=tla+

Workflow

Step 1: Analyze Topic

Parse the specification topic and determine:

  • What is being specified (protocol, lifecycle, system, algorithm)
  • Key properties to capture (safety, liveness, structure)
  • Appropriate formalism to use

Step 2: Select Specification Format

If format not specified, auto-detect based on topic:

Topic PatternRecommended Format
"protocol", "consensus", "distributed"TLA+
"lifecycle", "status", "workflow"State Machine
"system", "hardware", "embedded"SysML
"interaction", "flow", "sequence"UML

Step 3: Invoke Appropriate Skill

Load the relevant skill:

  • tla-specification for TLA+ specs
  • state-machine-design for state machines
  • sysml-modeling for SysML models
  • uml-modeling for UML diagrams

Step 4: Gather Requirements

If working in a project with specifications:

  • Search for related requirements in docs/​requirements/
  • Check for existing domain models
  • Look for related ADRs

Step 5: Generate Specification

Create the formal specification including:

  • Core specification (TLA+ module, SysML diagram, state machine)
  • Documentation and comments
  • Verification approach (if applicable)
  • Implementation guidance

Step 6: Output Result

Deliver:

  1. Specification in chosen format
  2. Diagram visualization (PlantUML/​Mermaid)
  3. Key properties documented
  4. Usage notes

Format-Specific Output

TLA+

--------------------------- MODULE TopicName ---------------------------
EXTENDS Integers, Sequences
CONSTANTS ...
VARIABLES ...
Init == ...
Next == ...
Spec == Init /\ [][Next]_vars
Safety == ...
Liveness == ...
=============================================================================

State Machine

@startuml
[*] --> Initial
Initial --> Active : trigger
Active --> Completed : complete
Completed --> [*]
@enduml

SysML

@startuml
class "<<block>>\nSystemName" as System {
  values
  --
  parts
  --
  operations
}
@enduml

Examples

Distributed Lock

/​specify "distributed lock with leader election" format=tla+

Output: TLA+ module with mutual exclusion safety property and eventual grant liveness property.

Order Lifecycle

/​specify "e-commerce order lifecycle"

Output: State machine diagram showing Draft → Submitted → Paid → Shipped → Delivered states with transitions and guards.

Vehicle System

/​specify "autonomous vehicle perception system" format=sysml

Output: SysML BDD showing sensors, processors, and data flows with parametric constraints.

Integration

The command integrates with:

  • enterprise-architecture: Links to ADRs
  • requirements-elicitation: Traces to requirements
  • systems-design: Aligns with architecture