Execution Fabric

How It Gets Done.

The Execution Fabric is the set of capabilities that actually perform work in external systems. It is the "hands" of SpineWorkspace — the layer that translates approved decisions into real-world actions.

Design Principles

1. Governed execution — Nothing executes without a governance token
2. Observable — Every action is traced and auditable
3. Reversible — Actions can be rolled back or compensated
4. Resilient — Retries, circuit breakers, graceful degradation
5. Cost-aware — Execution costs are tracked and budgeted

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Execution Components

Component	Purpose
APIs & Services	Direct API calls to external systems
MCP / Tools	Model Context Protocol tool invocations
Workflows	Multi-step process execution
Hermes	Execution service for complex actions
Functions / Workers	Serverless compute execution
External Integrations	Third-party service calls

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Execution Flow

Approved Action → Execution Token → Routing → Adapter → External System → Receipt → Reconciliation

1. Approved Action — An action approved by governance
2. Execution Token — Unique token for this execution
3. Routing — Select the right execution path
4. Adapter — Translate to target system format
5. External System — Execute in the target system
6. Receipt — Capture execution result
7. Reconciliation — Verify outcome, feed to Spine

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Execution Token

Every execution requires a unique token:

interface ExecutionToken {
  id: string;
  tenantId: string;
  workItemRef: string;
  action: ActionDef;
  approvedBy: ActorRef;
  approvedAt: string;
  expiresAt: string;
  constraints: Constraint[];
  budget: CostBudget;
}

Token Rules

• Tokens are single-use
• Tokens expire after a configurable TTL
• Tokens are scoped to a specific action
• Tokens cannot be reused or transferred
• Invalid or expired tokens reject execution

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MCP / Tools

The Model Context Protocol provides a standard interface for tool invocation:

Tool Category	Examples
Data Operations	Read, write, query, transform
Communication	Send message, schedule meeting
File Operations	Create, update, share document
Workflow	Start process, advance stage
Integration	Call external API, sync data

MCP Tool Contract

interface MCPTool {
  id: string;
  name: string;
  description: string;
  inputSchema: JSONSchema;
  outputSchema: JSONSchema;
  permissions: Permission[];
  cost: CostEstimate;
  
  execute(input: unknown, context: ExecutionContext): Promise<ToolResult>;
}

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Hermes (Execution Service)

Hermes is the primary execution service for complex actions:

Capability	Description
Multi-step execution	Execute chains of dependent actions
Parallel execution	Execute independent actions simultaneously
Compensation	Rollback or compensate on failure
Timeout handling	Graceful handling of slow operations
Idempotency	Safe retry of failed executions

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Functions / Workers

Serverless compute for custom execution logic:

Use Case	Implementation
Custom transforms	Data transformation functions
Validation	Custom validation rules
Enrichment	Data enrichment from multiple sources
Aggregation	Combine data from multiple systems
Notification	Custom notification logic

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Execution Monitoring

Metric	Description
Execution count	Total executions per time period
Success rate	Percentage of successful executions
Average latency	Time from token to receipt
Error rate	Percentage of failed executions
Cost per execution	Token and compute costs
External system health	Health of connected systems

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Governance

Rule	Description
Token required	No execution without a valid token
Scope limited	Token scoped to specific action
Time limited	Token expires after TTL
Budget limited	Execution cost tracked and limited
Audit logged	Every execution is audited
Rollback capable	Actions can be compensated