[!FROZEN] MPLP Protocol v1.0.0 Frozen Specification Freeze Date: 2025-12-03 Status: FROZEN (no breaking changes permitted) Governance: MPLP Protocol Governance Committee (MPGC) License: Apache-2.0 Note: Any normative change requires a new protocol version.

Single-Agent (SA) Profile

1. Purpose

The Single-Agent (SA) Profile is the baseline execution mode for MPLP. It defines the minimal set of modules, invariants, and events required to run a single autonomous agent within a project context.

Design Principle: "One agent, one context, one plan complete traceability"

2. Profile Classification

Attribute	Value
Profile ID	mplp:profile:sa:1.0.0
Requirement Level	REQUIRED (base profile)
Extends	(base)
Extended By	MAP Profile

3. Required Modules

All SA-compliant runtimes MUST implement:

Module	Requirement	Usage
Context	REQUIRED	Environment and constraints
Plan	REQUIRED	Task decomposition
Trace	REQUIRED	Execution audit trail
Role	REQUIRED	Agent identity
Core	REQUIRED	Protocol manifest

Optional modules:

Module	Recommendation	Usage
Confirm	RECOMMENDED	User approval
Dialog	OPTIONAL	User conversation
Extension	OPTIONAL	Plugin system

4. Invariants

From: schemas/v2/invariants/sa-invariants.yaml

4.1 Context Binding

ID	Rule	Description
sa_requires_context	context_id is UUID v4	SA requires valid Context
sa_context_must_be_active	status == 'active'	Context must be active

4.2 Plan Integrity

ID	Rule	Description
sa_plan_context_binding	plan.context_id == context.context_id	Plan bound to Context
sa_plan_has_steps	steps.length >= 1	At least one step
sa_steps_have_valid_ids	steps[*].step_id is UUID v4	Valid step IDs
sa_steps_have_agent_role	steps[*].agent_role non-empty	Role specified

4.3 Traceability

ID	Rule	Description
sa_trace_not_empty	events.length >= 1	At least one event
sa_trace_context_binding	trace.context_id == context.context_id	Trace bound to Context
sa_trace_plan_binding	trace.plan_id == plan.plan_id	Trace bound to Plan

4.4 Validation Code

function validateSAProfile(sa: SARuntime): ValidationResult {
  const errors: string[] = [];
  
  // Context binding
  if (!sa.context?.context_id) {
    errors.push('sa_requires_context: Missing context_id');
  }
  if (sa.context?.status !== 'active') {
    errors.push('sa_context_must_be_active: Context not active');
  }
  
  // Plan binding
  if (sa.plan?.context_id !== sa.context?.context_id) {
    errors.push('sa_plan_context_binding: Plan not bound to Context');
  }
  if (!sa.plan?.steps?.length) {
    errors.push('sa_plan_has_steps: Plan has no steps');
  }
  
  // Step validation
  for (const step of sa.plan?.steps || []) {
    if (!step.agent_role) {
      errors.push(`sa_steps_have_agent_role: Step ${step.step_id} missing role`);
    }
  }
  
  return { valid: errors.length === 0, errors };
}

5. Execution Lifecycle

5.1 State Machine

5.2 Phase Descriptions

Phase	Description	Events Emitted
Initialize	Boot agent runtime	SAInitialized
LoadContext	Validate and bind Context	SAContextLoaded
EvaluatePlan	Parse and validate Plan	SAPlanEvaluated
ExecuteStep	Run step (LLM, tool)	SAStepStarted, SAStepCompleted
EmitTrace	Persist to PSG	SATraceEmitted
Complete	Finalize	SACompleted

5.3 Sequence Diagram

6. Mandatory Events

From: schemas/v2/events/mplp-sa-event.schema.json

6.1 Event Table

Phase	Event Type	Required Fields
Initialize	SAInitialized	sa_id, timestamp
LoadContext	SAContextLoaded	sa_id, context_id
EvaluatePlan	SAPlanEvaluated	sa_id, plan_id, step_count
ExecuteStep	SAStepStarted	sa_id, step_id, agent_role
ExecuteStep	SAStepCompleted	sa_id, step_id, status, duration_ms
EmitTrace	SATraceEmitted	sa_id, trace_id, events_written
Complete	SACompleted	sa_id, status, total_duration_ms

6.2 Recommended Events

Scenario	Event Type	Rationale
Step failure	SAStepFailed	Debug and retry logic
Token usage	CostAndBudgetEvent	Cost tracking
Tool invocation	ToolExecutionEvent	Tool audit

6.3 Event Examples

SAStepCompleted:

{
  "event_type": "SAStepCompleted",
  "event_family": "RuntimeExecutionEvent",
  "sa_id": "sa-550e8400-e29b-41d4-a716-446655440000",
  "timestamp": "2025-12-07T00:00:05.000Z",
  "payload": {
    "step_id": "step-123",
    "agent_role": "coder",
    "status": "completed",
    "duration_ms": 1500,
    "tokens_used": 450
  }
}

SACompleted:

{
  "event_type": "SACompleted",
  "event_family": "RuntimeExecutionEvent",
  "sa_id": "sa-550e8400-e29b-41d4-a716-446655440000",
  "timestamp": "2025-12-07T00:05:00.000Z",
  "payload": {
    "status": "completed",
    "plan_id": "plan-123",
    "steps_executed": 5,
    "steps_succeeded": 5,
    "steps_failed": 0,
    "total_duration_ms": 30000
  }
}

7. Module Interactions

7.1 Data Flow

Context > Plan > Trace    
     owner_role          agent_role   segments   
         > Role <?

7.2 Module Binding Table

From	Field	To	Constraint
Plan	context_id	Context	MUST match
Trace	context_id	Context	MUST match
Trace	plan_id	Plan	MUST match
Plan.Step	agent_role	Role	MUST exist
Context	owner_role	Role	SHOULD exist

8. Usage Scenarios

8.1 Code Refactoring

Context: "Refactor auth service" 
     Plan: "Fix login bug" 
             Step 1: "Read error logs" (agent_role: debugger)
             Step 2: "Identify root cause" (agent_role: debugger)
             Step 3: "Write fix" (agent_role: coder)
             Step 4: "Test fix" (agent_role: tester)

8.2 Data Analysis

Context: "Quarterly report analysis" 
     Plan: "Generate Q4 report" 
             Step 1: "Query database" (agent_role: analyst)
             Step 2: "Process data" (agent_role: analyst)
             Step 3: "Create visualizations" (agent_role: reporter)

9. SDK Examples

9.1 TypeScript

interface SARuntime {
  sa_id: string;
  context: Context;
  plan: Plan;
  trace: Trace;
  status: 'initializing' | 'running' | 'completed' | 'failed';
}

async function runSAProfile(context_id: string, plan_id: string): Promise<void> {
  const sa: SARuntime = {
    sa_id: uuidv4(),
    context: await loadContext(context_id),
    plan: await loadPlan(plan_id),
    trace: createTrace(context_id, plan_id),
    status: 'initializing'
  };
  
  // Validate SA invariants
  const validation = validateSAProfile(sa);
  if (!validation.valid) {
    throw new Error(`SA validation failed: ${validation.errors.join(', ')}`);
  }
  
  // Emit initialization events
  await emit({ event_type: 'SAInitialized', sa_id: sa.sa_id });
  await emit({ event_type: 'SAContextLoaded', sa_id: sa.sa_id, context_id });
  await emit({ event_type: 'SAPlanEvaluated', sa_id: sa.sa_id, plan_id });
  
  sa.status = 'running';
  
  // Execute steps
  for (const step of sa.plan.steps) {
    await emit({ event_type: 'SAStepStarted', sa_id: sa.sa_id, step_id: step.step_id });
    
    try {
      await executeStep(step);
      await emit({ event_type: 'SAStepCompleted', sa_id: sa.sa_id, step_id: step.step_id, status: 'completed' });
    } catch (error) {
      await emit({ event_type: 'SAStepFailed', sa_id: sa.sa_id, step_id: step.step_id, error: error.message });
      throw error;
    }
  }
  
  // Complete
  sa.status = 'completed';
  await emit({ event_type: 'SACompleted', sa_id: sa.sa_id, status: 'completed' });
}

10. Related Documents

Architecture:

• L1 Core Protocol
• Orchestration

Profiles:

• MAP Profile - Multi-agent extension
• SA Events - Event details

Invariants:

• schemas/v2/invariants/sa-invariants.yaml

---

Document Status: Normative (Core Profile)
Profile ID: mplp:profile:sa:1.0.0
Required Modules: Context, Plan, Trace, Role, Core
Invariant Count: 9 normative rules
Event Count: 7 mandatory event types

2025 Bangshi Beijing Network Technology Limited Company Licensed under the Apache License, Version 2.0.