§
🏗️
Agent Architecture
QUAD Agent Communication Architecture (QACA) - How agents talk to each other
The Single Gateway
All agent invocations go through the QUAD Agent Runtime (QAR). Whether triggered by IDE, CLI, Chat, or CI/CD - QAR enforces permissions and routes to the right agent.
💻
IDE
VSCode
⌨️
CLI
Terminal
💬
Chat
Claude
🔄
Auto
CI/CD
🔌
MCP
Desktop
↓
QUAD Agent Runtime (QAR)
🔒 Permission Checker
• Who is invoking?• Can they invoke?• Audit everything
📋
Orchestrator
Sequential
📡
Event Bus
Parallel
🗄️
Shared Context
State
↓
Agent Pool
Circle 1: MGMT
Story
Estimation
Circle 2: DEV
Dev UI
Dev API
Circle 3: QA
Test
Perf
Circle 4: INFRA
Deploy DEV
Deploy PROD
Three Communication Patterns
1
Sequential (Orchestrator)
For: Estimation Pipeline, Code Review Chain
Code Agent
→ code_score
→
DB Agent
→ db_score
→
Flow Agent
→ flow_score
→
Estimation
→ final_estimate
Output → Input chainingOrder enforcedEach agent waits
2
Parallel (Event Bus)
For: Development Phase (UI + API simultaneously)
📡 Story Assigned Event
↙
↘
🎨
Dev Agent UI
Components
Interfaces
UI Tests
⚙️
Dev Agent API
Controllers
Services
DTOs
↘
↙
✅ Both Complete Event
Run simultaneouslyAsync pub/subIndependent work
3
Hybrid (Stages)
For: Full Development Pipeline
STAGE 1: DEVPARALLEL
🎨Dev Agent UI
⚙️Dev Agent API
↓ wait for all
STAGE 2: TESTPARALLEL
🧪Test Agent UI
🔬Test Agent API
↓ wait for all
STAGE 3: REVIEWSEQUENTIAL
📝Review Agent
Stages are sequentialWithin stage: parallelBest of both
Permission System
Permission Levels
❌
Level 0: NONE
Cannot access
👁️
Level 1: READ
Read-only
💡
Level 2: SUGGEST
Can suggest, human OK
✏️
Level 3: WRITE
Can modify (audited)
👑
Level 4: ADMIN
Full access (rare)
Example: Dev Agent UI
src/ui/**✅ WRITE
src/components/**✅ WRITE
src/api/**👁️ READ
database/**❌ NONE
tests/ui/**💡 SUGGEST
🔒Critical Rule
No agent can invoke Deploy PROD directly!
Only humans can trigger production deployment.
Who Can Invoke Whom
| Agent | ✅ Can Invoke | ❌ Cannot |
|---|---|---|
| Story Agent | Estimation Agent | Deploy PROD |
| Dev Agent UI | Test AgentReview | Deploy PRODDev API |
| Dev Agent API | Test AgentReview | Deploy PRODDev UI |
| Test Agent | Review Agent | Deploy PROD |
| Deploy DEV | (terminal agent) | Deploy PROD |
| Deploy PROD | (terminal agent) |
Key Takeaways
🚪
Single Gateway
QAR is the ONLY way to invoke agents
🔒
Permissions First
Checked BEFORE and AFTER every action
📝
Full Audit
Every action logged for compliance
👤
Human in Loop
PROD deployment requires approval
⚙️
Configurable
YAML config per project
🔄
Flexible
Sequential, Parallel, or Hybrid