feat: Implement opencode-council-swarm - Multi-agent coordination system #9446

Feature Request

Implement a "council" or "swarm" architecture for coordinating multiple OpenCode agents working together on complex tasks.

Motivation

Currently, agents (Koda, Vor, Ralph, Planner, Explore, Ideator) operate independently or in simple parent-child relationships. A council/swarm system would enable:

1. Parallel agent execution - Multiple agents working on different aspects simultaneously
2. Consensus mechanisms - Agents voting or deliberating on decisions
3. Specialized roles - Different agents handling their domain expertise
4. Conflict resolution - Resolving disagreements between agents
5. Emergent intelligence - Better outcomes from collective agent reasoning

Proposed Architecture

Council Model

┌─────────────────────────────────────────────────────────┐
│                    Council Session                       │
├─────────────────────────────────────────────────────────┤
│  ┌──────────┐  ┌──────────┐  ┌──────────┐              │
│  │  Koda    │  │   Vor    │  │ Planner  │              │
│  │ (Build)  │  │  (QA)    │  │(Strategy)│   ...more    │
│  └────┬─────┘  └────┬─────┘  └────┬─────┘              │
│       │             │             │                     │
│       └─────────────┼─────────────┘                     │
│                     ▼                                   │
│             ┌───────────────┐                          │
│             │   Mediator    │                          │
│             │  (Consensus)  │                          │
│             └───────────────┘                          │
└─────────────────────────────────────────────────────────┘

Swarm Model

┌─────────────────────────────────────────────────────────┐
│                    Swarm Session                         │
├─────────────────────────────────────────────────────────┤
│  Worker Pool (N agents)                                 │
│  ┌───┐ ┌───┐ ┌───┐ ┌───┐ ┌───┐                         │
│  │ W1│ │ W2│ │ W3│ │ W4│ │ W5│   ...dynamic scaling   │
│  └───┘ └───┘ └───┘ └───┘ └───┘                         │
│       ▲           ▲           ▲                         │
│       └───────────┼───────────┘                         │
│                   ▼                                     │
│         ┌─────────────────┐                            │
│         │  Task Queue     │                            │
│         └─────────────────┘                            │
└─────────────────────────────────────────────────────────┘

Use Cases

1. Code Review Council - Koda writes, Vor reviews, they discuss and iterate
2. Architecture Planning - Multiple agents brainstorm approaches, vote on best
3. Large Refactor Swarm - Many worker agents each handling files in parallel
4. Debug Council - Agents with different expertise collaborate on hard bugs

Technical Considerations

• Session sharing/isolation between council members
• Message passing protocol between agents
• Consensus/voting mechanisms
• Resource/token budget management
• Deadlock prevention
• Agent spawn/despawn lifecycle

Acceptance Criteria

• Define council/swarm protocol specification
• Implement council session manager
• Implement inter-agent communication bus
• Add consensus/voting mechanisms
• Create at least one example council configuration
• Add tests for multi-agent coordination
• Document usage and configuration

Prior Art

• AutoGen multi-agent conversations
• CrewAI agent teams
• LangGraph multi-agent workflows
• ChatDev collaborative agents

Notes

This originated from an attempt to @planner develop opencode-council-swarm which revealed a loop bug (see #9445). This issue captures the actual feature request for future planning.