ECC Harness Patterns Skill

Inspired by: ECC — the definitive cross-harness agent orchestration system

Purpose: Integrate multi-harness patterns from ECC into local-llm-server's agent orchestration layer.

What's Unique About ECC

ECC is a production-grade system supporting 7+ agent harnesses (Claude Code, Cursor, Codex, OpenCode, Gemini, Zed, GitHub Copilot) with:

• Harness abstraction layer — normalize API differences
• Hook lifecycle — session start/pause/stop/resume
• Memory persistence — skills learned across sessions
• Cross-harness routing — intelligent model/capability selection
• 182K+ stars — battle-tested in real workflows

Patterns to Adopt

1. Harness Detection & Adaptation

# agents/harness_adapter.py
class HarnessAdapter:
    HARNESSES = {
        "claude_code": {"context_key": "workspace", "supports": ["streaming"]},
        "cursor": {"context_key": "editor", "supports": ["streaming", "streaming_chunks"]},
        "codex": {"context_key": "project", "supports": ["completion"]},
    }
    
    def normalize_request(self, harness_id: str, request: dict) -> dict:
        """Convert harness-native request to local-llm-server format"""

2. Session Lifecycle Hooks

ECC's /hooks/session-* pattern applied to local-llm-server:

.claude/hooks/
  ├── session-start/
  │   ├── 10-detect-harness.sh       # Identify active harness
  │   ├── 20-load-harness-prefs.sh   # Load harness-specific settings
  │   └── 30-emit-telemetry.sh       # Send harness telemetry
  ├── session-pause/
  │   └── 10-checkpoint-state.sh
  └── session-stop/
      └── 10-summarize-session.sh

3. Cross-Harness Model Selection

Extend router/model_router.py to consider harness capabilities:

class CrossHarnessRouter(ModelRouter):
    def select_model(self, task: TaskRequest, harness: str) -> str:
        """Route considering harness limits and preferences"""
        # Claude Code + reasoning task → deepseek-r1 (powerful)
        # Cursor + quick fix → qwen3-coder (fast)
        # Codex + completion → fastest available

4. Persistent Harness Registry

Track which harnesses are active and their performance:

# .claude/state/harness-registry.json
{
  "active_harnesses": ["claude_code", "cursor"],
  "session_history": [
    {
      "harness": "claude_code",
      "session_id": "sess_123",
      "model": "deepseek-r1:32b",
      "duration_sec": 1847,
      "tasks_completed": 12,
      "success_rate": 0.92
    }
  ]
}

Implementation Plan

1. Create agents/harness_adapter.py — adapter pattern for harness differences
2. Extend .claude/hooks/ — add session lifecycle management
3. Update router/model_router.py — add cross-harness routing logic
4. Create services/harness_registry.py — track active harnesses and performance
5. Update backend/server.py — emit harness metadata in responses
6. Add tests — tests/test_harness_adapter.py, tests/test_cross_harness_router.py

Files to Create/Modify

• ✅ .claude/skills/ecc-harness-patterns/SKILL.md (this file)
• agents/harness_adapter.py (new)
• services/harness_registry.py (new)
• .claude/hooks/session-start/10-detect-harness.sh (new)
• router/model_router.py (extend)
• docs/architecture/cross-harness-support.md (new)

References

• ECC GitHub: https://github.com/affaan-m/ECC
• ECC Cross-Harness Docs: https://github.com/affaan-m/ECC/blob/main/docs/architecture/cross-harness.md
• Local-llm-server Agent Orchestration: docs/architecture/agent-orchestration.md
• Local-llm-server Router: docs/adrs/002-model-routing.md