agenthub — Claude Code skill: what it does, how to install

---
name: "agenthub"
description: "Multi-agent collaboration plugin that spawns N parallel subagents competing on the same task via git worktree isolation. Agents work independently, results are evaluated by metric or LLM judge, and the best branch is merged. Use when: user wants multiple approaches tried in parallel — code optimization, content variation, research exploration, or any task that benefits from parallel competition. Requires: a git repo."
license: MIT
metadata:
  version: 2.1.2
  author: Alireza Rezvani
  category: engineering
  updated: 2026-03-17
---

# AgentHub — Multi-Agent Collaboration

Spawn N parallel AI agents that compete on the same task. Each agent works in an isolated git worktree. The coordinator evaluates results and merges the winner.

## Slash Commands

| Command | Description |
|---------|-------------|
| `/hub:hub-init` | Create a new collaboration session — task, agent count, eval criteria |
| `/hub:spawn` | Launch N parallel subagents in isolated worktrees |
| `/hub:hub-status` | Show DAG state, agent progress, branch status |
| `/hub:eval` | Rank agent results by metric or LLM judge |
| `/hub:merge` | Merge winning branch, archive losers |
| `/hub:board` | Read/write the agent message board |
| `/hub:hub-run` | One-shot lifecycle: init → baseline → spawn → eval → merge |

## Agent Templates

When spawning with `--template`, agents follow a predefined iteration pattern:

| Template | Pattern | Use Case |
|----------|---------|----------|
| `optimizer` | Edit → eval → keep/discard → repeat x10 | Performance, latency, size |
| `refactorer` | Restructure → test → iterate until green | Code quality, tech debt |
| `test-writer` | Write tests → measure coverage → repeat | Test coverage gaps |
| `bug-fixer` | Reproduce → diagnose → fix → verify | Bug fix approaches |

Templates are defined in `references/agent-templates.md`.

## When This Skill Activates

Trigger phrases:
- "try multiple approaches"
- "have agents compete"
- "parallel optimization"
- "spawn N agents"
- "compare different solutions"
- "fan-out" or "tournament"
- "generate content variations"
- "compare different drafts"
- "A/B test copy"
- "explore multiple strategies"

## Coordinator Protocol

The main Claude Code session is the coordinator. It follows this lifecycle:

```
INIT → DISPATCH → MONITOR → EVALUATE → MERGE
```

### 1. Init

Run `/hub:hub-init` to create a session. This generates:
- `.agenthub/sessions/{session-id}/config.yaml` — task config
- `.agenthub/sessions/{session-id}/state.json` — state machine
- `.agenthub/board/` — message board channels

### 2. Dispatch

Run `/hub:spawn` to launch agents. For each agent 1..N:
- Post task assignment to `.agenthub/board/dispatch/`
- Spawn via Agent tool with `isolation: "worktree"`
- All agents launched in a single message (parallel)

### 3. Monitor

Run `/hub:hub-status` to check progress:
- `dag_analyzer.py --status --session {id}` shows branch state
- Board `progress/` channel has agent updates

### 4. Evaluate

Run `/hub:eval` to rank results:
- **Metric mode**: run eval command in each worktree, parse numeric result
- **Judge mode**: read diffs, coordinator ranks by quality
- **Hybrid**: metric first, LLM-judge for ties

### 5. Merge

Run `/hub:merge` to finalize:
- `git merge --no-ff` winner into base branch
- Tag losers: `git tag hub/archive/{session}/agent-{i}`
- Clean up worktrees
- Post merge summary to board

## Agent Protocol

Each subagent receives this prompt pattern:

```
You are agent-{i} in hub session {session-id}.
Your task: {task description}

Instructions:
1. Read your assignment at .agenthub/board/dispatch/{seq}-agent-{i}.md
2. Work in your worktree — make changes, run tests, iterate
3. Commit all changes with descriptive messages
4. Write your result summary to .agenthub/board/results/agent-{i}-result.md
5. Exit when done
```

Agents do NOT see each other's work. They do NOT communicate with each other. They only write to the board for the coordinator to read.

## DAG Model

### Branch Naming

```
hub/{session-id}/agent-{N}/attempt-{M}
```

- Session ID: timestamp-based (`YYYYMMDD-HHMMSS`)
- Agent N: sequential (1 to agent-count)
- Attempt M: increments on retry (usually 1)

### Frontier Detection

Frontier = branch tips with no child branches. Equivalent to AgentHub's "leaves" query.

```bash
python scripts/dag_analyzer.py --frontier --session {id}
```

### Immutability

The DAG is append-only:
- Never rebase or force-push agent branches
- Never delete commits (only branch refs after archival)
- Every approach preserved via git tags

## Message Board

Location: `.agenthub/board/`

### Channels

| Channel | Writer | Reader | Purpose |
|---------|--------|--------|---------|
| `dispatch/` | Coordinator | Agents | Task assignments |
| `progress/` | Agents | Coordinator | Status updates |
| `results/` | Agents + Coordinator | All | Final results + merge summary |

### Post Format

```markdown
---
author: agent-1
timestamp: 2026-03-17T14:30:22Z
channel: results
parent: null
---

## Result Summary

- **Approach**: Replaced O(n²) sort with hash map
- **Files changed**: 3
- **Metric**: 142ms (baseline: 180ms, delta: -38ms)
- **Confidence**: High — all tests pass
```

### Board Rules

- Append-only: never edit or delete posts
- Unique filenames: `{seq:03d}-{author}-{timestamp}.md`
- YAML frontmatter required on all posts

## Evaluation Modes

### Metric-Based

Best for: benchmarks, test pass rates, file sizes, response times.

```bash
python scripts/result_ranker.py --session {id} \
  --eval-cmd "pytest bench.py --json" \
  --metric p50_ms --direction lower
```

The ranker runs the eval command in each agent's worktree directory and parses the metric from stdout.

### LLM Judge

Best for: code quality, readability, architecture decisions.

The coordinator reads each agent's diff (`git diff base...agent-branch`) and ranks by:
1. Correctness (does it solve the task?)
2. Simplicity (fewer lines changed preferred)
3. Quality (clean execution, good structure)

### Hybrid

Run metric first. If top agents are within 10% of each other, use LLM judge to break ties.

## Session Lifecycle

```
init → running → evaluating → merged
                            → archived (if no winner)
```

State transitions managed by `session_manager.py`:

| From | To | Trigger |
|------|----|---------|
| `init` | `running` | `/hub:spawn` completes |
| `running` | `evaluating` | All agents return |
| `evaluating` | `merged` | `/hub:merge` completes |
| `evaluating` | `archived` | No winner / all failed |

## Proactive Triggers

The coordinator should act when:

| Signal | Action |
|--------|--------|
| All agents crashed | Post failure summary, suggest retry with different constraints |
| No improvement over baseline | Archive session, suggest different approaches |
| Orphan worktrees detected | Run `session_manager.py --cleanup {id}` |
| Session stuck in `running` | Check board for progress, consider timeout |

## Installation

```bash
# Copy to your Claude Code skills directory
cp -r engineering/agenthub ~/.claude/skills/agenthub

# Or install via ClawHub
clawhub install agenthub
```

## Scripts

| Script | Purpose |
|--------|---------|
| `hub_init.py` | Initialize `.agenthub/` structure and session |
| `dag_analyzer.py` | Frontier detection, DAG graph, branch status |
| `board_manager.py` | Message board CRUD (channels, posts, threads) |
| `result_ranker.py` | Rank agents by metric or diff quality |
| `session_manager.py` | Session state machine and cleanup |

## Related Skills

- **autoresearch-agent** — Single-agent optimization loop (use AgentHub when you want N agents competing)
- **self-improving-agent** — Self-modifying agent (use AgentHub when you want external competition)
- **git-worktree-manager** — Git worktree utilities (AgentHub uses worktrees internally)