How disler/fusion-harness works
fusion-harness is a Pi coding-agent extension for combining configured frontier models in shared coding workflows. A user invokes commands through Pi; the extension loads and validates a 2–5-slot model stack, then routes work to clean-room child agents. The main flows include independent opinions and debates, read-only research followed by a sole-writer fusion agent and synchronization, architect-led collaboration, direct single-slot routing, and gate-first auto-validation. Results are rendered in Pi and run artifacts are saved. The README documents capabilities beyond the sampled excerpts; command wiring is shown only where supported by excerpts or explicit documentation.
Main entry points: fusion-harness.ts Harness Extension · child-runner.ts Child Runner · cmd-build.ts Collaboration & Validation · cmd-fusion.ts Fusion Command
Components 19
Pi Integration
- Pi Agent Host
- Harness Extension
extensions/fusion-harness/fusion-harness.ts - Model Stack
extensions/fusion-harness/modules/model-stack.ts
Model Workflows
- Opinion & Debate
extensions/fusion-harness/modules/cmd-readonly.ts - Fusion Command
extensions/fusion-harness/modules/cmd-fusion.ts - Collaboration & Validation
extensions/fusion-harness/modules/cmd-build.ts - Direct Slot Route
extensions/fusion-harness/fusion-harness.ts
Coordination
- Prompt Contracts
extensions/fusion-harness/modules/prompt-library.ts - Prompt Templates
extensions/fusion-harness/prompts - Task DAG
extensions/fusion-harness/modules/collaboration-graph.ts - Writer Lease
extensions/fusion-harness/modules/writer-lease.ts
Agent Runtime
- Child Runner
extensions/fusion-harness/modules/child-runner.ts - Model Providers
- Shared Workspace
- Run Artifacts
- Run State & Contracts
extensions/fusion-harness/modules/runtime.ts
Results
- Transcript Renderer
extensions/fusion-harness/modules/tui.ts - Agent Grid Layout
extensions/fusion-harness/modules/agent-layout.ts
Other components
- Engineer
Connections 27
- Engineer → Pi Agent Host: invokes commands
- Pi Agent Host → Harness Extension: loads extension
- Harness Extension → Model Stack: loads stack
- Harness Extension → Direct Slot Route: routes slot
- Harness Extension → Opinion & Debate: dispatches commands
- Harness Extension → Fusion Command: dispatches command
- Harness Extension → Collaboration & Validation: dispatches commands
- Opinion & Debate → Prompt Contracts: builds prompts
- Fusion Command → Prompt Contracts: builds prompts
- Collaboration & Validation → Prompt Contracts: builds prompts
- Prompt Contracts → Prompt Templates: loads templates
- Opinion & Debate → Child Runner: spawns agents
- Fusion Command → Child Runner: spawns agents
- Collaboration & Validation → Child Runner: spawns agents
- Direct Slot Route → Child Runner: spawns agent
- Child Runner → Model Providers: requests model work
- Child Runner → Shared Workspace: runs tools in
- Fusion Command → Shared Workspace: fuser modifies
- Fusion Command → Run Artifacts: saves run outputs
- Collaboration & Validation → Run Artifacts: saves run outputs
- Collaboration & Validation → Task DAG: plans task DAG
- Collaboration & Validation → Writer Lease: coordinates writes
- Child Runner → Run State & Contracts: updates run state
- Harness Extension → Transcript Renderer: renders panels
- Transcript Renderer → Agent Grid Layout: computes grid
- Transcript Renderer → Run State & Contracts: formats run stats
- Pi Agent Host → Model Stack: sets host model