v0.1.57

🚀 Release Highlights — v0.1.57 (2026-02-27)

🔗 Subagent Delegation Protocol

• Container-to-Host Spawning: File-based delegation via SubagentLaunchWatcher with atomic JSON request/response exchange and workspace path validation
• Auto-Mounted Parent Workspace: Subagents get parent workspace (read-only) by default

🏗️ Builder Subagent

• Fresh-Context Artifact Generation: New subagent type for transformative redesigns and complex multi-file rewrites with prescriptive specs

📊 Smarter Convergence

• Substantiveness Tracking: Planned changes classified as transformative/structural/incremental — triggers builder or novelty subagent accordingly
• Diagnostic Report Gating: Optional quality gate — agents must submit a structured diagnostic report before checklist passes
• Per-Agent Checklist Scoring: Evaluate multiple agents separately with automatic format detection

🔧 Infrastructure

• Claude Code Reasoning: Unified reasoning config (type, effort, budget_tokens) replacing deprecated max_thinking_tokens
• Bug Fixes: Fixed Codex subagent spawning, subagent synchronization/timeout handling, temp workspace directories

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📖 Getting Started

• Quick Start Guide
• Try It:

  # Install or upgrade to v0.1.57
  pip install --upgrade massgen
  
  # Try builder subagent with checklist-driven refinement
  uv run massgen --config @examples/features/subagent_checklist.yaml \
    "Create a website for an AI company selling a creative sci-fi style product. Ensure polished visuals and cool interactive elements"

What's Changed

• feat: Improve subagent calling, eval criteria by @ncrispino in #955
• docs: docs for v0.1.57 by @Henry-811 in #956
• feat: v0.1.57 by @Henry-811 in #947

Full Changelog: v0.1.56...v0.1.57