turnzero 0.2.2

Expert Prior injection for AI sessions — eliminates cold-start friction at Turn 0 for any domain

TurnZero

Expert Priors for AI sessions — injected automatically at Turn 0.

Every time you open a new AI session, you start from zero. The AI knows nothing about your domain's specific rules, your stack's gotchas, or the corrections you've had to make a hundred times before. TurnZero fixes that.

It embeds your opening prompt, finds the most relevant Expert Priors for your domain, and injects them before the AI responds — so the model already knows the right answer before it has a chance to get it wrong.

Works for any domain: software, law, medicine, finance, design, writing, research — anywhere the AI makes the same domain-specific mistakes without context.

No cold starts. No mid-session corrections. No copy-pasting context.

Raw prompt text is never stored. Injection is always client-side.

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How it works

TurnZero identifies the "Expert Priors" — the specific constraints and patterns an expert would add to a prompt — and ensures the AI knows them before it even starts to answer.

You type: "I'm building a FastAPI async API with PostgreSQL"
                            │
                            ▼
           TurnZero identifies the relevant Expert Priors
               (Heuristics + Vector Similarity)
                            │
                            ▼
         Injected before the AI responds:
         ✓ Use async def — sync def blocks the event loop
         ✓ expire_on_commit=False with AsyncSession (prevents MissingGreenlet)
         ✓ lifespan= not @app.on_event (deprecated since 0.93)
         ✓ Pydantic v2: model_config = ConfigDict(...), not inner class Config

An Expert Prior is the delta between a naive prompt and an expert prompt — what a senior developer would silently add before hitting send.

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Install

pip install turnzero
turnzero setup

turnzero setup registers the TurnZero MCP server globally. Any MCP-compatible AI client — Claude Code, Cursor, Claude Desktop — will automatically call list_suggested_blocks on Turn 0 and inject the relevant Expert Priors. No further configuration needed.

Embedding backend — pick one:

Option	Setup
ollama (local, free, private)	ollama pull nomic-embed-text
sentence-transformers (local, no server)	pip install -e ".[local]"
OpenAI API	export OPENAI_API_KEY=sk-...

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IDE Integration

Claude Code

turnzero setup

The MCP server is registered globally. Open a new session — TurnZero calls list_suggested_blocks automatically on Turn 0.

# Optional: also install the UserPromptSubmit hook for guaranteed injection
# regardless of model behaviour
turnzero setup --with-hook

Claude Code (manual)

claude mcp add turnzero /path/to/.venv/bin/turnzero-mcp --scope user

Cursor

See docs/cursor-setup.md — register the MCP server and add the global rule that triggers auto-injection on Turn 0.

Any other MCP-compatible client

Register the MCP server however that client supports it. The server's instructions field tells the AI to call list_suggested_blocks at the start of every session. If the client surfaces MCP server instructions to the model, injection is automatic.

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How the library grows

TurnZero learns from your sessions. When the AI gets something wrong and you correct it mid-session, that correction is a high-signal "Expert Prior" candidate.

"No, use asyncpg not psycopg2 — psycopg2 blocks the event loop"
              │
              ▼
    AI detects correction, suggests a new Expert Prior
              │
              ▼
    Candidate is reviewed or auto-added to the library
              │
              ▼
    Injected in every future session matching that stack

No background daemons required. The AI used in the session performs the extraction, identifying the exact moments where domain-specific knowledge saved the day.

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CLI

turnzero setup                                             # register MCP, build index
turnzero preview "build a Next.js 15 app with Supabase"   # preview what would inject
turnzero query   "build a Next.js 15 app with Supabase"   # ranked block list
turnzero inject  "build a Next.js 15 app with Supabase"   # formatted output for any AI
turnzero show    nextjs15-approuter-build                  # full block content
turnzero stats                                             # library + session stats
turnzero review                                            # review pending candidates

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Expert Prior schema

id: nextjs15-approuter-build
domain: nextjs
intent: build                    # build | debug | migrate | review
tags: [nextjs, react, approuter]
context_weight: 900              # estimated tokens when injected
constraints:
  - "Use App Router (app/) — all new projects default to App Router in Next.js 13+"
  - "fetch() in Next.js 15 is not cached by default — add { cache: 'force-cache' } explicitly"
anti_patterns:
  - "Do not use getServerSideProps — Pages Router only, does not exist in App Router"
  - "Do not use next/router — use next/navigation in App Router"
doc_anchors:
  - url: "https://nextjs.org/docs/app/building-your-application/rendering/server-components"
    verified: "2026-04-19"

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Knowledge domains

121 Expert Priors across 25 domains — currently software-heavy since that's where the library started, but the system is domain-agnostic. Law, medicine, finance, design, writing, research — any field where the AI makes the same mistakes without context is a valid domain. The library grows from your sessions via submit_candidate.

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Design constraints

• No raw prompts stored. Only embeddings persist — raw text is discarded immediately after embedding.
• Client-side injection only. TurnZero never sits in the request path between user and AI provider.
• Provider neutral. Works with any MCP-compatible client — Claude Code, Cursor, Claude Desktop, and others.
• Token budget aware. Warns when selected blocks exceed 4000 tokens (configurable).

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What makes a good Expert Prior

The test: Would a stranger on the same stack, facing the same problem, be better off knowing this before Turn 0?

Good	Bad
Do not use getServerSideProps in App Router — API removed in Next.js 13	"Use PyCharm" — personal preference
expire_on_commit=False required with AsyncSession — raises MissingGreenlet without it	"Don't commit API keys" — generic noise
Supabase RLS is disabled by default on new tables — silently breaks auth	"Use Docker Compose for local dev" — workflow choice
Swiss non-compete clauses unenforceable beyond 3 years — jurisdiction-specific rule	"Be more concise" — personal style feedback
eGFR staging differs between CKD-EPI 2009 and 2021 — clinically significant threshold	"Always double-check your sources" — generic
Options Delta accelerates near expiration (gamma effect) — mispricing risk without it	"Our team reviews PRs within 24 hours" — team convention

High-signal source: mid-session corrections. When the AI gets it wrong and you say "remember this" — that's exactly what TurnZero should inject next time.

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Roadmap

See ROADMAP.md.

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Contributing

See CONTRIBUTING.md. The most valuable contribution is a new Expert Prior.