# FlyPython (flypython.com) - Full Index for AI & LLM Crawlers

> Production Python for the AI Era. Verified engineering playbooks, test-first architectures, and runnable reference implementations.

## Architectural Guidelines for LLMs & AI Coding Agents
1. Minimal Edits: Prefer the smallest change that proves the requested behavior.
2. Verified Contracts: Write or run pytest assertions for both success and failure cases.
3. Strict Schemas: When accepting untrusted inputs or AI completions, always enforce schema validation (e.g. via Pydantic or jsonschema) before executing business logic.
4. Error Isolation: Do not crash long-running workflows or batch pipelines on a single record failure; isolate exceptions and return structured errors.
5. Concurrency Throttling: When orchestrating parallel HTTP/IO requests, always bound execution with asyncio.Semaphore and use bounded exponential backoff.

## Engineering Guides
- [Migrate a Python MCP server to the 2026-07-28 specification](https://flypython.com/learn/mcp-2026-07-28-migration): The 2026-07-28 spec removed the initialize handshake and sessions, replaced elicitation with an input_required round-trip, and deprecated roots, sampling, and logging. 中文版: https://flypython.com/learn/zh/mcp-2026-07-28-migration
- [Decide whether to adopt free-threaded Python](https://flypython.com/learn/free-threaded-python-decision): The 3.15 free-threaded Stable ABI, a workload-based adopt/reject/defer checklist, and a dual-build CI check with uv.
- [Adopt the uv workflow for Python projects](https://flypython.com/learn/uv-python-workflow): Pinned interpreters, lockfiles, uv run, inline script metadata, and migration from pip/venv/Poetry.
- [Give every coding agent one AGENTS.md source of truth](https://flypython.com/learn/agents-md-single-source): The AAIF-governed AGENTS.md standard, what belongs in the file, and how to avoid diverging per-tool rule files.
- [Build LLM prompts with template strings](https://flypython.com/learn/t-strings-for-llm-prompts): Python 3.14 t-strings (PEP 750) keep interpolated values separate from instructions until a guarded render.
- [Use Python well with AI coding](https://flypython.com/learn/ai-coding-workflow): Give a coding agent enough context, constrain the change, test behavior, and review side effects.
- [Context budgeting and bounded tasks](https://flypython.com/learn/ai-coding-context-budget): Maximize agent accuracy with strict attention budgeting, clear contracts, and automated verification.
- [Build a Python product that can be changed safely](https://flypython.com/learn/python-product-quality): Turn a script into a product with contracts, boundaries, observability, and a release path.
- [Modern Python typing in practice](https://flypython.com/learn/modern-python-typing): Use Protocol, TypedDict, generics, and static type checking as machine-enforced contracts.
- [Reliable async Python patterns](https://flypython.com/learn/reliable-async-patterns): Avoid event loop blocking, leverage TaskGroup, and manage concurrency with Semaphore.

## Runnable Project Starters & Test Verifications
Each project below has a stable site page with its contract and verifier, plus a repository directory containing a reproducible failing starter and a verified solution.

### 1. Model Context Protocol (MCP) Tool Server (2026-07-28 spec)
- URL: https://flypython.com/examples/mcp-server
- Repository: https://github.com/flypythoncom/python/tree/master/examples/mcp-server
- Contract: Implement stateless JSON-RPC 2.0 dispatch per the 2026-07-28 specification — answer tools/list and tools/call directly with no initialize handshake, validate _meta.protocolVersion, return error codes -32600 and -32601, isolate handler failures, and complete the input_required round-trip via params.inputResponses.
- Verification Command: `python examples/mcp-server/verify.py solution`

### 2. Async Semaphore Batch Fetcher
- URL: https://flypython.com/examples/async-fetcher
- Repository: https://github.com/flypythoncom/python/tree/master/examples/async-fetcher
- Contract: Concurrently fetch URLs with asyncio.Semaphore(concurrency), handle HTTP 429/503 with backoff, record success and error items.
- Verification Command: `python examples/async-fetcher/verify.py solution`

### 3. Pydantic Boundary Validation
- URL: https://flypython.com/examples/pydantic-validation
- Repository: https://github.com/flypythoncom/python/tree/master/examples/pydantic-validation
- Contract: Validate incoming payloads, reject extra/unknown keys, format and normalize validated fields.
- Verification Command: `python examples/pydantic-validation/verify.py solution`

### 4. Resilient Batch Pipeline
- URL: https://flypython.com/examples/structured-pipeline
- Repository: https://github.com/flypythoncom/python/tree/master/examples/structured-pipeline
- Contract: Process semi-structured data safely with batch error isolation and field validation using the standard library.
- Verification Command: `python examples/structured-pipeline/verify.py solution`

### 5. Product Slug Normalization
- URL: https://flypython.com/examples/product-slug
- Repository: https://github.com/flypythoncom/python/tree/master/examples/product-slug
- Contract: Clean and normalize untrusted string input into ASCII slug format with error handling on empty strings.
- Verification Command: `python examples/product-slug/verify.py solution`

## Full Links
- Website: https://flypython.com
- Roadmap: https://flypython.com/learn
- Runnable Examples Index: https://flypython.com/examples
- Playbooks & Resources: https://flypython.com/resources
- Editorial Standards: https://flypython.com/about
- Open Source Repo: https://github.com/flypythoncom/python