OASBuilder Package Conventions

When creating a new OASBuilder pipeline stage package, follow these conventions established by oasb-demonstrative and confirmed across oasb-descriptive, oasb-merge, and oasb-enhance.

Package Layout

• src/oasb_{stage}/ with hatchling build backend
• pyproject.toml with [tool.hatch.build.targets.wheel] packages = ["src/oasb_{stage}"]
• Python >=3.12, use X | None not Optional[X], dict[str, str] not Dict
• from __future__ import annotations at top of every module

pyproject.toml Template

[project]
name = "oasb-{stage}"
version = "0.1.0"
description = "Stage N of OASBuilder: ..."
requires-python = ">=3.12"
dependencies = [
    "oasb-scraper",          # upstream dependency
    "anthropic>=0.52.0",     # omit if stage is deterministic (e.g., merge)
    "pydantic>=2.12.5",
    "python-dotenv>=1.0",
    "click>=8.3.1",
    "rich>=14.3.2",
]

[project.scripts]
oasb-{stage} = "oasb_{stage}.main:cli"

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

[tool.hatch.build.targets.wheel]
packages = ["src/oasb_{stage}"]

Required Files

File	Role
__init__.py	Exports run_pipeline() + {Stage}Result only
__main__.py	from .main import cli; cli()
schema.py	Pydantic models (see Schema Conventions below)
main.py	CLI (@click.command) + run_pipeline() orchestration
validate.py	Output validation + Rich summary table

Schema Conventions

Every stage result follows this shape:

from datetime import datetime
from typing import Any
from pydantic import BaseModel, Field

class Operation{Stage}(BaseModel):
    """Per-operation summary."""
    method: str
    endpoint_path: str  # or just `path`
    # stage-specific counters...
    errors: list[str] = Field(default_factory=list)

class {Stage}Metadata(BaseModel):
    timestamp: datetime
    source_url: str  # or source_scrape_url
    total_operations: int
    # stage-specific counters...
    llm_calls_made: int  # 0 for deterministic stages

class {Stage}Result(BaseModel):
    source_url: str
    base_url: str | None = None
    partial_oas: dict[str, Any]  # or merged_oas, enhanced_oas
    operations: list[Operation{Stage}]
    metadata: {Stage}Metadata

Use Field(default_factory=list) for all mutable defaults. Never use bare [].

Pipeline Function Pattern

async def run_pipeline(
    input: InputModel | str | Path,
    *,
    model: str = "claude-haiku-4-5",
    max_concurrent: int = 5,
    output_dir: Path | None = None,
) -> StageResult | None:

• Accepts Pydantic model object OR file path (str/Path)
• Returns None on failure, never raises
• load_dotenv() inside run_pipeline(), not at module level
• Deterministic stages (merge) omit model and max_concurrent params

CLI Pattern

@click.command()
@click.argument("input_file", type=click.Path(exists=True))
@click.option("--model", default="claude-haiku-4-5")
@click.option("--max-concurrent", default=5, type=int)
@click.option("--output-dir", default=None, type=click.Path())
@click.option("--verbose", is_flag=True, help="Enable verbose logging")
def cli(input_file, model, max_concurrent, output_dir, verbose):
    logging.basicConfig(
        level=logging.DEBUG if verbose else logging.INFO,
        format="%(asctime)s %(levelname)s %(name)s: %(message)s",
    )
    result = asyncio.run(run_pipeline(input_file, model=model, ...))
    if result is None:
        sys.exit(1)

Merge stage takes two positional args (demo_file, desc_file) instead of one.

Error Handling

• Best-effort per operation — individual failures don't crash the pipeline
• Errors collected in errors: list[str] on the per-operation model
• run_pipeline() returns None on complete failure

LLM Calls

• anthropic.AsyncAnthropic with asyncio.Semaphore(max_concurrent) for rate limiting
• LLMCallCounter (async lock + counter) for tracking total calls
• Retry on RateLimitError/APIConnectionError with exponential backoff (up to 3 attempts)
• Extract JSON from responses handling: direct parse, json fences, first-brace-to-last-brace

Validate Pattern

def validate_file(path: Path) -> StageResult | None:
    """Load, validate, check OAS structure, print Rich summary."""

def _check_oas_structure(oas: dict) -> list[str]:
    """Return list of structural issues."""

def _print_summary(result: StageResult) -> None:
    """Rich table with per-operation stats."""

def main() -> None:
    """CLI: python -m oasb_{stage}.validate <file.json>"""

Output Conventions

• Written to generated/ (gitignored)
• Filename: {stage}_{url_slug}.json where slug is derived from source URL
• Rich progress spinner via Progress(SpinnerColumn(), TextColumn(...))
• Final output path printed with [green]Output written to:[/green]

Test Conventions

• Tests in tests/ directory — no __init__.py (avoids namespace collisions in workspaces)
• Use pytest-asyncio with asyncio_mode = "auto" in pyproject.toml
• Mock LLM calls with unittest.mock.AsyncMock on the Anthropic client
• logging.getLogger(__name__) per module; --verbose flag for DEBUG