chore: configure legislation explainer project

.gitignore

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+# Python-generated files
+__pycache__/
+*.py[oc]
+build/
+dist/
+wheels/
+*.egg-info
+
+# Virtual environments
+.venv
+
+# env vars
+.env

.python-version

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+3.12

config.py

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+"""Configuration constants for the NITA bill Gradio app."""
+
+from __future__ import annotations
+
+import os
+import warnings
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Literal, Optional
+
+from dotenv import load_dotenv
+
+_PROJECT_ROOT = Path(__file__).resolve().parent
+while _PROJECT_ROOT.name and _PROJECT_ROOT.name not in {"", "."}:
+    if (_PROJECT_ROOT / "pyproject.toml").exists():
+        break
+    if _PROJECT_ROOT.parent == _PROJECT_ROOT:
+        break
+    _PROJECT_ROOT = _PROJECT_ROOT.parent
+
+load_dotenv(dotenv_path=_PROJECT_ROOT / ".env", override=False)
+
+# Hugging Face tokenizers can emit fork/parallelism warnings in Gradio dev
+# servers. Default this off unless the environment explicitly overrides it.
+os.environ.setdefault("TOKENIZERS_PARALLELISM", "false")
+
+# Suppress a known huggingface_hub deprecation warning emitted during first-time
+# model/tokenizer downloads. It is noisy but not actionable for app users.
+warnings.filterwarnings(
+    "ignore",
+    message=r"`resume_download` is deprecated and will be removed in version 1\.0\.0\.",
+    category=FutureWarning,
+)
+
+SUPPORTED_PROVIDERS = ["qwen", "openai", "anthropic", "gemini", "cohere"]
+DEFAULT_PROVIDER: str = "qwen"
+DEFAULT_QWEN_MODEL = "Qwen/Qwen3-32B:cheapest"
+DEFAULT_EMBEDDING_MODEL = "sentence-transformers/all-MiniLM-L6-v2"
+OPENAI_REASONING_EFFORT = "medium"
+ANTHROPIC_THINKING_BUDGET = 2048
+DEFAULT_CHUNK_SIZE = 350
+DEFAULT_CHUNK_OVERLAP = 60
+SCAN_CHUNK_SIZE = 1200
+SCAN_CHUNK_OVERLAP = 150
+SCAN_MAX_WINDOWS = 40
+SCAN_TOP_K = 5
+SCAN_BATCH_SIZE = 6
+TOP_K_RETRIEVAL = 5
+MAX_UPLOAD_SIZE_MB = 25
+TIMEOUT_SECONDS = 30
+
+ProviderLiteral = Literal["qwen", "openai", "anthropic", "gemini", "cohere"]
+
+# Conservative full-document QA input budgets derived from provider/model
+# context-window docs, with headroom reserved for prompts and outputs.
+PROVIDER_FULL_DOCUMENT_QA_TOKEN_BUDGETS: dict[ProviderLiteral, int] = {
+    "qwen": 24_000,
+    "openai": 900_000,
+    "anthropic": 900_000,
+    "gemini": 900_000,
+    "cohere": 220_000,
+}
+
+
+@dataclass(frozen=True)
+class ProviderConfig:
+    name: ProviderLiteral
+    key_prefix: Optional[str]
+    display_name: str
+    instructions: str
+
+
+def _read_env_key(var_name: str) -> Optional[str]:
+    value = os.getenv(var_name)
+    if value is None:
+        return None
+    sanitized = value.strip().strip('"').strip("'")
+    return sanitized or None
+
+
+OPENAI_API_KEY: Optional[str] = _read_env_key("OPENAI_API_KEY")
+ANTHROPIC_API_KEY: Optional[str] = _read_env_key("ANTHROPIC_API_KEY")
+GEMINI_API_KEY: Optional[str] = _read_env_key("GEMINI_API_KEY")
+COHERE_API_KEY: Optional[str] = _read_env_key("COHERE_API_KEY")
+DEFAULT_COHERE_KEY: Optional[str] = _read_env_key("DEFAULT_COHERE_KEY")
+HF_TOKEN: Optional[str] = _read_env_key("HF_TOKEN")
+
+
+PROVIDER_METADATA: list[ProviderConfig] = [
+    ProviderConfig(
+        name="qwen",
+        key_prefix=None,
+        display_name="Qwen3 32B",
+        instructions=(
+            "Use your Hugging Face token for the router-backed Qwen model. Leave blank to use HF_TOKEN from .env if configured."
+        ),
+    ),
+    ProviderConfig(
+        name="openai",
+        key_prefix="sk-",
+        display_name="OpenAI GPT-5.5",
+        instructions=(
+            "Enter your OpenAI API key. Leave blank to use OPENAI_API_KEY from .env if configured."
+        ),
+    ),
+    ProviderConfig(
+        name="anthropic",
+        key_prefix="sk-ant-",
+        display_name="Anthropic Claude Sonnet 4.6",
+        instructions=(
+            "Provide your Anthropic API key. Leave blank to use ANTHROPIC_API_KEY from .env if configured."
+        ),
+    ),
+    ProviderConfig(
+        name="gemini",
+        key_prefix=None,
+        display_name="Google Gemini 2.5 Flash",
+        instructions=(
+            "Use your Gemini API key. Leave blank to use the built-in GEMINI_API_KEY if configured."
+        ),
+    ),
+    ProviderConfig(
+        name="cohere",
+        key_prefix=None,
+        display_name="Cohere Command A Reasoning",
+        instructions=(
+            "Use your Cohere API key with Command R access. Leave blank to use COHERE_API_KEY or "
+            "DEFAULT_COHERE_KEY if configured."
+        ),
+    ),
+]
+
+
+APP_TITLE = "Legislation Explainer"
+APP_DESCRIPTION = (
+    "A Gradio policy assistant for Ghana's NITA bill and similar public-interest legislation. "
+    "Upload or link to a bill, generate a structured review, and ask grounded follow-up questions."
+)

pyproject.toml

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+[project]
+name = "legislation-explainer"
+version = "0.1.0"
+description = "A Gradio tool for reviewing Ghana's NITA bill and related policy documents with small models."
+readme = "README.md"
+requires-python = ">=3.12, <3.13"
+dependencies = [
+    "gradio==4.44.1",
+    "langchain==0.1.17",
+    "langchain-community==0.0.36",
+    "faiss-cpu==1.8.0",
+    "sentence-transformers==2.7.0",
+    "pydantic==2.6.4",
+    "requests==2.31.0",
+    "readability-lxml==0.8.1",
+    "lxml_html_clean>=0.4.3",
+    "python-docx==1.1.0",
+    "pypdf==4.2.0",
+    "anthropic==0.23.1",
+    "openai==1.25.0",
+    "httpx==0.27.2",
+    "google-generativeai==0.7.2",
+    "python-dotenv==1.0.1",
+    "cohere==5.5.5",
+    "pytest>=9.0.3",
+]

requirements.txt

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+gradio==4.44.1
+langchain==0.1.17
+langchain-community==0.0.36
+faiss-cpu==1.8.0
+sentence-transformers==2.7.0
+pydantic==2.6.4
+requests==2.31.0
+readability-lxml==0.8.1
+lxml_html_clean>=0.4.3
+python-docx==1.1.0
+pypdf==4.2.0
+anthropic==0.23.1
+openai==1.25.0
+httpx==0.27.2
+google-generativeai==0.7.2
+python-dotenv==1.0.1
+cohere==5.5.5
+pytest==8.2.0