pathcourse-sdk 0.3.3

Pay-per-inference billing in USDC on Base L2 via x402. No accounts required.

pathcourse-sdk

Official Python SDK for the PathCourse Health AI gateway.

Pay-per-inference billing in USDC on Base L2 via x402. No accounts required.

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Install

pip install pathcourse-sdk

How PathCourse works (in 30 seconds)

PathCourse is built for autonomous agents. You don't sign up. There's no dashboard. You fund an on-chain wallet, claim an API key, and make inference calls — all programmatically.

1. Your agent has (or creates) a Base L2 wallet holding at least 25 USDC.
2. You send that USDC to the PCH treasury wallet.
3. You call pathcourse.claim_key(tx_hash, wallet) to retrieve your API key.
4. You construct PathCourseClient(api_key=...) and make inference calls.
5. Balance is deducted per request. Check it any time with client.get_balance().

No credit card. No KYC. No human in the loop.

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First-time setup — get an API key

Requirements: a Base L2 wallet and at least 25 USDC in it. Treasury wallet address is published at gateway.pathcoursehealth.com/.well-known/agent.json under payment.treasury_wallet.

import pathcourse

# Step 1: You've already sent >= 25 USDC to the PCH treasury wallet on Base.
#         Capture the tx_hash and the wallet address you sent from.

# Step 2: Claim your API key. Polls up to ~3 minutes while the deposit confirms
#         and your account provisions.
result = pathcourse.claim_key(
    tx_hash="0xYourDepositTxHash",
    wallet="0xYourSendingWallet",
)

print(result["api_key"])      # pch_prod_b_...
print(result["tier"])         # uncertified | bronze | silver | gold
print(result["balance_usdc"]) # e.g. "25.00000000"

# Store result["api_key"] securely. It won't be shown again via this endpoint.

Set the key as an environment variable for future runs:

export PCH_API_KEY="pch_prod_b_..."

---

Quick Start (once you have a key)

from pathcourse import PathCourseClient, PCH_FAST

client = PathCourseClient()  # reads PCH_API_KEY from env
client.verify_key()          # confirms the key works (cheap, no billing)

response = client.chat(
    model=PCH_FAST,
    messages=[{"role": "user", "content": "Explain x402 micropayments in one paragraph."}],
)
print(response.text)

Embeddings, translation, rerank

from pathcourse import PathCourseClient, PCH_EMBED

client = PathCourseClient()

emb = client.embed("The quick brown fox jumps over the lazy dog.")
print(len(emb.embeddings[0]))  # embedding dimension

fr = client.translate("Hello world", target_language="fr")
print(fr["translated_text"])   # "Bonjour le monde"

ranked = client.rerank(
    query="how does x402 work?",
    documents=["USDC is a stablecoin...", "x402 is an HTTP status code...", "Base is an L2..."],
    top_n=2,
)

Account controls

# Current balance + top-up instructions
bal = client.get_balance()
print(bal["balance_usdc"], bal["low_balance"])

# Spend history from the on-chain ledger
usage = client.get_usage(limit=20)
print(usage["summary"]["total_spend_usdc"])

# Days of service at current burn rate
runway = client.get_runway()
print(runway["runway_days"], runway["status"])

# Server-side daily spend cap (resets at UTC midnight; pass 0 to remove)
client.set_budget(daily_limit_usdc=10.00)

# Webhook alerts when balance drops below threshold
client.register_webhook(
    url="https://my-agent.example.com/pch-events",
    threshold_usdc=25.00,
)

Models

Constant	Model	Use Case	Price
PCH_FAST	pch-fast	Fast reasoning, classification, routing	$0.44/M tokens
PCH_PRO	pch-pro	Deep reasoning, multi-step planning	$1.96/M tokens
PCH_CODER	pch-coder	Code generation, debugging	$3.50/M tokens
PCH_IMAGE	pch-image	Text-to-image generation	$0.028/image
PCH_AUDIO	pch-audio	Text-to-speech (standard)	$1.85/M chars
PCH_AUDIO_PREMIUM	pch-audio-premium	Text-to-speech (premium)	$37.00/M chars
PCH_DOCUMENTS	pch-documents	Document parsing, OCR	$0.26 in / $1.48 out per M tokens
PCH_TALK	pch-talk	Voice conversation	$0.001/min
CLAUDE_HAIKU	claude-haiku	Third-party (Silver+)	Markup over provider cost
CLAUDE_SONNET	claude-sonnet	Third-party (Gold)	Markup over provider cost
PCH_EMBED	pch-embed	Text embeddings	$0.015/M tokens
PCH_TRANSCRIBE	pch-transcribe	Speech-to-text	$0.0008/min
PCH_TRANSLATE	pch-translate	Translation	$0.08/M chars
PCH_EXTRACT	pch-extract	Zero-shot entity extraction	$0.012/M tokens
PCH_RERANK	pch-rerank	Retrieval reranking	$0.025/M tokens

Machine-readable rate sheet: gateway.pathcoursehealth.com/v1/pricing.

Environment variables

• PCH_API_KEY — your PathCourse API key
• PCH_BASE_URL — override gateway URL (default: https://gateway.pathcoursehealth.com)

Error handling

from pathcourse import (
    PathCourseClient,
    InsufficientBalanceError, AuthenticationError,
    ModelNotInTierError, InferenceUnavailableError,
)

client = PathCourseClient()

try:
    client.chat(model="pch-pro", messages=[{"role": "user", "content": "hi"}])
except InsufficientBalanceError:
    # balance hit the $10 floor — top up via the treasury_wallet
    ...
except AuthenticationError:
    # key is invalid or the service is suspended
    ...
except ModelNotInTierError:
    # this tier can't access the requested model — upgrade cert or pick another
    ...

Settlement

All billing is in USDC on Base L2 (chain_id 8453) via the x402 payment protocol. USDC contract: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913. No accounts, no credit cards, no KYC.

Links

• PathCourse Platform
• Agent Card (A2A discovery)
• Live rate sheet
• Model listing (OpenAI-compatible)
• GitHub