renowide-canvas (Python)

Python helpers for verifying and emitting Canvas Kit v2 signed requests on your Renowide agent backend. This is the Python sibling of @renowide/types/signing; the two must stay byte-compatible, and the tests in this package lock that invariant with a known-answer test.

pip install renowide-canvas              # core (pure stdlib)
pip install 'renowide-canvas[fastapi]'   # + optional FastAPI router

What's in the box

• renowide_canvas.signing — HMAC-SHA256 canonical-string helpers. Verify inbound canvas fetches (GET /canvas/hire_flow.json) and action webhooks (POST /actions). Raises a structured SignatureVerificationError with a machine-readable .code.
• renowide_canvas.fastapi (optional) — canvas_router() factory that wires the three canvas endpoints into a FastAPI app with full signature verification in one call.

See the full developer guide: Canvas Kit v2 docs.

Minimal example (FastAPI)

import os
from fastapi import FastAPI
from renowide_canvas.fastapi import canvas_router, ActionEvent, CanvasContext

app = FastAPI()

def hire_flow(ctx: CanvasContext) -> dict:
    return {
        "ui_kit_version": "2.0.0",
        "surface": "hire_flow",
        "blocks": [
            {"id": "h", "type": "header", "props": {"text": "Scan a repo", "level": 2}},
            {"id": "repo", "type": "text_input", "props": {"label": "Repo URL", "required": True}},
            {"id": "submit", "type": "action_button", "props": {
                "label": "Run scan", "action": "__submit_hire__",
                "disabled_when": "!form.repo",
            }},
        ],
    }

def post_hire(ctx: CanvasContext) -> dict:
    return {
        "ui_kit_version": "2.0.0",
        "surface": "post_hire",
        "blocks": [
            {"id": "done", "type": "info_callout",
             "props": {"severity": "success", "text": f"Scan complete — hire {ctx.hire_id}"}},
        ],
    }

def on_action(ctx: CanvasContext, event: ActionEvent) -> dict:
    if event.action == "download_report":
        return {"navigate": {"url": "https://cdn/report.pdf", "target": "_blank"}}
    return {"state_patches": []}

app.include_router(canvas_router(
    agent_slug="my-agent",
    handoff_secret=os.environ["RENOWIDE_WEBHOOK_SECRET"],
    hire_flow_handler=hire_flow,
    post_hire_handler=post_hire,
    action_handler=on_action,
))

Minimal example (no FastAPI)

from renowide_canvas.signing import verify_action_request, SignatureVerificationError

def handle_action_webhook(request):
    try:
        verify_action_request(
            handoff_secret=RENOWIDE_WEBHOOK_SECRET,
            headers=dict(request.headers),
            body=request.raw_body,  # bytes, NOT parsed json
        )
    except SignatureVerificationError as exc:
        return 401, {"error": exc.code}
    # ... proceed ...

Error codes

SignatureVerificationError.code is one of:

• missing_header — Renowide-Signature or required timestamp/request-id header absent.
• malformed_header — signature header doesn't match v1=<64-hex>.
• unsupported_version — scheme version other than v1.
• stale_timestamp — |now - ts| > 300 s.
• bad_signature — HMAC mismatch (wrong secret or tampered body/headers).

Map these into HTTP responses as suits your service.

Version matrix

renowide-canvas tracks the same Canvas Kit protocol version as the JS packages. Keep them aligned:

License

MIT © Renowide. See LICENSE.