6a8f5031be- Fix RESOURCE_MIME_TYPE to match spec: "text/html;profile=mcp-app" - Add CSP field to McpUiSandboxResourceReadyNotification type and schema - Update basic-host to extract and pass CSP metadata from resources - Update sandbox.ts to dynamically inject CSP meta tag into inner iframe - Remove static CSP from sandbox.html (now dynamic based on resource metadata) - Update QR server to use custom read_resource handler for _meta injection - Update requirements.txt to require mcp[cli]>=1.23.3 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude <noreply@anthropic.com>
126 lines
4.2 KiB
Python
126 lines
4.2 KiB
Python
"""
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QR Code MCP Server - Generates QR codes from text
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"""
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import os
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import sys
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import io
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import base64
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from pathlib import Path
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import qrcode
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import uvicorn
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from mcp.server.fastmcp import FastMCP
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from mcp import types
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from starlette.middleware.cors import CORSMiddleware
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WIDGET_URI = "ui://qr-server/widget.html"
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HOST = os.environ.get("HOST", "0.0.0.0") # 0.0.0.0 for Docker compatibility
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PORT = int(os.environ.get("PORT", "3108"))
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mcp = FastMCP("QR Server", port=PORT, stateless_http=True)
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@mcp.tool(meta={"ui/resourceUri": WIDGET_URI})
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def generate_qr(
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text: str,
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box_size: int = 10,
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border: int = 4,
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error_correction: str = "M",
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fill_color: str = "black",
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back_color: str = "white",
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) -> list[types.ImageContent]:
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"""Generate a QR code from text.
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Args:
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text: The text/URL to encode
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box_size: Size of each box in pixels (default: 10)
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border: Border size in boxes (default: 4)
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error_correction: Error correction level - L(7%), M(15%), Q(25%), H(30%)
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fill_color: Foreground color (hex like #FF0000 or name like red)
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back_color: Background color (hex like #FFFFFF or name like white)
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"""
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error_levels = {
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"L": qrcode.constants.ERROR_CORRECT_L,
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"M": qrcode.constants.ERROR_CORRECT_M,
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"Q": qrcode.constants.ERROR_CORRECT_Q,
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"H": qrcode.constants.ERROR_CORRECT_H,
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}
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qr = qrcode.QRCode(
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version=1,
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error_correction=error_levels.get(error_correction.upper(), qrcode.constants.ERROR_CORRECT_M),
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box_size=box_size,
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border=border,
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)
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qr.add_data(text)
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qr.make(fit=True)
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img = qr.make_image(fill_color=fill_color, back_color=back_color)
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buffer = io.BytesIO()
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img.save(buffer, format="PNG")
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b64 = base64.b64encode(buffer.getvalue()).decode()
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return [types.ImageContent(type="image", data=b64, mimeType="image/png")]
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# Register widget resource using FastMCP decorator (returns HTML string)
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@mcp.resource(WIDGET_URI, mime_type="text/html;profile=mcp-app")
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def widget() -> str:
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return Path(__file__).parent.joinpath("widget.html").read_text()
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# Override the read_resource handler to inject _meta into the response
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# This is needed because FastMCP doesn't support custom _meta on resources
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_low_level_server = mcp._mcp_server
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async def _read_resource_with_meta(req: types.ReadResourceRequest):
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"""Custom handler that injects CSP metadata for the widget resource."""
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uri = str(req.params.uri)
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html = Path(__file__).parent.joinpath("widget.html").read_text()
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if uri == WIDGET_URI:
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# NOTE: Must use model_validate with '_meta' key (not 'meta') due to Pydantic alias behavior
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content = types.TextResourceContents.model_validate({
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"uri": WIDGET_URI,
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"mimeType": "text/html;profile=mcp-app",
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"text": html,
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# IMPORTANT: all the external domains used by app must be listed
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# in the _meta.ui.csp.resourceDomains - otherwise they will be blocked by CSP policy
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"_meta": {"ui": {"csp": {"resourceDomains": ["https://unpkg.com"]}}}
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})
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return types.ServerResult(
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types.ReadResourceResult(contents=[content])
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)
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# Fallback for other resources (shouldn't happen for this server)
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return types.ServerResult(
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types.ReadResourceResult(
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contents=[
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types.TextResourceContents(
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uri=uri,
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mimeType="text/plain",
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text="Resource not found"
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)
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]
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)
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)
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# Replace the handler after FastMCP has registered its own
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_low_level_server.request_handlers[types.ReadResourceRequest] = _read_resource_with_meta
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if __name__ == "__main__":
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if "--stdio" in sys.argv:
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# Claude Desktop mode
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mcp.run(transport="stdio")
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else:
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# HTTP mode for basic-host (default) - with CORS
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app = mcp.streamable_http_app()
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app.add_middleware(
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CORSMiddleware,
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allow_origins=["*"],
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allow_methods=["*"],
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allow_headers=["*"],
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)
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print(f"QR Server listening on http://{HOST}:{PORT}/mcp")
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uvicorn.run(app, host=HOST, port=PORT)
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