feat(mcp): MPP payment sessions + execute_code tool#27
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Add Machine Payments Protocol (MPP) support to the MCP worker so agents can pay via Tempo stablecoins (USDC) and execute code without a human account. New MCP tool: execute_code — sandboxed JS execution via Dynamic Workers (worker_loaders). Agents pay $0.01 per execution using MPP session protocol. Code runs in V8 isolate with no outbound HTTP, no host secrets, 50ms CPU limit. Architecture: - ComputeSession Durable Object for session balance tracking - mppx SDK with Transport.mcp() handles payment challenges/receipts - MPP pseudo-auth bypass lets unauthenticated agents reach execute_code - Auth guard on stage_file/list_staged_files prevents KV tampering - WorkerEntrypoint wrapper for correct Dynamic Workers contract Also adds mpp-api template for deploying paid AI APIs with MPP, and removes mpp-compute template (replaced by platform primitive).
- Add receipt check in chargeSession — reject if DO returns 200 without a valid payment receipt (prevents free execution bypass) - Import err() in server.ts so requireAuth works for stage_file guard
The mppx handler returns a wrapper with .status/.challenge/.withReceipt, not a raw JSON-RPC response. Fix to check result.status === 402 and use result.withReceipt() to materialize receipts. Use explicit "tempo/session" key and add jsonrpc field to input.
Add /mcp/public endpoint that bypasses OAuth for MPP-paying agents. Inject Accept header for MCP SDK compatibility since tempo/mppx clients don't send it.
The MCP transport uses JSON-RPC error codes for payment challenges, which HTTP payment clients (tempo request, mppx) can't parse. Add a direct HTTP /execute endpoint that returns standard 402 + WWW-Authenticate headers. Same Dynamic Workers execution, HTTP transport for payments. Routes: - /execute — HTTP clients (tempo request, mppx, curl) - /mcp/public — MCP clients without OAuth (future) - /mcp — authenticated MCP clients (Claude, Cursor)
7 tasks
Static file at docs.getjack.org/SKILL.md that tells agents how to use Jack Cloud's /execute endpoint with tempo request. Follows the same pattern as tempo.xyz/SKILL.md — agents read it and know how to pay and run code.
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Summary
execute_codeMCP tool: sandboxed JS execution via Dynamic Workers ($0.01/call)mpp-apitemplate for deploying paid AI APIs with MPPmpp-computetemplate (replaced by platform primitive)Architecture
Test plan
worker_loaders,COMPUTE_SESSIONDO)MPP_SECRET_KEY,TEMPO_RECIPIENTexecute_codereturns 402 payment challenge for unauthenticated callsstage_filerejects MPP-only authtempo request