Add gated native OAuth verification and token exchange

[rgarcia]

Summary

Add a default-off native OAuth consumer without changing MCP hosting, public discovery or existing Clerk/API-key authentication.

• Select native credentials without falling back to Clerk; verify issuer, audience, epoch, signature and authoritative status with pinned configuration.
• Authenticate the configured MCP intermediary to exchange an MCP-audience token for narrower, parent-bound API access. Never forward the native MCP token to the API.
• Recheck native status on every request and cap native streams at a one-minute authorization lease.
• Accept additive service-principal auth-context responses and record bounded compatibility outcomes for retained verification/authorize/token/register paths.
• Reject native protocol credentials sent to the retained TypeScript issuer endpoints.

Deployment order

Depends on kernel/kernel#4236 being deployed first. Keep OAUTH_NATIVE_ENABLED=false until the issuer and test intermediary are configured. No deployment, DNS/discovery change or activation is included. Existing /mcp hosting remains unchanged.

Configuration uses only server-pinned issuer URLs, audiences, public keys, recovery epoch and an explicit intermediary client credential. JWT headers/claims never supply a fetch destination. Native connection context is not cached; independent API authorization still applies on every tool call. The issuer currently closes unsupported delegation/credential-producing API surfaces, so this is not full native tool parity.

Validation

• bunx tsc --noEmit passed.
• 69 focused tests passed across native exchange/lease, auth context, MCP transport and retained token/authorize/register suites.
• Prettier and diff whitespace checks passed.
• No real signed-in client, production issuer, Vercel stream or live telemetry-ingestion acceptance was run. Local native tests use real RSA signatures with mocked authority HTTP responses.

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Project	Deployment	Actions	Updated
mcp	Ready	Preview	Sep 20, 2026 2:50pm UTC

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