LangSmith Sandbox Auth Proxy
LangSmith's auth proxy is the sandbox credential and egress boundary: agent code can call external APIs without seeing the underlying secrets, while the platform controls which destinations the sandbox can reach.
Why It Matters
The LangChain bookmark names a specific production boundary: code generated by an agent should be able to use OpenAI, Anthropic, GitHub, AWS, GCP, or customer APIs without placing real credentials in files, environment variables, shell history, or logs. LangSmith implements that with a proxy sidecar that injects headers or cloud-provider auth on outbound requests from the sandbox. Source: LangSmith auth proxy docs, 2026-07-04; Source: X/@LangChain, 2026-05-21
The same proxy_config owns network policy. With no explicit access_control, HTTP and HTTPS are allowed while raw TCP ports are blocked; an allow list flips HTTP/S into default-deny and can open specific non-HTTP ports such as a database host on 5432. That makes the feature both a credential injector and an egress policy surface, not only a secret store. Source: LangSmith auth proxy docs, 2026-07-04
Security Model
Use this as the LangChain/LangSmith example for the Agent Security Model authority layer:
- keep real secrets in workspace secrets, opaque proxy values, or application-managed callbacks;
- inject credentials at request time instead of writing them into the sandbox;
- use allow lists when an agent should only reach known hosts;
- refresh short-lived credentials, such as GitHub App installation tokens, when reusing a sandbox;
- still pair the proxy with context/package scanning, because hiding credentials does not prove that the code or destination is trustworthy.
The comparison to Dedalus Auth and Vercel Connect is direct: all three are credential-boundary products for agent apps. LangSmith's flavor is sandbox-local outbound auth and egress policy; DAuth is Dedalus's multi-tenant MCP credential boundary; Vercel Connect is an account-linking and connector-token surface for Vercel-hosted agents.
Version Snapshot
The auth proxy is a hosted LangSmith Sandbox feature, so there is no separate public package version for the proxy itself. Primary source authority is the LangSmith sandbox-auth-proxy documentation, checked on 2026-07-04.
Related package snapshot: langsmith on npm was 0.7.15 (latest) and langchain was 1.5.2 (latest) on 2026-07-04. These packages are not the proxy's feature version, but they indicate the current LangChain/LangSmith JavaScript package surface around the docs. Source: npm registry, 2026-07-04
Timeline
- 2026-07-04 | Created from the LangChain Auth Proxy bookmark and current LangSmith docs. Promoted as an agent-sandbox credential and egress-control boundary, not as a generic replacement for context/package security. Source: X/@LangChain, 2026-05-21; Source: LangSmith docs, 2026-07-04