@nanoseil/nsid-mcp-auth

Local stdio credential broker for Nanoseil MCP services. It keeps the Nanoseil Identity API key outside Claude/Codex configuration and forwards MCP JSON-RPC to one exact, built-in production endpoint.

Requirements

• Node.js 20.12 or newer
• macOS, Linux, or WSL for P0. Native Windows invocation is not yet verified.

Create an identity explicitly

npx -y @nanoseil/nsid-mcp-auth@0.1.0-next.0 identity create

By default the identity lives at ~/.nanoseil/agent/identities/<sha256(cwd)[:32]>.json, matching the existing NSOS identity contract. The exact cwd string is hashed without realpath or case normalization. A different checkout, symlink path, or container path can therefore select a different identity. The directory is mode 0700 and files are written atomically with mode 0600.

--profile or NSID_PROFILE remains an explicit override; normal use does not require it.

P0 supports only the canonical default identity directory above.

• NANOSEIL_IDENTITY_DIR is not consumed by the broker.
• NSID_IDENTITY_FILE is not consumed by the broker.
• An nsos-codex proxy launch must fail before starting the broker when either legacy path override is active. Direct mode remains the rollback path.

Supporting an override later requires canonical-root containment and cwd-key validation; the broker will not accept an arbitrary identity file path.

The broker never creates a replacement identity after a 401. Repair or create a profile explicitly instead.

Run as an MCP stdio server

npx -y @nanoseil/nsid-mcp-auth@0.1.0-next.0 --server nsos

The production allowlist is exact:

• https://nsos.nanoseil.com/mcp
• https://islands.nanoseil.com/mcp (canonical URL confirmed; disabled pending deployment and three-point smoke)

The Islands alias fails closed before sending a credential while disabled. It is not part of the active production allowlist. Arbitrary URLs and redirects are rejected. Client-provided credentials are not forwarded; only the broker adds the profile's Bearer credential.

Generate client configuration

The command displays the proposed entry and prompts before changing a file. Use --yes only after reviewing it.

npx -y @nanoseil/nsid-mcp-auth@0.1.0-next.0 setup claude --server nsos
npx -y @nanoseil/nsid-mcp-auth@0.1.0-next.0 setup codex --server nsos

Claude updates ~/.claude.json without replacing unrelated mcpServers. Codex updates a marked table in ~/.codex/config.toml. Re-running setup is idempotent. Before changing an existing file it writes a timestamped mode-0600 .bak backup. Neither output contains a token.

Security model

• API keys never belong in argv, client config, logs, errors, or telemetry.
• Redirects and arbitrary upstream URLs are disabled.
• A profile is isolated from another profile, and each upstream gets its own MCP session in its own broker process.
• 401/403 stops the credential; upstream 5xx/timeouts fail closed and may be retried by the MCP client.

Publishing is intentionally separate from building and packing. Do not run npm publish until the operator gives an explicit release approval.