refactor(mcp): rename oauth/ to outbound_credentials/

The subdomain resolves every egress credential mode (api_key, none, aws_sigv4, passthrough),
not just OAuth grants, so outbound_credentials names it accurately. Pure rename: relative
imports are unaffected; the spike import, the absolute test imports, and the path mentions in
the module/README docstrings are updated. The RFC 8693 token-type URN is left untouched.

litellm/proxy/gateway/mcp/README.md

@@ -6,7 +6,7 @@ security code is v2-shaped from line one instead of rewritten when the full S0 c
 Phase 2. It imports nothing from v1; v1 will only ever reach it through a thin adapter built in
 Phase 1.
 
-Scope is deliberately small: the typed credential seam (`oauth/types.py`), the vendored `Result`
+Scope is deliberately small: the typed credential seam (`outbound_credentials/types.py`), the vendored `Result`
 (`result.py`), and the basedpyright match-exhaustiveness spike (`_spike_exhaustiveness.py`). No
 transport, registry, CI gate, semgrep rules, import-linter layers, LOC caps, or composition root;
 those land with the full S0 in Phase 2.

litellm/proxy/gateway/mcp/__init__.py

@@ -4,7 +4,7 @@ Written v2-native: nothing here imports from v1 (the rest of
 `litellm.proxy._experimental.mcp_server.*`). v1 only ever reaches v2 through a thin
 adapter built in Phase 1, never the other way round.
 
-Phase 0 scope = the typed OAuth-credential seam only (`oauth/types.py`), the vendored
+Phase 0 scope = the typed OAuth-credential seam only (`outbound_credentials/types.py`), the vendored
 `Result` (`result.py`), and the basedpyright match-exhaustiveness spike
 (`_spike_exhaustiveness.py`). No transport, registry, or CI/semgrep/composition-root
 infrastructure — those land in Phase 2 (S0).

litellm/proxy/gateway/mcp/_spike_exhaustiveness.py

@@ -6,7 +6,7 @@ the bet HOLDS, with two non-obvious rules taken from the sibling v2 package `lit
 
 Two `match` shapes are exhaustiveness-checked and are the only ones we use:
 
-  (A) `match` over a closed `Enum`  -> what `resolve()` dispatches on (`oauth/types.py`).
+  (A) `match` over a closed `Enum`  -> what `resolve()` dispatches on (`outbound_credentials/types.py`).
   (B) `match self.tag` over an Expression `@tagged_union` whose `tag` is a `Literal`
       -> what `CredError` uses for its `summary`.
 
@@ -25,7 +25,7 @@ from __future__ import annotations
 
 from typing_extensions import assert_never
 
-from .oauth.types import AuthSpecKind, CredError
+from .outbound_credentials.types import AuthSpecKind, CredError
 
 
 # (A) Enum dispatch — the load-bearing case (`resolve()` uses exactly this shape).

tests/mcp_tests/gateway/test_upstream_credentials.py

@@ -8,15 +8,15 @@ import httpx
 import pytest
 from pydantic import ValidationError
 
-from litellm.proxy.gateway.mcp.oauth.credential_store import (
+from litellm.proxy.gateway.mcp.outbound_credentials.credential_store import (
     CredentialKey,
     InMemoryCredentialStore,
 )
-from litellm.proxy.gateway.mcp.oauth.httpx_auth import (
+from litellm.proxy.gateway.mcp.outbound_credentials.httpx_auth import (
     NoOpAuth,
     StaticHeaderAuth,
 )
-from litellm.proxy.gateway.mcp.oauth.types import (
+from litellm.proxy.gateway.mcp.outbound_credentials.types import (
     ApiKeyConfig,
     AuthSpecKind,
     NoneConfig,
@@ -26,7 +26,7 @@ from litellm.proxy.gateway.mcp.oauth.types import (
     SharedKey,
     Subject,
 )
-from litellm.proxy.gateway.mcp.oauth.upstream_credentials import (
+from litellm.proxy.gateway.mcp.outbound_credentials.upstream_credentials import (
     UpstreamCredentialProvider,
 )
 from litellm.proxy.gateway.mcp.result import Error, Ok