feat(auth): per-server authorization and token URL overrides

Adds two optional per-server fields — `oauth.authorizationUrl` and
`oauth.tokenUrl` — that override the endpoints authorization-server
metadata discovery resolved, so a server can be pointed at a development
or staging authorization server without changing what it advertises.

SDK v2 routes both endpoints through the discovered metadata document and
neither through OAuthClientProvider, so the override is applied by
wrapping the client's base fetch and patching the metadata document in
flight (core/auth/endpointOverrides.ts). Wrapping the base fetch — rather
than only the auth fetch — also covers the discovery the SDK runs from
inside the transport on the 401/refresh path.

The fields round-trip through mcp.json, the /api/servers routes, the
runner (CLI/TUI), and the Server Settings → Authorization panel, where a
value that is not an absolute http(s) URL is flagged inline; at runtime
such a value is dropped with a single warning rather than failing the
connection.

Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/components/groups/ServerSettingsForm/ServerSettingsForm.test.tsx

@@ -701,6 +701,8 @@ describe("ServerSettingsForm", () => {
       clientSecret: "",
       scopes: "",
       authorizationParams: [],
+      authorizationUrl: "",
+      tokenUrl: "",
       enterpriseManaged: false,
     });
   });
@@ -966,6 +968,76 @@ describe("ServerSettingsForm", () => {
     expect(screen.getByText(/state, scope are set/)).toBeInTheDocument();
   });
 
+  // #1906 — the endpoint overrides ride the same `onOAuthChange` callback as
+  // the rest of the Authorization section.
+  it("invokes onOAuthChange when an endpoint override is typed", async () => {
+    const user = userEvent.setup();
+    const onOAuthChange = vi.fn();
+    renderWithMantine(
+      <ServerSettingsForm
+        {...baseHandlers}
+        onOAuthChange={onOAuthChange}
+        settings={emptySettings}
+        expandedSections={["oauth"]}
+      />,
+    );
+    await user.type(
+      screen.getByRole("textbox", { name: /Authorization URL override/i }),
+      "h",
+    );
+    expect(onOAuthChange).toHaveBeenCalledWith(
+      expect.objectContaining({ authorizationUrl: "h" }),
+    );
+
+    onOAuthChange.mockClear();
+    await user.type(
+      screen.getByRole("textbox", { name: /Token URL override/i }),
+      "h",
+    );
+    expect(onOAuthChange).toHaveBeenCalledWith(
+      expect.objectContaining({ tokenUrl: "h" }),
+    );
+  });
+
+  it("flags an endpoint override that is not an absolute http(s) URL", () => {
+    renderWithMantine(
+      <ServerSettingsForm
+        {...baseHandlers}
+        settings={{
+          ...emptySettings,
+          oauthAuthorizationUrl: "/authorize",
+          oauthTokenUrl: "https://staging.test/token",
+        }}
+        expandedSections={["oauth"]}
+      />,
+    );
+    expect(
+      screen.getByText('"/authorize" is not an absolute URL.'),
+    ).toBeInTheDocument();
+    expect(screen.queryByText(/is not an http\(s\) URL/)).toBeNull();
+  });
+
+  it("clears an endpoint override through its clear button", async () => {
+    const user = userEvent.setup();
+    const onOAuthChange = vi.fn();
+    renderWithMantine(
+      <ServerSettingsForm
+        {...baseHandlers}
+        onOAuthChange={onOAuthChange}
+        settings={{
+          ...emptySettings,
+          oauthTokenUrl: "https://staging.test/token",
+        }}
+        expandedSections={["oauth"]}
+      />,
+    );
+    const clearButtons = screen.getAllByRole("button", { name: /clear/i });
+    await user.click(clearButtons[clearButtons.length - 1]);
+    expect(onOAuthChange).toHaveBeenCalledWith(
+      expect.objectContaining({ tokenUrl: "" }),
+    );
+  });
+
   it("invokes onOAuthChange with the chosen insufficient-scope policy (SEP-2350)", async () => {
     const user = userEvent.setup();
     const onOAuthChange = vi.fn();
@@ -1007,6 +1079,8 @@ describe("ServerSettingsForm", () => {
       clientSecret: "",
       scopes: "",
       authorizationParams: [],
+      authorizationUrl: "",
+      tokenUrl: "",
       enterpriseManaged: true,
     });
   });
@@ -1112,6 +1186,8 @@ describe("ServerSettingsForm", () => {
       clientSecret: "z",
       scopes: "",
       authorizationParams: [],
+      authorizationUrl: "",
+      tokenUrl: "",
       enterpriseManaged: false,
     });
   });

clients/web/src/components/groups/ServerSettingsForm/ServerSettingsForm.tsx

@@ -32,6 +32,7 @@ import {
   authorizationParamKeyError,
   isReservedAuthorizationParam,
 } from "@inspector/core/auth/authorizationParams.js";
+import { oauthEndpointUrlError } from "@inspector/core/auth/endpointOverrides.js";
 import { ADVERTISABLE_EXTENSIONS } from "@inspector/core/mcp/extensions.js";
 import type { Root } from "@modelcontextprotocol/client";
 
@@ -478,6 +479,8 @@ export function ServerSettingsForm({
       clientSecret: settings.oauthClientSecret ?? "",
       scopes: settings.oauthScopes ?? "",
       authorizationParams,
+      authorizationUrl: settings.oauthAuthorizationUrl ?? "",
+      tokenUrl: settings.oauthTokenUrl ?? "",
       enterpriseManaged: settings.enterpriseManaged ?? false,
       onInsufficientScope: settings.oauthOnInsufficientScope,
     };
@@ -863,6 +866,55 @@ export function ServerSettingsForm({
                   + Add Parameter
                 </AddButton>
               </Stack>
+              <ClearableTextInput
+                label="Authorization URL override"
+                description="Leave blank to use the authorization_endpoint the authorization server's metadata advertises. Set it to point this server at a development or staging authorization server instead."
+                placeholder="https://staging.auth.example.com/authorize"
+                value={settings.oauthAuthorizationUrl ?? ""}
+                error={oauthEndpointUrlError(
+                  settings.oauthAuthorizationUrl ?? "",
+                )}
+                onChange={(e) =>
+                  onOAuthChange({
+                    ...currentOAuth(),
+                    authorizationUrl: e.currentTarget.value,
+                  })
+                }
+                rightSection={
+                  settings.oauthAuthorizationUrl ? (
+                    <ClearButton
+                      onClick={() =>
+                        onOAuthChange({
+                          ...currentOAuth(),
+                          authorizationUrl: "",
+                        })
+                      }
+                    />
+                  ) : null
+                }
+              />
+              <ClearableTextInput
+                label="Token URL override"
+                description="Leave blank to use the token_endpoint the authorization server's metadata advertises. Independent of the authorization URL — either can be overridden alone."
+                placeholder="https://staging.auth.example.com/token"
+                value={settings.oauthTokenUrl ?? ""}
+                error={oauthEndpointUrlError(settings.oauthTokenUrl ?? "")}
+                onChange={(e) =>
+                  onOAuthChange({
+                    ...currentOAuth(),
+                    tokenUrl: e.currentTarget.value,
+                  })
+                }
+                rightSection={
+                  settings.oauthTokenUrl ? (
+                    <ClearButton
+                      onClick={() =>
+                        onOAuthChange({ ...currentOAuth(), tokenUrl: "" })
+                      }
+                    />
+                  ) : null
+                }
+              />
               <Select
                 label="Insufficient-scope response"
                 description="On a 403 insufficient_scope challenge (SEP-2350): re-authorize with the accumulated scope union, or surface the error to you."