feat(auth): revoke OAuth tokens at the authorization server on clear (#2144)

Clearing the Inspector's OAuth state deleted the local copy of the tokens
and stopped there. The access token — and the refresh token, which is
long-lived by design — stayed valid at the authorization server until they
expired on their own, so a day of connect/disconnect iteration left it
holding grants for sessions that ended hours ago. RFC 7009 §1 describes
exactly that case, and nothing in the repo constructed a revocation
request, so a server author implementing `revocation_endpoint` had no way
to exercise it with the tool that exists to exercise this.

core/auth/revocation.ts builds and sends the request; the three clear paths
call it, so the behavior is written once — web's "Clear OAuth state and
disconnect" (both the active and stored-only paths), the TUI's Auth tab,
and the CLI's --relogin. It runs BEFORE the local clear, because the token,
the client credentials and the discovered `revocation_endpoint` all live in
the store the clear is about to empty. The request names the refresh token
when there is one: §2.1 asks the AS to also invalidate the access tokens
issued under the same grant, so one request covers both halves.

Best-effort by construction. Every path returns a TokenRevocationOutcome
rather than throwing: no advertised endpoint means nothing is sent and that
authorization server behaves exactly as before, and a network error, a
non-2xx, a 5s timeout or an unreadable store is reported and nothing more.
Forgetting the tokens is what the user asked for. `lost_authorization_state`
recovery deliberately skips it — it clears a half-finished flow to retry it,
and an authorization that never completed has no grant to revoke.

Client authentication resolves the preregistered slot first, mirroring
BaseOAuthClientProvider.clientInformation; reading only the dynamic slot
would send no authentication for a server configured with `oauth.clientId`.
The Basic credential is byte-identical to the SDK's applyBasicAuth so this
request and the token request cannot present the same secret differently.

Opt out per server with `oauth.revokeOnClear` (default on, only `false`
written to disk) or per CLI run with --no-revoke. Read at clear time rather
than connect time, so toggling needs no reconnect. Turning it off is a
testing affordance: a client that walks away still holding live tokens is a
case a server author may want to reproduce.

test-servers now advertises `revocation_endpoint` and serves POST
/oauth/revoke, faithful on §2.2 (an unknown token is a success) and §2.1
(revoking a refresh token invalidates the access tokens under the same
grant), with oauth-revocation-http.json / oauth-no-revocation-http.json as
showcase configs.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0177mPHAdECD18nLLCTwR5rh
Signed-off-by: cliffhall <cliff@futurescale.com>

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

@@ -156,6 +156,42 @@ describe("ServerSettingsModal", () => {
     );
   });
 
+  // #2144 — same omit-the-default shape as the refresh-token pair above.
+  it("maps the revoke-on-clear opt-out into settings, and back to unset", async () => {
+    const user = userEvent.setup();
+    const onSettingsChange = vi.fn();
+    const { rerender } = renderWithMantine(
+      <ServerSettingsModal
+        opened
+        settings={initialSettings}
+        serverType="streamable-http"
+        isStdio={false}
+        onClose={vi.fn()}
+        onSettingsChange={onSettingsChange}
+      />,
+    );
+    await user.click(screen.getByRole("button", { name: /OAuth Settings/i }));
+    await user.click(screen.getByLabelText("Revoke tokens on clear"));
+    expect(onSettingsChange).toHaveBeenLastCalledWith(
+      expect.objectContaining({ oauthRevokeOnClear: false }),
+    );
+
+    rerender(
+      <ServerSettingsModal
+        opened
+        settings={{ ...initialSettings, oauthRevokeOnClear: false }}
+        serverType="streamable-http"
+        isStdio={false}
+        onClose={vi.fn()}
+        onSettingsChange={onSettingsChange}
+      />,
+    );
+    await user.click(screen.getByLabelText("Revoke tokens on clear"));
+    expect(onSettingsChange).toHaveBeenLastCalledWith(
+      expect.objectContaining({ oauthRevokeOnClear: undefined }),
+    );
+  });
+
   it("maps the selected protocol era into settings (#1626)", async () => {
     const user = userEvent.setup();
     const onSettingsChange = vi.fn();

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

@@ -191,6 +191,8 @@ export function ServerSettingsModal({
       // server that never touched the switch writes no field at all.
       oauthRequestRefreshToken:
         oauth.requestRefreshToken === false ? false : undefined,
+      // #2144: same shape — `undefined` means on, so only the opt-out persists.
+      oauthRevokeOnClear: oauth.revokeOnClear === false ? false : undefined,
     });
   }