fix(auth): close the fail-open issuer check and the remaining clear races (#2144)

Copilot review rounds 8 and 9.

- A cached metadata document with no `issuer` was letting every issuer-bound
  token go to its single revocation endpoint. Absence establishes nothing, so
  that is now a mismatch: an issuer-bound grant must match, and only a legacy
  unkeyed grant — which nothing binds to a different authorization server —
  proceeds without the comparison. This was a credential-disclosure risk, not
  just a correctness one.
- The ctx-less grant read was skipped whenever it carried an issuer stamp, on
  the assumption that slot had already been enumerated. If `listIssuers` fails
  there is no enumerated slot behind the stamp, so the one readable grant went
  unrevoked while `clear` deleted it. Both reads now share one issuer+token
  key, and the stamped issuer is retained rather than discarded.
- `AuthTab`'s repeat guard read `clearState`, which is not updated until React
  re-renders, so two `s` events in one input turn both started a clear against
  the same store entry. It is a ref now, set before the call.
- A rejected clear left `ownClearRef` set — `handleClearOAuth` never reached
  its `oauthRevision` bump — so the next unrelated revision was swallowed and
  the failure banner stranded. Cleared on that path.
- The web `clearServerOAuthAndDisconnect` had the staleness the TUI path was
  already fixed for: `isActive`/`inspectorClient` are captured before a
  five-second await, so a switch during it disconnected the session the user
  had just moved to and ran the session-wide cleanup against it. Revalidated
  against `sessionRef` after each await.

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/tui/src/components/AuthTab.tsx

@@ -100,6 +100,13 @@ export function AuthTab({
    * — at which point server A's confirmation must not appear under server B.
    */
   const clearAttemptRef = useRef(0);
+  /**
+   * In-flight lock. A ref, not the `clearState` above: two `s` keypresses
+   * delivered in the same input turn both read the state React last rendered,
+   * so a state-based guard lets both start and race each other over the same
+   * store entry. A ref is set before the call and seen by the second read.
+   */
+  const clearInFlightRef = useRef(false);
   /**
    * Set synchronously when a clear starts, and consumed by the reset effect
    * below. The clear itself bumps `oauthRevision` on its way out, so without
@@ -115,6 +122,7 @@ export function AuthTab({
   // banner: neither belongs to the server now on screen.
   useEffect(() => {
     clearAttemptRef.current++;
+    clearInFlightRef.current = false;
     setClearState("idle");
     setClearFailure(null);
     setLastClearDisconnected(false);
@@ -207,8 +215,9 @@ export function AuthTab({
       } else if (input.toLowerCase() === "s") {
         // Ignore repeats while one is in flight: the second would race the
         // first over the same store entry, and the user cannot see that the
-        // first is still running except by this state.
-        if (clearState === "clearing") return;
+        // first is still running except by the pending line below.
+        if (clearInFlightRef.current) return;
+        clearInFlightRef.current = true;
         const attempt = ++clearAttemptRef.current;
         const attemptServer = serverName;
         setLastClearDisconnected(isLiveConnection);
@@ -222,13 +231,21 @@ export function AuthTab({
           serverNameRef.current === attemptServer;
         void Promise.resolve(onClearOAuth()).then(
           () => {
+            clearInFlightRef.current = false;
             if (current()) setClearState("cleared");
           },
           (err: unknown) => {
+            clearInFlightRef.current = false;
             // A rejection is NOT a revocation failure — those come back as
             // outcomes and are reported through the message line. This is the
             // local clear or the disconnect itself failing, so announcing
             // "OAuth state cleared" here would be a plain lie.
+            //
+            // It also means `handleClearOAuth` never reached its
+            // `oauthRevision` bump, so the marker below has no bump to skip.
+            // Left set, it would swallow the next *unrelated* revision change
+            // and strand this banner after the OAuth state moved on.
+            ownClearRef.current = false;
             if (!current()) return;
             setClearFailure(err instanceof Error ? err.message : String(err));
             setClearState("failed");