diff --git a/web/src/attach.ts b/web/src/attach.ts
index 3886680..a99734e 100644
--- a/web/src/attach.ts
+++ b/web/src/attach.ts
@@ -65,9 +65,17 @@ export interface AttachOptions {
    *  dropped — but NOT on an intentional `dispose()` (eviction / user close). The
    *  shell uses this to auto-close the pane rather than leave a dead one. */
   onClosed?: (sessionId: Uuid) => void;
+  /** Invoked when the handshake itself never completed — no retry was
+   *  attempted (see `shouldReconnect`'s `everOpened`). Unlike `onClosed`, this
+   *  is not "the session is gone": it is at least as likely a dormant
+   *  session's `409 not_attachable` caught mid-status-update (#168 review).
+   *  The shell re-renders rather than tearing the pane's leaf out, so a
+   *  dormant session's resume affordance can take over in place. */
+  onNeverAttached?: (sessionId: Uuid) => void;
   /** Asked on every close: should the socket be retried? The shell answers
-   *  from the catalog — see `shouldRetryClose`. */
-  shouldReconnect?: (sessionId: Uuid, code: number) => boolean;
+   *  from the catalog — see `shouldRetryClose`. `everOpened` is false when
+   *  this attempt never reached `open`. */
+  shouldReconnect?: (sessionId: Uuid, code: number, everOpened: boolean) => boolean;
 }
 
 /** What the header shows about the session (name / command). Optional — falls
@@ -379,6 +387,10 @@ export function createAttachConnection(
   let ws: WebSocket;
   let reconnectMs = INITIAL_RECONNECT_MS;
   let reconnectTimer: number | null = null;
+  // #168 review: a fresh attempt that never reaches `open` is a rejected
+  // handshake (dormant/unknown session), not a dropped stream — see
+  // `shouldRetryClose`'s `everOpened` param.
+  let everOpened = false;
 
   const sendControl = (msg: ClientControl) => {
     if (ws.readyState !== WebSocket.OPEN) return;
@@ -402,6 +414,7 @@ export function createAttachConnection(
     ws.binaryType = "arraybuffer";
 
     ws.onopen = () => {
+      everOpened = true;
       reconnectMs = INITIAL_RECONNECT_MS;
       setState("connected", "open");
       sendControl({ type: "Resize", cols: term.cols, rows: term.rows });
@@ -444,7 +457,7 @@ export function createAttachConnection(
       // close handle their own pane teardown.
       if (disposed) return;
 
-      if (opts.shouldReconnect?.(sessionId, ev.code)) {
+      if (opts.shouldReconnect?.(sessionId, ev.code, everOpened)) {
         const delay = Math.min(reconnectMs, MAX_RECONNECT_MS);
         setState("reconnecting…", "connecting");
         reconnectTimer = window.setTimeout(() => {
@@ -455,6 +468,12 @@ export function createAttachConnection(
         return;
       }
 
+      if (!everOpened) {
+        setState("not attached", "closed");
+        opts.onNeverAttached?.(sessionId);
+        return;
+      }
+
       setState(`closed (${ev.code})`, "closed");
       opts.onClosed?.(sessionId);
     };
diff --git a/web/src/connections.ts b/web/src/connections.ts
index 1f17afe..22c0ffa 100644
--- a/web/src/connections.ts
+++ b/web/src/connections.ts
@@ -25,8 +25,13 @@ export interface PoolOptions {
   /** Fired when a connection's socket closes on its own (session ended/dropped),
    *  not via an intentional close/eviction. The embedder closes the pane. */
   onClosed?: (id: Uuid) => void;
+  /** Fired when a connection's handshake never completed and so was never
+   *  retried (see `AttachOptions.onNeverAttached`). Unlike `onClosed`, the
+   *  embedder should not assume the session is gone — a dormant session's
+   *  pane wants its resume affordance, not teardown. */
+  onNeverAttached?: (id: Uuid) => void;
   /** Forwarded to each connection: should a dropped socket be retried? */
-  shouldReconnect?: (id: Uuid, code: number) => boolean;
+  shouldReconnect?: (id: Uuid, code: number, everOpened: boolean) => boolean;
 }
 
 /**
@@ -85,7 +90,9 @@ export class ConnectionPool {
         {
           onRequestClose: (sid) => this.opts.onRequestClose?.(sid),
           onClosed: (sid) => this.opts.onClosed?.(sid),
-          shouldReconnect: (sid, code) => this.opts.shouldReconnect?.(sid, code) ?? false,
+          onNeverAttached: (sid) => this.opts.onNeverAttached?.(sid),
+          shouldReconnect: (sid, code, everOpened) =>
+            this.opts.shouldReconnect?.(sid, code, everOpened) ?? false,
         },
         info,
       );
diff --git a/web/src/reconnect.test.ts b/web/src/reconnect.test.ts
index e885201..b4f296c 100644
--- a/web/src/reconnect.test.ts
+++ b/web/src/reconnect.test.ts
@@ -47,6 +47,13 @@ describe("shouldRetryClose", () => {
   it("never retries a clean close", () => {
     expect(shouldRetryClose("a", 1000, running)).toBe(false);
   });
+
+  // #168 review: a handshake that never opened is a rejection (e.g. a
+  // dormant session's 409 not_attachable), not a dropped stream. Retrying it
+  // loops forever if the catalog status hasn't caught up yet.
+  it("never retries a socket that never opened, even if the catalog still says running", () => {
+    expect(shouldRetryClose("a", 1006, running, false)).toBe(false);
+  });
 });
 
 describe("backoff bounds", () => {
diff --git a/web/src/reconnect.ts b/web/src/reconnect.ts
index 14624a0..2457ad9 100644
--- a/web/src/reconnect.ts
+++ b/web/src/reconnect.ts
@@ -26,7 +26,15 @@ export function shouldRetryClose(
   sessionId: Uuid,
   code: number,
   sessions: ReadonlyMap<Uuid, Session>,
+  /** Did this socket ever reach `open`? A handshake that never completed is
+   *  the daemon rejecting the attach (dormant/unknown) rather than a dropped
+   *  stream — retrying it spins in place until the catalog updates, which for
+   *  a dormant session it never will (#168 review). Defaults to `true` so
+   *  existing callers that only track drops of an established link are
+   *  unaffected. */
+  everOpened = true,
 ): boolean {
   if (code >= APPLICATION_CLOSE || code === CLEAN_CLOSE) return false;
+  if (!everOpened) return false;
   return sessions.get(sessionId)?.status === "Running";
 }