From e89bd7796e2dcecaf0c483a795225ed9ec549bbd Mon Sep 17 00:00:00 2001
From: "mr. m" <91018726+mr-cheffy@users.noreply.github.com>
Date: Sun, 30 Aug 2026 00:42:45 +0200
Subject: [PATCH] gh-15154: Fixed stale containers trying to sync across
 devices (gh-15166)

---
 src/zen/spaces/ZenSpaceManager.mjs        | 17 +++++++++++
 src/zen/sync/ZenSpacesSyncApplier.sys.mjs |  1 +
 src/zen/sync/ZenSpacesSyncModel.sys.mjs   | 35 ++++++++++++++++-------
 3 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/src/zen/spaces/ZenSpaceManager.mjs b/src/zen/spaces/ZenSpaceManager.mjs
index 6da584818..8439a1a67 100644
--- a/src/zen/spaces/ZenSpaceManager.mjs
+++ b/src/zen/spaces/ZenSpaceManager.mjs
@@ -156,11 +156,28 @@ class nsZenWorkspaces {
         this._invalidateBookmarkContainers();
       };
       Services.obs.addObserver(observerFunction, "workspace-bookmarks-updated");
+      const onContainerDeleted = subject => {
+        const userContextId = subject?.wrappedJSObject?.userContextId;
+        for (const workspace of this.getWorkspaces()) {
+          if (workspace.containerTabId === userContextId) {
+            workspace.containerTabId = 0;
+            this.saveWorkspace(workspace);
+          }
+        }
+      };
+      Services.obs.addObserver(
+        onContainerDeleted,
+        "contextual-identity-deleted"
+      );
       window.addEventListener("unload", () => {
         Services.obs.removeObserver(
           observerFunction,
           "workspace-bookmarks-updated"
         );
+        Services.obs.removeObserver(
+          onContainerDeleted,
+          "contextual-identity-deleted"
+        );
       });
     }
   }
diff --git a/src/zen/sync/ZenSpacesSyncApplier.sys.mjs b/src/zen/sync/ZenSpacesSyncApplier.sys.mjs
index c1068b25b..e166f5367 100644
--- a/src/zen/sync/ZenSpacesSyncApplier.sys.mjs
+++ b/src/zen/sync/ZenSpacesSyncApplier.sys.mjs
@@ -543,6 +543,7 @@ class nsZenSpacesSyncApplier {
       skipBackgroundNotify: true,
       lazyTabTitle: data.title || undefined,
       userContextId,
+      skipRoute: true,
     });
     // Setting the sync id before the queued TabOpen handler runs makes
     // window sync treat this tab as already replicated.
diff --git a/src/zen/sync/ZenSpacesSyncModel.sys.mjs b/src/zen/sync/ZenSpacesSyncModel.sys.mjs
index 27167bfa9..1e59ff1b6 100644
--- a/src/zen/sync/ZenSpacesSyncModel.sys.mjs
+++ b/src/zen/sync/ZenSpacesSyncModel.sys.mjs
@@ -181,10 +181,18 @@ class nsZenSpacesSyncModel {
     if (!Number.isSafeInteger(id) || id <= 0) {
       return null;
     }
+    const data = this.#data();
+    if (!lazy.ContextualIdentityService.getPublicIdentityFromId(id)) {
+      // A space or tab still pointing at a container that was deleted.
+      if (id in data.containers) {
+        delete data.containers[id];
+        this.#file.saveSoon();
+      }
+      return null;
+    }
     if (id <= BUILTIN_CONTAINER_MAX) {
       return `${BUILTIN_GUID_PREFIX}${id}`;
     }
-    const data = this.#data();
     const existing = data.containers[id];
     if (existing) {
       return existing;
@@ -202,17 +210,27 @@ class nsZenSpacesSyncModel {
     if (typeof guid !== "string" || !guid) {
       return null;
     }
+    const data = this.#data();
+    for (const [id, mapped] of Object.entries(data.containers)) {
+      if (mapped === guid) {
+        const contextId = Number(id);
+        if (lazy.ContextualIdentityService.getPublicIdentityFromId(contextId)) {
+          return contextId;
+        }
+        delete data.containers[id];
+        this.#file.saveSoon();
+        return null;
+      }
+    }
     if (guid.startsWith(BUILTIN_GUID_PREFIX)) {
       const id = Number(guid.slice(BUILTIN_GUID_PREFIX.length));
-      return Number.isSafeInteger(id) && id > 0 && id <= BUILTIN_CONTAINER_MAX
+      return Number.isSafeInteger(id) &&
+        id > 0 &&
+        id <= BUILTIN_CONTAINER_MAX &&
+        lazy.ContextualIdentityService.getPublicIdentityFromId(id)
         ? id
         : null;
     }
-    for (const [id, mapped] of Object.entries(this.#data().containers)) {
-      if (mapped === guid) {
-        return Number(id);
-      }
-    }
     return null;
   }
 
@@ -223,9 +241,6 @@ class nsZenSpacesSyncModel {
    * @param {number} userContextId
    */
   registerContainerGuid(guid, userContextId) {
-    if (guid.startsWith(BUILTIN_GUID_PREFIX)) {
-      return;
-    }
     this.#data().containers[userContextId] = guid;
     this.#file.saveSoon();
   }