diff --git a/apps/server/src/preview/Manager.test.ts b/apps/server/src/preview/Manager.test.ts
index 1c16992123206..6d6cdc911a379 100644
--- a/apps/server/src/preview/Manager.test.ts
+++ b/apps/server/src/preview/Manager.test.ts
@@ -229,6 +229,49 @@ it.layer(layer)("PreviewManager", (it) => {
     }),
   );
 
+  it.effect("gives a popup opened from an agent's tab to that agent", () =>
+    Effect.gen(function* () {
+      const threadId = freshThreadId();
+      const manager = yield* PreviewManager.PreviewManager;
+      const opener = yield* manager.open({
+        threadId,
+        url: "http://localhost:8765/popup.html",
+        runtime: "server",
+        automationOwner: "agent-1",
+      });
+
+      const popup = yield* manager.open({
+        threadId,
+        url: "https://example.org/",
+        runtime: "server",
+        openerTabId: opener.tabId,
+      });
+
+      expect(popup.automationOwner).toBe("agent-1");
+    }),
+  );
+
+  it.effect("does not take an owner from an opener in another thread", () =>
+    Effect.gen(function* () {
+      const manager = yield* PreviewManager.PreviewManager;
+      const opener = yield* manager.open({
+        threadId: freshThreadId(),
+        url: "http://localhost:8765/popup.html",
+        runtime: "server",
+        automationOwner: "agent-1",
+      });
+
+      const popup = yield* manager.open({
+        threadId: freshThreadId(),
+        url: "https://example.org/",
+        runtime: "server",
+        openerTabId: opener.tabId,
+      });
+
+      expect(popup.automationOwner).toBeUndefined();
+    }),
+  );
+
   it.effect("close with explicit tabId removes only that tab", () =>
     Effect.gen(function* () {
       const threadId = freshThreadId();
diff --git a/apps/server/src/preview/Manager.ts b/apps/server/src/preview/Manager.ts
index 55156d605a152..46a56531ee4c3 100644
--- a/apps/server/src/preview/Manager.ts
+++ b/apps/server/src/preview/Manager.ts
@@ -178,25 +178,31 @@ export const make = Effect.gen(function* PreviewManagerMake() {
       // Persisted client surfaces must not bind to a different tab after a server restart.
       const tabId = `${newPreviewTabId()}${runtime === "server" ? `_${serverEpoch}` : ""}`;
       const updatedAt = yield* currentIsoTimestamp;
-      const snapshot: PreviewSessionSnapshot = {
-        threadId: input.threadId,
-        tabId,
-        navStatus: input.url
-          ? { _tag: "Loading", url: yield* normalizeUrl(input.url), title: "" }
-          : { _tag: "Idle" },
-        canGoBack: false,
-        canGoForward: false,
-        viewport: input.viewport ?? FILL_PREVIEW_VIEWPORT,
-        ...(input.profileId === undefined ? {} : { profileId: input.profileId }),
-        ...(runtime === undefined ? {} : { runtime }),
-        ...(runtime === "server" && input.automationOwner !== undefined
-          ? { automationOwner: input.automationOwner }
-          : {}),
-        ...(input.reveal === undefined ? {} : { reveal: input.reveal }),
-        updatedAt,
-      };
-      yield* SynchronizedRef.modifyEffect(stateRef, (state) =>
+      const navStatus: PreviewSessionSnapshot["navStatus"] = input.url
+        ? { _tag: "Loading", url: yield* normalizeUrl(input.url), title: "" }
+        : { _tag: "Idle" };
+      return yield* SynchronizedRef.modifyEffect(stateRef, (state) =>
         Effect.gen(function* () {
+          // A popup inherits its opener's owner from this record, never from the client.
+          const automationOwner =
+            input.automationOwner ??
+            (input.openerTabId === undefined
+              ? undefined
+              : state.sessions.get(compositeKey(input.threadId, input.openerTabId))?.snapshot
+                  .automationOwner);
+          const snapshot: PreviewSessionSnapshot = {
+            threadId: input.threadId,
+            tabId,
+            navStatus,
+            canGoBack: false,
+            canGoForward: false,
+            viewport: input.viewport ?? FILL_PREVIEW_VIEWPORT,
+            ...(input.profileId === undefined ? {} : { profileId: input.profileId }),
+            ...(runtime === undefined ? {} : { runtime }),
+            ...(runtime === "server" && automationOwner !== undefined ? { automationOwner } : {}),
+            ...(input.reveal === undefined ? {} : { reveal: input.reveal }),
+            updatedAt,
+          };
           const revision = state.revision + 1;
           const sessions = new Map(state.sessions);
           sessions.set(compositeKey(input.threadId, tabId), {
@@ -217,7 +223,6 @@ export const make = Effect.gen(function* PreviewManagerMake() {
           return [snapshot, { sessions, revision }] as const;
         }),
       );
-      return snapshot;
     },
   );
 
diff --git a/apps/web/src/browser/ElectronBrowserHost.tsx b/apps/web/src/browser/ElectronBrowserHost.tsx
index d71b7a2b6b2ba..1cc9785edbd24 100644
--- a/apps/web/src/browser/ElectronBrowserHost.tsx
+++ b/apps/web/src/browser/ElectronBrowserHost.tsx
@@ -105,6 +105,7 @@ function openLinkInPreview({ tabId, url, background }: DesktopPreviewOpenLinkEve
     url,
     openPreview: (input) => runAtomCommand(appAtomRegistry, previewEnvironment.open, input),
     profileId: source.snapshot.profileId,
+    openerTabId: source.snapshot.tabId,
     background,
   });
 }
diff --git a/apps/web/src/browser/openFileInPreview.ts b/apps/web/src/browser/openFileInPreview.ts
index 109776a091e94..1c65d550f1a6a 100644
--- a/apps/web/src/browser/openFileInPreview.ts
+++ b/apps/web/src/browser/openFileInPreview.ts
@@ -55,6 +55,7 @@ export async function openUrlInPreview<E>(input: {
   readonly url: string;
   readonly openPreview: OpenPreviewMutation<E>;
   readonly profileId?: PreviewOpenInput["profileId"];
+  readonly openerTabId?: PreviewOpenInput["openerTabId"];
   readonly background?: boolean;
 }): Promise<AtomCommandResult<void, E | BrowserSettingsReadError>> {
   const defaults = await resolveBrowserDefaults().catch(
@@ -78,6 +79,7 @@ export async function openUrlInPreview<E>(input: {
       viewport: defaults.viewport,
       profileId: input.profileId ?? defaults.profileId,
       ...(runtime === undefined ? {} : { runtime }),
+      ...(input.openerTabId === undefined ? {} : { openerTabId: input.openerTabId }),
     },
   });
   return mapAtomCommandResult(result, (snapshot) => {
diff --git a/packages/contracts/src/preview.ts b/packages/contracts/src/preview.ts
index cbf8ac60b2690..fe567cc39ebc1 100644
--- a/packages/contracts/src/preview.ts
+++ b/packages/contracts/src/preview.ts
@@ -176,6 +176,7 @@ export const PreviewOpenInput = Schema.Struct({
   profileId: Schema.optional(BrowserProfileId),
   runtime: Schema.optional(PreviewRuntime),
   reveal: Schema.optional(Schema.Boolean),
+  openerTabId: Schema.optional(PreviewTabId),
 });
 export type PreviewOpenInput = typeof PreviewOpenInput.Type;