diff --git a/apps/web/src/components/ProjectGitHubAccountField.tsx b/apps/web/src/components/ProjectGitHubAccountField.tsx
new file mode 100644
index 000000000000..14cb8c3ede3f
Binary files /dev/null and b/apps/web/src/components/ProjectGitHubAccountField.tsx differ
diff --git a/apps/web/src/components/Sidebar.tsx b/apps/web/src/components/Sidebar.tsx
index 58ca61720848..7b77eb0abee3 100644
--- a/apps/web/src/components/Sidebar.tsx
+++ b/apps/web/src/components/Sidebar.tsx
@@ -22,6 +22,7 @@ import {
   ThreadWorktreeIndicator,
 } from "./ThreadStatusIndicators";
 import { ProjectDefaultAgentField } from "./ProjectDefaultAgentField";
+import { ProjectGitHubAccountField } from "./ProjectGitHubAccountField";
 import { ProjectFavicon } from "./ProjectFavicon";
 import { useAtomValue } from "@effect/atom-react";
 import { autoAnimate } from "@formkit/auto-animate";
@@ -44,6 +45,7 @@ import { restrictToFirstScrollableAncestor, restrictToVerticalAxis } from "@dnd-
 import { CSS } from "@dnd-kit/utilities";
 import {
   type ContextMenuItem,
+  type GitHubAccountRef,
   type ModelSelection,
   ProjectId,
   type ScopedThreadRef,
@@ -1655,7 +1657,7 @@ const SidebarProjectItem = memo(function SidebarProjectItem(props: SidebarProjec
 
         const clicked = await api.contextMenu.show(
           [
-            buildTargetedItem("rename", "Rename"),
+            buildTargetedItem("rename", "Project settings…"),
             buildTargetedItem("grouping", "Group into..."),
             buildTargetedItem("copy-path", "Copy Path"),
             buildTargetedItem("delete", "Remove", {
@@ -2090,6 +2092,26 @@ const SidebarProjectItem = memo(function SidebarProjectItem(props: SidebarProjec
     [updateProject],
   );
 
+  const updateProjectGitHubAccount = useCallback(
+    async (member: SidebarProjectGroupMember, account: GitHubAccountRef | null) => {
+      const result = await updateProject({
+        environmentId: member.environmentId,
+        input: { projectId: member.id, gitHubAccount: account },
+      });
+      if (result._tag === "Failure" && !isAtomCommandInterrupted(result)) {
+        const error = squashAtomCommandFailure(result);
+        toastManager.add(
+          stackedThreadToast({
+            type: "error",
+            title: "Failed to update project GitHub account",
+            description: error instanceof Error ? error.message : "An error occurred.",
+          }),
+        );
+      }
+    },
+    [updateProject],
+  );
+
   const closeProjectGroupingDialog = useCallback(() => {
     setProjectGroupingTarget(null);
     setProjectGroupingSelection("inherit");
@@ -2389,11 +2411,11 @@ const SidebarProjectItem = memo(function SidebarProjectItem(props: SidebarProjec
       >
         <DialogPopup className="max-w-lg">
           <DialogHeader>
-            <DialogTitle>Rename project</DialogTitle>
+            <DialogTitle>Project settings</DialogTitle>
             <DialogDescription>
               {projectRenameTarget
-                ? `Update the title for ${projectRenameTarget.workspaceRoot}.`
-                : "Update the project title."}
+                ? `Rename ${projectRenameTarget.workspaceRoot} and choose which account new threads use.`
+                : "Rename the project and choose which account new threads use."}
             </DialogDescription>
           </DialogHeader>
           <DialogPanel className="space-y-4">
@@ -2426,6 +2448,16 @@ const SidebarProjectItem = memo(function SidebarProjectItem(props: SidebarProjec
                 }}
               />
             ) : null}
+            {projectRenameTarget ? (
+              <ProjectGitHubAccountField
+                idPrefix={`project-agent-${projectRenameTarget.physicalProjectKey}`}
+                environmentId={projectRenameTarget.environmentId}
+                projectId={projectRenameTarget.id}
+                onChange={(account) => {
+                  void updateProjectGitHubAccount(projectRenameTarget, account);
+                }}
+              />
+            ) : null}
           </DialogPanel>
           <DialogFooter>
             <Button variant="outline" onClick={closeProjectRenameDialog}>
diff --git a/apps/web/src/components/SidebarV2.tsx b/apps/web/src/components/SidebarV2.tsx
index 2136aae00181..99df66bb50f8 100644
--- a/apps/web/src/components/SidebarV2.tsx
+++ b/apps/web/src/components/SidebarV2.tsx
@@ -1019,7 +1019,7 @@ function latestTurnDiff(
 const GITHUB_DEFAULT_ACCOUNT_VALUE = "__default__";
 
 function githubAccountValue(account: { readonly host: string; readonly login: string }): string {
-  return `${account.host} ${account.login}`;
+  return `${account.host}\u0000${account.login}`;
 }
 
 // github.com is the overwhelmingly common host, so hide it to keep the label
diff --git a/apps/web/src/components/settings/SettingsPanels.tsx b/apps/web/src/components/settings/SettingsPanels.tsx
index 9bd28763f69c..d656d004ff42 100644
--- a/apps/web/src/components/settings/SettingsPanels.tsx
+++ b/apps/web/src/components/settings/SettingsPanels.tsx
@@ -1759,8 +1759,10 @@ function MultiAccountGuide() {
           </li>
           <li>
             <span className="font-medium text-foreground">Attach an account to a project</span>: in
-            the sidebar, right-click a project → <span className="text-foreground">Project settings</span>{" "}
-            → <span className="text-foreground">Default agent</span>. New threads in that project
+            the sidebar, right-click a project (or open its{" "}
+            <span className="text-foreground">⋯</span> menu) →{" "}
+            <span className="text-foreground">Project settings</span> →{" "}
+            <span className="text-foreground">Default agent</span>. New threads in that project
             start on the account you pick (still overridable per thread).
           </li>
         </ol>
