fix(app): reuse open project root for nested folders

packages/app/src/context/layout.tsx

@@ -11,6 +11,7 @@ import { decode64 } from "@/utils/base64"
 import { same } from "@/utils/same"
 import { createScrollPersistence, type SessionScroll } from "./layout-scroll"
 import { createPathHelpers } from "./file/path"
+import { containingWorkspaceRoot } from "@/pages/layout/helpers"
 
 const AVATAR_COLOR_KEYS = ["pink", "mint", "orange", "purple", "cyan", "lime"] as const
 const DEFAULT_PANEL_WIDTH = 344
@@ -437,8 +438,6 @@ export const { use: useLayout, provider: LayoutProvider } = createSimpleContext(
 
     const rootFor = (directory: string) => {
       const map = roots()
-      if (map.size === 0) return directory
-
       const visited = new Set<string>()
       const chain = [directory]
 
@@ -447,7 +446,14 @@ export const { use: useLayout, provider: LayoutProvider } = createSimpleContext(
         if (!current) return directory
 
         const next = map.get(current)
-        if (!next) return current
+        if (!next) {
+          return (
+            containingWorkspaceRoot(
+              current,
+              server.projects.list().map((project) => project.worktree),
+            ) ?? current
+          )
+        }
 
         if (visited.has(next)) return directory
         visited.add(next)

packages/app/src/pages/layout.tsx

@@ -59,6 +59,7 @@ import { Titlebar } from "@/components/titlebar"
 import { useServer } from "@/context/server"
 import { useLanguage, type Locale } from "@/context/language"
 import {
+  containingWorkspaceRoot,
   displayName,
   effectiveWorkspaceOrder,
   errorMessage,
@@ -1127,6 +1128,12 @@ export default function Layout(props: ParentProps) {
   }
 
   function projectRoot(directory: string) {
+    const openRoot = containingWorkspaceRoot(
+      directory,
+      layout.projects.list().map((item) => item.worktree),
+    )
+    if (openRoot) return openRoot
+
     const project = layout.projects
       .list()
       .find((item) => item.worktree === directory || item.sandboxes?.includes(directory))

packages/app/src/pages/layout/helpers.test.ts

@@ -6,9 +6,17 @@ import {
   parseDeepLink,
   parseNewSessionDeepLink,
 } from "./deep-links"
-import { displayName, errorMessage, getDraggableId, syncWorkspaceOrder, workspaceKey } from "./helpers"
+import {
+  containingWorkspaceRoot,
+  displayName,
+  errorMessage,
+  getDraggableId,
+  hasProjectPermissions,
+  latestRootSession,
+  syncWorkspaceOrder,
+  workspaceKey,
+} from "./helpers"
 import { type Session } from "@opencode-ai/sdk/v2/client"
-import { hasProjectPermissions, latestRootSession } from "./helpers"
 
 const session = (input: Partial<Session> & Pick<Session, "id" | "directory">) =>
   ({
@@ -109,6 +117,15 @@ describe("layout workspace helpers", () => {
     expect(workspaceKey("C:///")).toBe("C:/")
   })
 
+  test("finds the deepest containing workspace root", () => {
+    expect(containingWorkspaceRoot("/repo/packages/app", ["/repo", "/repo/packages"]))
+      .toBe("/repo/packages")
+  })
+
+  test("does not match sibling workspace prefixes", () => {
+    expect(containingWorkspaceRoot("/repo-two/nested", ["/repo"])).toBeUndefined()
+  })
+
   test("keeps local first while preserving known order", () => {
     const result = syncWorkspaceOrder("/root", ["/root", "/b", "/c"], ["/root", "/c", "/a", "/b"])
     expect(result).toEqual(["/root", "/c", "/b"])

packages/app/src/pages/layout/helpers.ts

@@ -8,6 +8,24 @@ export const workspaceKey = (directory: string) => {
   return directory.replace(/[\\/]+$/, "")
 }
 
+function comparableWorkspaceKey(directory: string) {
+  return workspaceKey(directory).replaceAll("\\", "/")
+}
+
+function containsWorkspace(parent: string, child: string) {
+  const parentKey = comparableWorkspaceKey(parent)
+  const childKey = comparableWorkspaceKey(child)
+  if (parentKey === childKey) return true
+  if (parentKey === "/") return childKey.startsWith("/")
+  return childKey.startsWith(parentKey.endsWith("/") ? parentKey : `${parentKey}/`)
+}
+
+export function containingWorkspaceRoot(directory: string, roots: string[]) {
+  return [...roots]
+    .sort((a, b) => comparableWorkspaceKey(b).length - comparableWorkspaceKey(a).length)
+    .find((root) => containsWorkspace(root, directory))
+}
+
 export function sortSessions(now: number) {
   const oneMinuteAgo = now - 60 * 1000
   return (a: Session, b: Session) => {