diff --git a/.changeset/fix-web-add-workspace-invalid-path.md b/.changeset/fix-web-add-workspace-invalid-path.md
new file mode 100644
index 000000000..db33a2a52
--- /dev/null
+++ b/.changeset/fix-web-add-workspace-invalid-path.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Fix adding a workspace by path in the web UI failing silently when the daemon rejects the path; it now shows an error instead of a broken workspace.
diff --git a/apps/kimi-web/src/App.vue b/apps/kimi-web/src/App.vue
index 8b43e4936..f4b687197 100644
--- a/apps/kimi-web/src/App.vue
+++ b/apps/kimi-web/src/App.vue
@@ -244,6 +244,10 @@ type SubmitPayload = {
   attachments: { fileId: string; kind: 'image' | 'video' }[];
 };
 const pendingWorkspaceSubmit = ref<SubmitPayload | null>(null);
+// Inline error shown inside the add-workspace picker after the daemon rejects
+// a path. Kept separate from the global toast so the feedback is visible above
+// the picker's backdrop and persists until the user retries or closes.
+const addWorkspaceError = ref<string | null>(null);
 
 // Any of these modal/overlay layers, when open, owns Escape. The global
 // capture-phase handler must NOT close a background side panel out from under an
@@ -483,8 +487,17 @@ async function handleSubmit(payload: SubmitPayload): Promise<void> {
 }
 
 async function handleAddWorkspace(root: string): Promise<void> {
+  addWorkspaceError.value = null;
+  const added = await client.addWorkspaceByPath(root);
+  // Keep the picker open (and the pending submission intact) when the daemon
+  // rejects the path so the user can retry with a valid one. The error is shown
+  // inline in the picker. Closing via Escape goes through handleCloseAddWorkspace,
+  // which drops the pending prompt.
+  if (!added) {
+    addWorkspaceError.value = t('workspace.addFailed');
+    return;
+  }
   showAddWorkspace.value = false;
-  await client.addWorkspaceByPath(root);
   const pending = pendingWorkspaceSubmit.value;
   pendingWorkspaceSubmit.value = null;
   const wsId = client.activeWorkspaceId.value;
@@ -495,6 +508,7 @@ async function handleAddWorkspace(root: string): Promise<void> {
 
 function handleCloseAddWorkspace(): void {
   pendingWorkspaceSubmit.value = null;
+  addWorkspaceError.value = null;
   showAddWorkspace.value = false;
 }
 
@@ -881,6 +895,7 @@ function openPr(url: string): void {
       :browse-fs="client.browseFs"
       :get-fs-home="client.getFsHome"
       :default-path="client.visibleWorkspace.value?.root ?? client.status.value.cwd"
+      :error="addWorkspaceError"
       @add="handleAddWorkspace($event)"
       @close="handleCloseAddWorkspace"
     />
diff --git a/apps/kimi-web/src/api/daemon/client.ts b/apps/kimi-web/src/api/daemon/client.ts
index c855d7c0d..f47bdb3ba 100644
--- a/apps/kimi-web/src/api/daemon/client.ts
+++ b/apps/kimi-web/src/api/daemon/client.ts
@@ -973,8 +973,8 @@ export class DaemonKimiWebApi implements KimiWebApi {
 
   /**
    * Register a workspace by folder path.
-   * PRESUMED — POST /api/v1/workspaces { root, name? }. On error this throws so
-   * the composable can fall back to a locally-derived workspace from the path.
+   * PRESUMED — POST /api/v1/workspaces { root, name? }. Throws on error (e.g.
+   * path not found) so the caller can surface it to the user.
    */
   async addWorkspace(input: { root: string; name?: string }): Promise<AppWorkspace> {
     const body: Record<string, unknown> = { root: input.root };
diff --git a/apps/kimi-web/src/components/dialogs/AddWorkspaceDialog.vue b/apps/kimi-web/src/components/dialogs/AddWorkspaceDialog.vue
index 53291ddd1..1eb6598f9 100644
--- a/apps/kimi-web/src/components/dialogs/AddWorkspaceDialog.vue
+++ b/apps/kimi-web/src/components/dialogs/AddWorkspaceDialog.vue
@@ -16,6 +16,8 @@ const props = defineProps<{
   getFsHome: () => Promise<{ home: string; recentRoots: string[] }>;
   /** Where the browser opens by default — the path kimi-web is working in. */
   defaultPath?: string;
+  /** Inline error from a failed add attempt (e.g. daemon rejected the path). */
+  error?: string | null;
 }>();
 
 const emit = defineEmits<{
@@ -336,6 +338,10 @@ onUnmounted(() => {
         </template>
       </div>
 
+      <!-- Inline error from a failed add attempt. Shown inside the dialog so it
+           is visible above the backdrop and persists until the next attempt. -->
+      <div v-if="error" class="add-error" role="alert">{{ error }}</div>
+
       <!-- Actions -->
       <div class="actions">
         <button
@@ -591,6 +597,16 @@ onUnmounted(() => {
 .paste-add:disabled { opacity: 0.5; cursor: not-allowed; }
 
 /* Actions */
+.add-error {
+  margin: 0 14px 8px;
+  padding: 6px 10px;
+  font-family: var(--mono);
+  font-size: var(--ui-font-size-xs);
+  color: #b3261e;
+  background: rgba(179, 38, 30, 0.08);
+  border: 1px solid rgba(179, 38, 30, 0.25);
+  border-radius: 3px;
+}
 .actions {
   display: flex;
   gap: 8px;
diff --git a/apps/kimi-web/src/composables/client/useWorkspaceState.ts b/apps/kimi-web/src/composables/client/useWorkspaceState.ts
index be2a3ae63..52d44ce60 100644
--- a/apps/kimi-web/src/composables/client/useWorkspaceState.ts
+++ b/apps/kimi-web/src/composables/client/useWorkspaceState.ts
@@ -23,7 +23,6 @@ import type {
 } from '../../api/types';
 import { safeRemove, STORAGE_KEYS } from '../../lib/storage';
 import { parseDiff } from '../../lib/parseDiff';
-import { basename } from '../../lib/pathBasename';
 import { readSessionIdFromLocation, sessionUrl } from '../../lib/sessionRoute';
 import type { SessionUrlMode } from '../../lib/sessionRoute';
 import type {
@@ -661,34 +660,23 @@ export function useWorkspaceState(rawState: ExtendedState, deps: UseWorkspaceSta
   }
 
   /**
-   * Add a workspace by folder path. Tries the daemon registry; on failure (or in
-   * fallback mode) creates a locally-derived workspace from the path and
-   * remembers it, then selects it.
+   * Add a workspace by folder path, registering it with the daemon. Returns true
+   * when the workspace was registered and selected; false when the daemon
+   * rejected the path, so callers can keep the picker open and any pending
+   * submission instead of dropping it. The caller surfaces the failure to the
+   * user (e.g. an inline error in the picker).
    */
-  async function addWorkspaceByPath(root: string): Promise<void> {
+  async function addWorkspaceByPath(root: string): Promise<boolean> {
     const trimmed = root.trim();
-    if (!trimmed) return;
+    if (!trimmed) return false;
     const api = getKimiWebApi();
     try {
       const ws = await api.addWorkspace({ root: trimmed });
       upsertWorkspacePreserveOrder(ws);
       openWorkspaceDraft(ws.id);
+      return true;
     } catch {
-      // Fallback: remember a derived workspace locally (id = root = path).
-      const existing = rawState.workspaces.find((w) => w.root === trimmed);
-      if (!existing) {
-        rawState.workspaces = [
-          {
-            id: trimmed,
-            root: trimmed,
-            name: basename(trimmed),
-            isGitRepo: false,
-            sessionCount: 0,
-          },
-          ...rawState.workspaces,
-        ];
-      }
-      openWorkspaceDraft(trimmed);
+      return false;
     }
   }
 
diff --git a/apps/kimi-web/src/i18n/locales/en/workspace.ts b/apps/kimi-web/src/i18n/locales/en/workspace.ts
index 4f92b3c81..9ea386c97 100644
--- a/apps/kimi-web/src/i18n/locales/en/workspace.ts
+++ b/apps/kimi-web/src/i18n/locales/en/workspace.ts
@@ -24,6 +24,7 @@ export default {
   add: 'Add',
   cancel: 'Cancel',
   addHint: 'Paste an absolute folder path, or pick a recent one.',
+  addFailed: "Couldn't open this folder. Check the path and try again.",
   // Folder browser
   openThisFolder: 'Open this folder',
   up: 'Up',
diff --git a/apps/kimi-web/src/i18n/locales/zh/workspace.ts b/apps/kimi-web/src/i18n/locales/zh/workspace.ts
index 758cdb230..8c9d1132b 100644
--- a/apps/kimi-web/src/i18n/locales/zh/workspace.ts
+++ b/apps/kimi-web/src/i18n/locales/zh/workspace.ts
@@ -24,6 +24,7 @@ export default {
   add: '添加',
   cancel: '取消',
   addHint: '粘贴一个绝对路径，或从最近用过的文件夹中选择。',
+  addFailed: '无法打开此文件夹，请检查路径后重试。',
   // Folder browser
   openThisFolder: '打开此文件夹',
   up: '上一级',
diff --git a/apps/kimi-web/test/workspace-state.test.ts b/apps/kimi-web/test/workspace-state.test.ts
index ef6ff7a31..60f69c27c 100644
--- a/apps/kimi-web/test/workspace-state.test.ts
+++ b/apps/kimi-web/test/workspace-state.test.ts
@@ -9,6 +9,7 @@ import type { ExtendedState } from '../src/composables/useKimiWebClient';
 const apiMock = vi.hoisted(() => ({
   abortPrompt: vi.fn(),
   abortSession: vi.fn(),
+  addWorkspace: vi.fn(),
 }));
 
 vi.mock('../src/api', () => ({
@@ -214,3 +215,47 @@ describe('mergeWorkspaces', () => {
     expect(result.map((w) => w.root)).not.toContain('/agent/A');
   });
 });
+
+describe('useWorkspaceState — addWorkspaceByPath', () => {
+  beforeEach(() => {
+    apiMock.addWorkspace.mockReset();
+  });
+
+  it('registers the workspace with the daemon and selects it', async () => {
+    const registered = {
+      id: 'wd_abc',
+      root: '/abs/path',
+      name: 'path',
+      isGitRepo: false,
+      sessionCount: 0,
+    };
+    apiMock.addWorkspace.mockResolvedValue(registered);
+    const state = createState();
+    const deps = createDeps();
+    const workspace = useWorkspaceState(state, deps);
+
+    const ok = await workspace.addWorkspaceByPath('  /abs/path  ');
+
+    expect(ok).toBe(true);
+    expect(apiMock.addWorkspace).toHaveBeenCalledWith({ root: '/abs/path' });
+    expect(state.workspaces).toContainEqual(registered);
+    expect(state.activeWorkspaceId).toBe('wd_abc');
+    expect(deps.pushOperationFailure).not.toHaveBeenCalled();
+  });
+
+  it('returns false and adds no local workspace on failure', async () => {
+    const err = new Error('path not found');
+    apiMock.addWorkspace.mockRejectedValue(err);
+    const state = createState();
+    const deps = createDeps();
+    const workspace = useWorkspaceState(state, deps);
+
+    const ok = await workspace.addWorkspaceByPath('/abs/missing');
+
+    expect(ok).toBe(false);
+    // The caller (the picker) is responsible for surfacing the failure inline.
+    expect(deps.pushOperationFailure).not.toHaveBeenCalled();
+    expect(state.workspaces).toEqual([]);
+    expect(state.activeWorkspaceId).toBeNull();
+  });
+});