AlphaCatMeow · Nov 1, 2026 · Nov 1, 2026
diff --git a/crates/agent-gui/src/lib/kbrain/turn.ts b/crates/agent-gui/src/lib/kbrain/turn.ts
@@ -194,9 +194,11 @@ export type KBrainTurnParams = {
     request: KBrainQuestionRequest,
     signal?: AbortSignal,
   ) => Promise<KBrainQuestionAnswer[]>;
+  /** refusal: K-brain's reason for refusing the previous answer to this prompt (400). */
   onPermissionRequest?: (
     request: KBrainPermissionRequest,
     signal?: AbortSignal,
+    refusal?: string,
   ) => Promise<KBrainPermissionAnswer>;
   onPermissionAutoResolved?: (resolved: KBrainPermissionAutoResolved) => void;
   applyConversationState?: (state: ConversationViewState) => void;
@@ -926,8 +928,9 @@ async function executeKBrainTurn(params: KBrainTurnParams): Promise<AssistantMes
         pendingPermissions.set(request.permission_id, permissionController);
         const onPermissionRequest = params.onPermissionRequest;
         const answerPermission = async () => {
+          let refusal: string | undefined;
           for (let attempt = 0; ; attempt += 1) {
-            const answer = await onPermissionRequest(request, permissionController.signal);
+            const answer = await onPermissionRequest(request, permissionController.signal, refusal);
             if (permissionController.signal.aborted) return;
             const { decision, scope, reason } = permissionAnswerFields(answer);
             try {
@@ -951,6 +954,7 @@ async function executeKBrainTurn(params: KBrainTurnParams): Promise<AssistantMes
                 attempt < PERMISSION_ANSWER_RETRIES &&
                 !permissionController.signal.aborted
               ) {
+                refusal = error instanceof Error ? error.message : String(error);
                 continue;
               }
               throw error;

diff --git a/crates/agent-gui/src/lib/tools/toolApproval.ts b/crates/agent-gui/src/lib/tools/toolApproval.ts
@@ -13,6 +13,7 @@ import {
   normalizeToolApprovalRules,
   normalizeToolApprovalScope,
   type ToolApprovalAnswerOptions,
+  type ToolApprovalPreview,
   type ToolApprovalRememberScope,
 } from "@liveagent/ui/lib/chat/toolApprovalArgs";
 
@@ -43,6 +44,10 @@ type PendingToolApproval = {
   /** 允许并记住时后端会存的规则;空表示只能按本会话授权(或不能记住)。 */
   rememberRules: string[];
   defaultScope: ToolApprovalRememberScope;
+  /** Edit/Write 的改动预览。 */
+  preview?: ToolApprovalPreview;
+  /** 审批重新弹出的原因(后端拒绝了上次的应答),空表示没有。 */
+  notice: string;
   settle: (settlement: ToolApprovalSettlement) => void;
 };
 
@@ -120,6 +125,8 @@ export type PendingToolApprovalSummary = {
   sessionWide: boolean;
   rememberRules: string[];
   defaultScope: ToolApprovalRememberScope;
+  preview?: ToolApprovalPreview;
+  notice?: string;
 };
 
 export function listPendingToolApprovalsForConversation(
@@ -139,6 +146,8 @@ export function listPendingToolApprovalsForConversation(
         sessionWide: pending.sessionWide,
         rememberRules: pending.rememberRules,
         defaultScope: pending.defaultScope,
+        ...(pending.preview ? { preview: pending.preview } : {}),
+        ...(pending.notice ? { notice: pending.notice } : {}),
       });
     }
   }
@@ -207,6 +216,8 @@ export function requestToolApproval(params: {
   sessionWide?: boolean;
   rememberRules?: string[];
   defaultScope?: string;
+  preview?: ToolApprovalPreview;
+  notice?: string;
   signal?: AbortSignal;
   timeoutMs?: number | null;
 }): Promise<ToolApprovalSettlement> {
@@ -246,6 +257,8 @@ export function requestToolApproval(params: {
       sessionWide: params.sessionWide === true,
       rememberRules: normalizeToolApprovalRules(params.rememberRules),
       defaultScope: normalizeToolApprovalScope(params.defaultScope) ?? "session",
+      ...(params.preview ? { preview: params.preview } : {}),
+      notice: params.notice?.trim() ?? "",
       settle,
     };
     pendingByToolCallId.set(toolCallId, pending);

diff --git a/crates/agent-gui/src/pages/chat/turns/gatewayToolPreview.ts b/crates/agent-gui/src/pages/chat/turns/gatewayToolPreview.ts
@@ -15,11 +15,14 @@ import {
   TOOL_APPROVAL_ALLOW_SESSION_ARG,
   TOOL_APPROVAL_DEADLINE_ARG,
   TOOL_APPROVAL_DEFAULT_SCOPE_ARG,
+  TOOL_APPROVAL_NOTICE_ARG,
   TOOL_APPROVAL_PENDING_ARG,
+  TOOL_APPROVAL_PREVIEW_ARG,
   TOOL_APPROVAL_REMEMBER_RULES_ARG,
   TOOL_APPROVAL_SESSION_SCOPE_ARG,
   TOOL_APPROVAL_SESSION_WIDE_ARG,
   TOOL_APPROVAL_SUMMARY_ARG,
+  TOOL_APPROVAL_SYNTHETIC_ARG_KEYS,
   TOOL_PERMISSION_AUTO_RESOLVED_ARG,
 } from "@liveagent/ui/lib/chat/toolApprovalArgs";
 import {
@@ -135,14 +138,27 @@ function buildHeadTailPreview(input: string, maxChars = GATEWAY_TOOL_TEXT_PREVIE
   };
 }
 
+/**
+ * Approval markers come only from the desktop's own store: the same keys in the model's
+ * arguments are dropped before anything is synced, or a model could fake the WebUI
+ * approval card. Every tool_call sent to the Gateway goes through this.
+ */
+export function withoutApprovalSyntheticArgs(
+  args: Record<string, unknown> | undefined,
+): Record<string, unknown> {
+  return Object.fromEntries(
+    Object.entries(args || {}).filter(([key]) => !TOOL_APPROVAL_SYNTHETIC_ARG_KEYS.includes(key)),
+  );
+}
+
 // The canonical producer of streaming tool previews: bridge events
 // (tool_call / tool_call_delta / tool_result) and runtime snapshot entries
 // all pass through here, so every remote representation of a file tool's
 // args carries the same truncated text + true metrics + monotonic progress.
 export function buildGatewayToolCallPreviewArguments(
   toolCall: Pick<ToolCall, "id" | "name" | "arguments">,
 ) {
-  const sourceArgs = toolCall.arguments || {};
+  const sourceArgs = withoutApprovalSyntheticArgs(toolCall.arguments);
   // 待审批标记:任意工具在 beforeToolCall 处挂起等待批准时,盖到同步给 WebUI 的
   // 参数上,让远端渲染审批卡片并显示与桌面同源的倒计时。审批消解后重发的快照
   // 不再带此标记,卡片随之隐藏。__ 前缀合成参数不入展示、不影响本地执行。
@@ -181,6 +197,15 @@ export function buildGatewayToolCallPreviewArguments(
               [TOOL_APPROVAL_DEFAULT_SCOPE_ARG]: pending.defaultScope,
             }
           : {}),
+        ...(pending.preview ? { [TOOL_APPROVAL_PREVIEW_ARG]: pending.preview } : {}),
+        ...(pending.notice
+          ? {
+              [TOOL_APPROVAL_NOTICE_ARG]: clampApprovalText(
+                pending.notice,
+                TOOL_APPROVAL_SUMMARY_MAX_CHARS,
+              ),
+            }
+          : {}),
         ...(autoResolved ? { [TOOL_PERMISSION_AUTO_RESOLVED_ARG]: autoResolved } : {}),
       }
     : autoResolved

diff --git a/crates/agent-gui/src/pages/chat/turns/runKBrainConversationTurn.ts b/crates/agent-gui/src/pages/chat/turns/runKBrainConversationTurn.ts
@@ -1,7 +1,10 @@
 import type { AssistantMessage, ToolCall, ToolResultMessage } from "@liveagent/app/lib/agentTypes";
 import type { ComposerTurnCommand } from "@liveagent/ui/lib/chat/composerCommands";
 import { resolveKBrainPermissionMode } from "@liveagent/ui/lib/chat/permissionModes";
-import { clampApprovalText } from "@liveagent/ui/lib/chat/toolApprovalArgs";
+import {
+  approvalPreviewFromToolCall,
+  clampApprovalText,
+} from "@liveagent/ui/lib/chat/toolApprovalArgs";
 import { appendMessagesToConversation } from "../../../lib/chat/conversation/conversationState";
 import { buildConversationStateFromWindow } from "../../../lib/chat/history/chatHistory";
 import {
@@ -38,7 +41,10 @@ import { requestBackendQuestion } from "../../../lib/tools/askUserQuestionTools"
 import { recordPermissionAutoResolved } from "../../../lib/tools/permissionAutoResolved";
 import { projectBackendPlan } from "../../../lib/tools/planModeTools";
 import { hasPendingToolApproval, requestToolApproval } from "../../../lib/tools/toolApproval";
-import { buildGatewayToolCallPreviewArguments } from "./gatewayToolPreview";
+import {
+  buildGatewayToolCallPreviewArguments,
+  withoutApprovalSyntheticArgs,
+} from "./gatewayToolPreview";
 import type { RunAgentConversationTurnParams } from "./runAgentConversationTurn";
 import type { RunTextConversationTurnParams } from "./runTextConversationTurn";
 
@@ -162,7 +168,7 @@ export async function runKBrainConversationTurn(params: Params): Promise<void> {
       name: call.name,
       arguments: autoResolvedCallIds.has(call.id)
         ? buildGatewayToolCallPreviewArguments(call)
-        : call.arguments,
+        : withoutApprovalSyntheticArgs(call.arguments),
       conversation_id: params.conversationId,
       round,
     });
@@ -298,7 +304,7 @@ export async function runKBrainConversationTurn(params: Params): Promise<void> {
             ...(answer.custom ? { custom: true } : {}),
           }));
         },
-        onPermissionRequest: async (request, signal) => {
+        onPermissionRequest: async (request, signal, refusal) => {
           // Key the approval by its tool call so the Gateway preview overlays the
           // pending marker and scope on that call for WebUI; re-push the call when
           // the approval starts and settles. Without a known, free call id the
@@ -333,6 +339,9 @@ export async function runKBrainConversationTurn(params: Params): Promise<void> {
             sessionWide: request.scope === "session",
             rememberRules,
             defaultScope: request.suggestion?.default_scope,
+            // The edit being approved, from the call's full arguments.
+            preview: call ? approvalPreviewFromToolCall(request.tool, call.arguments) : undefined,
+            notice: refusal,
             signal: signal
               ? AbortSignal.any([approvalController.signal, signal])
               : approvalController.signal,

diff --git a/crates/agent-gui/test/chat/review-la2b-approval-card-r2.test.mjs b/crates/agent-gui/test/chat/review-la2b-approval-card-r2.test.mjs
@@ -0,0 +1,151 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { createDomTestEnv } from "../helpers/dom-test-env.mjs";
+import { createTsModuleLoader } from "../helpers/load-ts-module.mjs";
+
+// LA-2b review, round 2. The desktop preview is now capped by deriveFileToolPreview,
+// which keeps the first 4000 chars of each side independently. Diffing two independently
+// head-cut sides hides or invents changes. Assertions compare strings, numbers and
+// booleans only: a failing assert on a DOM node would print the whole jsdom tree.
+
+const lines = (n, f) => Array.from({ length: n }, (_, i) => f(i));
+
+async function createEnv() {
+  const env = await createDomTestEnv({
+    mocks: {
+      "@liveagent/ui/components/IconSet": new Proxy({}, { get: () => () => null }),
+      "@liveagent/ui/components/ui/button": {
+        Button: ({ children, size, variant, ...props }) => env.React.createElement("button", props, children),
+      },
+      "@liveagent/ui/components/ui/dropdown-menu": {
+        DropdownMenu: ({ children }) => env.React.createElement("div", null, children),
+        DropdownMenuTrigger: ({ render, children, ...props }) => env.React.cloneElement(render, props, children),
+        DropdownMenuContent: ({ children }) => env.React.createElement("div", { role: "menu" }, children),
+        DropdownMenuItem: ({ children, onSelect, disabled }) =>
+          env.React.createElement("button", { role: "menuitem", disabled, onClick: onSelect }, children),
+      },
+    },
+  });
+  return env;
+}
+
+// Renders the real approval card (real EditDiffView) for a desktop Edit call and returns
+// the changed rows the user sees.
+async function renderDesktopEdit(editArgs) {
+  const env = await createEnv();
+  const { ToolApprovalBar } = env.loadModule("@liveagent/ui/components/chat/ToolApprovalBar.tsx");
+  const args = env.loadModule("@liveagent/ui/lib/chat/toolApprovalArgs.ts");
+  // Exactly what runKBrainConversationTurn does with the call's full arguments.
+  const preview = args.approvalPreviewFromToolCall("Edit", editArgs);
+  const host = document.body.appendChild(document.createElement("div"));
+  const root = env.createRoot(host);
+  try {
+    await env.act(async () =>
+      root.render(
+        env.React.createElement(ToolApprovalBar, {
+          pending: [{ toolCallId: "e1", toolName: "Edit", summary: editArgs.path, preview }],
+          onDecide: async () => ({ ok: true }),
+          onDecideAll: async () => {},
+        }),
+      ),
+    );
+    const changed = [...host.querySelectorAll("[data-chat-code-diff] .grid")]
+      .map((row) => {
+        const sign = row.className.includes("emerald") ? "+" : row.className.includes("red") ? "-" : " ";
+        return [sign, row.querySelector("code")?.textContent ?? ""];
+      })
+      .filter(([sign]) => sign !== " ");
+    const header = host.querySelector("[data-chat-code-diff] figcaption")?.textContent ?? "";
+    return { changed, header, truncated: preview?.truncated ?? null };
+  } finally {
+    await env.act(async () => root.unmount());
+    host.remove();
+    env.cleanup();
+  }
+}
+
+test("a desktop Edit whose change lies past 4000 chars still shows the change", async () => {
+  const body = lines(150, (i) => `  const item${i} = load(${i});`);
+  const editArgs = {
+    path: "src/items.ts",
+    old_string: [...body, "  return 1;"].join("\n"),
+    new_string: [...body, "  return 2;"].join("\n"),
+  };
+  // Baseline: WebUI's Gateway copy (head + tail) keeps the change.
+  const loader = createTsModuleLoader();
+  const approval = loader.loadModule("src/lib/tools/toolApproval.ts");
+  const { buildGatewayToolCallPreviewArguments } = loader.loadModule("src/pages/chat/turns/gatewayToolPreview.ts");
+  const args = loader.loadModule("../agent-ui/src/lib/chat/toolApprovalArgs.ts");
+  const call = { type: "toolCall", id: "review-r2-tail", name: "Edit", arguments: editArgs };
+  approval.requestToolApproval({ toolCallId: call.id, toolName: "Edit", summary: "x", conversationId: "conv-r2", timeoutMs: null });
+  const remote = args.pendingToolApprovalFromToolCall({ ...call, arguments: buildGatewayToolCallPreviewArguments(call) });
+  approval.answerToolApproval(call.id, "deny", { conversationId: "conv-r2" });
+  assert.equal(remote?.preview?.after.includes("return 2;"), true, "WebUI preview shows the change");
+
+  const desktop = await renderDesktopEdit(editArgs);
+  const facts = { oldLen: editArgs.old_string.length, ...desktop };
+  assert.equal(
+    desktop.changed.some(([sign, text]) => sign === "+" && text.includes("return 2;")),
+    true,
+    `desktop card hides the edit it approves: ${JSON.stringify(facts)}`,
+  );
+});
+
+test("a desktop Edit cut on one side does not show kept lines as deleted", async () => {
+  const kept = lines(140, (i) => `  const item${i} = load(${i});`);
+  const oldText = kept.join("\n");
+  const newText = [...lines(30, (i) => `  import${i}();`), ...kept].join("\n");
+  assert.equal(oldText.length < 4000 && newText.length > 4000, true, "fixture: only new_string is over the cap");
+  const desktop = await renderDesktopEdit({ path: "src/items.ts", old_string: oldText, new_string: newText });
+  // Every old line survives in new_string, so a faithful preview deletes nothing.
+  const falseDeletions = desktop.changed.filter(([sign, text]) => sign === "-" && newText.includes(text));
+  assert.equal(
+    falseDeletions.length,
+    0,
+    `kept lines shown as deleted: ${JSON.stringify({ header: desktop.header, falseDeletions: falseDeletions.slice(0, 4), count: falseDeletions.length })}`,
+  );
+});
+
+// The "preview is cut" note sits at the end of the max-h-56 scroll box, after a diff that
+// is always long when truncated (>= 4000 chars, ~100 rows), so it is below the fold.
+test("the truncated-preview note is not hidden at the bottom of the scroll box", async () => {
+  const env = await createEnv();
+  const { ToolApprovalBar } = env.loadModule("@liveagent/ui/components/chat/ToolApprovalBar.tsx");
+  const args = env.loadModule("@liveagent/ui/lib/chat/toolApprovalArgs.ts");
+  const content = lines(300, (i) => `const value${i} = compute(${i});`).join("\n");
+  const preview = args.approvalPreviewFromToolCall("Write", { path: "src/big.ts", content });
+  const host = document.body.appendChild(document.createElement("div"));
+  const root = env.createRoot(host);
+  try {
+    await env.act(async () =>
+      root.render(
+        env.React.createElement(ToolApprovalBar, {
+          pending: [{ toolCallId: "w1", toolName: "Write", summary: "src/big.ts", preview }],
+          onDecide: async () => ({ ok: true }),
+          onDecideAll: async () => {},
+        }),
+      ),
+    );
+    const note = [...host.querySelectorAll("p")].find((p) => /预览已截断/.test(p.textContent));
+    const scroller = note?.closest(".overflow-auto");
+    const diff = host.querySelector("[data-chat-code-diff]");
+    const facts = {
+      truncated: preview?.truncated ?? null,
+      noteFound: Boolean(note),
+      noteInScroller: Boolean(scroller),
+      scrollerClass: scroller?.className ?? "",
+      noteAfterDiff: Boolean(note && diff && diff.compareDocumentPosition(note) & 4),
+      diffRows: host.querySelectorAll("[data-chat-code-diff] code").length,
+    };
+    assert.equal(facts.noteFound, true, JSON.stringify(facts));
+    assert.equal(
+      facts.noteInScroller && facts.noteAfterDiff,
+      false,
+      `note is below a ${facts.diffRows}-row diff inside the scroll box: ${JSON.stringify(facts)}`,
+    );
+  } finally {
+    await env.act(async () => root.unmount());
+    host.remove();
+    env.cleanup();
+  }
+});