diff --git a/AGENTS.md b/AGENTS.md
index f2b6b1f..622ab3e 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -79,7 +79,7 @@
 - Hashline 默认以 2 字符行哈希覆盖内置 `read` / `edit`，`grep` 和 `replaceText` 均关闭；它保证锚定编辑而不负责压缩，大文件上下文节省必须来自先定位/隔离分析、再做最小范围 `offset/limit` 读取。
 - 工具路由规则不得替换 Pi 默认系统提示词：代码结构、调用关系和待修改 symbol 优先 CodeGraph，定义/引用/类型/诊断优先 LSP；工作区内大文件探索、分析和总结优先 `ctx_execute_file`，日志、构建与不可预测命令输出优先 Context Mode；字面搜索先用 FFF `find` 收敛文件位置，再在收敛路径内用 `grep`/`multi_grep` 获取行号；真正修改前才用小范围 Hashline `read` 获取新鲜锚点并用锚定 `edit`。在线搜索按场景只先选一个服务：广泛发现、新闻和候选来源用 Tavily，官方/技术/论文和高确定性来源用 Exa，中文、站点限定和日期筛选用 Keenable；只有必要时才跨服务复核。遇到大量结果、截断或上限时继续缩小范围，不得靠提高 limit 或倾倒全部结果解决。
 - `ask_user_question` 只用于模型继续任务所必需的用户决定、偏好、确认或澄清；不得重复询问直接用户消息中已有的信息。工具仅支持交互式 TUI、顺序执行和最多 8 题；取消或 abort 必须返回 `cancelled: true`，不得伪造答案，且 `/qna` 不属于该扩展。其成功 `details.answers` 必须保留 `question` / `answer` 字段，以匹配 AutoReview 已有的可信结构化用户交互边界。
-- Tool Search 默认常驻核心 `read` / `write` / `edit` / `bash` / `grep` / `find`、`codegraph_explore`、`lsp_diagnostics` 与 `tool_search`；其余组合包工具必须优先使用 `pi-tool-search/extensions/bundle-groups.ts` 中提交的权威工作流分组。默认最多 3 个动态组、模型组最多 8 个工具、动态工具总数最多 20，加载或组内调用更新 LRU，超限先移除最久未用组。
+- Tool Search 默认常驻核心 `read` / `write` / `edit` / `bash` / `grep` / `find`、`codegraph_explore`、`lsp_diagnostics` 与 `tool_search`；Windows 上内置 `powershell` 必须与 `bash` 同属固定本地 Shell 核心工具，非 Windows 平台必须从目录中过滤。其余组合包工具必须优先使用 `pi-tool-search/extensions/bundle-groups.ts` 中提交的权威工作流分组；精确已有分组必须直接激活，不得等待无关未知工具的模型增强。默认最多 3 个动态组、模型组最多 8 个工具、动态工具总数最多 20，加载或组内调用更新 LRU，超限先移除最久未用组。
 - `pi-chrome` 在未授权时不注册 Chrome 工具；显式授权后出现的 21 个 `chrome_*` 工具必须由 Tool Search 分入 `chrome-navigation`、`chrome-interaction`、`chrome-debugging`，不得落入 unknown-tools 模型增强路径。Tool Search 重新激活 schema 不能替代上游每次执行时的授权校验。
 - 标准组合包工具全部命中预置目录时 Tool Search 不得调用模型、创建用户缓存或发送隐藏 schema。只有存在未识别第三方工具时才允许惰性模型增强；生成结果必须保留全部预置 assignment，模型元数据不得替代真实名称、参数或 schema。缓存必须位于 agent 目录且权限 `600`；模型失败必须继续使用预置目录 + 确定性未知工具分组。`groupOverrides` 优先级高于预置分组。
 - Tool Search 必须直接使用当前 `@earendil-works/pi-coding-agent`、`typebox`、`ModelRegistry.complete()` 和 `setActiveTools()`；首次纯增加载使用当前 Pi 的增量结果传播，LRU 替换允许走宿主安全 fallback。不得安装或映射旧 `@mariozechner` runtime，不得恢复 provider payload 改写、代理分发或隐藏 `sendMessage` steer/retry 兼容循环。
diff --git a/README.md b/README.md
index 6675bfc..3f9eb61 100644
--- a/README.md
+++ b/README.md
@@ -152,9 +152,9 @@ CodeGraph 本体不由组合包安装。需要使用 CodeGraph 的机器应自
 
 本地源码直接使用 `@earendil-works/pi-coding-agent`、当前 `typebox`、`ModelRegistry.complete()` 与 `setActiveTools()`，不安装、别名映射或加载旧 `@mariozechner` runtime，也不使用 provider payload 改写、代理执行或隐藏 `sendMessage` 循环。
 
-新 session 默认常驻 Pi 核心 `read`、`write`、`edit`、`bash`、`grep`、`find`，以及 `codegraph_explore`、`lsp_diagnostics` 和 `tool_search`。组合包在 `pi-tool-search/extensions/bundle-groups.ts` 中为自身暴露的工具预置权威分组，包括本地文件导航、SSH 远端文件/命令、Chrome 导航/交互/调试、用户交互、CodeGraph/LSP、Tavily、Exa、Keenable、Context Mode 执行/知识库/观测/管理、Memory 查询/维护、Skill 和 MCP 管理。不可用或尚未授权而未注册的可选工具会自动从组中滤除，固定工具也不占动态组额度。
+新 session 默认常驻 Pi 核心 `read`、`write`、`edit`、`bash`、`grep`、`find`，以及 `codegraph_explore`、`lsp_diagnostics` 和 `tool_search`；Windows 上额外把内置 `powershell` 与 `bash` 作为同类本地 Shell 核心工具固定启用，非 Windows 平台则从目录中过滤它。组合包在 `pi-tool-search/extensions/bundle-groups.ts` 中为自身暴露的工具预置权威分组，包括本地文件导航、SSH 远端文件/命令、Chrome 导航/交互/调试、用户交互、CodeGraph/LSP、Tavily、Exa、Keenable、Context Mode 执行/知识库/观测/管理、Memory 查询/维护、Skill 和 MCP 管理。不可用或尚未授权而未注册的可选工具会自动从组中滤除，固定工具也不占动态组额度。
 
-标准组合包的全部隐藏工具都能命中预置目录，因此首次使用不调用模型、不生成用户缓存，也不把完整隐藏 schema 发送给 provider。只有用户另外安装了未识别工具时，才先为新增工具提供确定性分组，并可在第一次 `tool_search` 时使用当前已认证模型补充目录；模型结果必须保留组合包预置分组，否则直接拒绝。有效增强缓存以 `0600` 写到 agent 目录的 `tool-search/catalog-v1.json`，调用用量计入工具结果。用户 `groupOverrides` 的优先级高于预置目录；`/tool-search-rebuild` 会立即恢复预置目录，只有仍存在额外工具时才可能在下次搜索惰性增强。
+标准组合包的全部隐藏工具都能命中预置目录，因此首次使用不调用模型、不生成用户缓存，也不把完整隐藏 schema 发送给 provider。只有用户另外安装了未识别工具，并且当前调用不是精确加载已有分组时，才可使用当前已认证模型补充目录；精确已有分组始终立即按当前确定性目录激活，不等待无关未知工具的模型增强。模型结果必须保留组合包预置分组，否则直接拒绝。有效增强缓存以 `0600` 写到 agent 目录的 `tool-search/catalog-v1.json`，调用用量计入工具结果。用户 `groupOverrides` 的优先级高于预置目录；`/tool-search-rebuild` 会立即恢复预置目录，只有仍存在额外工具时才可能在后续未知分组或 query 搜索中惰性增强。
 
 动态组默认最多同时加载 3 个、每个模型生成组最多 8 个工具、全部动态组最多 20 个工具。加载或调用组内工具会更新 LRU；加载第 4 组或超出工具总量时先卸载最久未使用的非固定组。首次纯增加载继续使用 Pi 原生增量传播；发生卸载和加载的替换不是纯增量，Pi 会自动走安全 fallback。
 
diff --git a/pi-tool-search/CHANGELOG.md b/pi-tool-search/CHANGELOG.md
index e818ca6..7985646 100644
--- a/pi-tool-search/CHANGELOG.md
+++ b/pi-tool-search/CHANGELOG.md
@@ -16,6 +16,10 @@
 - Added sequential `ssh_cd` to the authoritative remote-shell workflow and direct the model to wait for a successful workspace change before dependent remote calls, avoiding both the unknown-tools fallback and cwd races.
 - Added the authoritative `user-interaction` group for the maintained `ask_user_question` TUI tool.
 - Added authoritative `chrome-navigation`, `chrome-interaction`, and `chrome-debugging` groups for all 21 tools registered by the pinned `pi-chrome` bridge after explicit session authorization.
+### Fixed
+- Treat Pi's optional `powershell` definition as the same pinned local-shell/core class as `bash` on Windows, while excluding it from non-Windows catalogs so it cannot become an unknown-tool model group.
+- Activate exact existing groups from the current catalog before optional unknown-tool model enrichment, preventing unrelated catalog generation from delaying known group loads.
+
 
 ## [0.3.6] - 2026-04-24
 
diff --git a/pi-tool-search/README.md b/pi-tool-search/README.md
index df7702c..9c63525 100644
--- a/pi-tool-search/README.md
+++ b/pi-tool-search/README.md
@@ -10,15 +10,15 @@ Generated metadata never replaces executable schemas. Exact names, parameter typ
 
 ## Catalog lifecycle
 
-1. `session_start` keeps `tool_search`, Pi core tools, and configured `alwaysEnabled` names active.
+1. `session_start` keeps `tool_search`, Pi core tools, and configured `alwaysEnabled` names active. PowerShell is filtered out on non-Windows hosts; on Windows it is pinned beside Bash as the same local-shell capability class.
 2. Hidden tool definitions are hashed with the grouping constraints.
 3. Every tool exposed by the standard `my-pi` bundle is matched against the checked-in catalog in `extensions/bundle-groups.ts`. If all tools are recognized, no model call and no user cache are needed.
 4. User `groupOverrides` take priority over checked-in assignments. Optional or unavailable bundle tools are simply filtered out of their predefined groups.
 5. Additional user or third-party tools receive deterministic prefix/source groups immediately. A matching private model-enriched cache at `<agent-dir>/tool-search/catalog-v1.json` is reused when present.
-6. Only when unrecognized tools exist does the first `tool_search` call ask the current authenticated model to enrich the complete catalog. Validation requires all checked-in bundle tools to remain in their predefined groups before a `0600` cache is accepted.
+6. Only when unrecognized tools exist and the call does not name an exact existing group may `tool_search` ask the current authenticated model to enrich the complete catalog. Exact group activation always uses the current deterministic catalog immediately. Validation requires all checked-in bundle tools to remain in their predefined groups before a `0600` cache is accepted.
 7. Missing authentication, invalid JSON, timeout, cancellation, changed bundle assignments, or cache errors leave the checked-in plus deterministic hybrid catalog usable.
 
-A standard bundle installation therefore sends no tool definitions to a model during catalog setup. Complete definitions are sent to the selected provider only when extra unrecognized tools require enrichment; that nested call's usage is attached to the `tool_search` result.
+A standard bundle installation therefore sends no tool definitions to a model during catalog setup. Complete definitions are sent to the selected provider only when extra unrecognized tools require enrichment during an unknown-group or query lookup; exact existing group loads never wait for that nested call. Any nested-call usage is attached to the `tool_search` result.
 
 Run `/tool-search-rebuild` to remove model enrichment. Standard bundle tools immediately return to the checked-in catalog; extra tools can be enriched lazily on the next search.
 
diff --git a/pi-tool-search/docs/dynamic-tool-loading.md b/pi-tool-search/docs/dynamic-tool-loading.md
index 91b78df..3ccc906 100644
--- a/pi-tool-search/docs/dynamic-tool-loading.md
+++ b/pi-tool-search/docs/dynamic-tool-loading.md
@@ -2,11 +2,11 @@
 
 `pi-tool-search` keeps full low-frequency schemas hidden behind a compact, validated group catalog.
 
-1. `session_start` activates `tool_search`, the six Pi core tools, and configured `alwaysEnabled` names. These pinned tools do not consume the dynamic-group budget.
+1. `session_start` activates `tool_search`, the six cross-platform Pi core tools, and configured `alwaysEnabled` names. On Windows, `powershell` is pinned beside `bash` as a seventh local-shell/core tool; on non-Windows hosts it is excluded from the catalog. These pinned tools do not consume the dynamic-group budget.
 2. Hidden definitions are hashed with grouping constraints and matched against `extensions/bundle-groups.ts`. Available standard tools receive checked-in groups; unavailable optional tools are omitted.
 3. If every hidden tool is recognized, the bundle catalog is used directly. No model call or per-user cache is required.
 4. Additional tools receive immediate deterministic prefix/source groups. A matching model-enriched cache is reused only if it preserves all checked-in bundle assignments.
-5. Only a hybrid catalog with unrecognized tools can call `ModelRegistry.complete()`. The prompt marks bundle assignments as fixed; validation rejects any response that moves them.
+5. Only a hybrid catalog with unrecognized tools can call `ModelRegistry.complete()`, and an exact existing group skips that enrichment so activation cannot wait on an unrelated unknown tool. Unknown-group and query lookups may still enrich the catalog. The prompt marks bundle assignments as fixed; validation rejects any response that moves them.
 6. Code validation still requires every exact tool name exactly once and rejects unknown names, duplicates, oversized generated groups, omissions, and tool-card/group mismatches. Generated text never changes executable schemas.
 7. Loading a group calls `setActiveTools()` with its original full tool definitions. Pi supplies newly added schemas on the next model request.
 8. Group load and member execution update an in-session LRU counter. Loading past `maxActiveGroups` or `maxDynamicTools` removes the least-recently-used dynamic groups.
diff --git a/pi-tool-search/extensions/index.ts b/pi-tool-search/extensions/index.ts
index 1c29f65..6d4e924 100644
--- a/pi-tool-search/extensions/index.ts
+++ b/pi-tool-search/extensions/index.ts
@@ -31,10 +31,25 @@ import {
 import { ensureToolSearchDefaults, readToolSearchConfig } from "./config.ts";
 
 const TOOL_SEARCH_NAME = "tool_search";
+const POWERSHELL_TOOL_NAME = "powershell";
 const CORE_TOOLS = ["read", "write", "edit", "bash", "grep", "find"];
 
 type CatalogSource = "bundle" | "cache" | "fallback" | "hybrid" | "model";
 type ModelUsage = Awaited<ReturnType<ExtensionContext["modelRegistry"]["complete"]>>["usage"];
+type CatalogGenerationResult = { notice?: string; usage?: ModelUsage };
+
+export function platformToolPolicy<T extends { name: string }>(
+  definitions: readonly T[],
+  platform: NodeJS.Platform,
+): { tools: T[]; coreTools: string[] } {
+  const tools = platform === "win32"
+    ? [...definitions]
+    : definitions.filter((tool) => tool.name !== POWERSHELL_TOOL_NAME);
+  const coreTools = platform === "win32"
+    ? [...CORE_TOOLS, POWERSHELL_TOOL_NAME]
+    : [...CORE_TOOLS];
+  return { tools, coreTools };
+}
 
 function unique(values: Iterable<string>): string[] {
   return [...new Set(values)];
@@ -191,20 +206,14 @@ export default function toolSearchExtension(pi: ExtensionAPI): void {
       }),
       async execute(_toolCallId, params, signal, _onUpdate, ctx) {
         const requestedId = params.group?.trim().toLowerCase();
-        const preGenerationGroup = requestedId ? groupById(requestedId) : undefined;
-        const generation = await ensureModelCatalog(ctx, signal);
+        let selected = requestedId ? groupById(requestedId) : undefined;
+        const generation: CatalogGenerationResult = selected
+          ? {}
+          : await ensureModelCatalog(ctx, signal);
         const lines: string[] = [];
         if (generation.notice) lines.push(generation.notice);
 
-        let selected = requestedId ? groupById(requestedId) : undefined;
-        if (!selected && preGenerationGroup) {
-          const previousNames = new Set(preGenerationGroup.tools);
-          selected = [...catalog.groups]
-            .map((group) => ({ group, overlap: group.tools.filter((name) => previousNames.has(name)).length }))
-            .sort((left, right) => right.overlap - left.overlap || left.group.id.localeCompare(right.group.id))
-            .find((candidate) => candidate.overlap > 0)?.group;
-          if (selected) lines.push(`Mapped initial fallback group ${preGenerationGroup.id} to generated group ${selected.id}.`);
-        }
+        if (!selected && requestedId) selected = groupById(requestedId);
         const ranked = params.query ? rankGroups(catalog, params.query).slice(0, 3) : [];
         if (!selected && params.query && (ranked[0]?.score ?? 0) > 0) selected = ranked[0]?.group;
 
@@ -338,9 +347,13 @@ export default function toolSearchExtension(pi: ExtensionAPI): void {
 
   function refreshState(ctx: Pick<ExtensionContext, "ui">, forceReset: boolean): void {
     const nextConfig = readToolSearchConfig(agentDir);
-    const allTools = pi.getAllTools().filter((tool) => tool.name !== TOOL_SEARCH_NAME);
+    const registeredTools = pi.getAllTools().filter((tool) => tool.name !== TOOL_SEARCH_NAME);
+    const platformPolicy = platformToolPolicy(registeredTools, process.platform);
+    const allTools = platformPolicy.tools;
     const availableNames = new Set(allTools.map((tool) => tool.name));
-    const nextPinned = new Set([...CORE_TOOLS, ...nextConfig.alwaysEnabled].filter((name) => availableNames.has(name)));
+    const nextPinned = new Set(
+      [...platformPolicy.coreTools, ...nextConfig.alwaysEnabled].filter((name) => availableNames.has(name)),
+    );
     const hiddenTools = allTools.filter((tool) => !nextPinned.has(tool.name));
     const nextConstraints = {
       maxToolsPerGroup: Math.min(nextConfig.maxToolsPerGroup, nextConfig.maxDynamicTools),
diff --git a/pi-tool-search/test/extension.test.ts b/pi-tool-search/test/extension.test.ts
index 4c2262d..fadf108 100644
--- a/pi-tool-search/test/extension.test.ts
+++ b/pi-tool-search/test/extension.test.ts
@@ -5,7 +5,7 @@ import { join } from "node:path";
 import test from "node:test";
 
 import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
-import toolSearchExtension from "../extensions/index.ts";
+import toolSearchExtension, { platformToolPolicy } from "../extensions/index.ts";
 
 interface ToolSearchResult {
   details: {
@@ -249,3 +249,76 @@ test("uses the precomputed bundle groups without calling a model", async () => {
     await rm(agentDir, { recursive: true, force: true });
   }
 });
+
+test("keeps PowerShell with Bash only on Windows", () => {
+  const definitions = [
+    sourceTool("bash", "Run Bash commands"),
+    sourceTool("powershell", "Run PowerShell commands"),
+    sourceTool("read", "Read a file"),
+  ];
+
+  const nonWindows = platformToolPolicy(definitions, "darwin");
+  assert.deepEqual(nonWindows.tools.map((tool) => tool.name), ["bash", "read"]);
+  assert.ok(nonWindows.coreTools.includes("bash"));
+  assert.ok(!nonWindows.coreTools.includes("powershell"));
+
+  const windows = platformToolPolicy(definitions, "win32");
+  assert.deepEqual(windows.tools.map((tool) => tool.name), ["bash", "powershell", "read"]);
+  assert.ok(windows.coreTools.includes("bash"));
+  assert.ok(windows.coreTools.includes("powershell"));
+});
+
+test("loads an exact known group without waiting for unknown-tool model enrichment", async () => {
+  const agentDir = await mkdtemp(join(tmpdir(), "my-pi-tool-search-fast-path-"));
+  const previousAgentDir = process.env.PI_CODING_AGENT_DIR;
+  process.env.PI_CODING_AGENT_DIR = agentDir;
+
+  try {
+    const handlers = new Map<string, (...args: any[]) => unknown>();
+    const registered = new Map<string, RegisteredTool>();
+    let modelCalls = 0;
+    const sourceTools = [
+      sourceTool("read", "Read a file"),
+      sourceTool("tavily_web_search", "Search broadly for current web sources"),
+      sourceTool("tavily_web_fetch", "Fetch a selected Tavily source"),
+      sourceTool("unrecognized_extra", "An unrecognized third-party capability"),
+    ];
+    const api = {
+      getAllTools: () => sourceTools,
+      registerTool: (definition: unknown) => {
+        const tool = definition as RegisteredTool & { name: string };
+        registered.set(tool.name, tool);
+      },
+      registerCommand: () => {},
+      setActiveTools: () => {},
+      on: (event: string, handler: (...args: any[]) => unknown) => handlers.set(event, handler),
+    } as unknown as ExtensionAPI;
+    toolSearchExtension(api);
+    const ctx = testContext({
+      model: { provider: "test", id: "catalog-model" } as ExtensionContext["model"],
+      modelRegistry: {
+        hasConfiguredAuth: () => true,
+        complete: async () => {
+          modelCalls += 1;
+          throw new Error("an exact known group must not wait for model enrichment");
+        },
+      } as unknown as ExtensionContext["modelRegistry"],
+    });
+    handlers.get("session_start")?.({}, ctx);
+
+    const result = await registered.get("tool_search")?.execute(
+      "call-1",
+      { group: "web-tavily" },
+      undefined,
+      undefined,
+      ctx,
+    );
+    assert.equal(result?.details.loadedGroup, "web-tavily");
+    assert.equal(result?.details.catalogSource, "hybrid");
+    assert.equal(modelCalls, 0);
+  } finally {
+    if (previousAgentDir === undefined) delete process.env.PI_CODING_AGENT_DIR;
+    else process.env.PI_CODING_AGENT_DIR = previousAgentDir;
+    await rm(agentDir, { recursive: true, force: true });
+  }
+});