diff --git a/README.md b/README.md
index aeeccee..0cfd8a6 100644
--- a/README.md
+++ b/README.md
@@ -122,12 +122,10 @@ RC2 的 `credentials/reference-updated` 事件会刷新设置卡片中的“已
 
 ## 组合覆盖
 
-插件通过 `cordis.patch.yml`：
+插件通过 `cordis.patch.yml` 插入 `search-mcp` 行并提高 `tool-web` 上限；**不**在 patch 里写 `web.searchProvider`（Desktop 0.2 会死锁）。路由切换由 host `apply` 在注册后 **live-pin** `ctx.web.searchProviderId = search-mcp` 完成：
 
-- 注册 `search-mcp` provider。
-- 设置 `web.searchProvider: search-mcp`。
-- 禁用 `web-search-deepseek`。
-- 保持 `web_fetch` 关闭。
+- 注册 `search-mcp` provider，并热切换活跃搜索提供商。
+- 保持 `web_fetch` 关闭（`tool-web.fetch: false`）。
 - 请求 `tool-web.searchMaxResults: 50` 和 `searchMaxQueries: 4`。
 
 RC2 的 standard、code、cordis agent preset 各自包含 `tool-web` 行，并且都省略了 `searchMaxResults` 和 `searchMaxQueries`，因此实际采用 `dsh-tool-web` 默认值 8 和 4。agent-scoped 工具会遮蔽根层同名工具，所以根层 patch 中的 50 条请求不会提高这些 shipped preset 的实际上限。验证结果上限时必须检查 session 使用的 preset，不能只依据根层 `--dump-config`。
@@ -153,11 +151,12 @@ dsh --profile web --dump-config |
 
 预期至少包括：
 
-- `web.searchProvider: search-mcp`
-- `web-search-deepseek.disabled: true`
+- 组合中出现 `search-mcp` 行（bailian / `DASHSCOPE_API_KEY`）
 - `tool-web.disabled: false`
 - `fetch: false`
 
+说明：Desktop 0.2 下 `--dump-config` **不会**出现 `web.searchProvider: search-mcp`（避免启动死锁）；运行时由 host live-pin。验收应以错误密钥时出现 search-mcp/百炼错误、而非 DeepSeek HTTP 401 为准。
+
 实际 agent preset 的结果数和多查询上限应在隔离 profile/session 中单独验证。
 
 ## 故障排查
diff --git a/cordis.patch.yml b/cordis.patch.yml
index 1b47ce0..649aecd 100644
--- a/cordis.patch.yml
+++ b/cordis.patch.yml
@@ -5,9 +5,9 @@
 # load-order deadlock (web waits for search-mcp, search-mcp waits for web)
 # and freezes the UI on "Loading plugins…".
 #
-# The host `apply` registers the provider and then soft-switches the web
-# row via settings when available. Removing this package restores the
-# previous composition (no searchProvider pin left behind by this file).
+# The host `apply` registers the provider and then live-pins
+# `ctx.web.searchProviderId = search-mcp` (no settings mutate / no patch pin).
+# Removing this package restores the previous composition.
 
 - insert:
     - id: search-mcp
diff --git a/lib/index.js b/lib/index.js
index 9af7853..98f7211 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,59 +1,75 @@
 /**
  * dsh-search-mcp — replace dsh's built-in web search with search MCP servers.
  *
- * Adapted for DeepSeek Harness 0.1.2+: settings use
- * `ctx.settings.installSection` (the old free-function
- * `installSettingsSection` from 0.1.1-rc.2 no longer exists).
+ * Registers a `ctx.web` search provider under id `search-mcp`, then **live-pins**
+ * the underlying WebRuntime's `searchProviderId` so `web_search` stops using
+ * `deepseek-official`.
  *
- * A Cordis plugin that
- *   - registers a `ctx.web` search provider under the id `search-mcp`, and
- *   - installs a Settings section (`search-mcp`) where the user manages the
- *     search MCP server list (kind, endpoint/command, API key or key env
- *     reference, tool name) plus `defaultServer` / `maxResults` /
- *     `searchTimeoutMs` from the web Settings → Plugins page.
+ * Why not cordis.patch.yml?
+ * Pinning `web.searchProvider: search-mcp` (or disabling deepseek) in the
+ * bundle patch deadlocks Desktop 0.2 boot: `web` waits for `search-mcp` while
+ * this plugin `inject: ['web']`. Live-pin after `registerSearchProvider` avoids
+ * that cycle. Do not persist the pin into settings.yaml either — a restart
+ * would reintroduce the same deadlock.
  *
- * The package's `cordis.patch.yml` (bundle layer) switches
- * `web.searchProvider` to `search-mcp` and disables the built-in
- * `web-search-deepseek` provider, so while this plugin is enabled the
- * built-in search is unavailable and every `web_search` call runs through
- * the configured MCP server(s). Removing the package restores the built-in.
+ * Why unwrap cordis.original?
+ * `ctx.web` is a traceable Proxy. Assigning `ctx.web.searchProviderId = …`
+ * does not update the field `search()` reads; pin the unwrapped instance.
  */
+import { readFileSync, writeFileSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
 import z from '@deepseek-ai/schemastery';
 import { credentialRef } from '@deepseek-ai/dsh-credentials';
 import { launchEnvironmentOf } from '@deepseek-ai/dsh-launch-environment';
-import { SearchMCPProvider } from './provider.js';
+import { SEARCH_MCP_PROVIDER_ID, SearchMCPProvider } from './provider.js';
 
 /** Cordis plugin name used by loader diagnostics. */
 export const name = 'search-mcp';
 
+/** Module-load breadcrumb — proves Desktop resolved this build (even if apply never runs). */
+try {
+  const pkgVersion = JSON.parse(
+    readFileSync(join(dirname(fileURLToPath(import.meta.url)), '..', 'package.json'), 'utf8'),
+  ).version;
+  writeFileSync(
+    join(process.env.USERPROFILE || process.env.HOME || '', '.dsh', 'search-mcp-loaded.json'),
+    `${JSON.stringify({ t: new Date().toISOString(), version: pkgVersion, name }, null, 2)}\n`,
+  );
+} catch {
+  /* ignore */
+}
+
 /** The web seam this provider registers into. */
 export const inject = ['web'];
 
-/**
- * DSH ≥0.1.7 / 0.2.0 only projects Config fields marked `.volatile()` into the
- * settings UI. Zero volatile fields → the whole entry is silently filtered.
- * Older schemastery without `volatile` keeps the bare schema (≤0.1.5 path).
- */
-function vol(schema) {
-  return typeof schema?.volatile === 'function' ? schema.volatile() : schema;
-}
+/** Unwrap cordis service proxy → concrete Service instance. */
+const CORDIS_ORIGINAL = Symbol.for('cordis.original');
 
+/**
+ * Config schema — no `.volatile()` anywhere.
+ *
+ * Desktop 0.2 cordis rejects nested volatiles (`servers` + `servers.*.id`) with
+ * ValidationError and leaves the fiber inactive. The settings UI is a custom
+ * `settings.section` (client.browser.js), so Config does not need volatile
+ * projection for the form to appear.
+ */
 const serverSchema = z.object({
-  id: vol(z.string()),
-  kind: vol(z.string().default('custom')),
-  transport: vol(z.string().default('http')),
-  url: vol(z.string().default('')),
-  command: vol(z.string().default('')),
-  args: vol(z.array(z.string()).default([])),
-  apiKey: vol(z.string().role('secret')),
-  apiKeyEnv: vol(z.string().role('credential-ref').default('')),
-  authStyle: vol(z.string().default('')),
-  authParam: vol(z.string().default('')),
-  authPrefix: vol(z.string().default('')),
-  toolName: vol(z.string().default('')),
+  id: z.string(),
+  kind: z.string().default('custom'),
+  transport: z.string().default('http'),
+  url: z.string().default(''),
+  command: z.string().default(''),
+  args: z.array(z.string()).default([]),
+  apiKey: z.string().role('secret'),
+  apiKeyEnv: z.string().role('credential-ref').default(''),
+  authStyle: z.string().default(''),
+  authParam: z.string().default(''),
+  authPrefix: z.string().default(''),
+  toolName: z.string().default(''),
   // Note: this schemastery fork has no `.optional()`; object fields are
   // optional unless `.required()` is applied, so absence is already allowed.
-  maxResults: vol(z.number().step(1).min(1).max(50)),
+  maxResults: z.number().step(1).min(1).max(50),
 });
 
 const DEFAULT_BAILIAN_SERVER = {
@@ -63,34 +79,128 @@ const DEFAULT_BAILIAN_SERVER = {
 };
 
 export const Config = z.object({
-  defaultServer: vol(z.string().default('bailian')),
-  maxResults: vol(z.number().step(1).min(1).max(50).default(8)),
-  searchTimeoutMs: vol(z.number().step(1).min(1000).default(30000)),
-  servers: vol(z.array(serverSchema).default([DEFAULT_BAILIAN_SERVER])),
+  defaultServer: z.string().default('bailian'),
+  maxResults: z.number().step(1).min(1).max(50).default(8),
+  searchTimeoutMs: z.number().step(1).min(1000).default(30000),
+  servers: z.array(serverSchema).default([DEFAULT_BAILIAN_SERVER]),
 });
 
 /** Settings namespace owning this plugin's section (Settings → Plugins card). */
 export const SEARCH_MCP_SETTINGS_NAMESPACE = 'search-mcp';
 
-/** Normalize settings.describe() across DSH generations. */
-function describeRows(describe) {
-  if (typeof describe !== 'function') return [];
-  try {
-    const raw = describe();
-    if (Array.isArray(raw)) return raw;
-    if (raw && typeof raw === 'object' && Array.isArray(raw.namespaces)) return raw.namespaces;
-  } catch {
-    // describe can throw while the provider is settling
-  }
-  return [];
+/** Concrete WebRuntime behind `ctx.web` (cordis traceable proxy). */
+function unwrapWeb(web) {
+  if (!web || typeof web !== 'object') return null;
+  const raw = web[CORDIS_ORIGINAL];
+  return raw && typeof raw === 'object' ? raw : web;
 }
 
-/** Register the search provider. Settings UI is owned by the web client. */
+/** Match WebRuntime.capSources so direct dispatch keeps the same contract. */
+function capSources(result, maxResults) {
+  if (maxResults === undefined || !Array.isArray(result?.sources) || result.sources.length <= maxResults) {
+    return result;
+  }
+  return { ...result, sources: result.sources.slice(0, maxResults), truncated: true };
+}
+
+/**
+ * Hot-takeover for the life of this fiber:
+ * - pin + wrap on apply (enable / boot)
+ * - restore previous provider + unwrap on dispose (disable)
+ *
+ * No Desktop restart needed for enable/disable — only for loading a new
+ * package build into an already-running process.
+ */
+function takeOverWebSearch(ctx, provider) {
+  const web = unwrapWeb(ctx.web);
+  if (!web || typeof web.search !== 'function' || !provider) return false;
+
+  const previousId = web.searchProviderId;
+  // Leftover pin from a crashed unload → fall back to Desktop default.
+  const restoreId =
+    previousId === SEARCH_MCP_PROVIDER_ID || previousId === undefined
+      ? 'deepseek-official'
+      : previousId;
+
+  const previousSearch = web.search.__searchMcpWrapped ? web.search.__searchMcpOriginal : web.search;
+
+  try {
+    web.searchProviderId = SEARCH_MCP_PROVIDER_ID;
+  } catch (error) {
+    ctx.logger?.warn?.('search-mcp: failed to assign web.searchProviderId: %s', error);
+    return false;
+  }
+
+  async function searchMcpPinned(request, signal) {
+    web.searchProviderId = SEARCH_MCP_PROVIDER_ID;
+    if (typeof provider.available === 'function' && provider.available()) {
+      const result = await provider.search(request, signal);
+      return capSources(result, request?.maxResults);
+    }
+    return previousSearch.call(web, request, signal);
+  }
+  searchMcpPinned.__searchMcpWrapped = true;
+  searchMcpPinned.__searchMcpOriginal = previousSearch;
+  web.search = searchMcpPinned;
+
+  // Fiber unload (plugin disable) → hand search back to the built-in path.
+  ctx.effect(() => () => {
+    if (web.search === searchMcpPinned) {
+      web.search = previousSearch;
+    }
+    if (web.searchProviderId === SEARCH_MCP_PROVIDER_ID) {
+      web.searchProviderId = restoreId;
+    }
+    ctx.logger?.info?.(
+      'search-mcp: released web search (restored searchProviderId → %s)',
+      restoreId === undefined ? '(unset)' : restoreId,
+    );
+  });
+
+  ctx.logger?.info?.(
+    'search-mcp: took over web.search (%s → %s); disable plugin to release',
+    previousId === undefined ? '(unset)' : previousId,
+    SEARCH_MCP_PROVIDER_ID,
+  );
+  return true;
+}
+
+/** Best-effort runtime breadcrumb for Desktop diagnosis (~/.dsh/search-mcp-runtime.json). */
+async function writeRuntimeBreadcrumb(payload) {
+  try {
+    const { writeFileSync } = await import('node:fs');
+    const { join } = await import('node:path');
+    const home = process.env.USERPROFILE || process.env.HOME || '';
+    if (!home) return;
+    writeFileSync(
+      join(home, '.dsh', 'search-mcp-runtime.json'),
+      `${JSON.stringify({ t: new Date().toISOString(), ...payload }, null, 2)}\n`,
+    );
+  } catch {
+    /* ignore */
+  }
+}
+
+/** Register the search provider and take over web_search selection. */
 export function apply(ctx, config) {
   const current = () => config;
-  // Desktop 0.2: avoid soft-inject(['settings']) + describe poll during bring-up.
+  // Desktop 0.2: avoid soft-inject(['settings']) during bring-up.
   // Loader already projects Config from the cordis entry / patch insert.
-  ctx.web.registerSearchProvider(new SearchMCPProvider(() => resolveOptions(ctx, current())));
+  const provider = new SearchMCPProvider(() => resolveOptions(ctx, current()));
+  ctx.web.registerSearchProvider(provider);
+  // Hot path: enable = take over now; disable = effect disposer restores.
+  const tookOver = takeOverWebSearch(ctx, provider);
+  if (!tookOver) {
+    ctx.logger?.warn?.(
+      'search-mcp: could not take over search provider; web_search may still use deepseek-official',
+    );
+  }
+  void writeRuntimeBreadcrumb({
+    event: 'apply',
+    tookOver,
+    searchProviderId: unwrapWeb(ctx.web)?.searchProviderId,
+    servers: (config.servers ?? []).map((s) => ({ id: s.id, kind: s.kind })),
+  });
 }
 
 /**
diff --git a/lib/provider.js b/lib/provider.js
index 3dc22b4..1b4d507 100644
--- a/lib/provider.js
+++ b/lib/provider.js
@@ -1,10 +1,10 @@
 /**
  * The `search-mcp` web search provider.
  *
- * Registers into `ctx.web` under the stable id `search-mcp`; the profile
- * patch switches `web.searchProvider` to this id and disables the built-in
- * DeepSeek provider, so the model-facing `web_search` tool executes entirely
- * through the configured search MCP server(s).
+ * Registers into `ctx.web` under the stable id `search-mcp`. The host
+ * `apply` then live-pins `ctx.web.searchProviderId` to this id so
+ * model-facing `web_search` runs through the configured search MCP
+ * server(s) (Desktop 0.2 cannot safely pin via cordis.patch.yml).
  */
 import { WebError } from '@deepseek-ai/dsh-web';
 import { resolveServer } from './catalog.js';
diff --git a/package.json b/package.json
index 7d1c048..8388928 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "dsh-search-mcp",
-  "version": "0.2.32",
+  "version": "0.2.38",
   "description": "Replace dsh's built-in web search with search MCP servers (Tavily / Brave / Exa / Perplexity / DuckDuckGo / custom), configured from the web Settings page. When this plugin is enabled the built-in DeepSeek search provider is disabled.",
   "type": "module",
   "main": "lib/index.js",
diff --git a/scripts/_validate-config.mjs b/scripts/_validate-config.mjs
new file mode 100644
index 0000000..b296ea4
--- /dev/null
+++ b/scripts/_validate-config.mjs
@@ -0,0 +1,73 @@
+/**
+ * Reproduce Desktop Config validation for search-mcp.
+ * Usage: node scripts/_validate-config.mjs
+ */
+import { createRequire } from 'node:module'
+import { pathToFileURL } from 'node:url'
+import { join, dirname } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+const pkgRoot = join(dirname(fileURLToPath(import.meta.url)), '..')
+const nm = join(process.env.USERPROFILE || '', '.dsh', 'profiles', 'node_modules')
+const req = createRequire(join(nm, 'package.json'))
+const cordisUrl = pathToFileURL(req.resolve('@deepseek-ai/cordis')).href
+const { Context, Service } = await import(cordisUrl)
+const mod = await import(pathToFileURL(join(pkgRoot, 'lib', 'index.js')).href)
+
+class WebRuntime extends Service {
+  searchProviders = new Map()
+  searchProviderId = 'deepseek-official'
+  constructor(ctx) {
+    super(ctx, 'web')
+  }
+  registerSearchProvider(p) {
+    this.searchProviders.set(p.id, p)
+    return () => this.searchProviders.delete(p.id)
+  }
+  async search() {
+    return { used: this.searchProviderId }
+  }
+}
+
+function plugin(ctx, config) {
+  mod.apply(ctx, config)
+}
+plugin.inject = ['web']
+plugin.Config = mod.Config
+
+const root = new Context()
+try {
+  await root.plugin(WebRuntime)
+  await root.plugin(plugin, {
+    defaultServer: 'bailian',
+    maxResults: 8,
+    searchTimeoutMs: 30000,
+    servers: [{ id: 'bailian', kind: 'bailian', apiKeyEnv: 'DASHSCOPE_API_KEY' }],
+  })
+  const raw = root.web[Symbol.for('cordis.original')]
+  console.log(
+    JSON.stringify(
+      {
+        ok: true,
+        faceId: root.web.searchProviderId,
+        rawId: raw?.searchProviderId,
+        wrapped: !!raw?.search?.__searchMcpWrapped,
+      },
+      null,
+      2,
+    ),
+  )
+} catch (e) {
+  console.log(
+    JSON.stringify(
+      {
+        ok: false,
+        message: String(e?.message || e),
+        stack: String(e?.stack || '').slice(0, 1200),
+      },
+      null,
+      2,
+    ),
+  )
+  process.exit(1)
+}
diff --git a/scripts/_verify-takeover.mjs b/scripts/_verify-takeover.mjs
new file mode 100644
index 0000000..2c8d265
--- /dev/null
+++ b/scripts/_verify-takeover.mjs
@@ -0,0 +1,78 @@
+/**
+ * Prove unwrap + direct web.search wrap routes off deepseek-official.
+ * Run: node scripts/_verify-takeover.mjs
+ */
+import { createRequire } from 'node:module'
+import { dirname, join } from 'node:path'
+import { fileURLToPath, pathToFileURL } from 'node:url'
+
+const pkgRoot = join(dirname(fileURLToPath(import.meta.url)), '..')
+const profilesNm = join(process.env.USERPROFILE || '', '.dsh', 'profiles', 'node_modules')
+const require = createRequire(join(profilesNm, 'package.json'))
+const { Context, Service } = require('@deepseek-ai/cordis')
+const { apply } = await import(pathToFileURL(join(pkgRoot, 'lib', 'index.js')).href)
+const ORIGINAL = Symbol.for('cordis.original')
+
+class WebRuntime extends Service {
+  searchProviders = new Map()
+  searchProviderId
+  constructor(ctx, config = {}) {
+    super(ctx, 'web')
+    this.searchProviderId = config.searchProvider ?? 'deepseek-official'
+  }
+  registerSearchProvider(p) {
+    this.searchProviders.set(p.id, p)
+    return () => this.searchProviders.delete(p.id)
+  }
+  async search() {
+    if (this.searchProviderId === 'deepseek-official') {
+      return { used: 'deepseek-official', error: 'DeepSeek API error (HTTP 401)' }
+    }
+    const p = this.searchProviders.get(this.searchProviderId)
+    return { used: this.searchProviderId, via: p?.id }
+  }
+}
+
+const smcp = Object.assign(function (ctx) {
+  apply(ctx, {
+    defaultServer: 'bailian',
+    maxResults: 8,
+    searchTimeoutMs: 30000,
+    servers: [{ id: 'bailian', kind: 'bailian', apiKeyEnv: 'DASHSCOPE_API_KEY' }],
+  })
+}, { inject: ['web'] })
+
+const app = new Context()
+await app.plugin(WebRuntime, { searchProvider: 'deepseek-official' })
+const fiber = await app.plugin(smcp)
+
+const raw = app.web[ORIGINAL]
+let thrown
+try {
+  await app.web.search({ query: 'venezuela', maxResults: 5 })
+} catch (error) {
+  thrown = String(error?.message || error)
+}
+
+const enabledOk =
+  raw.searchProviderId === 'search-mcp'
+  && raw.search.__searchMcpWrapped === true
+  && /search-mcp/.test(thrown || '')
+
+await fiber.dispose()
+const afterDisable = await app.web.search({ query: 'venezuela', maxResults: 5 })
+const disabledOk =
+  raw.searchProviderId === 'deepseek-official'
+  && !raw.search.__searchMcpWrapped
+  && afterDisable?.used === 'deepseek-official'
+
+const ok = enabledOk && disabledOk
+console.log(JSON.stringify({
+  ok,
+  enabledOk,
+  disabledOk,
+  thrown: thrown?.slice(0, 160),
+  afterDisable,
+  rawId: raw.searchProviderId,
+}, null, 2))
+process.exit(ok ? 0 : 1)
diff --git a/test/compatibility.test.js b/test/compatibility.test.js
index f09fb17..b06a8ef 100644
--- a/test/compatibility.test.js
+++ b/test/compatibility.test.js
@@ -12,7 +12,7 @@ test('package exports resolve and peerDependencies stay open', async () => {
   assert.equal(pkg.exports['.'], './lib/index.js')
   assert.equal(pkg.exports['./client'], './lib/client.browser.js')
   assert.equal(pkg.engines.node, '>=20')
-  assert.equal(pkg.version, '0.2.32')
+  assert.equal(pkg.version, '0.2.38')
   assert.equal(pkg.dsh.client.immediately, false)
 
   for (const name of [
@@ -51,13 +51,24 @@ test('browser half registers Settings sidebar + deferred form attach', async ()
   assert.match(client, /legacyKeyBlocked/)
 })
 
-test('host registers search provider without settings soft-inject poll', async () => {
+test('host registers search provider and hot-takeover without settings mutate', async () => {
   const host = await read('lib/index.js')
-  assert.match(host, /function vol\(/)
   assert.match(host, /registerSearchProvider/)
+  assert.match(host, /function takeOverWebSearch/)
+  assert.match(host, /Symbol\.for\(['"]cordis\.original['"]\)/)
+  assert.match(host, /function unwrapWeb/)
+  assert.match(host, /provider\.search\(request, signal\)/)
+  assert.match(host, /web\.searchProviderId\s*=\s*SEARCH_MCP_PROVIDER_ID/)
+  assert.match(host, /released web search/)
+  assert.match(host, /takeOverWebSearch\(ctx, provider\)/)
+  assert.match(host, /ctx\.effect\(\(\) => \(\) => \{/)
+  // Desktop 0.2: Config must not call .volatile() (array inner is always blocked).
+  assert.doesNotMatch(host, /[.\w]\.volatile\s*\(/)
+  assert.doesNotMatch(host, /function vol\(/)
   const applyBody = host.slice(host.indexOf('export function apply'), host.indexOf('function resolveOptions'))
   assert.doesNotMatch(applyBody, /ctx\.inject\(\s*\[['"]settings['"]\]/)
   assert.doesNotMatch(applyBody, /setInterval\(/)
+  assert.doesNotMatch(applyBody, /settings\.mutate/)
 })
 
 test('known providers are CDKey-only while custom keeps advanced fields', async () => {