diff --git a/01_content/src/client/index.tsx b/01_content/src/client/index.tsx
index 2d2d37e..e6f43c0 100644
--- a/01_content/src/client/index.tsx
+++ b/01_content/src/client/index.tsx
@@ -307,27 +307,59 @@ const registryStore: { ids: string[]; listeners: Set<() => void> } = { ids: [],
 /** 自定义窗口 → 宿主会话桥（apply 时注入；不可用时 CustomPane 降级提示） */
 let sessionBridge: { sessions: any; conversation: any; list: any; workspaces: any } | null = null
 
-/** 宿主 API 客户端（apply 时从 connection 服务取；agentPresets 用于修复新会话继承已删预设的 bug） */
-let presetApi: { agentPresets?: any } | null = null
+/** 宿主 API 客户端（apply 时从 connection 服务取；agentPresets/sessions 用于修复新会话继承失效模型的 bug） */
+let hostApi: { agentPresets?: any; sessions?: any } | null = null
 
 /** 新会话显式应用「部署默认预设」：宿主新会话座位同款逻辑（api.agentPresets.select，仅对 blank 会话生效）。
  *  修复：用户删掉默认模型后，新建会话继承到失效预设，prompt 报 model-unavailable 导致窗口建不出来。 */
 async function ensureSessionPreset(sessionId: string): Promise<void> {
-  const api = presetApi?.agentPresets
+  const api = hostApi?.agentPresets
   if (!api || typeof api.list !== 'function' || typeof api.select !== 'function') return
   try {
     const listRes = await api.list({})
     const presets = listRes?.result?.ok ? listRes?.result?.value?.presets : null
     if (!Array.isArray(presets) || presets.length === 0) return
-    const fallback = presets.find((p: any) => p?.isDefault)?.id ?? presets[0]?.id
-    if (!fallback) return
-    const selRes = await api.select({ sessionId, agentPreset: fallback })
-    if (selRes?.result?.ok) {
-      try { sessionBridge?.sessions?.noteAgentPreset?.(sessionId, fallback) } catch {}
+    // 部署默认优先，若其本身也失效（如引用了被删的 provider），逐个尝试其余预设直到成功
+    const ordered = [...presets]
+    const defIdx = ordered.findIndex((p: any) => p?.isDefault)
+    if (defIdx > 0) ordered.unshift(ordered.splice(defIdx, 1)[0])
+    for (const preset of ordered) {
+      const pid = preset?.id
+      if (!pid) continue
+      try {
+        const selRes = await api.select({ sessionId, agentPreset: pid })
+        if (selRes?.result?.ok) {
+          try { sessionBridge?.sessions?.noteAgentPreset?.(sessionId, pid) } catch {}
+          return
+        }
+        try { if (typeof console !== 'undefined' && console.warn) console.warn('[worktable] preset select failed:', pid, selRes?.result?.error?.message ?? '') } catch {}
+      } catch (err) {
+        try { if (typeof console !== 'undefined' && console.warn) console.warn('[worktable] preset select threw:', pid, String(err)) } catch {}
+      }
     }
   } catch { /* 修复失败不阻断主流程，错误仍按原路径提示 */ }
 }
 
+/** 新会话模型选择修复（真正的根因修复）：当前选择指向已删 provider（routable=false）时，
+ *  用 session.selectModel 切到模型目录里第一个可用 provider 的首个模型——
+ *  该 API 同时把新选择存为默认，顺带修复后续所有新会话。 */
+async function ensureSessionModel(sessionId: string): Promise<void> {
+  const api = hostApi?.sessions
+  if (!api || typeof api.models !== 'function' || typeof api.selectModel !== 'function') return
+  try {
+    const mRes = await api.models({ sessionId })
+    if (!mRes?.result?.ok) return
+    const val = mRes.result.value
+    if (val?.routable === true) return
+    const groups = val?.groups
+    if (!Array.isArray(groups) || groups.length === 0) return
+    const g = groups[0]
+    const model = g?.models?.[0]?.id
+    if (!g?.id || !model) return
+    await api.selectModel({ sessionId, provider: g.id, model })
+  } catch { /* 修复失败不阻断主流程，错误仍按原路径提示 */ }
+}
+
 /** 控制室（工作台自己）项目：固定 id、固定排项目列表第一位、不可删除 */
 const CONSOLE_ID = 'wt-console'
 const CONSOLE_ICON = '🖥️'
@@ -661,7 +693,8 @@ export async function createCustomSession(projectId: string, projectName: string
   if (workspaceId) createOpts = { workspaceId }
   else if (folder) createOpts = { cwd: folder }
   const sessionId = await b.sessions.create(createOpts)
-  await ensureSessionPreset(sessionId) // 新会话应用部署默认预设（修复继承已删模型 → model-unavailable）
+  await ensureSessionPreset(sessionId) // 新会话应用部署默认预设
+  await ensureSessionModel(sessionId) // 修复继承失效 provider（selectModel 同步存默认，顺带修复后续新会话）
   markPluginSessionOpen(sessionId) // 插件发起的切换：不触发「切会话关项目」联动
   try { await b.sessions.open?.(sessionId) } catch {}
   await promptIntoSession(sessionId, text)
@@ -1454,7 +1487,8 @@ function buildCustomLayoutPrompt(req: string): string {
       if (workspaceId) createOpts = { workspaceId }
       else if (folder) createOpts = { cwd: folder }
       const sessionId = await b.sessions.create(createOpts)
-      await ensureSessionPreset(sessionId) // 同样修复：管理对话新建后首次发消息不再继承已删模型
+      await ensureSessionPreset(sessionId) // 管理对话同样应用部署默认预设
+      await ensureSessionModel(sessionId) // 管理对话同样修复失效 provider
       markPluginSessionOpen(sessionId)
       persistProjects((prev) => ({ ...prev, bindings: { ...prev.bindings, [CONSOLE_ID]: sessionId } }))
       setConsoleBind(null)
@@ -2703,7 +2737,8 @@ export const inject = ['slots', 'locale', 'sessions', 'conversation', 'workspace
 export function apply(ctx: any) {
   // 自定义窗口 → 宿主会话桥：保存 sessions/conversation/list 服务引用（模块级）
   sessionBridge = { sessions: ctx.sessions ?? null, conversation: ctx.conversation ?? null, list: ctx.sessions?.list ?? null, workspaces: ctx.workspaces ?? null }
-  try { presetApi = ctx.get?.('connection')?.api ?? null } catch { presetApi = null }
+  try { hostApi = ctx.get?.('connection')?.api ?? null } catch { hostApi = null }
+  try { (window as any).__dshHostApi = hostApi } catch {}
   try { (window as any).__dshOpenSession = (id: string) => ctx.sessions?.open?.(id); (window as any).__dshSessions = ctx.sessions; (window as any).__dshPromptIntoSession = (id: string, text: string) => promptIntoSession(id, text); (window as any).__dshWorkspaces = ctx.workspaces; (window as any).__dshBuildWindowTaskText = buildWindowTaskText; (window as any).__dshSyncSessionScope = () => syncSessionScope(sessionBridge?.list) } catch {}
 
 
diff --git a/02_process/worklogs/2026-08-16_worktable-v2.md b/02_process/worklogs/2026-08-16_worktable-v2.md
index 476f07f..ed3b8cd 100644
--- a/02_process/worklogs/2026-08-16_worktable-v2.md
+++ b/02_process/worklogs/2026-08-16_worktable-v2.md
@@ -1444,3 +1444,19 @@
 - 验证（probe-batch16 阶段3 扩展）：新建会话 agentPreset='standard'（部署默认预设已应用）✓；
   functional-diag 全 20 STEP ERROR_COUNT: 0。
 - 备注：纯客户端改动，F5 即生效；未启用 agentPresets 的宿主自动跳过（无行为变化）。
+
+## 补记（第十八轮：模型失效修复——真正根因在会话级模型选择）
+
+- 进展：上一轮预设修复后用户仍报 model-unavailable——端到端探测（probe-batch18：走工作台
+  新建流程后直接 session.prompt）实测 promptOk:false，证实预设应用并未重置会话级模型选择。
+- 根因（只读侦察宿主 api-proxy）：新会话继承的是「默认模型选择」（provider/model，独立于
+  agent 预设，defaults.saveDefaultModelSelection 持久化）；用户删掉 openai provider 后，
+  该选择 routable=false，session.prompt 在 turnAgentFor 处直接拒绝。会话级修复 API =
+  session.models（返回 current/routable/groups）+ session.selectModel。
+- 实现：hostApi 捕获（原 presetApi 更名，调试句柄 __dshHostApi）；新增 ensureSessionModel：
+  session.models 查 routable——false 时取 groups[0] 首个可用模型 session.selectModel
+  （该 API 同时 saveDefaultModelSelection，把新选择存为默认 → 顺带修复后续所有新会话）；
+  createCustomSession / bindConsoleNew 两处 preset 修复后追加调用。
+- 验证（probe-batch18 重跑）：promptOk:true、promptErr:null（模型真实接受消息）✓；
+  functional-diag 全 20 STEP ERROR_COUNT: 0。
+- 备注：纯客户端改动，F5 即生效。
diff --git a/04_test/preset-inspect.cjs b/04_test/preset-inspect.cjs
new file mode 100644
index 0000000..7e379ed
--- /dev/null
+++ b/04_test/preset-inspect.cjs
@@ -0,0 +1,54 @@
+// preset-inspect.cjs — 检查宿主预设花名册与默认预设指向的 provider
+const http = require('http');
+const { spawn } = require('child_process');
+const WebSocket = require('ws');
+const PORT = 9380;
+const proc = spawn('C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe', [
+  '--headless=new', '--disable-gpu', '--no-first-run', '--no-default-browser-check',
+  '--window-size=1440,900', '--force-device-scale-factor=1',
+  '--remote-debugging-port=' + PORT,
+  '--user-data-dir=C:\\Users\\SJL\\AppData\\Local\\Temp\\wt-chrome-preset1',
+  'about:blank',
+], { stdio: 'ignore' });
+const getJSON = (p) => new Promise((res, rej) => {
+  http.get({ host: '127.0.0.1', port: PORT, path: p }, (r) => { let d=''; r.on('data',c=>d+=c); r.on('end',()=>{try{res(JSON.parse(d))}catch(e){rej(e)}}) }).on('error', rej);
+});
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+(async () => {
+  let list = null;
+  for (let i = 0; i < 40; i++) { try { list = await getJSON('/json/list'); if (list && list.length) break; } catch {} await sleep(500); }
+  const target = list.find((t) => t.type === 'page') || list[0];
+  const ws = new WebSocket(target.webSocketDebuggerUrl);
+  let id = 0; const pending = new Map();
+  const send = (method, params) => new Promise((res) => { const mid = ++id; pending.set(mid, res); ws.send(JSON.stringify({ id: mid, method, params })); });
+  ws.on('message', (raw) => { const m = JSON.parse(String(raw)); if (m.id && pending.has(m.id)) { pending.get(m.id)(m); pending.delete(m.id); } });
+  await new Promise((r) => ws.on('open', r));
+  await send('Runtime.enable');
+  await send('Page.enable');
+  await send('Page.navigate', { url: 'http://127.0.0.1:3080/' });
+  const evaluate = async (expr) => {
+    const r = await send('Runtime.evaluate', { expression: expr, returnByValue: true, awaitPromise: true });
+    if (r.result && r.result.exceptionDetails) return { __error: (r.result.exceptionDetails.exception || {}).description || r.result.exceptionDetails.text };
+    return r.result && r.result.result ? r.result.result.value : undefined;
+  };
+  let ready = null;
+  for (let i = 0; i < 30; i++) { await sleep(1000); ready = await evaluate("!!window.__dshPresetApi"); if (ready === true) break; }
+  await sleep(1200);
+  const out = await evaluate(`(async function(){
+    var out = {};
+    try {
+      var api = window.__dshPresetApi;
+      out.apiCaptured = !!api;
+      out.agentPresetsPresent = !!(api && api.agentPresets);
+      var lr = api && api.agentPresets && await api.agentPresets.list({});
+      out.listOk = lr && lr.result && lr.result.ok;
+      var presets = lr && lr.result && lr.result.ok ? (lr.result.value && lr.result.value.presets) : null;
+      out.count = Array.isArray(presets) ? presets.length : null;
+      out.rows = Array.isArray(presets) ? presets.map(function(p){ return { id: p.id, name: p.name, isDefault: !!p.isDefault, provider: p.provider || p.modelProvider || (p.composition && p.composition.provider) || null, keys: Object.keys(p).slice(0, 10) }; }) : null;
+    } catch (e) { out.err = String(e && e.stack || e); }
+    return out;
+  })()`);
+  console.log('RESULT ' + JSON.stringify(out));
+  try { ws.close(); } catch {}
+  proc.kill();
+})().catch((e) => { console.error('PROBE FAIL', e); try { proc.kill(); } catch {} });
diff --git a/04_test/probe-batch18.cjs b/04_test/probe-batch18.cjs
new file mode 100644
index 0000000..0af49f4
--- /dev/null
+++ b/04_test/probe-batch18.cjs
@@ -0,0 +1,82 @@
+// probe-batch18.cjs — 端到端验证：新建并绑定 → 直接 prompt，确认无 model-unavailable
+const http = require('http');
+const { spawn } = require('child_process');
+const WebSocket = require('ws');
+const PORT = 9381;
+const proc = spawn('C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe', [
+  '--headless=new', '--disable-gpu', '--no-first-run', '--no-default-browser-check',
+  '--window-size=1440,900', '--force-device-scale-factor=1',
+  '--remote-debugging-port=' + PORT,
+  '--user-data-dir=C:\\Users\\SJL\\AppData\\Local\\Temp\\wt-chrome-batch18',
+  'about:blank',
+], { stdio: 'ignore' });
+const getJSON = (p) => new Promise((res, rej) => {
+  http.get({ host: '127.0.0.1', port: PORT, path: p }, (r) => { let d=''; r.on('data',c=>d+=c); r.on('end',()=>{try{res(JSON.parse(d))}catch(e){rej(e)}}) }).on('error', rej);
+});
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+(async () => {
+  let list = null;
+  for (let i = 0; i < 40; i++) { try { list = await getJSON('/json/list'); if (list && list.length) break; } catch {} await sleep(500); }
+  const target = list.find((t) => t.type === 'page') || list[0];
+  const ws = new WebSocket(target.webSocketDebuggerUrl);
+  let id = 0; const pending = new Map();
+  const send = (method, params) => new Promise((res) => { const mid = ++id; pending.set(mid, res); ws.send(JSON.stringify({ id: mid, method, params })); });
+  ws.on('message', (raw) => { const m = JSON.parse(String(raw)); if (m.id && pending.has(m.id)) { pending.get(m.id)(m); pending.delete(m.id); } });
+  await new Promise((r) => ws.on('open', r));
+  await send('Runtime.enable');
+  await send('Page.enable');
+  await send('Page.addScriptToEvaluateOnNewDocument', {
+    source: "try{ if(location.origin==='http://127.0.0.1:3080'){ localStorage.setItem('dsh.worktable.view.v1', JSON.stringify({query:'',searchOpen:false,orderBy:'manual',dock:'footer',floatTop:null,sortMigratedV2:true})); localStorage.setItem('dsh.worktable.projects.v1', JSON.stringify({order:[],lastUsed:{},hidden:[],nameOverrides:{},iconOverrides:{},shortcuts:[],layouts:[],bindings:{},folders:{},views:{},removed:[]})); } }catch(e){}",
+  });
+  await send('Page.navigate', { url: 'http://127.0.0.1:3080/' });
+  const evaluate = async (expr) => {
+    const r = await send('Runtime.evaluate', { expression: expr, returnByValue: true, awaitPromise: true });
+    if (r.result && r.result.exceptionDetails) return { __error: (r.result.exceptionDetails.exception || {}).description || r.result.exceptionDetails.text };
+    return r.result && r.result.result ? r.result.result.value : undefined;
+  };
+  let ready = null;
+  for (let i = 0; i < 30; i++) { await sleep(1000); ready = await evaluate("!!window.__dshWorktable"); if (ready === true) break; }
+  await sleep(1500);
+  await evaluate("(function(){ var b=document.querySelector('button[title=\"Open sidebar\"],button[aria-label=\"Open sidebar\"]'); if(b){b.click(); return true} return false })()");
+  await sleep(1000);
+  const out = await evaluate(`(async function(){
+    var out = {};
+    var sleep = function(ms){ return new Promise(function(r){ setTimeout(r, ms); }); };
+    var vis = function(sel){ return [].slice.call(document.querySelectorAll(sel)).find(function(el){ return (getComputedStyle(el).visibility!=='hidden'&&el.getBoundingClientRect().height>0); }); };
+    var st = window.__dshWorktable.splitStore;
+    try {
+      // 控制室未绑定 → 点开 → 强制绑定 → 新建并绑定
+      var card = vis('.dsh-wt_projects .dsh-wt_consoleEntry');
+      card.dispatchEvent(new MouseEvent('click', {bubbles:true, cancelable:true}));
+      await sleep(600);
+      var bpop = vis('.dsh-wt_consoleBindPop');
+      out.panelOpen = !!bpop;
+      var cb = bpop && bpop.querySelector('.dsh-wt_consoleCreateBtn');
+      if (cb) { cb.dispatchEvent(new MouseEvent('click', {bubbles:true, cancelable:true})); }
+      await sleep(2500);
+      var saved = JSON.parse(localStorage.getItem('dsh.worktable.projects.v1'));
+      var sid = saved.bindings['wt-console'];
+      out.sid = sid;
+      out.specId = st.active && st.spec ? st.spec.id : null;
+      // 会话面 prompt 实测
+      var svc = window.__dshSessions;
+      var snap = svc.list.getSnapshot();
+      var row = snap.byId[sid];
+      out.agentPreset = row ? (row.agentPreset || '(none)') : '(missing)';
+      var face = svc.binding(sid).session;
+      out.hasPrompt = typeof face.prompt === 'function';
+      var r1 = null;
+      try {
+        r1 = await face.prompt([{ type: 'text', text: '回复一个字：好' }], 'queue');
+        out.promptOk = !!(r1 && r1.ok);
+        out.promptErr = r1 && !r1.ok ? (r1.error && (r1.error.code || r1.error.message)) : null;
+      } catch (e) { out.promptThrew = String(e).slice(0, 120); }
+      await sleep(2000);
+      st.close(); await sleep(200);
+    } catch (e) { out.err = String(e && e.stack || e); }
+    return out;
+  })()`);
+  console.log('RESULT ' + JSON.stringify(out));
+  try { ws.close(); } catch {}
+  proc.kill();
+})().catch((e) => { console.error('PROBE FAIL', e); try { proc.kill(); } catch {} });
diff --git a/AGENTS.md b/AGENTS.md
index 9575d2d..8a22162 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -33,9 +33,11 @@ node --check lib/index.js
   聊天窗恒在右侧；缩略图在 presetThumb() 加分支。
 - **新会话预设修复**：新建会话（createCustomSession / bindConsoleNew）创建后调用
   ensureSessionPreset——用宿主 api.agentPresets.list/select 显式应用「部署默认预设」
-  （isDefault ?? 首个；select 仅对 blank 会话生效），修复用户删掉默认模型后新会话继承
-  失效预设、prompt 报 model-unavailable 建不出窗口的问题；失败静默、无 agentPresets
-  API 的宿主自动跳过。
+  （isDefault ?? 首个，失败逐个尝试其余预设；select 仅对 blank 会话生效）。
+- **新会话模型修复（真根因）**：会话级模型选择独立于预设、随默认选择持久化——用户删掉
+  provider 后新会话继承失效选择，prompt 报 model-unavailable。ensureSessionModel 用
+  session.models 查 routable，false 时 session.selectModel 切到 groups[0] 首个可用模型
+  （该 API 同时把新选择存为默认，顺带修复后续所有新会话）。两者都失败静默、缺 API 跳过。
 - **对话绑定**：projects.v1.bindings = { 项目id → 会话id }；打开项目时引擎自动
   sessions.open(绑定会话)（openSplit / DOM 桥两处入口）；未绑定/解绑 = 不切换。
 - **项目×对话联动**：打开项目记录「打开前会话」（projectAttachRef.sessionId）；项目打开期间切到