feat(page-data): add validation suggestions, repair path, and thinking fixes

Map Page Data failure codes to Chinese remediation hints, trigger one-shot
goosed repair for remediable cases, and recover poisoned thinking sessions.
Route local DeepSeek through the no-think proxy via host.docker.internal so
tool rounds no longer hit reasoning_content 400; document gate and case-study
scenarios for event registration repair.

Co-authored-by: Cursor <cursoragent@cursor.com>

llm-providers.mjs

@@ -760,6 +760,18 @@ export async function updateSessionProvider(
   }
 }
 
+function isMissingCustomProviderResponse(status, text) {
+  return status === 404 || /provider not found/i.test(text);
+}
+
+function resolveGoosedProviderId(profile, goosedProviderId) {
+  if (goosedProviderId) return goosedProviderId;
+  if (profile.providerKind === 'custom') {
+    return profile.goosedProviderId ?? profile.providerId;
+  }
+  return profile.providerId;
+}
+
 async function upsertCustomProviderOnGoosed(apiTarget, apiSecret, profile, fetchImpl) {
   const headers = profile.relayProvider
     ? { 'X-Provider': profile.relayProvider }
@@ -788,9 +800,11 @@ async function upsertCustomProviderOnGoosed(apiTarget, apiSecret, profile, fetch
       fetchImpl,
     );
     if (upstream.ok) return profile.goosedProviderId;
-    // First-time ensure: fixed ids may 404 until created.
-    if (upstream.status !== 404) {
-      const text = await upstream.text().catch(() => '');
+    const text = await upstream.text().catch(() => '');
+    // First-time ensure: older TKMind Agent builds may report a missing fixed id
+    // as 500 with a JSON "Provider not found" message instead of HTTP 404.
+    const providerMissing = isMissingCustomProviderResponse(upstream.status, text);
+    if (!providerMissing) {
       throw new Error(`更新 TKMind Agent 自定义 provider 失败: ${text || upstream.status}`);
     }
   }
@@ -863,8 +877,9 @@ async function removeCustomProviderOnGoosed(apiTarget, apiSecret, goosedProvider
     { method: 'DELETE' },
     fetchImpl,
   );
-  if (!upstream.ok && upstream.status !== 404) {
+  if (!upstream.ok) {
     const text = await upstream.text().catch(() => '');
+    if (isMissingCustomProviderResponse(upstream.status, text)) return;
     throw new Error(`删除 TKMind Agent 自定义 provider 失败: ${text || upstream.status}`);
   }
 }
@@ -1157,10 +1172,7 @@ export function createLlmProviderService(
     try {
       const goosedProviderId = await syncRowWithModel(row, binding.model, fetchImpl);
       const profile = profileFromRow(row, decryptRow);
-      const providerId =
-        profile.providerKind === 'custom'
-          ? (goosedProviderId ?? profile.goosedProviderId ?? profile.providerId)
-          : profile.providerId;
+      const providerId = resolveGoosedProviderId(profile, goosedProviderId);
       return {
         ok: true,
         providerId,
@@ -1355,10 +1367,7 @@ export function createLlmProviderService(
     }
     try {
       const goosedProviderId = await syncRow(row, fetchImpl);
-      const providerId =
-        profile.providerKind === 'custom'
-          ? (goosedProviderId ?? profile.goosedProviderId ?? profile.providerId)
-          : profile.providerId;
+      const providerId = resolveGoosedProviderId(profile, goosedProviderId);
       return {
         ok: true,
         providerId,