diff --git a/backend/script/sql/update/aihr_20260718_unify_all_collations_mysql8.sql b/backend/script/sql/update/aihr_20260718_unify_all_collations_mysql8.sql
new file mode 100644
index 00000000..7ae345c9
--- /dev/null
+++ b/backend/script/sql/update/aihr_20260718_unify_all_collations_mysql8.sql
@@ -0,0 +1,121 @@
+-- Unify the collation of EVERY aihr table (tables and all string columns).
+--
+-- History: the 2026-07-18 release aligned the 18 newly added tables to the
+-- collation of aihr_knowledge_info.tenant_id, and a same-day hotfix aligned
+-- aihr_practice_assignment.ext_party_id. Both were partial: older tables kept
+-- utf8mb4_0900_ai_ci columns (e.g. aihr_practice_session.ext_party_id), so any
+-- join between the two families still raises error 1267
+-- (Illegal mix of collations). Seen in production on
+-- /api/aihr/mobile/practice/assignments and /api/aihr/mobile/practice/mistakes.
+--
+-- This migration converts ALL aihr tables to the canonical collation derived
+-- at run time, ending the per-join whack-a-mole. CONVERT TO rewrites the table
+-- default plus every character column, and is idempotent.
+
+SET @aihr_uni_collation := (
+  SELECT collation_name
+    FROM information_schema.columns
+   WHERE table_schema = DATABASE()
+     AND table_name = 'aihr_knowledge_info'
+     AND column_name = 'tenant_id'
+   LIMIT 1
+);
+SET @aihr_uni_collation := COALESCE(@aihr_uni_collation, 'utf8mb4_0900_ai_ci');
+
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_candidate_employee_link` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_candidate_material` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_case_record` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_interview_result` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_answer_feedback` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_attach` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_fragment` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_gap` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_import_task` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_info` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_upload_item` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_model_config` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_model_provider` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_onboard_task` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_org_snapshot` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_position_responsibility` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_annotation` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_assignment` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_audio` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_audio_upload` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_calibration` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_rubric` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_rubric_dimension` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_scenario` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_session` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_prompt_template` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_qualification_gate` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_sop_answer_review` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_sop_applicability` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_community_answer` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_community_question` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_incentive_rule` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_admin_audit` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_app` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_app_space` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_query_log` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_knowledge_space_grant` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_learning_question` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_onboard_exam` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_onboard_exam_answer` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_onboard_exam_attempt` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_onboard_exam_question` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_onboard_exam_target` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_points_ledger` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_practice_question_feedback` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_web_ai_query_audit` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+SET @aihr_uni_ddl := CONCAT('ALTER TABLE `aihr_web_search_provider` CONVERT TO CHARACTER SET utf8mb4 COLLATE ', @aihr_uni_collation);
+PREPARE aihr_uni_stmt FROM @aihr_uni_ddl; EXECUTE aihr_uni_stmt; DEALLOCATE PREPARE aihr_uni_stmt;
+
+SET @aihr_uni_ddl := NULL;
+SET @aihr_uni_collation := NULL;
diff --git a/mobile-uni/src/services/api.ts b/mobile-uni/src/services/api.ts
index c2fe5ee9..01255a11 100644
--- a/mobile-uni/src/services/api.ts
+++ b/mobile-uni/src/services/api.ts
@@ -1,5 +1,5 @@
 import type { ApiPayload } from '@/types/api';
-import { clearAuth, getAuth } from './auth';
+import { clearAuth, getAuth, redirectToLoginForAuthLoss } from './auth';
 
 const apiBase = import.meta.env.VITE_API_BASE || '/dev-api';
 
@@ -48,8 +48,11 @@ export const readPayload = <T>(statusCode: number, data: unknown, clearAuthOnUna
   const payload = data as ApiPayload<T>;
   const code = typeof payload?.code === 'number' ? payload.code : undefined;
   if (statusCode < 200 || statusCode >= 300 || (code !== undefined && code !== 200)) {
-    if (clearAuthOnUnauthorized && (statusCode === 401 || statusCode === 403 || code === 401 || code === 403)) {
+    // Only a real login failure (401) drops the local session; business 403
+    // (permission denied) must surface as a message, never a silent logout.
+    if (clearAuthOnUnauthorized && (statusCode === 401 || code === 401)) {
       clearAuth();
+      redirectToLoginForAuthLoss();
     }
     throw new ApiError(payload?.msg || `HTTP ${statusCode}`, statusCode, code);
   }
@@ -61,7 +64,10 @@ export const parsePayloadText = (statusCode: number, text: string, clearAuthOnUn
   try {
     return JSON.parse(text || '{}');
   } catch (error) {
-    if (clearAuthOnUnauthorized && (statusCode === 401 || statusCode === 403)) clearAuth();
+    if (clearAuthOnUnauthorized && statusCode === 401) {
+      clearAuth();
+      redirectToLoginForAuthLoss();
+    }
     throw error instanceof SyntaxError
       ? new ApiError(statusCode >= 400 ? `HTTP ${statusCode}` : '响应解析失败', statusCode)
       : error;
@@ -138,7 +144,10 @@ export const authenticatedFileUrl = async (url: string): Promise<string> => {
           resolve(URL.createObjectURL(xhr.response));
           return;
         }
-        if (xhr.status === 401 || xhr.status === 403) clearAuth();
+        if (xhr.status === 401) {
+          clearAuth();
+          redirectToLoginForAuthLoss();
+        }
         reject(new Error(`HTTP ${xhr.status}`));
       };
       xhr.onerror = () => reject(new Error('网络请求失败'));
@@ -155,7 +164,10 @@ export const authenticatedFileUrl = async (url: string): Promise<string> => {
           resolve(response.tempFilePath);
           return;
         }
-        if (response.statusCode === 401 || response.statusCode === 403) clearAuth();
+        if (response.statusCode === 401) {
+          clearAuth();
+          redirectToLoginForAuthLoss();
+        }
         reject(new Error(`HTTP ${response.statusCode}`));
       },
       fail: () => reject(new Error('网络请求失败'))
diff --git a/mobile-uni/src/services/auth.ts b/mobile-uni/src/services/auth.ts
index a9ac1f58..c4d0c8e1 100644
--- a/mobile-uni/src/services/auth.ts
+++ b/mobile-uni/src/services/auth.ts
@@ -160,6 +160,29 @@ export const rememberLoginRedirect = (url: string) => {
   uni.setStorageSync(loginRedirectKey, url);
 };
 
+let lastAuthLossRedirectAt = 0;
+
+/**
+ * Central recovery for a lost login (HTTP/biz 401): remember the current page,
+ * then relaunch to login. Debounced because parallel requests can 401 together.
+ * Business 403 must NOT end up here — permission denials are not logouts.
+ */
+export const redirectToLoginForAuthLoss = () => {
+  const now = Date.now();
+  if (now - lastAuthLossRedirectAt < 2000) return;
+  lastAuthLossRedirectAt = now;
+  try {
+    const pages = getCurrentPages();
+    const current = pages[pages.length - 1] as { route?: string; $page?: { fullPath?: string } } | undefined;
+    const path = current?.$page?.fullPath || (current?.route ? `/${current.route}` : '');
+    if (path.startsWith('/pages/auth/')) return;
+    if (path.startsWith('/pages/')) uni.setStorageSync(loginRedirectKey, path);
+  } catch {
+    // Best effort only; still return to login below.
+  }
+  uni.reLaunch({ url: '/pages/auth/login/index' });
+};
+
 export const consumeLoginRedirect = () => {
   const url = uni.getStorageSync(loginRedirectKey) || '';
   uni.removeStorageSync(loginRedirectKey);