diff --git a/backend/internal/repository/account_repo.go b/backend/internal/repository/account_repo.go
index a668f578cb..6ab4446ba4 100644
--- a/backend/internal/repository/account_repo.go
+++ b/backend/internal/repository/account_repo.go
@@ -708,8 +708,11 @@ func (r *accountRepository) UpdateCredentials(ctx context.Context, id int64, cre
 		SET
 			credentials = $1::jsonb,
 			extra = CASE
+				-- 凭证整体未变化 ⇒ Ollama 组身份必然未变化；顶层 DISTINCT 守卫防止
+				-- 非 Ollama 账号的无变化持久化误清 openai 探测快照或重写 NULL extra。
 				WHEN platform IN ('openai', 'anthropic')
 					AND type = 'apikey'
+					AND credentials IS DISTINCT FROM $1::jsonb
 					AND (
 						credentials -> 'api_key' IS DISTINCT FROM $1::jsonb -> 'api_key'
 						OR NOT (
diff --git a/backend/internal/repository/account_repo_ollama_cloud_usage_integration_test.go b/backend/internal/repository/account_repo_ollama_cloud_usage_integration_test.go
index f261323439..a7dc861249 100644
--- a/backend/internal/repository/account_repo_ollama_cloud_usage_integration_test.go
+++ b/backend/internal/repository/account_repo_ollama_cloud_usage_integration_test.go
@@ -360,3 +360,56 @@ func TestProxyIdentityUpdateInvalidatesOllamaSnapshotAndRejectsInFlightCAS(t *te
 	})
 	require.ErrorIs(t, err, service.ErrOllamaCloudUsageIdentityChanged)
 }
+
+// 无变化的凭证持久化（如 CRS 同步重放同一凭证）不得触发任何 extra 清理；
+// 真实变化仍必须按旧语义清 openai 探测快照。
+func TestUpdateCredentialsUnchangedCredentialsPreserveManagedExtra(t *testing.T) {
+	ctx := context.Background()
+	tx := testEntTx(t)
+	repo := newAccountRepositoryWithSQL(tx.Client(), tx, nil)
+
+	probeAccount := mustCreateAccount(t, tx.Client(), &service.Account{
+		Name: "openai-probe-unchanged", Platform: service.PlatformOpenAI, Type: service.AccountTypeAPIKey,
+		Credentials: map[string]any{"api_key": "sk-probe", "base_url": "https://relay.example.com/v1"},
+		Extra: map[string]any{
+			service.UpstreamBillingProbeEnabledExtraKey: true,
+			service.UpstreamBillingProbeExtraKey:        map[string]any{"status": "ok"},
+		},
+	})
+	require.NoError(t, repo.UpdateCredentials(ctx, probeAccount.ID, map[string]any{
+		"api_key": "sk-probe", "base_url": "https://relay.example.com/v1",
+	}))
+	probeLoaded, err := repo.GetByID(ctx, probeAccount.ID)
+	require.NoError(t, err)
+	require.Contains(t, probeLoaded.Extra, service.UpstreamBillingProbeExtraKey,
+		"unchanged credentials must not clear the probe snapshot")
+
+	now := time.Now().UTC()
+	ollamaAccount := mustCreateAccount(t, tx.Client(), &service.Account{
+		Name: "ollama-unchanged", Platform: service.PlatformAnthropic, Type: service.AccountTypeAPIKey,
+		Credentials: map[string]any{"api_key": "ollama-key", "base_url": "https://ollama.com"},
+		Extra: map[string]any{
+			service.OllamaCloudUsageSessionExtraKey:     "cipher:wos-session=fixture",
+			service.OllamaCloudUsageAutoRefreshExtraKey: true,
+			service.OllamaCloudUsageSnapshotExtraKey: map[string]any{
+				"status": service.OllamaCloudUsageStatusOK, "last_attempt_at": now, "next_refresh_at": now.Add(time.Hour),
+			},
+		},
+	})
+	require.NoError(t, repo.UpdateCredentials(ctx, ollamaAccount.ID, map[string]any{
+		"api_key": "ollama-key", "base_url": "https://ollama.com",
+	}))
+	ollamaLoaded, err := repo.GetByID(ctx, ollamaAccount.ID)
+	require.NoError(t, err)
+	require.Equal(t, "cipher:wos-session=fixture", ollamaLoaded.Extra[service.OllamaCloudUsageSessionExtraKey])
+	require.Equal(t, true, ollamaLoaded.Extra[service.OllamaCloudUsageAutoRefreshExtraKey])
+	require.Contains(t, ollamaLoaded.Extra, service.OllamaCloudUsageSnapshotExtraKey)
+
+	require.NoError(t, repo.UpdateCredentials(ctx, probeAccount.ID, map[string]any{
+		"api_key": "sk-probe", "base_url": "https://relay.example.org/v1",
+	}))
+	probeLoaded, err = repo.GetByID(ctx, probeAccount.ID)
+	require.NoError(t, err)
+	require.NotContains(t, probeLoaded.Extra, service.UpstreamBillingProbeExtraKey,
+		"changed credentials must keep clearing the probe snapshot")
+}
diff --git a/backend/internal/repository/account_repo_ollama_cloud_usage_test.go b/backend/internal/repository/account_repo_ollama_cloud_usage_test.go
index a7f5bb92a4..07b67287ba 100644
--- a/backend/internal/repository/account_repo_ollama_cloud_usage_test.go
+++ b/backend/internal/repository/account_repo_ollama_cloud_usage_test.go
@@ -277,3 +277,25 @@ func TestDisableOllamaCloudUsageAutoRefreshUsesGroupIdentityCAS(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, mock.ExpectationsWereMet())
 }
+
+// Ollama 清理分支必须带顶层 credentials DISTINCT 守卫：没有它，非 Ollama 的
+// openai/anthropic apikey 账号在凭证未变化的持久化上也会误清探测快照。
+func TestUpdateCredentialsCleanupBranchRequiresChangedCredentials(t *testing.T) {
+	client, mock := newOllamaCloudUsageRepositoryTestClient(t)
+	mock.ExpectBegin()
+	mock.ExpectExec(`(?s)UPDATE accounts.*CASE.*AND credentials IS DISTINCT FROM \$1::jsonb\s+AND \(\s+credentials -> 'api_key' IS DISTINCT FROM`).
+		WithArgs(`{"api_key":"same-key","base_url":"https://relay.example.com/v1"}`, int64(17)).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec(regexp.QuoteMeta("INSERT INTO scheduler_outbox")).
+		WithArgs(service.SchedulerOutboxEventAccountChanged, int64(17), nil, nil, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(1, 1))
+	mock.ExpectCommit()
+	repo := newAccountRepositoryWithSQL(client, nil, nil)
+
+	err := repo.UpdateCredentials(context.Background(), 17, map[string]any{
+		"api_key": "same-key", "base_url": "https://relay.example.com/v1",
+	})
+
+	require.NoError(t, err)
+	require.NoError(t, mock.ExpectationsWereMet())
+}
diff --git a/backend/internal/server/middleware/audit_log.go b/backend/internal/server/middleware/audit_log.go
index c07deea49f..98cfff1b44 100644
--- a/backend/internal/server/middleware/audit_log.go
+++ b/backend/internal/server/middleware/audit_log.go
@@ -146,13 +146,14 @@ var auditActionOverrides = map[string]string{
 // auditBodyOmittedRoutes 请求体几乎整体由凭证构成的路由（如整块粘贴 auth JSON 的导入接口）。
 // 这类 body 的凭证内嵌在普通字符串值里，键级脱敏无法覆盖，整体不入库。
 var auditBodyOmittedRoutes = map[string]struct{}{
-	"POST /api/v1/admin/accounts/import/codex-session":        {},
-	"PUT /api/v1/admin/prompt-audit/config":                   {},
-	"POST /api/v1/admin/prompt-audit/endpoints/probe":         {},
-	"DELETE /api/v1/admin/prompt-audit/events/:id":            {},
-	"POST /api/v1/admin/prompt-audit/events/batch-delete":     {},
-	"POST /api/v1/admin/prompt-audit/events/delete-preview":   {},
-	"POST /api/v1/admin/prompt-audit/events/delete-by-filter": {},
+	"POST /api/v1/admin/accounts/import/codex-session":          {},
+	"PUT /api/v1/admin/accounts/:id/ollama-cloud-usage/session": {},
+	"PUT /api/v1/admin/prompt-audit/config":                     {},
+	"POST /api/v1/admin/prompt-audit/endpoints/probe":           {},
+	"DELETE /api/v1/admin/prompt-audit/events/:id":              {},
+	"POST /api/v1/admin/prompt-audit/events/batch-delete":       {},
+	"POST /api/v1/admin/prompt-audit/events/delete-preview":     {},
+	"POST /api/v1/admin/prompt-audit/events/delete-by-filter":   {},
 }
 
 // NewAuditLogMiddleware 创建审计中间件。
diff --git a/backend/internal/server/middleware/audit_log_test.go b/backend/internal/server/middleware/audit_log_test.go
index 026e9163bf..4892fc6d0b 100644
--- a/backend/internal/server/middleware/audit_log_test.go
+++ b/backend/internal/server/middleware/audit_log_test.go
@@ -145,3 +145,40 @@ func TestPromptAuditMutationAuditRoutesHaveStableActionsAndOmitBodies(t *testing
 		require.Truef(t, omitted, "%s must not persist its credential or confirmation-bearing body", route)
 	}
 }
+
+// Ollama 会话保存的请求体整体就是浏览器 Cookie 明文，键级脱敏清单曾漏掉裸键
+// "session"，必须走整体不入库路径，防止会话凭证长期留存在 audit_logs。
+func TestOllamaCloudUsageSessionRouteOmitsAuditBody(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	require.Contains(t, auditBodyOmittedRoutes, "PUT /api/v1/admin/accounts/:id/ollama-cloud-usage/session")
+
+	repository := &auditCaptureRepository{}
+	auditService := service.NewAuditLogService(repository, nil)
+	auditService.Start()
+
+	router := gin.New()
+	router.Use(func(c *gin.Context) {
+		c.Set(string(ContextKeyUser), AuthSubject{UserID: 77})
+		c.Set(string(ContextKeyUserRole), "admin")
+		c.Next()
+	})
+	router.Use(gin.HandlerFunc(NewAuditLogMiddleware(auditService)))
+	router.PUT("/api/v1/admin/accounts/:id/ollama-cloud-usage/session", func(c *gin.Context) {
+		c.JSON(http.StatusOK, gin.H{"ok": true})
+	})
+
+	request := httptest.NewRequest(http.MethodPut, "/api/v1/admin/accounts/7/ollama-cloud-usage/session",
+		bytes.NewBufferString(`{"session":"wos-session=audit-canary-cookie; __Secure-authjs.session-token.0=audit-canary-shard"}`))
+	request.Header.Set("Content-Type", "application/json")
+	recorder := httptest.NewRecorder()
+	router.ServeHTTP(recorder, request)
+	require.Equal(t, http.StatusOK, recorder.Code)
+	auditService.Stop()
+
+	repository.mu.Lock()
+	logs := append([]*service.AuditLog(nil), repository.logs...)
+	repository.mu.Unlock()
+	require.Len(t, logs, 1)
+	require.Equal(t, "<credential-bearing body omitted>", logs[0].RequestBody)
+	require.NotContains(t, logs[0].RequestBody, "audit-canary")
+}
diff --git a/backend/internal/service/audit_log.go b/backend/internal/service/audit_log.go
index 9ca75ccab9..02b85682d7 100644
--- a/backend/internal/service/audit_log.go
+++ b/backend/internal/service/audit_log.go
@@ -129,8 +129,9 @@ var auditBodySensitiveExactKeys = func() map[string]struct{} {
 		"key",
 		// 字符串值内嵌完整凭证的字段：
 		// proxy_key 为 protocol|host|port|username|password 拼接，
-		// custom_key 为用户自设的平台 API Key 明文。
-		"proxy_key", "custom_key",
+		// custom_key 为用户自设的平台 API Key 明文，
+		// session 为 Ollama Cloud 用量的浏览器会话 Cookie 明文。
+		"proxy_key", "custom_key", "session",
 	}
 	set := make(map[string]struct{}, len(builtin)+len(SensitiveCredentialKeys)+16)
 	for _, k := range builtin {
diff --git a/backend/internal/service/audit_log_test.go b/backend/internal/service/audit_log_test.go
index ad4b4b8805..0045c936f2 100644
--- a/backend/internal/service/audit_log_test.go
+++ b/backend/internal/service/audit_log_test.go
@@ -62,6 +62,20 @@ func TestRedactAuditBody_JSONRedactsSecrets(t *testing.T) {
 	}
 }
 
+// 裸键 "session"（Ollama Cloud 会话保存的请求体字段）值整体就是浏览器 Cookie 明文，
+// 必须命中键级脱敏；session_id 等运行态标识不受影响，保留以便追责。
+func TestRedactAuditBody_BareSessionKeyRedacted(t *testing.T) {
+	raw := []byte(`{"session": "wos-session=cookie-canary", "session_id": "sid-visible"}`)
+	out := RedactAuditBody(raw, "application/json")
+
+	if strings.Contains(out, "cookie-canary") {
+		t.Fatalf("redacted body still contains the session cookie: %s", out)
+	}
+	if !strings.Contains(out, "sid-visible") {
+		t.Fatalf("session_id should be preserved for accountability: %s", out)
+	}
+}
+
 // TestRedactAuditBody_AuthoritativeTablesSynced 覆盖曾经漏网的凭证字段：
 // 账号 credentials 敏感子键、支付渠道无分隔符密钥、字符串值内嵌凭证的 proxy_key / custom_key，
 // 以及 camelCase 等命名变体（归一化比对）。