From b276bc8a8f27c86cbb9bccbda8950ecbe0f38692 Mon Sep 17 00:00:00 2001
From: Jesse_Chen <chen.yue@mevixaga.com>
Date: Wed, 12 Aug 2026 01:05:36 +0800
Subject: [PATCH] fix(rectification): bind default session model

---
 docs/BUG_HISTORY.md                           | 15 ++++++
 ...00_rectification_session_default_model.sql | 49 +++++++++++++++++++
 .../tests/rectification-v9-database.test.ts   | 21 ++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 frontend/supabase/migrations/20260811040000_rectification_session_default_model.sql

diff --git a/docs/BUG_HISTORY.md b/docs/BUG_HISTORY.md
index a7198eb2..51e9ce80 100644
--- a/docs/BUG_HISTORY.md
+++ b/docs/BUG_HISTORY.md
@@ -2899,3 +2899,18 @@
 - 防复发：任何对启用 RLS 的表新增 runtime grant 时，必须同时测试对应运行时角色的真实可见行，而不能只断言 `has_table_privilege=true`；feature flag 种子测试必须以 Web 实际使用的 `admin_runtime` 读取。
 - 相关记录：BUG-151、BUG-166
 - 修复版本：待提交
+
+## BUG-169 | V9 新建生时校正 Session 未绑定模型导致 Agent 立即返回模型不可用
+
+- 状态：resolved（本地候选）
+- 首次发现：2026-08-11
+- 最近更新：2026-08-11
+- 影响面：V9 `open_agentic_rectification_case` 新建会话、既有 `model_id is null` 的生时校正会话，以及 `POST /api/rectification/agent` 的模型解析。
+- 用户现象：运行时开关恢复后，原请求继续返回 `409 模型暂不可用`；请求体包含有效 `modelId`，管理端模型及供应商也均为 published/enabled。
+- 触发条件：V9 Open Case RPC 原子创建 `birth_time_rectification` Session 后立即发送 opening。
+- 根因：RPC 插入 `chat_sessions` 时没有写入 `model_id`；前端仅在内存中把目录默认模型显示为当前选择，而 Agent 路由按安全合同只解析服务端持久化的 `chatSession.model_id/model_config_version`，不会信任请求体覆盖会话模型。
+- 修复：新增向前迁移 `20260811040000_rectification_session_default_model.sql`；数据库触发器为缺少模型的生时校正 Session 绑定当前 published/enabled 默认模型，由既有 pin trigger 固定配置版本，并一次性回填同类历史 Session。普通咨询 Session 与已有明确模型选择均不改变。
+- 验证：V9 PostgreSQL fixture 在创建 Case 前播种默认模型，要求 RPC 新建 Session 后持久化为 `v9-default-model:1`；staging 还需核对迁移账本、原 Session 回填结果和真实 opening 请求。
+- 防复发：任何服务器端创建 `birth_time_rectification` Session 的路径都必须在同一事务内得到可解析的持久化模型与版本；前端显示的默认模型不能替代数据库绑定。
+- 相关记录：BUG-060、BUG-163、BUG-168
+- 修复版本：待提交
diff --git a/frontend/supabase/migrations/20260811040000_rectification_session_default_model.sql b/frontend/supabase/migrations/20260811040000_rectification_session_default_model.sql
new file mode 100644
index 00000000..6da1ece2
--- /dev/null
+++ b/frontend/supabase/migrations/20260811040000_rectification_session_default_model.sql
@@ -0,0 +1,49 @@
+begin;
+
+create or replace function public.default_rectification_chat_session_model()
+returns trigger
+language plpgsql
+security definer
+set search_path = ''
+as $$
+begin
+  if new.session_type = 'birth_time_rectification' and new.model_id is null then
+    select c.model_id into new.model_id
+    from public.model_config_versions v
+    join public.model_configs c on c.id = v.config_id
+    join public.model_providers p on p.id = v.provider_id
+    where v.status = 'published'
+      and v.enabled
+      and v.is_default
+      and p.enabled
+    limit 1;
+  end if;
+  return new;
+end
+$$;
+
+revoke all on function public.default_rectification_chat_session_model() from public, anon, authenticated;
+
+drop trigger if exists chat_sessions_default_rectification_model on public.chat_sessions;
+create trigger chat_sessions_default_rectification_model
+before insert or update of session_type, model_id on public.chat_sessions
+for each row execute function public.default_rectification_chat_session_model();
+
+with default_model as (
+  select c.model_id
+  from public.model_config_versions v
+  join public.model_configs c on c.id = v.config_id
+  join public.model_providers p on p.id = v.provider_id
+  where v.status = 'published'
+    and v.enabled
+    and v.is_default
+    and p.enabled
+  limit 1
+)
+update public.chat_sessions s
+set model_id = default_model.model_id
+from default_model
+where s.session_type = 'birth_time_rectification'
+  and s.model_id is null;
+
+commit;
diff --git a/frontend/tests/rectification-v9-database.test.ts b/frontend/tests/rectification-v9-database.test.ts
index f831f0a9..19fc3c85 100644
--- a/frontend/tests/rectification-v9-database.test.ts
+++ b/frontend/tests/rectification-v9-database.test.ts
@@ -101,6 +101,23 @@ test("v9 open is atomic, idempotent and resumes instead of duplicating", { skip:
       where id = '${userId}';
     `);
 
+    fixture.psql(`
+      with provider as (
+        insert into public.model_providers (code, name, provider_type, encrypted_api_key, enabled)
+        values ('v9-test', 'V9 Test', 'openai', 'test-ciphertext', true)
+        returning id
+      ), config as (
+        insert into public.model_configs (model_id)
+        values ('v9-default-model')
+        returning id
+      )
+      insert into public.model_config_versions (
+        config_id, version, provider_id, label, provider_model, enabled, is_default, status, published_at
+      )
+      select config.id, 1, provider.id, 'V9 Default', 'gpt-test', true, true, 'published', now()
+      from config cross join provider;
+    `);
+
     const service = createLocalPostgresDataClient(
       fixture.connectionUrl("service_runtime", "service-runtime-test-password"),
       null,
@@ -134,6 +151,10 @@ test("v9 open is atomic, idempotent and resumes instead of duplicating", { skip:
       fixture.psql(`select count(*) from public.chat_sessions where user_id = '${userId}'`),
       "1",
     );
+    assert.equal(
+      fixture.psql(`select model_id || ':' || model_config_version from public.chat_sessions where id = '${sessionId}'`),
+      "v9-default-model:1",
+    );
     assert.equal(
       fixture.psql(
         `select count(*) from public.agentic_rectification_open_ledger where user_id = '${userId}'`,