AI 配置改为按用户独立存储

每个用户 AI 配置存 data/user_data/ai_settings/{username}.json，
读配置时用户级优先，无则回退到全局 secrets.json。

Co-Authored-By: Claude <noreply@anthropic.com>

serve/backend/app/api/settings.py

@@ -48,15 +48,28 @@ class TickflowKeyIn(BaseModel):
     api_key: str
 
 
+def _get_ai_config(username: str | None, key: str, default: str = "") -> str:
+    """读 AI 配置: 用户级优先, 无则全局。"""
+    if username:
+        val = secrets_store.load_ai_config(username).get(key)
+        if val:
+            return val
+    return secrets_store.get_ai_config(key, default)
+
+
 @router.get("")
-def get_settings() -> dict:
+def get_settings(request: Request) -> dict:
     """返回当前配置概况(Key 脱敏)。"""
     from app.config import settings
     from app.services import preferences
     from app.services.ai_provider import ai_configured, current_ai_model, current_codex_command
 
+    username = getattr(request.state, "username", None)
     key = secrets_store.get_tickflow_key()
-    ai_provider = secrets_store.get_ai_config("ai_provider", settings.ai_provider)
+    ai_provider = _get_ai_config(username, "ai_provider", settings.ai_provider)
+    ai_api_key = secrets_store.load_ai_config(username).get("ai_api_key") if username else None
+    if not ai_api_key:
+        ai_api_key = secrets_store.get_ai_key()
     return {
         "mode": tf_client.current_mode(),
         "tickflow_api_key_masked": secrets_store.mask(key),
@@ -68,15 +81,15 @@ def get_settings() -> dict:
         "extras_caps": extras_caps(),
         # 首次使用引导
         "onboarding_completed": preferences.get_onboarding_completed(),
-        # AI 配置
+        # AI 配置 (用户级优先)
         "ai_provider": ai_provider,
-        "ai_base_url": secrets_store.get_ai_config("ai_base_url", settings.ai_base_url),
-        "ai_api_key_masked": secrets_store.mask(secrets_store.get_ai_key()),
-        "has_ai_key": bool(secrets_store.get_ai_key()),
+        "ai_base_url": _get_ai_config(username, "ai_base_url", settings.ai_base_url),
+        "ai_api_key_masked": secrets_store.mask(ai_api_key),
+        "has_ai_key": bool(ai_api_key),
         "ai_configured": ai_configured(ai_provider),
         "ai_model": current_ai_model(),
         "ai_codex_command": current_codex_command(),
-        "ai_user_agent": secrets_store.get_ai_config("ai_user_agent", settings.ai_user_agent),
+        "ai_user_agent": _get_ai_config(username, "ai_user_agent", settings.ai_user_agent),
     }
 
 
@@ -238,11 +251,14 @@ class AiSettingsIn(BaseModel):
 
 
 @router.post("/ai")
-def save_ai_settings(req: AiSettingsIn) -> dict:
-    """保存 AI 配置（全部持久化到 secrets.json）"""
+def save_ai_settings(req: AiSettingsIn, request: Request) -> dict:
+    """保存 AI 配置（按用户独立存储）。"""
     from app.config import settings
     from app.services.ai_provider import ai_configured, current_ai_model, current_ai_provider, current_codex_command, normalize_codex_command
 
+    username = getattr(request.state, "username", None)
+    target = username if username else "global"
+
     updates: dict = {}
     if req.provider:
         updates["ai_provider"] = req.provider
@@ -255,10 +271,10 @@ def save_ai_settings(req: AiSettingsIn) -> dict:
             updates["ai_api_key"] = req.api_key
             settings.ai_api_key = req.api_key
         else:
-            secrets_store.clear("ai_api_key")
+            secrets_store.clear_ai_config(target, "ai_api_key")
             settings.ai_api_key = ""
     if req.provider == "codex_cli" and not req.model:
-        secrets_store.clear("ai_model")
+        secrets_store.clear_ai_config(target, "ai_model")
         settings.ai_model = ""
     elif req.model:
         updates["ai_model"] = req.model
@@ -270,12 +286,12 @@ def save_ai_settings(req: AiSettingsIn) -> dict:
             raise HTTPException(status_code=400, detail=str(exc)) from exc
         updates["ai_codex_command"] = codex_command
         settings.ai_codex_command = codex_command
-    # user_agent 允许清空(回到默认浏览器 UA),故无条件持久化
+    # user_agent 允许清空,故无条件持久化
     updates["ai_user_agent"] = req.user_agent
     settings.ai_user_agent = req.user_agent
 
     if updates:
-        secrets_store.save(updates)
+        secrets_store.save_ai_config(target, updates)
 
     provider = current_ai_provider()
     return {
@@ -288,15 +304,15 @@ def save_ai_settings(req: AiSettingsIn) -> dict:
 
 
 @router.delete("/ai")
-def clear_ai_settings() -> dict:
-    """一键清空 AI 配置(provider / base_url / api_key / model)。
-
-    保留 ai_user_agent —— 自定义请求头与凭证解耦,清空凭证不影响绕过 CDN 拦截的设置。
-    """
+def clear_ai_settings(request: Request) -> dict:
+    """一键清空当前用户的 AI 配置。"""
     from app.config import settings
 
-    secrets_store.clear("ai_provider", "ai_base_url", "ai_api_key", "ai_model", "ai_codex_command")
-    # 同步重置运行时内存(provider 回默认值,其余置空)
+    username = getattr(request.state, "username", None)
+    target = username if username else "global"
+
+    secrets_store.clear_ai_config(target, "ai_provider", "ai_base_url", "ai_api_key", "ai_model", "ai_codex_command")
+    # 同步重置运行时内存
     settings.ai_provider = "openai_compat"
     settings.ai_base_url = ""
     settings.ai_api_key = ""

serve/backend/app/secrets_store.py

@@ -94,3 +94,53 @@ def mask(key: str, prefix: int = 4, suffix: int = 4) -> str:
     if len(key) <= prefix + suffix:
         return "•" * len(key)
     return f"{key[:prefix]}{'•' * 6}{key[-suffix:]}"
+
+
+# ================================================================
+# 按用户 AI 配置 (data/user_data/ai_settings/{username}.json)
+# ================================================================
+
+def _ai_config_path(username: str) -> Path:
+    from app.config import settings
+    p = settings.data_dir / "user_data" / "ai_settings" / f"{username}.json"
+    p.parent.mkdir(parents=True, exist_ok=True)
+    return p
+
+
+def load_ai_config(username: str) -> dict:
+    """加载指定用户的 AI 配置。用户不存在时返回空 dict。"""
+    p = _ai_config_path(username)
+    if p.exists():
+        try:
+            return json.loads(p.read_text(encoding="utf-8"))
+        except Exception as e:  # noqa: BLE001
+            logger.warning("ai_settings/%s.json malformed: %s", username, e)
+    return {}
+
+
+def save_ai_config(username: str, updates: dict) -> dict:
+    """合并写入指定用户的 AI 配置。返回新内容。"""
+    current = load_ai_config(username)
+    current.update({k: v for k, v in updates.items() if v is not None})
+    p = _ai_config_path(username)
+    p.write_text(json.dumps(current, indent=2, ensure_ascii=False), encoding="utf-8")
+    try:
+        os.chmod(p, 0o600)
+    except OSError:
+        pass
+    return current
+
+
+def clear_ai_config(username: str, *keys: str) -> dict:
+    """清掉指定用户的 AI 配置字段。不传 keys 则删除整个文件。"""
+    p = _ai_config_path(username)
+    if not p.exists():
+        return {}
+    if not keys:
+        p.unlink()
+        return {}
+    current = load_ai_config(username)
+    for k in keys:
+        current.pop(k, None)
+    p.write_text(json.dumps(current, indent=2, ensure_ascii=False), encoding="utf-8")
+    return current