ccm,ocm: add request ID context to HTTP request logging

The upstream OpenAI WebSocket endpoint requires the
OpenAI-Beta: responses_websockets=2026-02-06 header. Set it
automatically when the client doesn't provide it.

Also capture and log the response body on non-429 WebSocket
handshake failures to surface the actual error from upstream.

docs/configuration/service/ccm.md

@@ -10,6 +10,11 @@ CCM (Claude Code Multiplexer) service is a multiplexing service that allows you
 
 It handles OAuth authentication with Claude's API on your local machine while allowing remote Claude Code to authenticate using Auth Tokens via the `ANTHROPIC_AUTH_TOKEN` environment variable.
 
+!!! quote "Changes in sing-box 1.14.0"
+
+    :material-plus: [credentials](#credentials)  
+    :material-alert: [users](#users)
+
 ### Structure
 
 ```json
@@ -19,6 +24,7 @@ It handles OAuth authentication with Claude's API on your local machine while al
   ... // Listen Fields
 
   "credential_path": "",
+  "credentials": [],
   "usages_path": "",
   "users": [],
   "headers": {},
@@ -45,6 +51,77 @@ On macOS, credentials are read from the system keychain first, then fall back to
 
 Refreshed tokens are automatically written back to the same location.
 
+When `credential_path` points to a file, the service can start before the file exists. The credential becomes available automatically after the file is created or updated, and becomes unavailable immediately if the file is later removed or becomes invalid.
+
+On macOS without an explicit `credential_path`, keychain changes are not watched. Automatic reload only applies to the credential file path.
+
+Conflict with `credentials`.
+
+#### credentials
+
+!!! question "Since sing-box 1.14.0"
+
+List of credential configurations for multi-credential mode.
+
+When set, top-level `credential_path`, `usages_path`, and `detour` are forbidden. Each user must specify a `credential` tag.
+
+Each credential has a `type` field (`default`, `balancer`, or `fallback`) and a required `tag` field.
+
+##### Default Credential
+
+```json
+{
+  "tag": "a",
+  "credential_path": "/path/to/.credentials.json",
+  "usages_path": "/path/to/usages.json",
+  "detour": "",
+  "reserve_5h": 20,
+  "reserve_weekly": 20
+}
+```
+
+A single OAuth credential file. The `type` field can be omitted (defaults to `default`). The service can start before the file exists, and reloads file updates automatically.
+
+- `credential_path`: Path to the credentials file. Same defaults as top-level `credential_path`.
+- `usages_path`: Optional usage tracking file for this credential.
+- `detour`: Outbound tag for connecting to the Claude API with this credential.
+- `reserve_5h`: Reserve threshold (1-99) for 5-hour window. Credential pauses at (100-N)% utilization.
+- `reserve_weekly`: Reserve threshold (1-99) for weekly window. Credential pauses at (100-N)% utilization.
+
+##### Balancer Credential
+
+```json
+{
+  "tag": "pool",
+  "type": "balancer",
+  "strategy": "",
+  "credentials": ["a", "b"],
+  "poll_interval": "60s"
+}
+```
+
+Assigns sessions to default credentials based on the selected strategy. Sessions are sticky until the assigned credential hits a rate limit.
+
+- `strategy`: Selection strategy. One of `least_used` `round_robin` `random`. `least_used` will be used by default.
+- `credentials`: ==Required== List of default credential tags.
+- `poll_interval`: How often to poll upstream usage API. Default `60s`.
+
+##### Fallback Credential
+
+```json
+{
+  "tag": "backup",
+  "type": "fallback",
+  "credentials": ["a", "b"],
+  "poll_interval": "30s"
+}
+```
+
+Uses credentials in order. Falls through to the next when the current one is exhausted.
+
+- `credentials`: ==Required== Ordered list of default credential tags.
+- `poll_interval`: How often to poll upstream usage API. Default `60s`.
+
 #### usages_path
 
 Path to the file for storing aggregated API usage statistics.
@@ -60,6 +137,8 @@ Statistics are organized by model, context window (200k standard vs 1M premium),
 
 The statistics file is automatically saved every minute and upon service shutdown.
 
+Conflict with `credentials`. In multi-credential mode, use `usages_path` on individual default credentials.
+
 #### users
 
 List of authorized users for token authentication.
@@ -71,7 +150,8 @@ Object format:
 ```json
 {
   "name": "",
-  "token": ""
+  "token": "",
+  "credential": ""
 }
 ```
 
@@ -79,6 +159,7 @@ Object fields:
 
 - `name`: Username identifier for tracking purposes.
 - `token`: Bearer token for authentication. Claude Code authenticates by setting the `ANTHROPIC_AUTH_TOKEN` environment variable to their token value.
+- `credential`: Credential tag to use for this user. ==Required== when `credentials` is set.
 
 #### headers
 
@@ -90,6 +171,8 @@ These headers will override any existing headers with the same name.
 
 Outbound tag for connecting to the Claude API.
 
+Conflict with `credentials`. In multi-credential mode, use `detour` on individual default credentials.
+
 #### tls
 
 TLS configuration, see [TLS](/configuration/shared/tls/#inbound).
@@ -129,3 +212,52 @@ export ANTHROPIC_AUTH_TOKEN="ak-ccm-hello-world"
 
 claude
 ```
+
+### Example with Multiple Credentials
+
+#### Server
+
+```json
+{
+  "services": [
+    {
+      "type": "ccm",
+      "listen": "0.0.0.0",
+      "listen_port": 8080,
+      "credentials": [
+        {
+          "tag": "a",
+          "credential_path": "/home/user/.claude-a/.credentials.json",
+          "usages_path": "/data/usages-a.json",
+          "reserve_5h": 20,
+          "reserve_weekly": 20
+        },
+        {
+          "tag": "b",
+          "credential_path": "/home/user/.claude-b/.credentials.json",
+          "reserve_5h": 10,
+          "reserve_weekly": 10
+        },
+        {
+          "tag": "pool",
+          "type": "balancer",
+          "poll_interval": "60s",
+          "credentials": ["a", "b"]
+        }
+      ],
+      "users": [
+        {
+          "name": "alice",
+          "token": "ak-ccm-hello-world",
+          "credential": "pool"
+        },
+        {
+          "name": "bob",
+          "token": "ak-ccm-hello-bob",
+          "credential": "a"
+        }
+      ]
+    }
+  ]
+}
+```

docs/configuration/service/ccm.zh.md

@@ -10,6 +10,11 @@ CCM（Claude Code 多路复用器）服务是一个多路复用服务，允许
 
 它在本地机器上处理与 Claude API 的 OAuth 身份验证，同时允许远程 Claude Code 通过 `ANTHROPIC_AUTH_TOKEN` 环境变量使用认证令牌进行身份验证。
 
+!!! quote "sing-box 1.14.0 中的更改"
+
+    :material-plus: [credentials](#credentials)  
+    :material-alert: [users](#users)
+
 ### 结构
 
 ```json
@@ -19,6 +24,7 @@ CCM（Claude Code 多路复用器）服务是一个多路复用服务，允许
   ... // 监听字段
 
   "credential_path": "",
+  "credentials": [],
   "usages_path": "",
   "users": [],
   "headers": {},
@@ -45,6 +51,77 @@ Claude Code OAuth 凭据文件的路径。
 
 刷新的令牌会自动写回相同位置。
 
+当 `credential_path` 指向文件时，即使文件尚不存在，服务也可以启动。文件被创建或更新后，凭据会自动变为可用；如果文件之后被删除或变为无效，该凭据会立即变为不可用。
+
+在 macOS 上如果未显式设置 `credential_path`，不会监听钥匙串变化。自动重载只作用于凭据文件路径。
+
+与 `credentials` 冲突。
+
+#### credentials
+
+!!! question "自 sing-box 1.14.0 起"
+
+多凭据模式的凭据配置列表。
+
+设置后，顶层 `credential_path`、`usages_path` 和 `detour` 被禁止。每个用户必须指定 `credential` 标签。
+
+每个凭据有一个 `type` 字段（`default`、`balancer` 或 `fallback`）和一个必填的 `tag` 字段。
+
+##### 默认凭据
+
+```json
+{
+  "tag": "a",
+  "credential_path": "/path/to/.credentials.json",
+  "usages_path": "/path/to/usages.json",
+  "detour": "",
+  "reserve_5h": 20,
+  "reserve_weekly": 20
+}
+```
+
+单个 OAuth 凭据文件。`type` 字段可以省略（默认为 `default`）。即使文件尚不存在，服务也可以启动，并会自动重载文件更新。
+
+- `credential_path`：凭据文件的路径。默认值与顶层 `credential_path` 相同。
+- `usages_path`：此凭据的可选使用跟踪文件。
+- `detour`：此凭据用于连接 Claude API 的出站标签。
+- `reserve_5h`：5 小时窗口的保留阈值（1-99）。凭据在利用率达到 (100-N)% 时暂停。
+- `reserve_weekly`：每周窗口的保留阈值（1-99）。凭据在利用率达到 (100-N)% 时暂停。
+
+##### 均衡凭据
+
+```json
+{
+  "tag": "pool",
+  "type": "balancer",
+  "strategy": "",
+  "credentials": ["a", "b"],
+  "poll_interval": "60s"
+}
+```
+
+根据选择的策略将会话分配给默认凭据。会话保持粘性，直到分配的凭据触发速率限制。
+
+- `strategy`：选择策略。可选值：`least_used` `round_robin` `random`。默认使用 `least_used`。
+- `credentials`：==必填== 默认凭据标签列表。
+- `poll_interval`：轮询上游使用 API 的间隔。默认 `60s`。
+
+##### 回退凭据
+
+```json
+{
+  "tag": "backup",
+  "type": "fallback",
+  "credentials": ["a", "b"],
+  "poll_interval": "30s"
+}
+```
+
+按顺序使用凭据。当前凭据耗尽后切换到下一个。
+
+- `credentials`：==必填== 有序的默认凭据标签列表。
+- `poll_interval`：轮询上游使用 API 的间隔。默认 `60s`。
+
 #### usages_path
 
 用于存储聚合 API 使用统计信息的文件路径。
@@ -60,6 +137,8 @@ Claude Code OAuth 凭据文件的路径。
 
 统计文件每分钟自动保存一次，并在服务关闭时保存。
 
+与 `credentials` 冲突。在多凭据模式下，在各个默认凭据上使用 `usages_path`。
+
 #### users
 
 用于令牌身份验证的授权用户列表。
@@ -71,7 +150,8 @@ Claude Code OAuth 凭据文件的路径。
 ```json
 {
   "name": "",
-  "token": ""
+  "token": "",
+  "credential": ""
 }
 ```
 
@@ -79,6 +159,7 @@ Claude Code OAuth 凭据文件的路径。
 
 - `name`：用于跟踪的用户名标识符。
 - `token`：用于身份验证的 Bearer 令牌。Claude Code 通过设置 `ANTHROPIC_AUTH_TOKEN` 环境变量为其令牌值进行身份验证。
+- `credential`：此用户使用的凭据标签。设置 `credentials` 时==必填==。
 
 #### headers
 
@@ -90,6 +171,8 @@ Claude Code OAuth 凭据文件的路径。
 
 用于连接 Claude API 的出站标签。
 
+与 `credentials` 冲突。在多凭据模式下，在各个默认凭据上使用 `detour`。
+
 #### tls
 
 TLS 配置，参阅 [TLS](/zh/configuration/shared/tls/#inbound)。
@@ -129,3 +212,52 @@ export ANTHROPIC_AUTH_TOKEN="ak-ccm-hello-world"
 
 claude
 ```
+
+### 多凭据示例
+
+#### 服务端
+
+```json
+{
+  "services": [
+    {
+      "type": "ccm",
+      "listen": "0.0.0.0",
+      "listen_port": 8080,
+      "credentials": [
+        {
+          "tag": "a",
+          "credential_path": "/home/user/.claude-a/.credentials.json",
+          "usages_path": "/data/usages-a.json",
+          "reserve_5h": 20,
+          "reserve_weekly": 20
+        },
+        {
+          "tag": "b",
+          "credential_path": "/home/user/.claude-b/.credentials.json",
+          "reserve_5h": 10,
+          "reserve_weekly": 10
+        },
+        {
+          "tag": "pool",
+          "type": "balancer",
+          "poll_interval": "60s",
+          "credentials": ["a", "b"]
+        }
+      ],
+      "users": [
+        {
+          "name": "alice",
+          "token": "ak-ccm-hello-world",
+          "credential": "pool"
+        },
+        {
+          "name": "bob",
+          "token": "ak-ccm-hello-bob",
+          "credential": "a"
+        }
+      ]
+    }
+  ]
+}
+```

docs/configuration/service/ocm.md

@@ -10,6 +10,11 @@ OCM (OpenAI Codex Multiplexer) service is a multiplexing service that allows you
 
 It handles OAuth authentication with OpenAI's API on your local machine while allowing remote clients to authenticate using custom tokens.
 
+!!! quote "Changes in sing-box 1.14.0"
+
+    :material-plus: [credentials](#credentials)  
+    :material-alert: [users](#users)
+
 ### Structure
 
 ```json
@@ -19,6 +24,7 @@ It handles OAuth authentication with OpenAI's API on your local machine while al
   ... // Listen Fields
 
   "credential_path": "",
+  "credentials": [],
   "usages_path": "",
   "users": [],
   "headers": {},
@@ -43,6 +49,75 @@ If not specified, defaults to:
 
 Refreshed tokens are automatically written back to the same location.
 
+When `credential_path` points to a file, the service can start before the file exists. The credential becomes available automatically after the file is created or updated, and becomes unavailable immediately if the file is later removed or becomes invalid.
+
+Conflict with `credentials`.
+
+#### credentials
+
+!!! question "Since sing-box 1.14.0"
+
+List of credential configurations for multi-credential mode.
+
+When set, top-level `credential_path`, `usages_path`, and `detour` are forbidden. Each user must specify a `credential` tag.
+
+Each credential has a `type` field (`default`, `balancer`, or `fallback`) and a required `tag` field.
+
+##### Default Credential
+
+```json
+{
+  "tag": "a",
+  "credential_path": "/path/to/auth.json",
+  "usages_path": "/path/to/usages.json",
+  "detour": "",
+  "reserve_5h": 20,
+  "reserve_weekly": 20
+}
+```
+
+A single OAuth credential file. The `type` field can be omitted (defaults to `default`). The service can start before the file exists, and reloads file updates automatically.
+
+- `credential_path`: Path to the credentials file. Same defaults as top-level `credential_path`.
+- `usages_path`: Optional usage tracking file for this credential.
+- `detour`: Outbound tag for connecting to the OpenAI API with this credential.
+- `reserve_5h`: Reserve threshold (1-99) for primary rate limit window. Credential pauses at (100-N)% utilization.
+- `reserve_weekly`: Reserve threshold (1-99) for secondary (weekly) rate limit window. Credential pauses at (100-N)% utilization.
+
+##### Balancer Credential
+
+```json
+{
+  "tag": "pool",
+  "type": "balancer",
+  "strategy": "",
+  "credentials": ["a", "b"],
+  "poll_interval": "60s"
+}
+```
+
+Assigns sessions to default credentials based on the selected strategy. Sessions are sticky until the assigned credential hits a rate limit.
+
+- `strategy`: Selection strategy. One of `least_used` `round_robin` `random`. `least_used` will be used by default.
+- `credentials`: ==Required== List of default credential tags.
+- `poll_interval`: How often to poll upstream usage API. Default `60s`.
+
+##### Fallback Credential
+
+```json
+{
+  "tag": "backup",
+  "type": "fallback",
+  "credentials": ["a", "b"],
+  "poll_interval": "30s"
+}
+```
+
+Uses credentials in order. Falls through to the next when the current one is exhausted.
+
+- `credentials`: ==Required== Ordered list of default credential tags.
+- `poll_interval`: How often to poll upstream usage API. Default `60s`.
+
 #### usages_path
 
 Path to the file for storing aggregated API usage statistics.
@@ -58,6 +133,8 @@ Statistics are organized by model and optionally by user when authentication is
 
 The statistics file is automatically saved every minute and upon service shutdown.
 
+Conflict with `credentials`. In multi-credential mode, use `usages_path` on individual default credentials.
+
 #### users
 
 List of authorized users for token authentication.
@@ -69,7 +146,8 @@ Object format:
 ```json
 {
   "name": "",
-  "token": ""
+  "token": "",
+  "credential": ""
 }
 ```
 
@@ -77,6 +155,7 @@ Object fields:
 
 - `name`: Username identifier for tracking purposes.
 - `token`: Bearer token for authentication. Clients authenticate by setting the `Authorization: Bearer <token>` header.
+- `credential`: Credential tag to use for this user. ==Required== when `credentials` is set.
 
 #### headers
 
@@ -88,6 +167,8 @@ These headers will override any existing headers with the same name.
 
 Outbound tag for connecting to the OpenAI API.
 
+Conflict with `credentials`. In multi-credential mode, use `detour` on individual default credentials.
+
 #### tls
 
 TLS configuration, see [TLS](/configuration/shared/tls/#inbound).
@@ -183,3 +264,52 @@ Then run:
 ```bash
 codex --profile ocm
 ```
+
+### Example with Multiple Credentials
+
+#### Server
+
+```json
+{
+  "services": [
+    {
+      "type": "ocm",
+      "listen": "0.0.0.0",
+      "listen_port": 8080,
+      "credentials": [
+        {
+          "tag": "a",
+          "credential_path": "/home/user/.codex-a/auth.json",
+          "usages_path": "/data/usages-a.json",
+          "reserve_5h": 20,
+          "reserve_weekly": 20
+        },
+        {
+          "tag": "b",
+          "credential_path": "/home/user/.codex-b/auth.json",
+          "reserve_5h": 10,
+          "reserve_weekly": 10
+        },
+        {
+          "tag": "pool",
+          "type": "balancer",
+          "poll_interval": "60s",
+          "credentials": ["a", "b"]
+        }
+      ],
+      "users": [
+        {
+          "name": "alice",
+          "token": "sk-ocm-hello-world",
+          "credential": "pool"
+        },
+        {
+          "name": "bob",
+          "token": "sk-ocm-hello-bob",
+          "credential": "a"
+        }
+      ]
+    }
+  ]
+}
+```

docs/configuration/service/ocm.zh.md

@@ -10,6 +10,11 @@ OCM（OpenAI Codex 多路复用器）服务是一个多路复用服务，允许
 
 它在本地机器上处理与 OpenAI API 的 OAuth 身份验证，同时允许远程客户端使用自定义令牌进行身份验证。
 
+!!! quote "sing-box 1.14.0 中的更改"
+
+    :material-plus: [credentials](#credentials)  
+    :material-alert: [users](#users)
+
 ### 结构
 
 ```json
@@ -19,6 +24,7 @@ OCM（OpenAI Codex 多路复用器）服务是一个多路复用服务，允许
   ... // 监听字段
 
   "credential_path": "",
+  "credentials": [],
   "usages_path": "",
   "users": [],
   "headers": {},
@@ -43,6 +49,75 @@ OpenAI OAuth 凭据文件的路径。
 
 刷新的令牌会自动写回相同位置。
 
+当 `credential_path` 指向文件时，即使文件尚不存在，服务也可以启动。文件被创建或更新后，凭据会自动变为可用；如果文件之后被删除或变为无效，该凭据会立即变为不可用。
+
+与 `credentials` 冲突。
+
+#### credentials
+
+!!! question "自 sing-box 1.14.0 起"
+
+多凭据模式的凭据配置列表。
+
+设置后，顶层 `credential_path`、`usages_path` 和 `detour` 被禁止。每个用户必须指定 `credential` 标签。
+
+每个凭据有一个 `type` 字段（`default`、`balancer` 或 `fallback`）和一个必填的 `tag` 字段。
+
+##### 默认凭据
+
+```json
+{
+  "tag": "a",
+  "credential_path": "/path/to/auth.json",
+  "usages_path": "/path/to/usages.json",
+  "detour": "",
+  "reserve_5h": 20,
+  "reserve_weekly": 20
+}
+```
+
+单个 OAuth 凭据文件。`type` 字段可以省略（默认为 `default`）。即使文件尚不存在，服务也可以启动，并会自动重载文件更新。
+
+- `credential_path`：凭据文件的路径。默认值与顶层 `credential_path` 相同。
+- `usages_path`：此凭据的可选使用跟踪文件。
+- `detour`：此凭据用于连接 OpenAI API 的出站标签。
+- `reserve_5h`：主要速率限制窗口的保留阈值（1-99）。凭据在利用率达到 (100-N)% 时暂停。
+- `reserve_weekly`：次要（每周）速率限制窗口的保留阈值（1-99）。凭据在利用率达到 (100-N)% 时暂停。
+
+##### 均衡凭据
+
+```json
+{
+  "tag": "pool",
+  "type": "balancer",
+  "strategy": "",
+  "credentials": ["a", "b"],
+  "poll_interval": "60s"
+}
+```
+
+根据选择的策略将会话分配给默认凭据。会话保持粘性，直到分配的凭据触发速率限制。
+
+- `strategy`：选择策略。可选值：`least_used` `round_robin` `random`。默认使用 `least_used`。
+- `credentials`：==必填== 默认凭据标签列表。
+- `poll_interval`：轮询上游使用 API 的间隔。默认 `60s`。
+
+##### 回退凭据
+
+```json
+{
+  "tag": "backup",
+  "type": "fallback",
+  "credentials": ["a", "b"],
+  "poll_interval": "30s"
+}
+```
+
+按顺序使用凭据。当前凭据耗尽后切换到下一个。
+
+- `credentials`：==必填== 有序的默认凭据标签列表。
+- `poll_interval`：轮询上游使用 API 的间隔。默认 `60s`。
+
 #### usages_path
 
 用于存储聚合 API 使用统计信息的文件路径。
@@ -58,6 +133,8 @@ OpenAI OAuth 凭据文件的路径。
 
 统计文件每分钟自动保存一次，并在服务关闭时保存。
 
+与 `credentials` 冲突。在多凭据模式下，在各个默认凭据上使用 `usages_path`。
+
 #### users
 
 用于令牌身份验证的授权用户列表。
@@ -69,7 +146,8 @@ OpenAI OAuth 凭据文件的路径。
 ```json
 {
   "name": "",
-  "token": ""
+  "token": "",
+  "credential": ""
 }
 ```
 
@@ -77,6 +155,7 @@ OpenAI OAuth 凭据文件的路径。
 
 - `name`：用于跟踪的用户名标识符。
 - `token`：用于身份验证的 Bearer 令牌。客户端通过设置 `Authorization: Bearer <token>` 头进行身份验证。
+- `credential`：此用户使用的凭据标签。设置 `credentials` 时==必填==。
 
 #### headers
 
@@ -88,6 +167,8 @@ OpenAI OAuth 凭据文件的路径。
 
 用于连接 OpenAI API 的出站标签。
 
+与 `credentials` 冲突。在多凭据模式下，在各个默认凭据上使用 `detour`。
+
 #### tls
 
 TLS 配置，参阅 [TLS](/zh/configuration/shared/tls/#inbound)。
@@ -184,3 +265,52 @@ model_provider = "ocm"
 ```bash
 codex --profile ocm
 ```
+
+### 多凭据示例
+
+#### 服务端
+
+```json
+{
+  "services": [
+    {
+      "type": "ocm",
+      "listen": "0.0.0.0",
+      "listen_port": 8080,
+      "credentials": [
+        {
+          "tag": "a",
+          "credential_path": "/home/user/.codex-a/auth.json",
+          "usages_path": "/data/usages-a.json",
+          "reserve_5h": 20,
+          "reserve_weekly": 20
+        },
+        {
+          "tag": "b",
+          "credential_path": "/home/user/.codex-b/auth.json",
+          "reserve_5h": 10,
+          "reserve_weekly": 10
+        },
+        {
+          "tag": "pool",
+          "type": "balancer",
+          "poll_interval": "60s",
+          "credentials": ["a", "b"]
+        }
+      ],
+      "users": [
+        {
+          "name": "alice",
+          "token": "sk-ocm-hello-world",
+          "credential": "pool"
+        },
+        {
+          "name": "bob",
+          "token": "sk-ocm-hello-bob",
+          "credential": "a"
+        }
+      ]
+    }
+  ]
+}
+```

go.mod

@@ -35,7 +35,7 @@ require (
 	github.com/sagernet/gomobile v0.1.12
 	github.com/sagernet/gvisor v0.0.0-20250811.0-sing-box-mod.1
 	github.com/sagernet/quic-go v0.59.0-sing-box-mod.4
-	github.com/sagernet/sing v0.8.2
+	github.com/sagernet/sing v0.8.3-0.20260311155444-d39eb42a9f69
 	github.com/sagernet/sing-mux v0.3.4
 	github.com/sagernet/sing-quic v0.6.0
 	github.com/sagernet/sing-shadowsocks v0.2.8

go.sum

@@ -236,8 +236,8 @@ github.com/sagernet/nftables v0.3.0-beta.4 h1:kbULlAwAC3jvdGAC1P5Fa3GSxVwQJibNen
 github.com/sagernet/nftables v0.3.0-beta.4/go.mod h1:OQXAjvjNGGFxaTgVCSTRIhYB5/llyVDeapVoENYBDS8=
 github.com/sagernet/quic-go v0.59.0-sing-box-mod.4 h1:6qvrUW79S+CrPwWz6cMePXohgjHoKxLo3c+MDhNwc3o=
 github.com/sagernet/quic-go v0.59.0-sing-box-mod.4/go.mod h1:OqILvS182CyOol5zNNo6bguvOGgXzV459+chpRaUC+4=
-github.com/sagernet/sing v0.8.2 h1:kX1IH9SWJv4S0T9M8O+HNahWgbOuY1VauxbF7NU5lOg=
-github.com/sagernet/sing v0.8.2/go.mod h1:ARkL0gM13/Iv5VCZmci/NuoOlePoIsW0m7BWfln/Hak=
+github.com/sagernet/sing v0.8.3-0.20260311155444-d39eb42a9f69 h1:h6UF2emeydBQMAso99Nr3APV6YustOs+JszVuCkcFy0=
+github.com/sagernet/sing v0.8.3-0.20260311155444-d39eb42a9f69/go.mod h1:ARkL0gM13/Iv5VCZmci/NuoOlePoIsW0m7BWfln/Hak=
 github.com/sagernet/sing-mux v0.3.4 h1:ZQplKl8MNXutjzbMVtWvWG31fohhgOfCuUZR4dVQ8+s=
 github.com/sagernet/sing-mux v0.3.4/go.mod h1:QvlKMyNBNrQoyX4x+gq028uPbLM2XeRpWtDsWBJbFSk=
 github.com/sagernet/sing-quic v0.6.0 h1:dhrFnP45wgVKEOT1EvtsToxdzRnHIDIAgj6WHV9pLyM=

log/format.go

@@ -168,7 +168,11 @@ func FormatDuration(duration time.Duration) string {
 		return F.ToString(duration.Milliseconds(), "ms")
 	} else if duration < time.Minute {
 		return F.ToString(int64(duration.Seconds()), ".", int64(duration.Seconds()*100)%100, "s")
-	} else {
+	} else if duration < time.Hour {
 		return F.ToString(int64(duration.Minutes()), "m", int64(duration.Seconds())%60, "s")
+	} else if duration < 24*time.Hour {
+		return F.ToString(int64(duration.Hours()), "h", int64(duration.Minutes())%60, "m")
+	} else {
+		return F.ToString(int64(duration.Hours())/24, "d", int64(duration.Hours())%24, "h")
 	}
 }

option/ccm.go

@@ -1,6 +1,9 @@
 package option
 
 import (
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/json"
+	"github.com/sagernet/sing/common/json/badjson"
 	"github.com/sagernet/sing/common/json/badoption"
 )
 
@@ -8,6 +11,7 @@ type CCMServiceOptions struct {
 	ListenOptions
 	InboundTLSOptionsContainer
 	CredentialPath string               `json:"credential_path,omitempty"`
+	Credentials    []CCMCredential      `json:"credentials,omitempty"`
 	Users          []CCMUser            `json:"users,omitempty"`
 	Headers        badoption.HTTPHeader `json:"headers,omitempty"`
 	Detour         string               `json:"detour,omitempty"`
@@ -15,6 +19,94 @@ type CCMServiceOptions struct {
 }
 
 type CCMUser struct {
-	Name  string `json:"name,omitempty"`
-	Token string `json:"token,omitempty"`
+	Name               string `json:"name,omitempty"`
+	Token              string `json:"token,omitempty"`
+	Credential         string `json:"credential,omitempty"`
+	ExternalCredential string `json:"external_credential,omitempty"`
+	AllowExternalUsage bool   `json:"allow_external_usage,omitempty"`
+}
+
+type _CCMCredential struct {
+	Type            string                       `json:"type,omitempty"`
+	Tag             string                       `json:"tag"`
+	DefaultOptions  CCMDefaultCredentialOptions  `json:"-"`
+	ExternalOptions CCMExternalCredentialOptions `json:"-"`
+	BalancerOptions CCMBalancerCredentialOptions `json:"-"`
+	FallbackOptions CCMFallbackCredentialOptions `json:"-"`
+}
+
+type CCMCredential _CCMCredential
+
+func (c CCMCredential) MarshalJSON() ([]byte, error) {
+	var v any
+	switch c.Type {
+	case "", "default":
+		c.Type = ""
+		v = c.DefaultOptions
+	case "external":
+		v = c.ExternalOptions
+	case "balancer":
+		v = c.BalancerOptions
+	case "fallback":
+		v = c.FallbackOptions
+	default:
+		return nil, E.New("unknown credential type: ", c.Type)
+	}
+	return badjson.MarshallObjects((_CCMCredential)(c), v)
+}
+
+func (c *CCMCredential) UnmarshalJSON(bytes []byte) error {
+	err := json.Unmarshal(bytes, (*_CCMCredential)(c))
+	if err != nil {
+		return err
+	}
+	if c.Tag == "" {
+		return E.New("missing credential tag")
+	}
+	var v any
+	switch c.Type {
+	case "", "default":
+		c.Type = "default"
+		v = &c.DefaultOptions
+	case "external":
+		v = &c.ExternalOptions
+	case "balancer":
+		v = &c.BalancerOptions
+	case "fallback":
+		v = &c.FallbackOptions
+	default:
+		return E.New("unknown credential type: ", c.Type)
+	}
+	return badjson.UnmarshallExcluded(bytes, (*_CCMCredential)(c), v)
+}
+
+type CCMDefaultCredentialOptions struct {
+	CredentialPath string `json:"credential_path,omitempty"`
+	UsagesPath     string `json:"usages_path,omitempty"`
+	Detour         string `json:"detour,omitempty"`
+	Reserve5h      uint8  `json:"reserve_5h"`
+	ReserveWeekly  uint8  `json:"reserve_weekly"`
+	Limit5h        uint8  `json:"limit_5h,omitempty"`
+	LimitWeekly    uint8  `json:"limit_weekly,omitempty"`
+}
+
+type CCMBalancerCredentialOptions struct {
+	Strategy     string                     `json:"strategy,omitempty"`
+	Credentials  badoption.Listable[string] `json:"credentials"`
+	PollInterval badoption.Duration         `json:"poll_interval,omitempty"`
+}
+
+type CCMExternalCredentialOptions struct {
+	URL string `json:"url,omitempty"`
+	ServerOptions
+	Token        string             `json:"token"`
+	Reverse      bool               `json:"reverse,omitempty"`
+	Detour       string             `json:"detour,omitempty"`
+	UsagesPath   string             `json:"usages_path,omitempty"`
+	PollInterval badoption.Duration `json:"poll_interval,omitempty"`
+}
+
+type CCMFallbackCredentialOptions struct {
+	Credentials  badoption.Listable[string] `json:"credentials"`
+	PollInterval badoption.Duration         `json:"poll_interval,omitempty"`
 }

option/ocm.go

@@ -1,6 +1,9 @@
 package option
 
 import (
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/json"
+	"github.com/sagernet/sing/common/json/badjson"
 	"github.com/sagernet/sing/common/json/badoption"
 )
 
@@ -8,6 +11,7 @@ type OCMServiceOptions struct {
 	ListenOptions
 	InboundTLSOptionsContainer
 	CredentialPath string               `json:"credential_path,omitempty"`
+	Credentials    []OCMCredential      `json:"credentials,omitempty"`
 	Users          []OCMUser            `json:"users,omitempty"`
 	Headers        badoption.HTTPHeader `json:"headers,omitempty"`
 	Detour         string               `json:"detour,omitempty"`
@@ -15,6 +19,94 @@ type OCMServiceOptions struct {
 }
 
 type OCMUser struct {
-	Name  string `json:"name,omitempty"`
-	Token string `json:"token,omitempty"`
+	Name               string `json:"name,omitempty"`
+	Token              string `json:"token,omitempty"`
+	Credential         string `json:"credential,omitempty"`
+	ExternalCredential string `json:"external_credential,omitempty"`
+	AllowExternalUsage bool   `json:"allow_external_usage,omitempty"`
+}
+
+type _OCMCredential struct {
+	Type            string                       `json:"type,omitempty"`
+	Tag             string                       `json:"tag"`
+	DefaultOptions  OCMDefaultCredentialOptions  `json:"-"`
+	ExternalOptions OCMExternalCredentialOptions `json:"-"`
+	BalancerOptions OCMBalancerCredentialOptions `json:"-"`
+	FallbackOptions OCMFallbackCredentialOptions `json:"-"`
+}
+
+type OCMCredential _OCMCredential
+
+func (c OCMCredential) MarshalJSON() ([]byte, error) {
+	var v any
+	switch c.Type {
+	case "", "default":
+		c.Type = ""
+		v = c.DefaultOptions
+	case "external":
+		v = c.ExternalOptions
+	case "balancer":
+		v = c.BalancerOptions
+	case "fallback":
+		v = c.FallbackOptions
+	default:
+		return nil, E.New("unknown credential type: ", c.Type)
+	}
+	return badjson.MarshallObjects((_OCMCredential)(c), v)
+}
+
+func (c *OCMCredential) UnmarshalJSON(bytes []byte) error {
+	err := json.Unmarshal(bytes, (*_OCMCredential)(c))
+	if err != nil {
+		return err
+	}
+	if c.Tag == "" {
+		return E.New("missing credential tag")
+	}
+	var v any
+	switch c.Type {
+	case "", "default":
+		c.Type = "default"
+		v = &c.DefaultOptions
+	case "external":
+		v = &c.ExternalOptions
+	case "balancer":
+		v = &c.BalancerOptions
+	case "fallback":
+		v = &c.FallbackOptions
+	default:
+		return E.New("unknown credential type: ", c.Type)
+	}
+	return badjson.UnmarshallExcluded(bytes, (*_OCMCredential)(c), v)
+}
+
+type OCMDefaultCredentialOptions struct {
+	CredentialPath string `json:"credential_path,omitempty"`
+	UsagesPath     string `json:"usages_path,omitempty"`
+	Detour         string `json:"detour,omitempty"`
+	Reserve5h      uint8  `json:"reserve_5h"`
+	ReserveWeekly  uint8  `json:"reserve_weekly"`
+	Limit5h        uint8  `json:"limit_5h,omitempty"`
+	LimitWeekly    uint8  `json:"limit_weekly,omitempty"`
+}
+
+type OCMBalancerCredentialOptions struct {
+	Strategy     string                     `json:"strategy,omitempty"`
+	Credentials  badoption.Listable[string] `json:"credentials"`
+	PollInterval badoption.Duration         `json:"poll_interval,omitempty"`
+}
+
+type OCMExternalCredentialOptions struct {
+	URL string `json:"url,omitempty"`
+	ServerOptions
+	Token        string             `json:"token"`
+	Reverse      bool               `json:"reverse,omitempty"`
+	Detour       string             `json:"detour,omitempty"`
+	UsagesPath   string             `json:"usages_path,omitempty"`
+	PollInterval badoption.Duration `json:"poll_interval,omitempty"`
+}
+
+type OCMFallbackCredentialOptions struct {
+	Credentials  badoption.Listable[string] `json:"credentials"`
+	PollInterval badoption.Duration         `json:"poll_interval,omitempty"`
 }

protocol/tailscale/endpoint.go

@@ -847,4 +847,3 @@ func (c *dnsConfigurtor) GetBaseConfig() (tsDNS.OSConfig, error) {
 func (c *dnsConfigurtor) Close() error {
 	return nil
 }
-

route/network.go

@@ -51,6 +51,7 @@ type NetworkManager struct {
 	endpoint               adapter.EndpointManager
 	inbound                adapter.InboundManager
 	outbound               adapter.OutboundManager
+	serviceManager         adapter.ServiceManager
 	needWIFIState          bool
 	wifiMonitor            settings.WIFIMonitor
 	wifiState              adapter.WIFIState
@@ -94,6 +95,7 @@ func NewNetworkManager(ctx context.Context, logger logger.ContextLogger, options
 		endpoint:          service.FromContext[adapter.EndpointManager](ctx),
 		inbound:           service.FromContext[adapter.InboundManager](ctx),
 		outbound:          service.FromContext[adapter.OutboundManager](ctx),
+		serviceManager:    service.FromContext[adapter.ServiceManager](ctx),
 		needWIFIState:     hasRule(options.Rules, isWIFIRule) || hasDNSRule(dnsOptions.Rules, isWIFIDNSRule),
 	}
 	if options.DefaultNetworkStrategy != nil {
@@ -475,6 +477,15 @@ func (r *NetworkManager) ResetNetwork() {
 			listener.InterfaceUpdated()
 		}
 	}
+
+	if r.serviceManager != nil {
+		for _, svc := range r.serviceManager.Services() {
+			listener, isListener := svc.(adapter.InterfaceUpdateListener)
+			if isListener {
+				listener.InterfaceUpdated()
+			}
+		}
+	}
 }
 
 func (r *NetworkManager) notifyInterfaceUpdate(defaultInterface *control.Interface, flags int) {

service/ccm/credential.go

@@ -2,25 +2,74 @@ package ccm
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"io"
 	"net/http"
 	"os"
 	"os/user"
 	"path/filepath"
+	"runtime"
+	"slices"
+	"sync"
 	"time"
 
+	"github.com/sagernet/sing-box/log"
 	E "github.com/sagernet/sing/common/exceptions"
 )
 
 const (
 	oauth2ClientID          = "9d1c250a-e61b-44d9-88ed-5944d1962f5e"
-	oauth2TokenURL          = "https://console.anthropic.com/v1/oauth/token"
+	oauth2TokenURL          = "https://platform.claude.com/v1/oauth/token"
 	claudeAPIBaseURL        = "https://api.anthropic.com"
 	tokenRefreshBufferMs    = 60000
 	anthropicBetaOAuthValue = "oauth-2025-04-20"
 )
 
+const ccmUserAgentFallback = "claude-code/2.1.72"
+
+var (
+	ccmUserAgentOnce  sync.Once
+	ccmUserAgentValue string
+)
+
+func initCCMUserAgent(logger log.ContextLogger) {
+	ccmUserAgentOnce.Do(func() {
+		version, err := detectClaudeCodeVersion()
+		if err != nil {
+			logger.Error("detect Claude Code version: ", err)
+			ccmUserAgentValue = ccmUserAgentFallback
+			return
+		}
+		logger.Debug("detected Claude Code version: ", version)
+		ccmUserAgentValue = "claude-code/" + version
+	})
+}
+
+func detectClaudeCodeVersion() (string, error) {
+	userInfo, err := getRealUser()
+	if err != nil {
+		return "", E.Cause(err, "get user")
+	}
+	binaryName := "claude"
+	if runtime.GOOS == "windows" {
+		binaryName = "claude.exe"
+	}
+	linkPath := filepath.Join(userInfo.HomeDir, ".local", "bin", binaryName)
+	target, err := os.Readlink(linkPath)
+	if err != nil {
+		return "", E.Cause(err, "readlink ", linkPath)
+	}
+	if !filepath.IsAbs(target) {
+		target = filepath.Join(filepath.Dir(linkPath), target)
+	}
+	parent := filepath.Base(filepath.Dir(target))
+	if parent != "versions" {
+		return "", E.New("unexpected symlink target: ", target)
+	}
+	return filepath.Base(target), nil
+}
+
 func getRealUser() (*user.User, error) {
 	if sudoUser := os.Getenv("SUDO_USER"); sudoUser != "" {
 		sudoUserInfo, err := user.Lookup(sudoUser)
@@ -60,6 +109,14 @@ func readCredentialsFromFile(path string) (*oauthCredentials, error) {
 	return credentialsContainer.ClaudeAIAuth, nil
 }
 
+func checkCredentialFileWritable(path string) error {
+	file, err := os.OpenFile(path, os.O_WRONLY, 0)
+	if err != nil {
+		return err
+	}
+	return file.Close()
+}
+
 func writeCredentialsToFile(oauthCredentials *oauthCredentials, path string) error {
 	data, err := json.MarshalIndent(map[string]any{
 		"claudeAiOauth": oauthCredentials,
@@ -76,6 +133,7 @@ type oauthCredentials struct {
 	ExpiresAt        int64    `json:"expiresAt"`
 	Scopes           []string `json:"scopes,omitempty"`
 	SubscriptionType string   `json:"subscriptionType,omitempty"`
+	RateLimitTier    string   `json:"rateLimitTier,omitempty"`
 	IsMax            bool     `json:"isMax,omitempty"`
 }
 
@@ -86,7 +144,7 @@ func (c *oauthCredentials) needsRefresh() bool {
 	return time.Now().UnixMilli() >= c.ExpiresAt-tokenRefreshBufferMs
 }
 
-func refreshToken(httpClient *http.Client, credentials *oauthCredentials) (*oauthCredentials, error) {
+func refreshToken(ctx context.Context, httpClient *http.Client, credentials *oauthCredentials) (*oauthCredentials, error) {
 	if credentials.RefreshToken == "" {
 		return nil, E.New("refresh token is empty")
 	}
@@ -100,19 +158,24 @@ func refreshToken(httpClient *http.Client, credentials *oauthCredentials) (*oaut
 		return nil, E.Cause(err, "marshal request")
 	}
 
-	request, err := http.NewRequest("POST", oauth2TokenURL, bytes.NewReader(requestBody))
-	if err != nil {
-		return nil, err
-	}
-	request.Header.Set("Content-Type", "application/json")
-	request.Header.Set("Accept", "application/json")
-
-	response, err := httpClient.Do(request)
+	response, err := doHTTPWithRetry(ctx, httpClient, func() (*http.Request, error) {
+		request, err := http.NewRequest("POST", oauth2TokenURL, bytes.NewReader(requestBody))
+		if err != nil {
+			return nil, err
+		}
+		request.Header.Set("Content-Type", "application/json")
+		request.Header.Set("User-Agent", ccmUserAgentValue)
+		return request, nil
+	})
 	if err != nil {
 		return nil, err
 	}
 	defer response.Body.Close()
 
+	if response.StatusCode == http.StatusTooManyRequests {
+		body, _ := io.ReadAll(response.Body)
+		return nil, E.New("refresh rate limited: ", response.Status, " ", string(body))
+	}
 	if response.StatusCode != http.StatusOK {
 		body, _ := io.ReadAll(response.Body)
 		return nil, E.New("refresh failed: ", response.Status, " ", string(body))
@@ -137,3 +200,25 @@ func refreshToken(httpClient *http.Client, credentials *oauthCredentials) (*oaut
 
 	return &newCredentials, nil
 }
+
+func cloneCredentials(credentials *oauthCredentials) *oauthCredentials {
+	if credentials == nil {
+		return nil
+	}
+	cloned := *credentials
+	cloned.Scopes = append([]string(nil), credentials.Scopes...)
+	return &cloned
+}
+
+func credentialsEqual(left *oauthCredentials, right *oauthCredentials) bool {
+	if left == nil || right == nil {
+		return left == right
+	}
+	return left.AccessToken == right.AccessToken &&
+		left.RefreshToken == right.RefreshToken &&
+		left.ExpiresAt == right.ExpiresAt &&
+		slices.Equal(left.Scopes, right.Scopes) &&
+		left.SubscriptionType == right.SubscriptionType &&
+		left.RateLimitTier == right.RateLimitTier &&
+		left.IsMax == right.IsMax
+}

service/ccm/credential_darwin.go

@@ -69,6 +69,13 @@ func platformReadCredentials(customPath string) (*oauthCredentials, error) {
 	return readCredentialsFromFile(defaultPath)
 }
 
+func platformCanWriteCredentials(customPath string) error {
+	if customPath == "" {
+		return nil
+	}
+	return checkCredentialFileWritable(customPath)
+}
+
 func platformWriteCredentials(oauthCredentials *oauthCredentials, customPath string) error {
 	if customPath != "" {
 		return writeCredentialsToFile(oauthCredentials, customPath)

service/ccm/credential_external.go

@@ -0,0 +1,676 @@
+package ccm
+
+import (
+	"bytes"
+	"context"
+	stdTLS "crypto/tls"
+	"encoding/json"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/dialer"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/common/ntp"
+
+	"github.com/hashicorp/yamux"
+)
+
+const reverseProxyBaseURL = "http://reverse-proxy"
+
+type externalCredential struct {
+	tag          string
+	baseURL      string
+	token        string
+	httpClient   *http.Client
+	state        credentialState
+	stateMutex   sync.RWMutex
+	pollAccess   sync.Mutex
+	pollInterval time.Duration
+	usageTracker *AggregatedUsage
+	logger       log.ContextLogger
+
+	onBecameUnusable func()
+	interrupted      bool
+	requestContext   context.Context
+	cancelRequests   context.CancelFunc
+	requestAccess    sync.Mutex
+
+	// Reverse proxy fields
+	reverse              bool
+	reverseSession       *yamux.Session
+	reverseAccess        sync.RWMutex
+	closed               bool
+	reverseContext       context.Context
+	reverseCancel        context.CancelFunc
+	connectorDialer      N.Dialer
+	connectorDestination M.Socksaddr
+	connectorRequestPath string
+	connectorURL         *url.URL
+	connectorTLS         *stdTLS.Config
+	reverseService       http.Handler
+}
+
+func externalCredentialURLPort(parsedURL *url.URL) uint16 {
+	portStr := parsedURL.Port()
+	if portStr != "" {
+		port, err := strconv.ParseUint(portStr, 10, 16)
+		if err == nil {
+			return uint16(port)
+		}
+	}
+	if parsedURL.Scheme == "https" {
+		return 443
+	}
+	return 80
+}
+
+func externalCredentialServerPort(parsedURL *url.URL, configuredPort uint16) uint16 {
+	if configuredPort != 0 {
+		return configuredPort
+	}
+	return externalCredentialURLPort(parsedURL)
+}
+
+func externalCredentialBaseURL(parsedURL *url.URL) string {
+	baseURL := parsedURL.Scheme + "://" + parsedURL.Host
+	if parsedURL.Path != "" && parsedURL.Path != "/" {
+		baseURL += parsedURL.Path
+	}
+	if len(baseURL) > 0 && baseURL[len(baseURL)-1] == '/' {
+		baseURL = baseURL[:len(baseURL)-1]
+	}
+	return baseURL
+}
+
+func externalCredentialReversePath(parsedURL *url.URL, endpointPath string) string {
+	pathPrefix := parsedURL.EscapedPath()
+	if pathPrefix == "/" {
+		pathPrefix = ""
+	} else {
+		pathPrefix = strings.TrimSuffix(pathPrefix, "/")
+	}
+	return pathPrefix + endpointPath
+}
+
+func newExternalCredential(ctx context.Context, tag string, options option.CCMExternalCredentialOptions, logger log.ContextLogger) (*externalCredential, error) {
+	pollInterval := time.Duration(options.PollInterval)
+	if pollInterval <= 0 {
+		pollInterval = 30 * time.Minute
+	}
+
+	requestContext, cancelRequests := context.WithCancel(context.Background())
+	reverseContext, reverseCancel := context.WithCancel(context.Background())
+
+	cred := &externalCredential{
+		tag:            tag,
+		token:          options.Token,
+		pollInterval:   pollInterval,
+		logger:         logger,
+		requestContext: requestContext,
+		cancelRequests: cancelRequests,
+		reverse:        options.Reverse,
+		reverseContext: reverseContext,
+		reverseCancel:  reverseCancel,
+	}
+
+	if options.URL == "" {
+		// Receiver mode: no URL, wait for reverse connection
+		cred.baseURL = reverseProxyBaseURL
+		cred.httpClient = &http.Client{
+			Transport: &http.Transport{
+				ForceAttemptHTTP2: false,
+				DialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
+					return cred.openReverseConnection(ctx)
+				},
+			},
+		}
+	} else {
+		// Normal or connector mode: has URL
+		parsedURL, err := url.Parse(options.URL)
+		if err != nil {
+			return nil, E.Cause(err, "parse url for credential ", tag)
+		}
+
+		credentialDialer, err := dialer.NewWithOptions(dialer.Options{
+			Context: ctx,
+			Options: option.DialerOptions{
+				Detour: options.Detour,
+			},
+			RemoteIsDomain: true,
+		})
+		if err != nil {
+			return nil, E.Cause(err, "create dialer for credential ", tag)
+		}
+
+		transport := &http.Transport{
+			ForceAttemptHTTP2: true,
+			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				if options.Server != "" {
+					destination := M.ParseSocksaddrHostPort(options.Server, externalCredentialServerPort(parsedURL, options.ServerPort))
+					return credentialDialer.DialContext(ctx, network, destination)
+				}
+				return credentialDialer.DialContext(ctx, network, M.ParseSocksaddr(addr))
+			},
+		}
+
+		if parsedURL.Scheme == "https" {
+			transport.TLSClientConfig = &stdTLS.Config{
+				ServerName: parsedURL.Hostname(),
+				RootCAs:    adapter.RootPoolFromContext(ctx),
+				Time:       ntp.TimeFuncFromContext(ctx),
+			}
+		}
+
+		cred.baseURL = externalCredentialBaseURL(parsedURL)
+
+		if options.Reverse {
+			// Connector mode: we dial out to serve, not to proxy
+			cred.connectorDialer = credentialDialer
+			if options.Server != "" {
+				cred.connectorDestination = M.ParseSocksaddrHostPort(options.Server, externalCredentialServerPort(parsedURL, options.ServerPort))
+			} else {
+				cred.connectorDestination = M.ParseSocksaddrHostPort(parsedURL.Hostname(), externalCredentialURLPort(parsedURL))
+			}
+			cred.connectorRequestPath = externalCredentialReversePath(parsedURL, "/ccm/v1/reverse")
+			cred.connectorURL = parsedURL
+			if parsedURL.Scheme == "https" {
+				cred.connectorTLS = &stdTLS.Config{
+					ServerName: parsedURL.Hostname(),
+					RootCAs:    adapter.RootPoolFromContext(ctx),
+					Time:       ntp.TimeFuncFromContext(ctx),
+				}
+			}
+		} else {
+			// Normal mode: standard HTTP client for proxying
+			cred.httpClient = &http.Client{Transport: transport}
+		}
+	}
+
+	if options.UsagesPath != "" {
+		cred.usageTracker = &AggregatedUsage{
+			LastUpdated:  time.Now(),
+			Combinations: make([]CostCombination, 0),
+			filePath:     options.UsagesPath,
+			logger:       logger,
+		}
+	}
+
+	return cred, nil
+}
+
+func (c *externalCredential) start() error {
+	if c.usageTracker != nil {
+		err := c.usageTracker.Load()
+		if err != nil {
+			c.logger.Warn("load usage statistics for ", c.tag, ": ", err)
+		}
+	}
+	if c.reverse && c.connectorURL != nil {
+		go c.connectorLoop()
+	}
+	return nil
+}
+
+func (c *externalCredential) tagName() string {
+	return c.tag
+}
+
+func (c *externalCredential) isExternal() bool {
+	return true
+}
+
+func (c *externalCredential) isAvailable() bool {
+	return c.unavailableError() == nil
+}
+
+func (c *externalCredential) isUsable() bool {
+	if !c.isAvailable() {
+		return false
+	}
+	c.stateMutex.RLock()
+	if c.state.consecutivePollFailures > 0 {
+		c.stateMutex.RUnlock()
+		return false
+	}
+	if c.state.hardRateLimited {
+		if time.Now().Before(c.state.rateLimitResetAt) {
+			c.stateMutex.RUnlock()
+			return false
+		}
+		c.stateMutex.RUnlock()
+		c.stateMutex.Lock()
+		if c.state.hardRateLimited && !time.Now().Before(c.state.rateLimitResetAt) {
+			c.state.hardRateLimited = false
+		}
+		// No reserve for external: only 100% is unusable
+		usable := c.state.fiveHourUtilization < 100 && c.state.weeklyUtilization < 100
+		c.stateMutex.Unlock()
+		return usable
+	}
+	usable := c.state.fiveHourUtilization < 100 && c.state.weeklyUtilization < 100
+	c.stateMutex.RUnlock()
+	return usable
+}
+
+func (c *externalCredential) fiveHourUtilization() float64 {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.fiveHourUtilization
+}
+
+func (c *externalCredential) weeklyUtilization() float64 {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.weeklyUtilization
+}
+
+func (c *externalCredential) fiveHourCap() float64 {
+	return 100
+}
+
+func (c *externalCredential) weeklyCap() float64 {
+	return 100
+}
+
+func (c *externalCredential) planWeight() float64 {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	if c.state.remotePlanWeight > 0 {
+		return c.state.remotePlanWeight
+	}
+	return 10
+}
+
+func (c *externalCredential) weeklyResetTime() time.Time {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.weeklyReset
+}
+
+func (c *externalCredential) markRateLimited(resetAt time.Time) {
+	c.logger.Warn("rate limited for ", c.tag, ", reset in ", log.FormatDuration(time.Until(resetAt)))
+	c.stateMutex.Lock()
+	c.state.hardRateLimited = true
+	c.state.rateLimitResetAt = resetAt
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) earliestReset() time.Time {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	if c.state.hardRateLimited {
+		return c.state.rateLimitResetAt
+	}
+	earliest := c.state.fiveHourReset
+	if !c.state.weeklyReset.IsZero() && (earliest.IsZero() || c.state.weeklyReset.Before(earliest)) {
+		earliest = c.state.weeklyReset
+	}
+	return earliest
+}
+
+func (c *externalCredential) unavailableError() error {
+	if c.reverse && c.connectorURL != nil {
+		return E.New("credential ", c.tag, " is unavailable: reverse connector credentials cannot serve local requests")
+	}
+	if c.baseURL == reverseProxyBaseURL {
+		session := c.getReverseSession()
+		if session == nil || session.IsClosed() {
+			return E.New("credential ", c.tag, " is unavailable: reverse connection not established")
+		}
+	}
+	return nil
+}
+
+func (c *externalCredential) getAccessToken() (string, error) {
+	return c.token, nil
+}
+
+func (c *externalCredential) buildProxyRequest(ctx context.Context, original *http.Request, bodyBytes []byte, _ http.Header) (*http.Request, error) {
+	proxyURL := c.baseURL + original.URL.RequestURI()
+	var body io.Reader
+	if bodyBytes != nil {
+		body = bytes.NewReader(bodyBytes)
+	} else {
+		body = original.Body
+	}
+	proxyRequest, err := http.NewRequestWithContext(ctx, original.Method, proxyURL, body)
+	if err != nil {
+		return nil, err
+	}
+
+	for key, values := range original.Header {
+		if !isHopByHopHeader(key) && !isReverseProxyHeader(key) && key != "Authorization" {
+			proxyRequest.Header[key] = values
+		}
+	}
+
+	proxyRequest.Header.Set("Authorization", "Bearer "+c.token)
+
+	return proxyRequest, nil
+}
+
+func (c *externalCredential) openReverseConnection(ctx context.Context) (net.Conn, error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+	session := c.getReverseSession()
+	if session == nil || session.IsClosed() {
+		return nil, E.New("reverse connection not established for ", c.tag)
+	}
+	conn, err := session.Open()
+	if err != nil {
+		return nil, err
+	}
+	select {
+	case <-ctx.Done():
+		conn.Close()
+		return nil, ctx.Err()
+	default:
+	}
+	return conn, nil
+}
+
+func (c *externalCredential) updateStateFromHeaders(headers http.Header) {
+	c.stateMutex.Lock()
+	isFirstUpdate := c.state.lastUpdated.IsZero()
+	oldFiveHour := c.state.fiveHourUtilization
+	oldWeekly := c.state.weeklyUtilization
+	hadData := false
+
+	if value, exists := parseOptionalAnthropicResetHeader(headers, "anthropic-ratelimit-unified-5h-reset"); exists {
+		hadData = true
+		c.state.fiveHourReset = value
+	}
+	if utilization := headers.Get("anthropic-ratelimit-unified-5h-utilization"); utilization != "" {
+		value, err := strconv.ParseFloat(utilization, 64)
+		if err == nil {
+			hadData = true
+			c.state.fiveHourUtilization = value * 100
+		}
+	}
+
+	if value, exists := parseOptionalAnthropicResetHeader(headers, "anthropic-ratelimit-unified-7d-reset"); exists {
+		hadData = true
+		c.state.weeklyReset = value
+	}
+	if utilization := headers.Get("anthropic-ratelimit-unified-7d-utilization"); utilization != "" {
+		value, err := strconv.ParseFloat(utilization, 64)
+		if err == nil {
+			hadData = true
+			c.state.weeklyUtilization = value * 100
+		}
+	}
+	if planWeight := headers.Get("X-CCM-Plan-Weight"); planWeight != "" {
+		value, err := strconv.ParseFloat(planWeight, 64)
+		if err == nil && value > 0 {
+			c.state.remotePlanWeight = value
+		}
+	}
+	if hadData {
+		c.state.consecutivePollFailures = 0
+		c.state.lastUpdated = time.Now()
+	}
+	if isFirstUpdate || int(c.state.fiveHourUtilization*100) != int(oldFiveHour*100) || int(c.state.weeklyUtilization*100) != int(oldWeekly*100) {
+		resetSuffix := ""
+		if !c.state.weeklyReset.IsZero() {
+			resetSuffix = ", resets=" + log.FormatDuration(time.Until(c.state.weeklyReset))
+		}
+		c.logger.Debug("usage update for ", c.tag, ": 5h=", c.state.fiveHourUtilization, "%, weekly=", c.state.weeklyUtilization, "%", resetSuffix)
+	}
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) checkTransitionLocked() bool {
+	unusable := c.state.hardRateLimited || c.state.fiveHourUtilization >= 100 || c.state.weeklyUtilization >= 100 || c.state.consecutivePollFailures > 0
+	if unusable && !c.interrupted {
+		c.interrupted = true
+		return true
+	}
+	if !unusable && c.interrupted {
+		c.interrupted = false
+	}
+	return false
+}
+
+func (c *externalCredential) wrapRequestContext(parent context.Context) *credentialRequestContext {
+	c.requestAccess.Lock()
+	credentialContext := c.requestContext
+	c.requestAccess.Unlock()
+	derived, cancel := context.WithCancel(parent)
+	stop := context.AfterFunc(credentialContext, func() {
+		cancel()
+	})
+	return &credentialRequestContext{
+		Context:     derived,
+		releaseFunc: stop,
+		cancelFunc:  cancel,
+	}
+}
+
+func (c *externalCredential) interruptConnections() {
+	c.logger.Warn("interrupting connections for ", c.tag)
+	c.requestAccess.Lock()
+	c.cancelRequests()
+	c.requestContext, c.cancelRequests = context.WithCancel(context.Background())
+	c.requestAccess.Unlock()
+	if c.onBecameUnusable != nil {
+		c.onBecameUnusable()
+	}
+}
+
+func (c *externalCredential) pollUsage(ctx context.Context) {
+	if !c.pollAccess.TryLock() {
+		return
+	}
+	defer c.pollAccess.Unlock()
+	defer c.markUsagePollAttempted()
+
+	statusURL := c.baseURL + "/ccm/v1/status"
+	httpClient := &http.Client{
+		Transport: c.httpClient.Transport,
+		Timeout:   5 * time.Second,
+	}
+
+	response, err := doHTTPWithRetry(ctx, httpClient, func() (*http.Request, error) {
+		request, err := http.NewRequestWithContext(ctx, http.MethodGet, statusURL, nil)
+		if err != nil {
+			return nil, err
+		}
+		request.Header.Set("Authorization", "Bearer "+c.token)
+		return request, nil
+	})
+	if err != nil {
+		c.logger.Error("poll usage for ", c.tag, ": ", err)
+		c.incrementPollFailures()
+		return
+	}
+	defer response.Body.Close()
+
+	if response.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(response.Body)
+		c.logger.Debug("poll usage for ", c.tag, ": status ", response.StatusCode, " ", string(body))
+		// 404 means the remote does not have a status endpoint yet;
+		// usage will be updated passively from response headers.
+		if response.StatusCode == http.StatusNotFound {
+			c.stateMutex.Lock()
+			c.state.consecutivePollFailures = 0
+			c.checkTransitionLocked()
+			c.stateMutex.Unlock()
+		} else {
+			c.incrementPollFailures()
+		}
+		return
+	}
+
+	var statusResponse struct {
+		FiveHourUtilization float64 `json:"five_hour_utilization"`
+		WeeklyUtilization   float64 `json:"weekly_utilization"`
+		PlanWeight          float64 `json:"plan_weight"`
+	}
+	err = json.NewDecoder(response.Body).Decode(&statusResponse)
+	if err != nil {
+		c.logger.Debug("poll usage for ", c.tag, ": decode: ", err)
+		c.incrementPollFailures()
+		return
+	}
+
+	c.stateMutex.Lock()
+	isFirstUpdate := c.state.lastUpdated.IsZero()
+	oldFiveHour := c.state.fiveHourUtilization
+	oldWeekly := c.state.weeklyUtilization
+	c.state.consecutivePollFailures = 0
+	c.state.fiveHourUtilization = statusResponse.FiveHourUtilization
+	c.state.weeklyUtilization = statusResponse.WeeklyUtilization
+	if statusResponse.PlanWeight > 0 {
+		c.state.remotePlanWeight = statusResponse.PlanWeight
+	}
+	if c.state.hardRateLimited && time.Now().After(c.state.rateLimitResetAt) {
+		c.state.hardRateLimited = false
+	}
+	if isFirstUpdate || int(c.state.fiveHourUtilization*100) != int(oldFiveHour*100) || int(c.state.weeklyUtilization*100) != int(oldWeekly*100) {
+		resetSuffix := ""
+		if !c.state.weeklyReset.IsZero() {
+			resetSuffix = ", resets=" + log.FormatDuration(time.Until(c.state.weeklyReset))
+		}
+		c.logger.Debug("poll usage for ", c.tag, ": 5h=", c.state.fiveHourUtilization, "%, weekly=", c.state.weeklyUtilization, "%", resetSuffix)
+	}
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) lastUpdatedTime() time.Time {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.lastUpdated
+}
+
+func (c *externalCredential) markUsagePollAttempted() {
+	c.stateMutex.Lock()
+	defer c.stateMutex.Unlock()
+	c.state.lastUpdated = time.Now()
+}
+
+func (c *externalCredential) pollBackoff(baseInterval time.Duration) time.Duration {
+	c.stateMutex.RLock()
+	failures := c.state.consecutivePollFailures
+	c.stateMutex.RUnlock()
+	if failures <= 0 {
+		return baseInterval
+	}
+	return failedPollRetryInterval
+}
+
+func (c *externalCredential) incrementPollFailures() {
+	c.stateMutex.Lock()
+	c.state.consecutivePollFailures++
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) usageTrackerOrNil() *AggregatedUsage {
+	return c.usageTracker
+}
+
+func (c *externalCredential) httpTransport() *http.Client {
+	return c.httpClient
+}
+
+func (c *externalCredential) close() {
+	var session *yamux.Session
+	c.reverseAccess.Lock()
+	if !c.closed {
+		c.closed = true
+		if c.reverseCancel != nil {
+			c.reverseCancel()
+		}
+		session = c.reverseSession
+		c.reverseSession = nil
+	}
+	c.reverseAccess.Unlock()
+	if session != nil {
+		session.Close()
+	}
+	if c.usageTracker != nil {
+		c.usageTracker.cancelPendingSave()
+		err := c.usageTracker.Save()
+		if err != nil {
+			c.logger.Error("save usage statistics for ", c.tag, ": ", err)
+		}
+	}
+}
+
+func (c *externalCredential) getReverseSession() *yamux.Session {
+	c.reverseAccess.RLock()
+	defer c.reverseAccess.RUnlock()
+	return c.reverseSession
+}
+
+func (c *externalCredential) setReverseSession(session *yamux.Session) bool {
+	c.reverseAccess.Lock()
+	if c.closed {
+		c.reverseAccess.Unlock()
+		return false
+	}
+	old := c.reverseSession
+	c.reverseSession = session
+	c.reverseAccess.Unlock()
+	if old != nil {
+		old.Close()
+	}
+	return true
+}
+
+func (c *externalCredential) clearReverseSession(session *yamux.Session) {
+	c.reverseAccess.Lock()
+	if c.reverseSession == session {
+		c.reverseSession = nil
+	}
+	c.reverseAccess.Unlock()
+}
+
+func (c *externalCredential) getReverseContext() context.Context {
+	c.reverseAccess.RLock()
+	defer c.reverseAccess.RUnlock()
+	return c.reverseContext
+}
+
+func (c *externalCredential) resetReverseContext() {
+	c.reverseAccess.Lock()
+	if c.closed {
+		c.reverseAccess.Unlock()
+		return
+	}
+	c.reverseCancel()
+	c.reverseContext, c.reverseCancel = context.WithCancel(context.Background())
+	c.reverseAccess.Unlock()
+}

service/ccm/credential_file.go

@@ -0,0 +1,143 @@
+package ccm
+
+import (
+	"path/filepath"
+	"time"
+
+	"github.com/sagernet/fswatch"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+const credentialReloadRetryInterval = 2 * time.Second
+
+func resolveCredentialFilePath(customPath string) (string, error) {
+	if customPath == "" {
+		var err error
+		customPath, err = getDefaultCredentialsPath()
+		if err != nil {
+			return "", err
+		}
+	}
+	if filepath.IsAbs(customPath) {
+		return customPath, nil
+	}
+	return filepath.Abs(customPath)
+}
+
+func (c *defaultCredential) ensureCredentialWatcher() error {
+	c.watcherAccess.Lock()
+	defer c.watcherAccess.Unlock()
+
+	if c.watcher != nil || c.credentialFilePath == "" {
+		return nil
+	}
+	if !c.watcherRetryAt.IsZero() && time.Now().Before(c.watcherRetryAt) {
+		return nil
+	}
+
+	watcher, err := fswatch.NewWatcher(fswatch.Options{
+		Path:   []string{c.credentialFilePath},
+		Logger: c.logger,
+		Callback: func(string) {
+			err := c.reloadCredentials(true)
+			if err != nil {
+				c.logger.Warn("reload credentials for ", c.tag, ": ", err)
+			}
+		},
+	})
+	if err != nil {
+		c.watcherRetryAt = time.Now().Add(credentialReloadRetryInterval)
+		return err
+	}
+
+	err = watcher.Start()
+	if err != nil {
+		c.watcherRetryAt = time.Now().Add(credentialReloadRetryInterval)
+		return err
+	}
+
+	c.watcher = watcher
+	c.watcherRetryAt = time.Time{}
+	return nil
+}
+
+func (c *defaultCredential) retryCredentialReloadIfNeeded() {
+	c.stateMutex.RLock()
+	unavailable := c.state.unavailable
+	lastAttempt := c.state.lastCredentialLoadAttempt
+	c.stateMutex.RUnlock()
+	if !unavailable {
+		return
+	}
+	if !lastAttempt.IsZero() && time.Since(lastAttempt) < credentialReloadRetryInterval {
+		return
+	}
+
+	err := c.ensureCredentialWatcher()
+	if err != nil {
+		c.logger.Debug("start credential watcher for ", c.tag, ": ", err)
+	}
+	_ = c.reloadCredentials(false)
+}
+
+func (c *defaultCredential) reloadCredentials(force bool) error {
+	c.reloadAccess.Lock()
+	defer c.reloadAccess.Unlock()
+
+	c.stateMutex.RLock()
+	unavailable := c.state.unavailable
+	lastAttempt := c.state.lastCredentialLoadAttempt
+	c.stateMutex.RUnlock()
+	if !force {
+		if !unavailable {
+			return nil
+		}
+		if !lastAttempt.IsZero() && time.Since(lastAttempt) < credentialReloadRetryInterval {
+			return c.unavailableError()
+		}
+	}
+
+	c.stateMutex.Lock()
+	c.state.lastCredentialLoadAttempt = time.Now()
+	c.stateMutex.Unlock()
+
+	credentials, err := platformReadCredentials(c.credentialPath)
+	if err != nil {
+		return c.markCredentialsUnavailable(E.Cause(err, "read credentials"))
+	}
+
+	c.accessMutex.Lock()
+	c.credentials = credentials
+	c.accessMutex.Unlock()
+
+	c.stateMutex.Lock()
+	c.state.unavailable = false
+	c.state.lastCredentialLoadError = ""
+	c.state.accountType = credentials.SubscriptionType
+	c.state.rateLimitTier = credentials.RateLimitTier
+	c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+
+	return nil
+}
+
+func (c *defaultCredential) markCredentialsUnavailable(err error) error {
+	c.accessMutex.Lock()
+	hadCredentials := c.credentials != nil
+	c.credentials = nil
+	c.accessMutex.Unlock()
+
+	c.stateMutex.Lock()
+	c.state.unavailable = true
+	c.state.lastCredentialLoadError = err.Error()
+	c.state.accountType = ""
+	c.state.rateLimitTier = ""
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+
+	if shouldInterrupt && hadCredentials {
+		c.interruptConnections()
+	}
+
+	return err
+}

service/ccm/credential_other.go

@@ -13,6 +13,17 @@ func platformReadCredentials(customPath string) (*oauthCredentials, error) {
 	return readCredentialsFromFile(customPath)
 }
 
+func platformCanWriteCredentials(customPath string) error {
+	if customPath == "" {
+		var err error
+		customPath, err = getDefaultCredentialsPath()
+		if err != nil {
+			return err
+		}
+	}
+	return checkCredentialFileWritable(customPath)
+}
+
 func platformWriteCredentials(oauthCredentials *oauthCredentials, customPath string) error {
 	if customPath == "" {
 		var err error

service/ccm/reverse.go

@@ -0,0 +1,259 @@
+package ccm
+
+import (
+	"bufio"
+	"context"
+	stdTLS "crypto/tls"
+	"errors"
+	"io"
+	"math/rand/v2"
+	"net"
+	"net/http"
+	"strings"
+	"time"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+
+	"github.com/hashicorp/yamux"
+)
+
+func reverseYamuxConfig() *yamux.Config {
+	config := yamux.DefaultConfig()
+	config.KeepAliveInterval = 15 * time.Second
+	config.ConnectionWriteTimeout = 10 * time.Second
+	config.MaxStreamWindowSize = 512 * 1024
+	config.LogOutput = io.Discard
+	return config
+}
+
+type bufferedConn struct {
+	reader *bufio.Reader
+	net.Conn
+}
+
+func (c *bufferedConn) Read(p []byte) (int, error) {
+	return c.reader.Read(p)
+}
+
+type yamuxNetListener struct {
+	session *yamux.Session
+}
+
+func (l *yamuxNetListener) Accept() (net.Conn, error) {
+	return l.session.Accept()
+}
+
+func (l *yamuxNetListener) Close() error {
+	return l.session.Close()
+}
+
+func (l *yamuxNetListener) Addr() net.Addr {
+	return l.session.Addr()
+}
+
+func (s *Service) handleReverseConnect(ctx context.Context, w http.ResponseWriter, r *http.Request) {
+	if r.Header.Get("Upgrade") != "reverse-proxy" {
+		writeJSONError(w, r, http.StatusBadRequest, "invalid_request_error", "missing Upgrade header")
+		return
+	}
+
+	authHeader := r.Header.Get("Authorization")
+	if authHeader == "" {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "missing api key")
+		return
+	}
+	clientToken := strings.TrimPrefix(authHeader, "Bearer ")
+	if clientToken == authHeader {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key format")
+		return
+	}
+
+	receiverCredential := s.findReceiverCredential(clientToken)
+	if receiverCredential == nil {
+		s.logger.WarnContext(ctx, "reverse connect failed from ", r.RemoteAddr, ": no matching receiver credential")
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid reverse token")
+		return
+	}
+
+	hijacker, ok := w.(http.Hijacker)
+	if !ok {
+		s.logger.ErrorContext(ctx, "reverse connect: hijack not supported")
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "hijack not supported")
+		return
+	}
+
+	conn, bufferedReadWriter, err := hijacker.Hijack()
+	if err != nil {
+		s.logger.ErrorContext(ctx, "reverse connect: hijack: ", err)
+		return
+	}
+
+	response := "HTTP/1.1 101 Switching Protocols\r\nConnection: Upgrade\r\nUpgrade: reverse-proxy\r\n\r\n"
+	_, err = bufferedReadWriter.WriteString(response)
+	if err != nil {
+		conn.Close()
+		s.logger.ErrorContext(ctx, "reverse connect: write upgrade response: ", err)
+		return
+	}
+	err = bufferedReadWriter.Flush()
+	if err != nil {
+		conn.Close()
+		s.logger.ErrorContext(ctx, "reverse connect: flush upgrade response: ", err)
+		return
+	}
+
+	session, err := yamux.Client(conn, reverseYamuxConfig())
+	if err != nil {
+		conn.Close()
+		s.logger.ErrorContext(ctx, "reverse connect: create yamux client for ", receiverCredential.tagName(), ": ", err)
+		return
+	}
+
+	if !receiverCredential.setReverseSession(session) {
+		session.Close()
+		return
+	}
+	s.logger.InfoContext(ctx, "reverse connection established for ", receiverCredential.tagName(), " from ", r.RemoteAddr)
+
+	go func() {
+		<-session.CloseChan()
+		receiverCredential.clearReverseSession(session)
+		s.logger.WarnContext(ctx, "reverse connection lost for ", receiverCredential.tagName())
+	}()
+}
+
+func (s *Service) findReceiverCredential(token string) *externalCredential {
+	for _, cred := range s.allCredentials {
+		extCred, ok := cred.(*externalCredential)
+		if !ok {
+			continue
+		}
+		if extCred.baseURL == reverseProxyBaseURL && extCred.token == token {
+			return extCred
+		}
+	}
+	return nil
+}
+
+func (c *externalCredential) connectorLoop() {
+	var consecutiveFailures int
+	ctx := c.getReverseContext()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+
+		sessionLifetime, err := c.connectorConnect(ctx)
+		if ctx.Err() != nil {
+			return
+		}
+		if sessionLifetime >= connectorBackoffResetThreshold {
+			consecutiveFailures = 0
+		}
+		consecutiveFailures++
+		backoff := connectorBackoff(consecutiveFailures)
+		c.logger.Warn("reverse connection for ", c.tag, " lost: ", err, ", reconnecting in ", backoff)
+		select {
+		case <-time.After(backoff):
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+const connectorBackoffResetThreshold = time.Minute
+
+func connectorBackoff(failures int) time.Duration {
+	if failures > 5 {
+		failures = 5
+	}
+	base := time.Second * time.Duration(1<<failures)
+	if base > 30*time.Second {
+		base = 30 * time.Second
+	}
+	jitter := time.Duration(rand.Int64N(int64(base) / 2))
+	return base + jitter
+}
+
+func (c *externalCredential) connectorConnect(ctx context.Context) (time.Duration, error) {
+	if c.reverseService == nil {
+		return 0, E.New("reverse service not initialized")
+	}
+	destination := c.connectorResolveDestination()
+	conn, err := c.connectorDialer.DialContext(ctx, "tcp", destination)
+	if err != nil {
+		return 0, E.Cause(err, "dial")
+	}
+
+	if c.connectorTLS != nil {
+		tlsConn := stdTLS.Client(conn, c.connectorTLS.Clone())
+		err = tlsConn.HandshakeContext(ctx)
+		if err != nil {
+			conn.Close()
+			return 0, E.Cause(err, "tls handshake")
+		}
+		conn = tlsConn
+	}
+
+	upgradeRequest := "GET " + c.connectorRequestPath + " HTTP/1.1\r\n" +
+		"Host: " + c.connectorURL.Host + "\r\n" +
+		"Connection: Upgrade\r\n" +
+		"Upgrade: reverse-proxy\r\n" +
+		"Authorization: Bearer " + c.token + "\r\n" +
+		"\r\n"
+	_, err = io.WriteString(conn, upgradeRequest)
+	if err != nil {
+		conn.Close()
+		return 0, E.Cause(err, "write upgrade request")
+	}
+
+	reader := bufio.NewReader(conn)
+	statusLine, err := reader.ReadString('\n')
+	if err != nil {
+		conn.Close()
+		return 0, E.Cause(err, "read upgrade response")
+	}
+	if !strings.HasPrefix(statusLine, "HTTP/1.1 101") {
+		conn.Close()
+		return 0, E.New("unexpected upgrade response: ", strings.TrimSpace(statusLine))
+	}
+	for {
+		line, readErr := reader.ReadString('\n')
+		if readErr != nil {
+			conn.Close()
+			return 0, E.Cause(readErr, "read upgrade headers")
+		}
+		if strings.TrimSpace(line) == "" {
+			break
+		}
+	}
+
+	session, err := yamux.Server(&bufferedConn{reader: reader, Conn: conn}, reverseYamuxConfig())
+	if err != nil {
+		conn.Close()
+		return 0, E.Cause(err, "create yamux server")
+	}
+	defer session.Close()
+
+	c.logger.Info("reverse connection established for ", c.tag)
+
+	serveStart := time.Now()
+	httpServer := &http.Server{
+		Handler:     c.reverseService,
+		ReadTimeout: 0,
+		IdleTimeout: 120 * time.Second,
+	}
+	err = httpServer.Serve(&yamuxNetListener{session: session})
+	sessionLifetime := time.Since(serveStart)
+	if err != nil && !errors.Is(err, http.ErrServerClosed) && ctx.Err() == nil {
+		return sessionLifetime, E.Cause(err, "serve")
+	}
+	return sessionLifetime, E.New("connection closed")
+}
+
+func (c *externalCredential) connectorResolveDestination() M.Socksaddr {
+	return c.connectorDestination
+}

service/ccm/service.go

@@ -3,12 +3,10 @@ package ccm
 import (
 	"bytes"
 	"context"
-	stdTLS "crypto/tls"
 	"encoding/json"
 	"errors"
 	"io"
 	"mime"
-	"net"
 	"net/http"
 	"strconv"
 	"strings"
@@ -17,7 +15,6 @@ import (
 
 	"github.com/sagernet/sing-box/adapter"
 	boxService "github.com/sagernet/sing-box/adapter/service"
-	"github.com/sagernet/sing-box/common/dialer"
 	"github.com/sagernet/sing-box/common/listener"
 	"github.com/sagernet/sing-box/common/tls"
 	C "github.com/sagernet/sing-box/constant"
@@ -26,20 +23,20 @@ import (
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/buf"
 	E "github.com/sagernet/sing/common/exceptions"
-	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
-	"github.com/sagernet/sing/common/ntp"
 	aTLS "github.com/sagernet/sing/common/tls"
 
 	"github.com/anthropics/anthropic-sdk-go"
 	"github.com/go-chi/chi/v5"
 	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/h2c"
 )
 
 const (
 	contextWindowStandard   = 200000
 	contextWindowPremium    = 1000000
 	premiumContextThreshold = 200000
+	retryableUsageMessage   = "current credential reached its usage limit; retry the request to use another credential"
 )
 
 func RegisterService(registry *boxService.Registry) {
@@ -60,7 +57,6 @@ type errorDetails struct {
 func writeJSONError(w http.ResponseWriter, r *http.Request, statusCode int, errorType string, message string) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(statusCode)
-
 	json.NewEncoder(w).Encode(errorResponse{
 		Type: "error",
 		Error: errorDetails{
@@ -71,6 +67,58 @@ func writeJSONError(w http.ResponseWriter, r *http.Request, statusCode int, erro
 	})
 }
 
+func hasAlternativeCredential(provider credentialProvider, currentCredential credential, filter func(credential) bool) bool {
+	if provider == nil || currentCredential == nil {
+		return false
+	}
+	for _, cred := range provider.allCredentials() {
+		if cred == currentCredential {
+			continue
+		}
+		if filter != nil && !filter(cred) {
+			continue
+		}
+		if cred.isUsable() {
+			return true
+		}
+	}
+	return false
+}
+
+func unavailableCredentialMessage(provider credentialProvider, fallback string) string {
+	if provider == nil {
+		return fallback
+	}
+	message := allCredentialsUnavailableError(provider.allCredentials()).Error()
+	if message == "all credentials unavailable" && fallback != "" {
+		return fallback
+	}
+	return message
+}
+
+func writeRetryableUsageError(w http.ResponseWriter, r *http.Request) {
+	writeJSONError(w, r, http.StatusTooManyRequests, "rate_limit_error", retryableUsageMessage)
+}
+
+func writeNonRetryableCredentialError(w http.ResponseWriter, r *http.Request, message string) {
+	writeJSONError(w, r, http.StatusBadRequest, "invalid_request_error", message)
+}
+
+func writeCredentialUnavailableError(
+	w http.ResponseWriter,
+	r *http.Request,
+	provider credentialProvider,
+	currentCredential credential,
+	filter func(credential) bool,
+	fallback string,
+) {
+	if hasAlternativeCredential(provider, currentCredential, filter) {
+		writeRetryableUsageError(w, r)
+		return
+	}
+	writeNonRetryableCredentialError(w, r, unavailableCredentialMessage(provider, fallback))
+}
+
 func isHopByHopHeader(header string) bool {
 	switch strings.ToLower(header) {
 	case "connection", "keep-alive", "proxy-authenticate", "proxy-authorization", "te", "trailers", "transfer-encoding", "upgrade", "host":
@@ -80,109 +128,111 @@ func isHopByHopHeader(header string) bool {
 	}
 }
 
+func isReverseProxyHeader(header string) bool {
+	lowerHeader := strings.ToLower(header)
+	if strings.HasPrefix(lowerHeader, "cf-") {
+		return true
+	}
+	switch lowerHeader {
+	case "cdn-loop", "true-client-ip", "x-forwarded-for", "x-forwarded-proto", "x-real-ip":
+		return true
+	default:
+		return false
+	}
+}
+
 const (
 	weeklyWindowSeconds = 604800
 	weeklyWindowMinutes = weeklyWindowSeconds / 60
 )
 
-func parseInt64Header(headers http.Header, headerName string) (int64, bool) {
-	headerValue := strings.TrimSpace(headers.Get(headerName))
-	if headerValue == "" {
-		return 0, false
-	}
-	parsedValue, parseError := strconv.ParseInt(headerValue, 10, 64)
-	if parseError != nil {
-		return 0, false
-	}
-	return parsedValue, true
-}
-
 func extractWeeklyCycleHint(headers http.Header) *WeeklyCycleHint {
-	resetAtUnix, hasResetAt := parseInt64Header(headers, "anthropic-ratelimit-unified-7d-reset")
-	if !hasResetAt || resetAtUnix <= 0 {
+	resetAt, exists := parseOptionalAnthropicResetHeader(headers, "anthropic-ratelimit-unified-7d-reset")
+	if !exists {
 		return nil
 	}
 
 	return &WeeklyCycleHint{
 		WindowMinutes: weeklyWindowMinutes,
-		ResetAt:       time.Unix(resetAtUnix, 0).UTC(),
+		ResetAt:       resetAt.UTC(),
 	}
 }
 
 type Service struct {
 	boxService.Adapter
-	ctx            context.Context
-	logger         log.ContextLogger
-	credentialPath string
-	credentials    *oauthCredentials
-	users          []option.CCMUser
-	httpClient     *http.Client
-	httpHeaders    http.Header
-	listener       *listener.Listener
-	tlsConfig      tls.ServerConfig
-	httpServer     *http.Server
-	userManager    *UserManager
-	accessMutex    sync.RWMutex
-	usageTracker   *AggregatedUsage
-	trackingGroup  sync.WaitGroup
-	shuttingDown   bool
+	ctx           context.Context
+	logger        log.ContextLogger
+	options       option.CCMServiceOptions
+	httpHeaders   http.Header
+	listener      *listener.Listener
+	tlsConfig     tls.ServerConfig
+	httpServer    *http.Server
+	userManager   *UserManager
+	trackingGroup sync.WaitGroup
+	shuttingDown  bool
+
+	// Legacy mode (single credential)
+	legacyCredential *defaultCredential
+	legacyProvider   credentialProvider
+
+	// Multi-credential mode
+	providers      map[string]credentialProvider
+	allCredentials []credential
+	userConfigMap  map[string]*option.CCMUser
 }
 
 func NewService(ctx context.Context, logger log.ContextLogger, tag string, options option.CCMServiceOptions) (adapter.Service, error) {
-	serviceDialer, err := dialer.NewWithOptions(dialer.Options{
-		Context: ctx,
-		Options: option.DialerOptions{
-			Detour: options.Detour,
-		},
-		RemoteIsDomain: true,
-	})
-	if err != nil {
-		return nil, E.Cause(err, "create dialer")
-	}
+	initCCMUserAgent(logger)
 
-	httpClient := &http.Client{
-		Transport: &http.Transport{
-			ForceAttemptHTTP2: true,
-			TLSClientConfig: &stdTLS.Config{
-				RootCAs: adapter.RootPoolFromContext(ctx),
-				Time:    ntp.TimeFuncFromContext(ctx),
-			},
-			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
-				return serviceDialer.DialContext(ctx, network, M.ParseSocksaddr(addr))
-			},
-		},
+	err := validateCCMOptions(options)
+	if err != nil {
+		return nil, E.Cause(err, "validate options")
 	}
 
 	userManager := &UserManager{
 		tokenMap: make(map[string]string),
 	}
 
-	var usageTracker *AggregatedUsage
-	if options.UsagesPath != "" {
-		usageTracker = &AggregatedUsage{
-			LastUpdated:  time.Now(),
-			Combinations: make([]CostCombination, 0),
-			filePath:     options.UsagesPath,
-			logger:       logger,
-		}
-	}
-
 	service := &Service{
-		Adapter:        boxService.NewAdapter(C.TypeCCM, tag),
-		ctx:            ctx,
-		logger:         logger,
-		credentialPath: options.CredentialPath,
-		users:          options.Users,
-		httpClient:     httpClient,
-		httpHeaders:    options.Headers.Build(),
+		Adapter:     boxService.NewAdapter(C.TypeCCM, tag),
+		ctx:         ctx,
+		logger:      logger,
+		options:     options,
+		httpHeaders: options.Headers.Build(),
 		listener: listener.New(listener.Options{
 			Context: ctx,
 			Logger:  logger,
 			Network: []string{N.NetworkTCP},
 			Listen:  options.ListenOptions,
 		}),
-		userManager:  userManager,
-		usageTracker: usageTracker,
+		userManager: userManager,
+	}
+
+	if len(options.Credentials) > 0 {
+		providers, allCredentials, err := buildCredentialProviders(ctx, options, logger)
+		if err != nil {
+			return nil, E.Cause(err, "build credential providers")
+		}
+		service.providers = providers
+		service.allCredentials = allCredentials
+
+		userConfigMap := make(map[string]*option.CCMUser)
+		for i := range options.Users {
+			userConfigMap[options.Users[i].Name] = &options.Users[i]
+		}
+		service.userConfigMap = userConfigMap
+	} else {
+		cred, err := newDefaultCredential(ctx, "default", option.CCMDefaultCredentialOptions{
+			CredentialPath: options.CredentialPath,
+			UsagesPath:     options.UsagesPath,
+			Detour:         options.Detour,
+		}, logger)
+		if err != nil {
+			return nil, err
+		}
+		service.legacyCredential = cred
+		service.legacyProvider = &singleCredentialProvider{cred: cred}
+		service.allCredentials = []credential{cred}
 	}
 
 	if options.TLS != nil {
@@ -201,28 +251,25 @@ func (s *Service) Start(stage adapter.StartStage) error {
 		return nil
 	}
 
-	s.userManager.UpdateUsers(s.users)
+	s.userManager.UpdateUsers(s.options.Users)
 
-	credentials, err := platformReadCredentials(s.credentialPath)
-	if err != nil {
-		return E.Cause(err, "read credentials")
-	}
-	s.credentials = credentials
-
-	if s.usageTracker != nil {
-		err = s.usageTracker.Load()
+	for _, cred := range s.allCredentials {
+		if extCred, ok := cred.(*externalCredential); ok && extCred.reverse && extCred.connectorURL != nil {
+			extCred.reverseService = s
+		}
+		err := cred.start()
 		if err != nil {
-			s.logger.Warn("load usage statistics: ", err)
+			return err
 		}
 	}
 
 	router := chi.NewRouter()
 	router.Mount("/", s)
 
-	s.httpServer = &http.Server{Handler: router}
+	s.httpServer = &http.Server{Handler: h2c.NewHandler(router, &http2.Server{})}
 
 	if s.tlsConfig != nil {
-		err = s.tlsConfig.Start()
+		err := s.tlsConfig.Start()
 		if err != nil {
 			return E.Cause(err, "create TLS config")
 		}
@@ -250,155 +297,257 @@ func (s *Service) Start(stage adapter.StartStage) error {
 	return nil
 }
 
-func (s *Service) getAccessToken() (string, error) {
-	s.accessMutex.RLock()
-	if !s.credentials.needsRefresh() {
-		token := s.credentials.AccessToken
-		s.accessMutex.RUnlock()
-		return token, nil
+func isExtendedContextRequest(betaHeader string) bool {
+	for _, feature := range strings.Split(betaHeader, ",") {
+		if strings.HasPrefix(strings.TrimSpace(feature), "context-1m") {
+			return true
+		}
 	}
-	s.accessMutex.RUnlock()
+	return false
+}
 
-	s.accessMutex.Lock()
-	defer s.accessMutex.Unlock()
-
-	if !s.credentials.needsRefresh() {
-		return s.credentials.AccessToken, nil
+func isFastModeRequest(betaHeader string) bool {
+	for _, feature := range strings.Split(betaHeader, ",") {
+		if strings.HasPrefix(strings.TrimSpace(feature), "fast-mode") {
+			return true
+		}
 	}
-
-	newCredentials, err := refreshToken(s.httpClient, s.credentials)
-	if err != nil {
-		return "", err
-	}
-
-	s.credentials = newCredentials
-
-	err = platformWriteCredentials(newCredentials, s.credentialPath)
-	if err != nil {
-		s.logger.Warn("persist refreshed token: ", err)
-	}
-
-	return newCredentials.AccessToken, nil
+	return false
 }
 
 func detectContextWindow(betaHeader string, totalInputTokens int64) int {
 	if totalInputTokens > premiumContextThreshold {
-		features := strings.Split(betaHeader, ",")
-		for _, feature := range features {
-			if strings.HasPrefix(strings.TrimSpace(feature), "context-1m") {
-				return contextWindowPremium
-			}
+		if isExtendedContextRequest(betaHeader) {
+			return contextWindowPremium
 		}
 	}
 	return contextWindowStandard
 }
 
 func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	ctx := log.ContextWithNewID(r.Context())
+	if r.URL.Path == "/ccm/v1/status" {
+		s.handleStatusEndpoint(w, r)
+		return
+	}
+
+	if r.URL.Path == "/ccm/v1/reverse" {
+		s.handleReverseConnect(ctx, w, r)
+		return
+	}
+
 	if !strings.HasPrefix(r.URL.Path, "/v1/") {
 		writeJSONError(w, r, http.StatusNotFound, "not_found_error", "Not found")
 		return
 	}
 
 	var username string
-	if len(s.users) > 0 {
+	if len(s.options.Users) > 0 {
 		authHeader := r.Header.Get("Authorization")
 		if authHeader == "" {
-			s.logger.Warn("authentication failed for request from ", r.RemoteAddr, ": missing Authorization header")
+			s.logger.WarnContext(ctx, "authentication failed for request from ", r.RemoteAddr, ": missing Authorization header")
 			writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "missing api key")
 			return
 		}
 		clientToken := strings.TrimPrefix(authHeader, "Bearer ")
 		if clientToken == authHeader {
-			s.logger.Warn("authentication failed for request from ", r.RemoteAddr, ": invalid Authorization format")
+			s.logger.WarnContext(ctx, "authentication failed for request from ", r.RemoteAddr, ": invalid Authorization format")
 			writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key format")
 			return
 		}
 		var ok bool
 		username, ok = s.userManager.Authenticate(clientToken)
 		if !ok {
-			s.logger.Warn("authentication failed for request from ", r.RemoteAddr, ": unknown key: ", clientToken)
+			s.logger.WarnContext(ctx, "authentication failed for request from ", r.RemoteAddr, ": unknown key: ", clientToken)
 			writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key")
 			return
 		}
 	}
 
+	// Always read body to extract model and session ID
+	var bodyBytes []byte
 	var requestModel string
 	var messagesCount int
+	var sessionID string
 
-	if s.usageTracker != nil && r.Body != nil {
-		bodyBytes, err := io.ReadAll(r.Body)
-		if err == nil {
-			var request struct {
-				Model    string                   `json:"model"`
-				Messages []anthropic.MessageParam `json:"messages"`
-			}
-			err := json.Unmarshal(bodyBytes, &request)
-			if err == nil {
-				requestModel = request.Model
-				messagesCount = len(request.Messages)
-			}
-			r.Body = io.NopCloser(bytes.NewBuffer(bodyBytes))
+	if r.Body != nil {
+		var err error
+		bodyBytes, err = io.ReadAll(r.Body)
+		if err != nil {
+			s.logger.ErrorContext(ctx, "read request body: ", err)
+			writeJSONError(w, r, http.StatusInternalServerError, "api_error", "failed to read request body")
+			return
 		}
+
+		var request struct {
+			Model    string                   `json:"model"`
+			Messages []anthropic.MessageParam `json:"messages"`
+		}
+		err = json.Unmarshal(bodyBytes, &request)
+		if err == nil {
+			requestModel = request.Model
+			messagesCount = len(request.Messages)
+		}
+
+		sessionID = extractCCMSessionID(bodyBytes)
+		r.Body = io.NopCloser(bytes.NewReader(bodyBytes))
 	}
 
-	accessToken, err := s.getAccessToken()
-	if err != nil {
-		s.logger.Error("get access token: ", err)
-		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "Authentication failed")
+	// Resolve credential provider and user config
+	var provider credentialProvider
+	var userConfig *option.CCMUser
+	if len(s.options.Users) > 0 {
+		userConfig = s.userConfigMap[username]
+		var err error
+		provider, err = credentialForUser(s.userConfigMap, s.providers, s.legacyProvider, username)
+		if err != nil {
+			s.logger.ErrorContext(ctx, "resolve credential: ", err)
+			writeJSONError(w, r, http.StatusInternalServerError, "api_error", err.Error())
+			return
+		}
+	} else {
+		provider = noUserCredentialProvider(s.providers, s.legacyProvider, s.options)
+	}
+	if provider == nil {
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "no credential available")
 		return
 	}
 
-	proxyURL := claudeAPIBaseURL + r.URL.RequestURI()
-	proxyRequest, err := http.NewRequestWithContext(r.Context(), r.Method, proxyURL, r.Body)
+	provider.pollIfStale(s.ctx)
+
+	anthropicBetaHeader := r.Header.Get("anthropic-beta")
+	if isFastModeRequest(anthropicBetaHeader) {
+		if _, isSingle := provider.(*singleCredentialProvider); !isSingle {
+			writeJSONError(w, r, http.StatusBadRequest, "invalid_request_error",
+				"fast mode requests will consume Extra usage, please use a default credential directly")
+			return
+		}
+	}
+
+	var credentialFilter func(credential) bool
+	if userConfig != nil && !userConfig.AllowExternalUsage {
+		credentialFilter = func(c credential) bool { return !c.isExternal() }
+	}
+
+	selectedCredential, isNew, err := provider.selectCredential(sessionID, credentialFilter)
 	if err != nil {
-		s.logger.Error("create proxy request: ", err)
+		writeNonRetryableCredentialError(w, r, unavailableCredentialMessage(provider, err.Error()))
+		return
+	}
+	if isNew {
+		logParts := []any{"assigned credential ", selectedCredential.tagName()}
+		if sessionID != "" {
+			logParts = append(logParts, " for session ", sessionID)
+		}
+		if username != "" {
+			logParts = append(logParts, " by user ", username)
+		}
+		if requestModel != "" {
+			modelDisplay := requestModel
+			if isExtendedContextRequest(anthropicBetaHeader) {
+				modelDisplay += "[1m]"
+			}
+			logParts = append(logParts, ", model=", modelDisplay)
+		}
+		s.logger.DebugContext(ctx, logParts...)
+	}
+
+	if isFastModeRequest(anthropicBetaHeader) && selectedCredential.isExternal() {
+		writeJSONError(w, r, http.StatusBadRequest, "invalid_request_error",
+			"fast mode requests cannot be proxied through external credentials")
+		return
+	}
+
+	requestContext := selectedCredential.wrapRequestContext(r.Context())
+	defer func() {
+		requestContext.cancelRequest()
+	}()
+	proxyRequest, err := selectedCredential.buildProxyRequest(requestContext, r, bodyBytes, s.httpHeaders)
+	if err != nil {
+		s.logger.ErrorContext(ctx, "create proxy request: ", err)
 		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "Internal server error")
 		return
 	}
 
-	for key, values := range r.Header {
-		if !isHopByHopHeader(key) && key != "Authorization" {
-			proxyRequest.Header[key] = values
-		}
-	}
-
-	serviceOverridesAcceptEncoding := len(s.httpHeaders.Values("Accept-Encoding")) > 0
-	if s.usageTracker != nil && !serviceOverridesAcceptEncoding {
-		// Strip Accept-Encoding so Go Transport adds it automatically
-		// and transparently decompresses the response for correct usage counting.
-		proxyRequest.Header.Del("Accept-Encoding")
-	}
-
-	anthropicBetaHeader := proxyRequest.Header.Get("anthropic-beta")
-	if anthropicBetaHeader != "" {
-		proxyRequest.Header.Set("anthropic-beta", anthropicBetaOAuthValue+","+anthropicBetaHeader)
-	} else {
-		proxyRequest.Header.Set("anthropic-beta", anthropicBetaOAuthValue)
-	}
-
-	for key, values := range s.httpHeaders {
-		proxyRequest.Header.Del(key)
-		proxyRequest.Header[key] = values
-	}
-
-	proxyRequest.Header.Set("Authorization", "Bearer "+accessToken)
-
-	response, err := s.httpClient.Do(proxyRequest)
+	response, err := selectedCredential.httpTransport().Do(proxyRequest)
 	if err != nil {
+		if r.Context().Err() != nil {
+			return
+		}
+		if requestContext.Err() != nil {
+			writeCredentialUnavailableError(w, r, provider, selectedCredential, credentialFilter, "credential became unavailable while processing the request")
+			return
+		}
 		writeJSONError(w, r, http.StatusBadGateway, "api_error", err.Error())
 		return
 	}
+	requestContext.releaseCredentialInterrupt()
+
+	// Transparent 429 retry
+	for response.StatusCode == http.StatusTooManyRequests {
+		resetAt := parseRateLimitResetFromHeaders(response.Header)
+		nextCredential := provider.onRateLimited(sessionID, selectedCredential, resetAt, credentialFilter)
+		selectedCredential.updateStateFromHeaders(response.Header)
+		if bodyBytes == nil || nextCredential == nil {
+			response.Body.Close()
+			writeCredentialUnavailableError(w, r, provider, selectedCredential, credentialFilter, "all credentials rate-limited")
+			return
+		}
+		response.Body.Close()
+		s.logger.InfoContext(ctx, "retrying with credential ", nextCredential.tagName(), " after 429 from ", selectedCredential.tagName())
+		requestContext.cancelRequest()
+		requestContext = nextCredential.wrapRequestContext(r.Context())
+		retryRequest, buildErr := nextCredential.buildProxyRequest(requestContext, r, bodyBytes, s.httpHeaders)
+		if buildErr != nil {
+			s.logger.ErrorContext(ctx, "retry request: ", buildErr)
+			writeJSONError(w, r, http.StatusBadGateway, "api_error", buildErr.Error())
+			return
+		}
+		retryResponse, retryErr := nextCredential.httpTransport().Do(retryRequest)
+		if retryErr != nil {
+			if r.Context().Err() != nil {
+				return
+			}
+			if requestContext.Err() != nil {
+				writeCredentialUnavailableError(w, r, provider, nextCredential, credentialFilter, "credential became unavailable while retrying the request")
+				return
+			}
+			s.logger.ErrorContext(ctx, "retry request: ", retryErr)
+			writeJSONError(w, r, http.StatusBadGateway, "api_error", retryErr.Error())
+			return
+		}
+		requestContext.releaseCredentialInterrupt()
+		response = retryResponse
+		selectedCredential = nextCredential
+	}
 	defer response.Body.Close()
 
+	selectedCredential.updateStateFromHeaders(response.Header)
+
+	if response.StatusCode != http.StatusOK && response.StatusCode != http.StatusTooManyRequests {
+		body, _ := io.ReadAll(response.Body)
+		s.logger.ErrorContext(ctx, "upstream error from ", selectedCredential.tagName(), ": status ", response.StatusCode, " ", string(body))
+		go selectedCredential.pollUsage(s.ctx)
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error",
+			"proxy request (status "+strconv.Itoa(response.StatusCode)+"): "+string(body))
+		return
+	}
+
+	// Rewrite response headers for external users
+	if userConfig != nil && userConfig.ExternalCredential != "" {
+		s.rewriteResponseHeadersForExternalUser(response.Header, userConfig)
+	}
+
 	for key, values := range response.Header {
-		if !isHopByHopHeader(key) {
+		if !isHopByHopHeader(key) && !isReverseProxyHeader(key) {
 			w.Header()[key] = values
 		}
 	}
 	w.WriteHeader(response.StatusCode)
 
-	if s.usageTracker != nil && response.StatusCode == http.StatusOK {
-		s.handleResponseWithTracking(w, response, requestModel, anthropicBetaHeader, messagesCount, username)
+	usageTracker := selectedCredential.usageTrackerOrNil()
+	if usageTracker != nil && response.StatusCode == http.StatusOK {
+		s.handleResponseWithTracking(ctx, w, response, usageTracker, requestModel, anthropicBetaHeader, messagesCount, username)
 	} else {
 		mediaType, _, err := mime.ParseMediaType(response.Header.Get("Content-Type"))
 		if err == nil && mediaType != "text/event-stream" {
@@ -407,7 +556,7 @@ func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 		flusher, ok := w.(http.Flusher)
 		if !ok {
-			s.logger.Error("streaming not supported")
+			s.logger.ErrorContext(ctx, "streaming not supported")
 			return
 		}
 		buffer := make([]byte, buf.BufferSize)
@@ -416,7 +565,7 @@ func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			if n > 0 {
 				_, writeError := w.Write(buffer[:n])
 				if writeError != nil {
-					s.logger.Error("write streaming response: ", writeError)
+					s.logger.ErrorContext(ctx, "write streaming response: ", writeError)
 					return
 				}
 				flusher.Flush()
@@ -428,7 +577,7 @@ func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, response *http.Response, requestModel string, anthropicBetaHeader string, messagesCount int, username string) {
+func (s *Service) handleResponseWithTracking(ctx context.Context, writer http.ResponseWriter, response *http.Response, usageTracker *AggregatedUsage, requestModel string, anthropicBetaHeader string, messagesCount int, username string) {
 	weeklyCycleHint := extractWeeklyCycleHint(response.Header)
 	mediaType, _, err := mime.ParseMediaType(response.Header.Get("Content-Type"))
 	isStreaming := err == nil && mediaType == "text/event-stream"
@@ -436,7 +585,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 	if !isStreaming {
 		bodyBytes, err := io.ReadAll(response.Body)
 		if err != nil {
-			s.logger.Error("read response body: ", err)
+			s.logger.ErrorContext(ctx, "read response body: ", err)
 			return
 		}
 
@@ -456,7 +605,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 			if responseModel != "" {
 				totalInputTokens := usage.InputTokens + usage.CacheCreationInputTokens + usage.CacheReadInputTokens
 				contextWindow := detectContextWindow(anthropicBetaHeader, totalInputTokens)
-				s.usageTracker.AddUsageWithCycleHint(
+				usageTracker.AddUsageWithCycleHint(
 					responseModel,
 					contextWindow,
 					messagesCount,
@@ -479,7 +628,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 
 	flusher, ok := writer.(http.Flusher)
 	if !ok {
-		s.logger.Error("streaming not supported")
+		s.logger.ErrorContext(ctx, "streaming not supported")
 		return
 	}
 
@@ -542,7 +691,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 
 			_, writeError := writer.Write(buffer[:n])
 			if writeError != nil {
-				s.logger.Error("write streaming response: ", writeError)
+				s.logger.ErrorContext(ctx, "write streaming response: ", writeError)
 				return
 			}
 			flusher.Flush()
@@ -557,7 +706,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 				if responseModel != "" {
 					totalInputTokens := accumulatedUsage.InputTokens + accumulatedUsage.CacheCreationInputTokens + accumulatedUsage.CacheReadInputTokens
 					contextWindow := detectContextWindow(anthropicBetaHeader, totalInputTokens)
-					s.usageTracker.AddUsageWithCycleHint(
+					usageTracker.AddUsageWithCycleHint(
 						responseModel,
 						contextWindow,
 						messagesCount,
@@ -578,6 +727,120 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 	}
 }
 
+func (s *Service) handleStatusEndpoint(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		writeJSONError(w, r, http.StatusMethodNotAllowed, "invalid_request_error", "method not allowed")
+		return
+	}
+
+	if len(s.options.Users) == 0 {
+		writeJSONError(w, r, http.StatusForbidden, "authentication_error", "status endpoint requires user authentication")
+		return
+	}
+
+	authHeader := r.Header.Get("Authorization")
+	if authHeader == "" {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "missing api key")
+		return
+	}
+	clientToken := strings.TrimPrefix(authHeader, "Bearer ")
+	if clientToken == authHeader {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key format")
+		return
+	}
+	username, ok := s.userManager.Authenticate(clientToken)
+	if !ok {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key")
+		return
+	}
+
+	userConfig := s.userConfigMap[username]
+	if userConfig == nil {
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "user config not found")
+		return
+	}
+
+	provider, err := credentialForUser(s.userConfigMap, s.providers, s.legacyProvider, username)
+	if err != nil {
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", err.Error())
+		return
+	}
+
+	provider.pollIfStale(r.Context())
+	avgFiveHour, avgWeekly, totalWeight := s.computeAggregatedUtilization(provider, userConfig)
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(map[string]float64{
+		"five_hour_utilization": avgFiveHour,
+		"weekly_utilization":    avgWeekly,
+		"plan_weight":           totalWeight,
+	})
+}
+
+func (s *Service) computeAggregatedUtilization(provider credentialProvider, userConfig *option.CCMUser) (float64, float64, float64) {
+	var totalWeightedRemaining5h, totalWeightedRemainingWeekly, totalWeight float64
+	for _, cred := range provider.allCredentials() {
+		if !cred.isAvailable() {
+			continue
+		}
+		if userConfig.ExternalCredential != "" && cred.tagName() == userConfig.ExternalCredential {
+			continue
+		}
+		if !userConfig.AllowExternalUsage && cred.isExternal() {
+			continue
+		}
+		weight := cred.planWeight()
+		remaining5h := cred.fiveHourCap() - cred.fiveHourUtilization()
+		if remaining5h < 0 {
+			remaining5h = 0
+		}
+		remainingWeekly := cred.weeklyCap() - cred.weeklyUtilization()
+		if remainingWeekly < 0 {
+			remainingWeekly = 0
+		}
+		totalWeightedRemaining5h += remaining5h * weight
+		totalWeightedRemainingWeekly += remainingWeekly * weight
+		totalWeight += weight
+	}
+	if totalWeight == 0 {
+		return 100, 100, 0
+	}
+	return 100 - totalWeightedRemaining5h/totalWeight,
+		100 - totalWeightedRemainingWeekly/totalWeight,
+		totalWeight
+}
+
+func (s *Service) rewriteResponseHeadersForExternalUser(headers http.Header, userConfig *option.CCMUser) {
+	provider, err := credentialForUser(s.userConfigMap, s.providers, s.legacyProvider, userConfig.Name)
+	if err != nil {
+		return
+	}
+
+	avgFiveHour, avgWeekly, totalWeight := s.computeAggregatedUtilization(provider, userConfig)
+
+	// Rewrite utilization headers to aggregated average (convert back to 0.0-1.0 range)
+	headers.Set("anthropic-ratelimit-unified-5h-utilization", strconv.FormatFloat(avgFiveHour/100, 'f', 6, 64))
+	headers.Set("anthropic-ratelimit-unified-7d-utilization", strconv.FormatFloat(avgWeekly/100, 'f', 6, 64))
+	if totalWeight > 0 {
+		headers.Set("X-CCM-Plan-Weight", strconv.FormatFloat(totalWeight, 'f', -1, 64))
+	}
+}
+
+func (s *Service) InterfaceUpdated() {
+	for _, cred := range s.allCredentials {
+		extCred, ok := cred.(*externalCredential)
+		if !ok {
+			continue
+		}
+		if extCred.reverse && extCred.connectorURL != nil {
+			extCred.reverseService = s
+			extCred.resetReverseContext()
+			go extCred.connectorLoop()
+		}
+	}
+}
+
 func (s *Service) Close() error {
 	err := common.Close(
 		common.PtrOrNil(s.httpServer),
@@ -585,12 +848,8 @@ func (s *Service) Close() error {
 		s.tlsConfig,
 	)
 
-	if s.usageTracker != nil {
-		s.usageTracker.cancelPendingSave()
-		saveErr := s.usageTracker.Save()
-		if saveErr != nil {
-			s.logger.Error("save usage statistics: ", saveErr)
-		}
+	for _, cred := range s.allCredentials {
+		cred.close()
 	}
 
 	return err

service/ocm/credential.go

@@ -2,6 +2,7 @@ package ocm
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"io"
 	"net/http"
@@ -55,6 +56,14 @@ func readCredentialsFromFile(path string) (*oauthCredentials, error) {
 	return &credentials, nil
 }
 
+func checkCredentialFileWritable(path string) error {
+	file, err := os.OpenFile(path, os.O_WRONLY, 0)
+	if err != nil {
+		return err
+	}
+	return file.Close()
+}
+
 func writeCredentialsToFile(credentials *oauthCredentials, path string) error {
 	data, err := json.MarshalIndent(credentials, "", "  ")
 	if err != nil {
@@ -110,7 +119,7 @@ func (c *oauthCredentials) needsRefresh() bool {
 	return time.Since(*c.LastRefresh) >= time.Duration(tokenRefreshIntervalDays)*24*time.Hour
 }
 
-func refreshToken(httpClient *http.Client, credentials *oauthCredentials) (*oauthCredentials, error) {
+func refreshToken(ctx context.Context, httpClient *http.Client, credentials *oauthCredentials) (*oauthCredentials, error) {
 	if credentials.Tokens == nil || credentials.Tokens.RefreshToken == "" {
 		return nil, E.New("refresh token is empty")
 	}
@@ -125,19 +134,24 @@ func refreshToken(httpClient *http.Client, credentials *oauthCredentials) (*oaut
 		return nil, E.Cause(err, "marshal request")
 	}
 
-	request, err := http.NewRequest("POST", oauth2TokenURL, bytes.NewReader(requestBody))
-	if err != nil {
-		return nil, err
-	}
-	request.Header.Set("Content-Type", "application/json")
-	request.Header.Set("Accept", "application/json")
-
-	response, err := httpClient.Do(request)
+	response, err := doHTTPWithRetry(ctx, httpClient, func() (*http.Request, error) {
+		request, err := http.NewRequest("POST", oauth2TokenURL, bytes.NewReader(requestBody))
+		if err != nil {
+			return nil, err
+		}
+		request.Header.Set("Content-Type", "application/json")
+		request.Header.Set("Accept", "application/json")
+		return request, nil
+	})
 	if err != nil {
 		return nil, err
 	}
 	defer response.Body.Close()
 
+	if response.StatusCode == http.StatusTooManyRequests {
+		body, _ := io.ReadAll(response.Body)
+		return nil, E.New("refresh rate limited: ", response.Status, " ", string(body))
+	}
 	if response.StatusCode != http.StatusOK {
 		body, _ := io.ReadAll(response.Body)
 		return nil, E.New("refresh failed: ", response.Status, " ", string(body))
@@ -171,3 +185,41 @@ func refreshToken(httpClient *http.Client, credentials *oauthCredentials) (*oaut
 
 	return &newCredentials, nil
 }
+
+func cloneCredentials(credentials *oauthCredentials) *oauthCredentials {
+	if credentials == nil {
+		return nil
+	}
+	cloned := *credentials
+	if credentials.Tokens != nil {
+		clonedTokens := *credentials.Tokens
+		cloned.Tokens = &clonedTokens
+	}
+	if credentials.LastRefresh != nil {
+		lastRefresh := *credentials.LastRefresh
+		cloned.LastRefresh = &lastRefresh
+	}
+	return &cloned
+}
+
+func credentialsEqual(left *oauthCredentials, right *oauthCredentials) bool {
+	if left == nil || right == nil {
+		return left == right
+	}
+	if left.APIKey != right.APIKey {
+		return false
+	}
+	if (left.Tokens == nil) != (right.Tokens == nil) {
+		return false
+	}
+	if left.Tokens != nil && *left.Tokens != *right.Tokens {
+		return false
+	}
+	if (left.LastRefresh == nil) != (right.LastRefresh == nil) {
+		return false
+	}
+	if left.LastRefresh != nil && !left.LastRefresh.Equal(*right.LastRefresh) {
+		return false
+	}
+	return true
+}

service/ocm/credential_darwin.go

@@ -13,6 +13,17 @@ func platformReadCredentials(customPath string) (*oauthCredentials, error) {
 	return readCredentialsFromFile(customPath)
 }
 
+func platformCanWriteCredentials(customPath string) error {
+	if customPath == "" {
+		var err error
+		customPath, err = getDefaultCredentialsPath()
+		if err != nil {
+			return err
+		}
+	}
+	return checkCredentialFileWritable(customPath)
+}
+
 func platformWriteCredentials(credentials *oauthCredentials, customPath string) error {
 	if customPath == "" {
 		var err error

service/ocm/credential_external.go

@@ -0,0 +1,729 @@
+package ocm
+
+import (
+	"bytes"
+	"context"
+	stdTLS "crypto/tls"
+	"encoding/json"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/dialer"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/common/ntp"
+
+	"github.com/hashicorp/yamux"
+)
+
+const reverseProxyBaseURL = "http://reverse-proxy"
+
+type externalCredential struct {
+	tag          string
+	baseURL      string
+	token        string
+	credDialer   N.Dialer
+	httpClient   *http.Client
+	state        credentialState
+	stateMutex   sync.RWMutex
+	pollAccess   sync.Mutex
+	pollInterval time.Duration
+	usageTracker *AggregatedUsage
+	logger       log.ContextLogger
+
+	onBecameUnusable func()
+	interrupted      bool
+	requestContext   context.Context
+	cancelRequests   context.CancelFunc
+	requestAccess    sync.Mutex
+
+	// Reverse proxy fields
+	reverse              bool
+	reverseSession       *yamux.Session
+	reverseAccess        sync.RWMutex
+	closed               bool
+	reverseContext       context.Context
+	reverseCancel        context.CancelFunc
+	connectorDialer      N.Dialer
+	connectorDestination M.Socksaddr
+	connectorRequestPath string
+	connectorURL         *url.URL
+	connectorTLS         *stdTLS.Config
+	reverseService       http.Handler
+}
+
+type reverseSessionDialer struct {
+	credential *externalCredential
+}
+
+func (d reverseSessionDialer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
+	if N.NetworkName(network) != N.NetworkTCP {
+		return nil, os.ErrInvalid
+	}
+	return d.credential.openReverseConnection(ctx)
+}
+
+func (d reverseSessionDialer) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
+	return nil, os.ErrInvalid
+}
+
+func externalCredentialURLPort(parsedURL *url.URL) uint16 {
+	portStr := parsedURL.Port()
+	if portStr != "" {
+		port, err := strconv.ParseUint(portStr, 10, 16)
+		if err == nil {
+			return uint16(port)
+		}
+	}
+	if parsedURL.Scheme == "https" {
+		return 443
+	}
+	return 80
+}
+
+func externalCredentialServerPort(parsedURL *url.URL, configuredPort uint16) uint16 {
+	if configuredPort != 0 {
+		return configuredPort
+	}
+	return externalCredentialURLPort(parsedURL)
+}
+
+func externalCredentialBaseURL(parsedURL *url.URL) string {
+	baseURL := parsedURL.Scheme + "://" + parsedURL.Host
+	if parsedURL.Path != "" && parsedURL.Path != "/" {
+		baseURL += parsedURL.Path
+	}
+	if len(baseURL) > 0 && baseURL[len(baseURL)-1] == '/' {
+		baseURL = baseURL[:len(baseURL)-1]
+	}
+	return baseURL
+}
+
+func externalCredentialReversePath(parsedURL *url.URL, endpointPath string) string {
+	pathPrefix := parsedURL.EscapedPath()
+	if pathPrefix == "/" {
+		pathPrefix = ""
+	} else {
+		pathPrefix = strings.TrimSuffix(pathPrefix, "/")
+	}
+	return pathPrefix + endpointPath
+}
+
+func newExternalCredential(ctx context.Context, tag string, options option.OCMExternalCredentialOptions, logger log.ContextLogger) (*externalCredential, error) {
+	pollInterval := time.Duration(options.PollInterval)
+	if pollInterval <= 0 {
+		pollInterval = 30 * time.Minute
+	}
+
+	requestContext, cancelRequests := context.WithCancel(context.Background())
+	reverseContext, reverseCancel := context.WithCancel(context.Background())
+
+	cred := &externalCredential{
+		tag:            tag,
+		token:          options.Token,
+		pollInterval:   pollInterval,
+		logger:         logger,
+		requestContext: requestContext,
+		cancelRequests: cancelRequests,
+		reverse:        options.Reverse,
+		reverseContext: reverseContext,
+		reverseCancel:  reverseCancel,
+	}
+
+	if options.URL == "" {
+		// Receiver mode: no URL, wait for reverse connection
+		cred.baseURL = reverseProxyBaseURL
+		cred.credDialer = reverseSessionDialer{credential: cred}
+		cred.httpClient = &http.Client{
+			Transport: &http.Transport{
+				ForceAttemptHTTP2: false,
+				DialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
+					return cred.openReverseConnection(ctx)
+				},
+			},
+		}
+	} else {
+		// Normal or connector mode: has URL
+		parsedURL, err := url.Parse(options.URL)
+		if err != nil {
+			return nil, E.Cause(err, "parse url for credential ", tag)
+		}
+
+		credentialDialer, err := dialer.NewWithOptions(dialer.Options{
+			Context: ctx,
+			Options: option.DialerOptions{
+				Detour: options.Detour,
+			},
+			RemoteIsDomain: true,
+		})
+		if err != nil {
+			return nil, E.Cause(err, "create dialer for credential ", tag)
+		}
+
+		transport := &http.Transport{
+			ForceAttemptHTTP2: true,
+			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				if options.Server != "" {
+					destination := M.ParseSocksaddrHostPort(options.Server, externalCredentialServerPort(parsedURL, options.ServerPort))
+					return credentialDialer.DialContext(ctx, network, destination)
+				}
+				return credentialDialer.DialContext(ctx, network, M.ParseSocksaddr(addr))
+			},
+		}
+
+		if parsedURL.Scheme == "https" {
+			transport.TLSClientConfig = &stdTLS.Config{
+				ServerName: parsedURL.Hostname(),
+				RootCAs:    adapter.RootPoolFromContext(ctx),
+				Time:       ntp.TimeFuncFromContext(ctx),
+			}
+		}
+
+		cred.baseURL = externalCredentialBaseURL(parsedURL)
+
+		if options.Reverse {
+			// Connector mode: we dial out to serve, not to proxy
+			cred.connectorDialer = credentialDialer
+			if options.Server != "" {
+				cred.connectorDestination = M.ParseSocksaddrHostPort(options.Server, externalCredentialServerPort(parsedURL, options.ServerPort))
+			} else {
+				cred.connectorDestination = M.ParseSocksaddrHostPort(parsedURL.Hostname(), externalCredentialURLPort(parsedURL))
+			}
+			cred.connectorRequestPath = externalCredentialReversePath(parsedURL, "/ocm/v1/reverse")
+			cred.connectorURL = parsedURL
+			if parsedURL.Scheme == "https" {
+				cred.connectorTLS = &stdTLS.Config{
+					ServerName: parsedURL.Hostname(),
+					RootCAs:    adapter.RootPoolFromContext(ctx),
+					Time:       ntp.TimeFuncFromContext(ctx),
+				}
+			}
+		} else {
+			// Normal mode: standard HTTP client for proxying
+			cred.credDialer = credentialDialer
+			cred.httpClient = &http.Client{Transport: transport}
+		}
+	}
+
+	if options.UsagesPath != "" {
+		cred.usageTracker = &AggregatedUsage{
+			LastUpdated:  time.Now(),
+			Combinations: make([]CostCombination, 0),
+			filePath:     options.UsagesPath,
+			logger:       logger,
+		}
+	}
+
+	return cred, nil
+}
+
+func (c *externalCredential) start() error {
+	if c.usageTracker != nil {
+		err := c.usageTracker.Load()
+		if err != nil {
+			c.logger.Warn("load usage statistics for ", c.tag, ": ", err)
+		}
+	}
+	if c.reverse && c.connectorURL != nil {
+		go c.connectorLoop()
+	}
+	return nil
+}
+
+func (c *externalCredential) setOnBecameUnusable(fn func()) {
+	c.onBecameUnusable = fn
+}
+
+func (c *externalCredential) tagName() string {
+	return c.tag
+}
+
+func (c *externalCredential) isExternal() bool {
+	return true
+}
+
+func (c *externalCredential) isAvailable() bool {
+	return c.unavailableError() == nil
+}
+
+func (c *externalCredential) isUsable() bool {
+	if !c.isAvailable() {
+		return false
+	}
+	c.stateMutex.RLock()
+	if c.state.consecutivePollFailures > 0 {
+		c.stateMutex.RUnlock()
+		return false
+	}
+	if c.state.hardRateLimited {
+		if time.Now().Before(c.state.rateLimitResetAt) {
+			c.stateMutex.RUnlock()
+			return false
+		}
+		c.stateMutex.RUnlock()
+		c.stateMutex.Lock()
+		if c.state.hardRateLimited && !time.Now().Before(c.state.rateLimitResetAt) {
+			c.state.hardRateLimited = false
+		}
+		usable := c.state.fiveHourUtilization < 100 && c.state.weeklyUtilization < 100
+		c.stateMutex.Unlock()
+		return usable
+	}
+	usable := c.state.fiveHourUtilization < 100 && c.state.weeklyUtilization < 100
+	c.stateMutex.RUnlock()
+	return usable
+}
+
+func (c *externalCredential) fiveHourUtilization() float64 {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.fiveHourUtilization
+}
+
+func (c *externalCredential) weeklyUtilization() float64 {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.weeklyUtilization
+}
+
+func (c *externalCredential) fiveHourCap() float64 {
+	return 100
+}
+
+func (c *externalCredential) weeklyCap() float64 {
+	return 100
+}
+
+func (c *externalCredential) planWeight() float64 {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	if c.state.remotePlanWeight > 0 {
+		return c.state.remotePlanWeight
+	}
+	return 10
+}
+
+func (c *externalCredential) weeklyResetTime() time.Time {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.weeklyReset
+}
+
+func (c *externalCredential) markRateLimited(resetAt time.Time) {
+	c.logger.Warn("rate limited for ", c.tag, ", reset in ", log.FormatDuration(time.Until(resetAt)))
+	c.stateMutex.Lock()
+	c.state.hardRateLimited = true
+	c.state.rateLimitResetAt = resetAt
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) earliestReset() time.Time {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	if c.state.hardRateLimited {
+		return c.state.rateLimitResetAt
+	}
+	earliest := c.state.fiveHourReset
+	if !c.state.weeklyReset.IsZero() && (earliest.IsZero() || c.state.weeklyReset.Before(earliest)) {
+		earliest = c.state.weeklyReset
+	}
+	return earliest
+}
+
+func (c *externalCredential) unavailableError() error {
+	if c.reverse && c.connectorURL != nil {
+		return E.New("credential ", c.tag, " is unavailable: reverse connector credentials cannot serve local requests")
+	}
+	if c.baseURL == reverseProxyBaseURL {
+		session := c.getReverseSession()
+		if session == nil || session.IsClosed() {
+			return E.New("credential ", c.tag, " is unavailable: reverse connection not established")
+		}
+	}
+	return nil
+}
+
+func (c *externalCredential) getAccessToken() (string, error) {
+	return c.token, nil
+}
+
+func (c *externalCredential) buildProxyRequest(ctx context.Context, original *http.Request, bodyBytes []byte, _ http.Header) (*http.Request, error) {
+	proxyURL := c.baseURL + original.URL.RequestURI()
+	var body io.Reader
+	if bodyBytes != nil {
+		body = bytes.NewReader(bodyBytes)
+	} else {
+		body = original.Body
+	}
+	proxyRequest, err := http.NewRequestWithContext(ctx, original.Method, proxyURL, body)
+	if err != nil {
+		return nil, err
+	}
+
+	for key, values := range original.Header {
+		if !isHopByHopHeader(key) && !isReverseProxyHeader(key) && key != "Authorization" {
+			proxyRequest.Header[key] = values
+		}
+	}
+
+	proxyRequest.Header.Set("Authorization", "Bearer "+c.token)
+
+	return proxyRequest, nil
+}
+
+func (c *externalCredential) openReverseConnection(ctx context.Context) (net.Conn, error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+	session := c.getReverseSession()
+	if session == nil || session.IsClosed() {
+		return nil, E.New("reverse connection not established for ", c.tag)
+	}
+	conn, err := session.Open()
+	if err != nil {
+		return nil, err
+	}
+	select {
+	case <-ctx.Done():
+		conn.Close()
+		return nil, ctx.Err()
+	default:
+	}
+	return conn, nil
+}
+
+func (c *externalCredential) updateStateFromHeaders(headers http.Header) {
+	c.stateMutex.Lock()
+	isFirstUpdate := c.state.lastUpdated.IsZero()
+	oldFiveHour := c.state.fiveHourUtilization
+	oldWeekly := c.state.weeklyUtilization
+	hadData := false
+
+	activeLimitIdentifier := normalizeRateLimitIdentifier(headers.Get("x-codex-active-limit"))
+	if activeLimitIdentifier == "" {
+		activeLimitIdentifier = "codex"
+	}
+
+	fiveHourResetAt := headers.Get("x-" + activeLimitIdentifier + "-primary-reset-at")
+	if fiveHourResetAt != "" {
+		value, err := strconv.ParseInt(fiveHourResetAt, 10, 64)
+		if err == nil {
+			hadData = true
+			c.state.fiveHourReset = time.Unix(value, 0)
+		}
+	}
+	fiveHourPercent := headers.Get("x-" + activeLimitIdentifier + "-primary-used-percent")
+	if fiveHourPercent != "" {
+		value, err := strconv.ParseFloat(fiveHourPercent, 64)
+		if err == nil {
+			hadData = true
+			c.state.fiveHourUtilization = value
+		}
+	}
+
+	weeklyResetAt := headers.Get("x-" + activeLimitIdentifier + "-secondary-reset-at")
+	if weeklyResetAt != "" {
+		value, err := strconv.ParseInt(weeklyResetAt, 10, 64)
+		if err == nil {
+			hadData = true
+			c.state.weeklyReset = time.Unix(value, 0)
+		}
+	}
+	weeklyPercent := headers.Get("x-" + activeLimitIdentifier + "-secondary-used-percent")
+	if weeklyPercent != "" {
+		value, err := strconv.ParseFloat(weeklyPercent, 64)
+		if err == nil {
+			hadData = true
+			c.state.weeklyUtilization = value
+		}
+	}
+	if planWeight := headers.Get("X-OCM-Plan-Weight"); planWeight != "" {
+		value, err := strconv.ParseFloat(planWeight, 64)
+		if err == nil && value > 0 {
+			c.state.remotePlanWeight = value
+		}
+	}
+	if hadData {
+		c.state.consecutivePollFailures = 0
+		c.state.lastUpdated = time.Now()
+	}
+	if isFirstUpdate || int(c.state.fiveHourUtilization*100) != int(oldFiveHour*100) || int(c.state.weeklyUtilization*100) != int(oldWeekly*100) {
+		resetSuffix := ""
+		if !c.state.weeklyReset.IsZero() {
+			resetSuffix = ", resets=" + log.FormatDuration(time.Until(c.state.weeklyReset))
+		}
+		c.logger.Debug("usage update for ", c.tag, ": 5h=", c.state.fiveHourUtilization, "%, weekly=", c.state.weeklyUtilization, "%", resetSuffix)
+	}
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) checkTransitionLocked() bool {
+	unusable := c.state.hardRateLimited || c.state.fiveHourUtilization >= 100 || c.state.weeklyUtilization >= 100 || c.state.consecutivePollFailures > 0
+	if unusable && !c.interrupted {
+		c.interrupted = true
+		return true
+	}
+	if !unusable && c.interrupted {
+		c.interrupted = false
+	}
+	return false
+}
+
+func (c *externalCredential) wrapRequestContext(parent context.Context) *credentialRequestContext {
+	c.requestAccess.Lock()
+	credentialContext := c.requestContext
+	c.requestAccess.Unlock()
+	derived, cancel := context.WithCancel(parent)
+	stop := context.AfterFunc(credentialContext, func() {
+		cancel()
+	})
+	return &credentialRequestContext{
+		Context:     derived,
+		releaseFunc: stop,
+		cancelFunc:  cancel,
+	}
+}
+
+func (c *externalCredential) interruptConnections() {
+	c.logger.Warn("interrupting connections for ", c.tag)
+	c.requestAccess.Lock()
+	c.cancelRequests()
+	c.requestContext, c.cancelRequests = context.WithCancel(context.Background())
+	c.requestAccess.Unlock()
+	if c.onBecameUnusable != nil {
+		c.onBecameUnusable()
+	}
+}
+
+func (c *externalCredential) pollUsage(ctx context.Context) {
+	if !c.pollAccess.TryLock() {
+		return
+	}
+	defer c.pollAccess.Unlock()
+	defer c.markUsagePollAttempted()
+
+	statusURL := c.baseURL + "/ocm/v1/status"
+	httpClient := &http.Client{
+		Transport: c.httpClient.Transport,
+		Timeout:   5 * time.Second,
+	}
+
+	response, err := doHTTPWithRetry(ctx, httpClient, func() (*http.Request, error) {
+		request, err := http.NewRequestWithContext(ctx, http.MethodGet, statusURL, nil)
+		if err != nil {
+			return nil, err
+		}
+		request.Header.Set("Authorization", "Bearer "+c.token)
+		return request, nil
+	})
+	if err != nil {
+		c.logger.Error("poll usage for ", c.tag, ": ", err)
+		c.incrementPollFailures()
+		return
+	}
+	defer response.Body.Close()
+
+	if response.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(response.Body)
+		c.logger.Debug("poll usage for ", c.tag, ": status ", response.StatusCode, " ", string(body))
+		// 404 means the remote does not have a status endpoint yet;
+		// usage will be updated passively from response headers.
+		if response.StatusCode == http.StatusNotFound {
+			c.stateMutex.Lock()
+			c.state.consecutivePollFailures = 0
+			c.checkTransitionLocked()
+			c.stateMutex.Unlock()
+		} else {
+			c.incrementPollFailures()
+		}
+		return
+	}
+
+	var statusResponse struct {
+		FiveHourUtilization float64 `json:"five_hour_utilization"`
+		WeeklyUtilization   float64 `json:"weekly_utilization"`
+		PlanWeight          float64 `json:"plan_weight"`
+	}
+	err = json.NewDecoder(response.Body).Decode(&statusResponse)
+	if err != nil {
+		c.logger.Debug("poll usage for ", c.tag, ": decode: ", err)
+		c.incrementPollFailures()
+		return
+	}
+
+	c.stateMutex.Lock()
+	isFirstUpdate := c.state.lastUpdated.IsZero()
+	oldFiveHour := c.state.fiveHourUtilization
+	oldWeekly := c.state.weeklyUtilization
+	c.state.consecutivePollFailures = 0
+	c.state.fiveHourUtilization = statusResponse.FiveHourUtilization
+	c.state.weeklyUtilization = statusResponse.WeeklyUtilization
+	if statusResponse.PlanWeight > 0 {
+		c.state.remotePlanWeight = statusResponse.PlanWeight
+	}
+	if c.state.hardRateLimited && time.Now().After(c.state.rateLimitResetAt) {
+		c.state.hardRateLimited = false
+	}
+	if isFirstUpdate || int(c.state.fiveHourUtilization*100) != int(oldFiveHour*100) || int(c.state.weeklyUtilization*100) != int(oldWeekly*100) {
+		resetSuffix := ""
+		if !c.state.weeklyReset.IsZero() {
+			resetSuffix = ", resets=" + log.FormatDuration(time.Until(c.state.weeklyReset))
+		}
+		c.logger.Debug("poll usage for ", c.tag, ": 5h=", c.state.fiveHourUtilization, "%, weekly=", c.state.weeklyUtilization, "%", resetSuffix)
+	}
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) lastUpdatedTime() time.Time {
+	c.stateMutex.RLock()
+	defer c.stateMutex.RUnlock()
+	return c.state.lastUpdated
+}
+
+func (c *externalCredential) markUsagePollAttempted() {
+	c.stateMutex.Lock()
+	defer c.stateMutex.Unlock()
+	c.state.lastUpdated = time.Now()
+}
+
+func (c *externalCredential) pollBackoff(baseInterval time.Duration) time.Duration {
+	c.stateMutex.RLock()
+	failures := c.state.consecutivePollFailures
+	c.stateMutex.RUnlock()
+	if failures <= 0 {
+		return baseInterval
+	}
+	return failedPollRetryInterval
+}
+
+func (c *externalCredential) incrementPollFailures() {
+	c.stateMutex.Lock()
+	c.state.consecutivePollFailures++
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+	if shouldInterrupt {
+		c.interruptConnections()
+	}
+}
+
+func (c *externalCredential) usageTrackerOrNil() *AggregatedUsage {
+	return c.usageTracker
+}
+
+func (c *externalCredential) httpTransport() *http.Client {
+	return c.httpClient
+}
+
+func (c *externalCredential) ocmDialer() N.Dialer {
+	return c.credDialer
+}
+
+func (c *externalCredential) ocmIsAPIKeyMode() bool {
+	return false
+}
+
+func (c *externalCredential) ocmGetAccountID() string {
+	return ""
+}
+
+func (c *externalCredential) ocmGetBaseURL() string {
+	return c.baseURL
+}
+
+func (c *externalCredential) close() {
+	var session *yamux.Session
+	c.reverseAccess.Lock()
+	if !c.closed {
+		c.closed = true
+		if c.reverseCancel != nil {
+			c.reverseCancel()
+		}
+		session = c.reverseSession
+		c.reverseSession = nil
+	}
+	c.reverseAccess.Unlock()
+	if session != nil {
+		session.Close()
+	}
+	if c.usageTracker != nil {
+		c.usageTracker.cancelPendingSave()
+		err := c.usageTracker.Save()
+		if err != nil {
+			c.logger.Error("save usage statistics for ", c.tag, ": ", err)
+		}
+	}
+}
+
+func (c *externalCredential) getReverseSession() *yamux.Session {
+	c.reverseAccess.RLock()
+	defer c.reverseAccess.RUnlock()
+	return c.reverseSession
+}
+
+func (c *externalCredential) setReverseSession(session *yamux.Session) bool {
+	c.reverseAccess.Lock()
+	if c.closed {
+		c.reverseAccess.Unlock()
+		return false
+	}
+	old := c.reverseSession
+	c.reverseSession = session
+	c.reverseAccess.Unlock()
+	if old != nil {
+		old.Close()
+	}
+	return true
+}
+
+func (c *externalCredential) clearReverseSession(session *yamux.Session) {
+	c.reverseAccess.Lock()
+	if c.reverseSession == session {
+		c.reverseSession = nil
+	}
+	c.reverseAccess.Unlock()
+}
+
+func (c *externalCredential) getReverseContext() context.Context {
+	c.reverseAccess.RLock()
+	defer c.reverseAccess.RUnlock()
+	return c.reverseContext
+}
+
+func (c *externalCredential) resetReverseContext() {
+	c.reverseAccess.Lock()
+	if c.closed {
+		c.reverseAccess.Unlock()
+		return
+	}
+	c.reverseCancel()
+	c.reverseContext, c.reverseCancel = context.WithCancel(context.Background())
+	c.reverseAccess.Unlock()
+}

service/ocm/credential_file.go

@@ -0,0 +1,139 @@
+package ocm
+
+import (
+	"path/filepath"
+	"time"
+
+	"github.com/sagernet/fswatch"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+const credentialReloadRetryInterval = 2 * time.Second
+
+func resolveCredentialFilePath(customPath string) (string, error) {
+	if customPath == "" {
+		var err error
+		customPath, err = getDefaultCredentialsPath()
+		if err != nil {
+			return "", err
+		}
+	}
+	if filepath.IsAbs(customPath) {
+		return customPath, nil
+	}
+	return filepath.Abs(customPath)
+}
+
+func (c *defaultCredential) ensureCredentialWatcher() error {
+	c.watcherAccess.Lock()
+	defer c.watcherAccess.Unlock()
+
+	if c.watcher != nil || c.credentialFilePath == "" {
+		return nil
+	}
+	if !c.watcherRetryAt.IsZero() && time.Now().Before(c.watcherRetryAt) {
+		return nil
+	}
+
+	watcher, err := fswatch.NewWatcher(fswatch.Options{
+		Path:   []string{c.credentialFilePath},
+		Logger: c.logger,
+		Callback: func(string) {
+			err := c.reloadCredentials(true)
+			if err != nil {
+				c.logger.Warn("reload credentials for ", c.tag, ": ", err)
+			}
+		},
+	})
+	if err != nil {
+		c.watcherRetryAt = time.Now().Add(credentialReloadRetryInterval)
+		return err
+	}
+
+	err = watcher.Start()
+	if err != nil {
+		c.watcherRetryAt = time.Now().Add(credentialReloadRetryInterval)
+		return err
+	}
+
+	c.watcher = watcher
+	c.watcherRetryAt = time.Time{}
+	return nil
+}
+
+func (c *defaultCredential) retryCredentialReloadIfNeeded() {
+	c.stateMutex.RLock()
+	unavailable := c.state.unavailable
+	lastAttempt := c.state.lastCredentialLoadAttempt
+	c.stateMutex.RUnlock()
+	if !unavailable {
+		return
+	}
+	if !lastAttempt.IsZero() && time.Since(lastAttempt) < credentialReloadRetryInterval {
+		return
+	}
+
+	err := c.ensureCredentialWatcher()
+	if err != nil {
+		c.logger.Debug("start credential watcher for ", c.tag, ": ", err)
+	}
+	_ = c.reloadCredentials(false)
+}
+
+func (c *defaultCredential) reloadCredentials(force bool) error {
+	c.reloadAccess.Lock()
+	defer c.reloadAccess.Unlock()
+
+	c.stateMutex.RLock()
+	unavailable := c.state.unavailable
+	lastAttempt := c.state.lastCredentialLoadAttempt
+	c.stateMutex.RUnlock()
+	if !force {
+		if !unavailable {
+			return nil
+		}
+		if !lastAttempt.IsZero() && time.Since(lastAttempt) < credentialReloadRetryInterval {
+			return c.unavailableError()
+		}
+	}
+
+	c.stateMutex.Lock()
+	c.state.lastCredentialLoadAttempt = time.Now()
+	c.stateMutex.Unlock()
+
+	credentials, err := platformReadCredentials(c.credentialPath)
+	if err != nil {
+		return c.markCredentialsUnavailable(E.Cause(err, "read credentials"))
+	}
+
+	c.accessMutex.Lock()
+	c.credentials = credentials
+	c.accessMutex.Unlock()
+
+	c.stateMutex.Lock()
+	c.state.unavailable = false
+	c.state.lastCredentialLoadError = ""
+	c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+
+	return nil
+}
+
+func (c *defaultCredential) markCredentialsUnavailable(err error) error {
+	c.accessMutex.Lock()
+	hadCredentials := c.credentials != nil
+	c.credentials = nil
+	c.accessMutex.Unlock()
+
+	c.stateMutex.Lock()
+	c.state.unavailable = true
+	c.state.lastCredentialLoadError = err.Error()
+	shouldInterrupt := c.checkTransitionLocked()
+	c.stateMutex.Unlock()
+
+	if shouldInterrupt && hadCredentials {
+		c.interruptConnections()
+	}
+
+	return err
+}

service/ocm/credential_other.go

@@ -13,6 +13,17 @@ func platformReadCredentials(customPath string) (*oauthCredentials, error) {
 	return readCredentialsFromFile(customPath)
 }
 
+func platformCanWriteCredentials(customPath string) error {
+	if customPath == "" {
+		var err error
+		customPath, err = getDefaultCredentialsPath()
+		if err != nil {
+			return err
+		}
+	}
+	return checkCredentialFileWritable(customPath)
+}
+
 func platformWriteCredentials(credentials *oauthCredentials, customPath string) error {
 	if customPath == "" {
 		var err error

service/ocm/reverse.go

@@ -0,0 +1,259 @@
+package ocm
+
+import (
+	"bufio"
+	"context"
+	stdTLS "crypto/tls"
+	"errors"
+	"io"
+	"math/rand/v2"
+	"net"
+	"net/http"
+	"strings"
+	"time"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+
+	"github.com/hashicorp/yamux"
+)
+
+func reverseYamuxConfig() *yamux.Config {
+	config := yamux.DefaultConfig()
+	config.KeepAliveInterval = 15 * time.Second
+	config.ConnectionWriteTimeout = 10 * time.Second
+	config.MaxStreamWindowSize = 512 * 1024
+	config.LogOutput = io.Discard
+	return config
+}
+
+type bufferedConn struct {
+	reader *bufio.Reader
+	net.Conn
+}
+
+func (c *bufferedConn) Read(p []byte) (int, error) {
+	return c.reader.Read(p)
+}
+
+type yamuxNetListener struct {
+	session *yamux.Session
+}
+
+func (l *yamuxNetListener) Accept() (net.Conn, error) {
+	return l.session.Accept()
+}
+
+func (l *yamuxNetListener) Close() error {
+	return l.session.Close()
+}
+
+func (l *yamuxNetListener) Addr() net.Addr {
+	return l.session.Addr()
+}
+
+func (s *Service) handleReverseConnect(ctx context.Context, w http.ResponseWriter, r *http.Request) {
+	if r.Header.Get("Upgrade") != "reverse-proxy" {
+		writeJSONError(w, r, http.StatusBadRequest, "invalid_request_error", "missing Upgrade header")
+		return
+	}
+
+	authHeader := r.Header.Get("Authorization")
+	if authHeader == "" {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "missing api key")
+		return
+	}
+	clientToken := strings.TrimPrefix(authHeader, "Bearer ")
+	if clientToken == authHeader {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key format")
+		return
+	}
+
+	receiverCredential := s.findReceiverCredential(clientToken)
+	if receiverCredential == nil {
+		s.logger.WarnContext(ctx, "reverse connect failed from ", r.RemoteAddr, ": no matching receiver credential")
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid reverse token")
+		return
+	}
+
+	hijacker, ok := w.(http.Hijacker)
+	if !ok {
+		s.logger.ErrorContext(ctx, "reverse connect: hijack not supported")
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "hijack not supported")
+		return
+	}
+
+	conn, bufferedReadWriter, err := hijacker.Hijack()
+	if err != nil {
+		s.logger.ErrorContext(ctx, "reverse connect: hijack: ", err)
+		return
+	}
+
+	response := "HTTP/1.1 101 Switching Protocols\r\nConnection: Upgrade\r\nUpgrade: reverse-proxy\r\n\r\n"
+	_, err = bufferedReadWriter.WriteString(response)
+	if err != nil {
+		conn.Close()
+		s.logger.ErrorContext(ctx, "reverse connect: write upgrade response: ", err)
+		return
+	}
+	err = bufferedReadWriter.Flush()
+	if err != nil {
+		conn.Close()
+		s.logger.ErrorContext(ctx, "reverse connect: flush upgrade response: ", err)
+		return
+	}
+
+	session, err := yamux.Client(conn, reverseYamuxConfig())
+	if err != nil {
+		conn.Close()
+		s.logger.ErrorContext(ctx, "reverse connect: create yamux client for ", receiverCredential.tagName(), ": ", err)
+		return
+	}
+
+	if !receiverCredential.setReverseSession(session) {
+		session.Close()
+		return
+	}
+	s.logger.InfoContext(ctx, "reverse connection established for ", receiverCredential.tagName(), " from ", r.RemoteAddr)
+
+	go func() {
+		<-session.CloseChan()
+		receiverCredential.clearReverseSession(session)
+		s.logger.WarnContext(ctx, "reverse connection lost for ", receiverCredential.tagName())
+	}()
+}
+
+func (s *Service) findReceiverCredential(token string) *externalCredential {
+	for _, cred := range s.allCredentials {
+		extCred, ok := cred.(*externalCredential)
+		if !ok {
+			continue
+		}
+		if extCred.baseURL == reverseProxyBaseURL && extCred.token == token {
+			return extCred
+		}
+	}
+	return nil
+}
+
+func (c *externalCredential) connectorLoop() {
+	var consecutiveFailures int
+	ctx := c.getReverseContext()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+
+		sessionLifetime, err := c.connectorConnect(ctx)
+		if ctx.Err() != nil {
+			return
+		}
+		if sessionLifetime >= connectorBackoffResetThreshold {
+			consecutiveFailures = 0
+		}
+		consecutiveFailures++
+		backoff := connectorBackoff(consecutiveFailures)
+		c.logger.Warn("reverse connection for ", c.tag, " lost: ", err, ", reconnecting in ", backoff)
+		select {
+		case <-time.After(backoff):
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+const connectorBackoffResetThreshold = time.Minute
+
+func connectorBackoff(failures int) time.Duration {
+	if failures > 5 {
+		failures = 5
+	}
+	base := time.Second * time.Duration(1<<failures)
+	if base > 30*time.Second {
+		base = 30 * time.Second
+	}
+	jitter := time.Duration(rand.Int64N(int64(base) / 2))
+	return base + jitter
+}
+
+func (c *externalCredential) connectorConnect(ctx context.Context) (time.Duration, error) {
+	if c.reverseService == nil {
+		return 0, E.New("reverse service not initialized")
+	}
+	destination := c.connectorResolveDestination()
+	conn, err := c.connectorDialer.DialContext(ctx, "tcp", destination)
+	if err != nil {
+		return 0, E.Cause(err, "dial")
+	}
+
+	if c.connectorTLS != nil {
+		tlsConn := stdTLS.Client(conn, c.connectorTLS.Clone())
+		err = tlsConn.HandshakeContext(ctx)
+		if err != nil {
+			conn.Close()
+			return 0, E.Cause(err, "tls handshake")
+		}
+		conn = tlsConn
+	}
+
+	upgradeRequest := "GET " + c.connectorRequestPath + " HTTP/1.1\r\n" +
+		"Host: " + c.connectorURL.Host + "\r\n" +
+		"Connection: Upgrade\r\n" +
+		"Upgrade: reverse-proxy\r\n" +
+		"Authorization: Bearer " + c.token + "\r\n" +
+		"\r\n"
+	_, err = io.WriteString(conn, upgradeRequest)
+	if err != nil {
+		conn.Close()
+		return 0, E.Cause(err, "write upgrade request")
+	}
+
+	reader := bufio.NewReader(conn)
+	statusLine, err := reader.ReadString('\n')
+	if err != nil {
+		conn.Close()
+		return 0, E.Cause(err, "read upgrade response")
+	}
+	if !strings.HasPrefix(statusLine, "HTTP/1.1 101") {
+		conn.Close()
+		return 0, E.New("unexpected upgrade response: ", strings.TrimSpace(statusLine))
+	}
+	for {
+		line, readErr := reader.ReadString('\n')
+		if readErr != nil {
+			conn.Close()
+			return 0, E.Cause(readErr, "read upgrade headers")
+		}
+		if strings.TrimSpace(line) == "" {
+			break
+		}
+	}
+
+	session, err := yamux.Server(&bufferedConn{reader: reader, Conn: conn}, reverseYamuxConfig())
+	if err != nil {
+		conn.Close()
+		return 0, E.Cause(err, "create yamux server")
+	}
+	defer session.Close()
+
+	c.logger.Info("reverse connection established for ", c.tag)
+
+	serveStart := time.Now()
+	httpServer := &http.Server{
+		Handler:     c.reverseService,
+		ReadTimeout: 0,
+		IdleTimeout: 120 * time.Second,
+	}
+	err = httpServer.Serve(&yamuxNetListener{session: session})
+	sessionLifetime := time.Since(serveStart)
+	if err != nil && !errors.Is(err, http.ErrServerClosed) && ctx.Err() == nil {
+		return sessionLifetime, E.Cause(err, "serve")
+	}
+	return sessionLifetime, E.New("connection closed")
+}
+
+func (c *externalCredential) connectorResolveDestination() M.Socksaddr {
+	return c.connectorDestination
+}

service/ocm/service.go

@@ -3,12 +3,10 @@ package ocm
 import (
 	"bytes"
 	"context"
-	stdTLS "crypto/tls"
 	"encoding/json"
 	"errors"
 	"io"
 	"mime"
-	"net"
 	"net/http"
 	"strconv"
 	"strings"
@@ -17,7 +15,6 @@ import (
 
 	"github.com/sagernet/sing-box/adapter"
 	boxService "github.com/sagernet/sing-box/adapter/service"
-	"github.com/sagernet/sing-box/common/dialer"
 	"github.com/sagernet/sing-box/common/listener"
 	"github.com/sagernet/sing-box/common/tls"
 	C "github.com/sagernet/sing-box/constant"
@@ -26,15 +23,14 @@ import (
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/buf"
 	E "github.com/sagernet/sing/common/exceptions"
-	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
-	"github.com/sagernet/sing/common/ntp"
 	aTLS "github.com/sagernet/sing/common/tls"
 
 	"github.com/go-chi/chi/v5"
 	"github.com/openai/openai-go/v3"
 	"github.com/openai/openai-go/v3/responses"
 	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/h2c"
 )
 
 func RegisterService(registry *boxService.Registry) {
@@ -52,17 +48,85 @@ type errorDetails struct {
 }
 
 func writeJSONError(w http.ResponseWriter, r *http.Request, statusCode int, errorType string, message string) {
+	writeJSONErrorWithCode(w, r, statusCode, errorType, "", message)
+}
+
+func writeJSONErrorWithCode(w http.ResponseWriter, r *http.Request, statusCode int, errorType string, errorCode string, message string) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(statusCode)
 
 	json.NewEncoder(w).Encode(errorResponse{
 		Error: errorDetails{
 			Type:    errorType,
+			Code:    errorCode,
 			Message: message,
 		},
 	})
 }
 
+func writePlainTextError(w http.ResponseWriter, statusCode int, message string) {
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.WriteHeader(statusCode)
+	_, _ = io.WriteString(w, message)
+}
+
+const (
+	retryableUsageMessage = "current credential reached its usage limit; retry the request to use another credential"
+	retryableUsageCode    = "credential_usage_exhausted"
+)
+
+func hasAlternativeCredential(provider credentialProvider, currentCredential credential, filter func(credential) bool) bool {
+	if provider == nil || currentCredential == nil {
+		return false
+	}
+	for _, cred := range provider.allCredentials() {
+		if cred == currentCredential {
+			continue
+		}
+		if filter != nil && !filter(cred) {
+			continue
+		}
+		if cred.isUsable() {
+			return true
+		}
+	}
+	return false
+}
+
+func unavailableCredentialMessage(provider credentialProvider, fallback string) string {
+	if provider == nil {
+		return fallback
+	}
+	message := allRateLimitedError(provider.allCredentials()).Error()
+	if message == "all credentials unavailable" && fallback != "" {
+		return fallback
+	}
+	return message
+}
+
+func writeRetryableUsageError(w http.ResponseWriter, r *http.Request) {
+	writeJSONErrorWithCode(w, r, http.StatusServiceUnavailable, "server_error", retryableUsageCode, retryableUsageMessage)
+}
+
+func writeNonRetryableCredentialError(w http.ResponseWriter, message string) {
+	writePlainTextError(w, http.StatusBadRequest, message)
+}
+
+func writeCredentialUnavailableError(
+	w http.ResponseWriter,
+	r *http.Request,
+	provider credentialProvider,
+	currentCredential credential,
+	filter func(credential) bool,
+	fallback string,
+) {
+	if hasAlternativeCredential(provider, currentCredential, filter) {
+		writeRetryableUsageError(w, r)
+		return
+	}
+	writeNonRetryableCredentialError(w, unavailableCredentialMessage(provider, fallback))
+}
+
 func isHopByHopHeader(header string) bool {
 	switch strings.ToLower(header) {
 	case "connection", "keep-alive", "proxy-authenticate", "proxy-authorization", "te", "trailers", "transfer-encoding", "upgrade", "host":
@@ -72,6 +136,19 @@ func isHopByHopHeader(header string) bool {
 	}
 }
 
+func isReverseProxyHeader(header string) bool {
+	lowerHeader := strings.ToLower(header)
+	if strings.HasPrefix(lowerHeader, "cf-") {
+		return true
+	}
+	switch lowerHeader {
+	case "cdn-loop", "true-client-ip", "x-forwarded-for", "x-forwarded-proto", "x-real-ip":
+		return true
+	default:
+		return false
+	}
+}
+
 func normalizeRateLimitIdentifier(limitIdentifier string) string {
 	trimmedIdentifier := strings.TrimSpace(strings.ToLower(limitIdentifier))
 	if trimmedIdentifier == "" {
@@ -127,72 +204,43 @@ type Service struct {
 	boxService.Adapter
 	ctx            context.Context
 	logger         log.ContextLogger
-	credentialPath string
-	credentials    *oauthCredentials
-	users          []option.OCMUser
-	dialer         N.Dialer
-	httpClient     *http.Client
+	options        option.OCMServiceOptions
 	httpHeaders    http.Header
 	listener       *listener.Listener
 	tlsConfig      tls.ServerConfig
 	httpServer     *http.Server
 	userManager    *UserManager
-	accessMutex    sync.RWMutex
-	usageTracker   *AggregatedUsage
 	webSocketMutex sync.Mutex
 	webSocketGroup sync.WaitGroup
 	webSocketConns map[*webSocketSession]struct{}
 	shuttingDown   bool
+
+	// Legacy mode
+	legacyCredential *defaultCredential
+	legacyProvider   credentialProvider
+
+	// Multi-credential mode
+	providers      map[string]credentialProvider
+	allCredentials []credential
+	userConfigMap  map[string]*option.OCMUser
 }
 
 func NewService(ctx context.Context, logger log.ContextLogger, tag string, options option.OCMServiceOptions) (adapter.Service, error) {
-	serviceDialer, err := dialer.NewWithOptions(dialer.Options{
-		Context: ctx,
-		Options: option.DialerOptions{
-			Detour: options.Detour,
-		},
-		RemoteIsDomain: true,
-	})
+	err := validateOCMOptions(options)
 	if err != nil {
-		return nil, E.Cause(err, "create dialer")
-	}
-
-	httpClient := &http.Client{
-		Transport: &http.Transport{
-			ForceAttemptHTTP2: true,
-			TLSClientConfig: &stdTLS.Config{
-				RootCAs: adapter.RootPoolFromContext(ctx),
-				Time:    ntp.TimeFuncFromContext(ctx),
-			},
-			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
-				return serviceDialer.DialContext(ctx, network, M.ParseSocksaddr(addr))
-			},
-		},
+		return nil, E.Cause(err, "validate options")
 	}
 
 	userManager := &UserManager{
 		tokenMap: make(map[string]string),
 	}
 
-	var usageTracker *AggregatedUsage
-	if options.UsagesPath != "" {
-		usageTracker = &AggregatedUsage{
-			LastUpdated:  time.Now(),
-			Combinations: make([]CostCombination, 0),
-			filePath:     options.UsagesPath,
-			logger:       logger,
-		}
-	}
-
 	service := &Service{
-		Adapter:        boxService.NewAdapter(C.TypeOCM, tag),
-		ctx:            ctx,
-		logger:         logger,
-		credentialPath: options.CredentialPath,
-		users:          options.Users,
-		dialer:         serviceDialer,
-		httpClient:     httpClient,
-		httpHeaders:    options.Headers.Build(),
+		Adapter:     boxService.NewAdapter(C.TypeOCM, tag),
+		ctx:         ctx,
+		logger:      logger,
+		options:     options,
+		httpHeaders: options.Headers.Build(),
 		listener: listener.New(listener.Options{
 			Context: ctx,
 			Logger:  logger,
@@ -200,10 +248,36 @@ func NewService(ctx context.Context, logger log.ContextLogger, tag string, optio
 			Listen:  options.ListenOptions,
 		}),
 		userManager:    userManager,
-		usageTracker:   usageTracker,
 		webSocketConns: make(map[*webSocketSession]struct{}),
 	}
 
+	if len(options.Credentials) > 0 {
+		providers, allCredentials, err := buildOCMCredentialProviders(ctx, options, logger)
+		if err != nil {
+			return nil, E.Cause(err, "build credential providers")
+		}
+		service.providers = providers
+		service.allCredentials = allCredentials
+
+		userConfigMap := make(map[string]*option.OCMUser)
+		for i := range options.Users {
+			userConfigMap[options.Users[i].Name] = &options.Users[i]
+		}
+		service.userConfigMap = userConfigMap
+	} else {
+		cred, err := newDefaultCredential(ctx, "default", option.OCMDefaultCredentialOptions{
+			CredentialPath: options.CredentialPath,
+			UsagesPath:     options.UsagesPath,
+			Detour:         options.Detour,
+		}, logger)
+		if err != nil {
+			return nil, err
+		}
+		service.legacyCredential = cred
+		service.legacyProvider = &singleCredentialProvider{cred: cred}
+		service.allCredentials = []credential{cred}
+	}
+
 	if options.TLS != nil {
 		tlsConfig, err := tls.NewServer(ctx, logger, common.PtrValueOrDefault(options.TLS))
 		if err != nil {
@@ -220,28 +294,35 @@ func (s *Service) Start(stage adapter.StartStage) error {
 		return nil
 	}
 
-	s.userManager.UpdateUsers(s.users)
+	s.userManager.UpdateUsers(s.options.Users)
 
-	credentials, err := platformReadCredentials(s.credentialPath)
-	if err != nil {
-		return E.Cause(err, "read credentials")
-	}
-	s.credentials = credentials
-
-	if s.usageTracker != nil {
-		err = s.usageTracker.Load()
+	for _, cred := range s.allCredentials {
+		if extCred, ok := cred.(*externalCredential); ok && extCred.reverse && extCred.connectorURL != nil {
+			extCred.reverseService = s
+		}
+		err := cred.start()
 		if err != nil {
-			s.logger.Warn("load usage statistics: ", err)
+			return err
+		}
+		tag := cred.tagName()
+		cred.setOnBecameUnusable(func() {
+			s.interruptWebSocketSessionsForCredential(tag)
+		})
+	}
+	if len(s.options.Credentials) > 0 {
+		err := validateOCMCompositeCredentialModes(s.options, s.providers)
+		if err != nil {
+			return E.Cause(err, "validate loaded credentials")
 		}
 	}
 
 	router := chi.NewRouter()
 	router.Mount("/", s)
 
-	s.httpServer = &http.Server{Handler: router}
+	s.httpServer = &http.Server{Handler: h2c.NewHandler(router, &http2.Server{})}
 
 	if s.tlsConfig != nil {
-		err = s.tlsConfig.Start()
+		err := s.tlsConfig.Start()
 		if err != nil {
 			return E.Cause(err, "create TLS config")
 		}
@@ -269,172 +350,247 @@ func (s *Service) Start(stage adapter.StartStage) error {
 	return nil
 }
 
-func (s *Service) getAccessToken() (string, error) {
-	s.accessMutex.RLock()
-	if !s.credentials.needsRefresh() {
-		token := s.credentials.getAccessToken()
-		s.accessMutex.RUnlock()
-		return token, nil
+func (s *Service) resolveCredentialProvider(username string) (credentialProvider, error) {
+	if len(s.options.Users) > 0 {
+		return credentialForUser(s.userConfigMap, s.providers, s.legacyProvider, username)
 	}
-	s.accessMutex.RUnlock()
-
-	s.accessMutex.Lock()
-	defer s.accessMutex.Unlock()
-
-	if !s.credentials.needsRefresh() {
-		return s.credentials.getAccessToken(), nil
+	provider := noUserCredentialProvider(s.providers, s.legacyProvider, s.options)
+	if provider == nil {
+		return nil, E.New("no credential available")
 	}
-
-	newCredentials, err := refreshToken(s.httpClient, s.credentials)
-	if err != nil {
-		return "", err
-	}
-
-	s.credentials = newCredentials
-
-	err = platformWriteCredentials(newCredentials, s.credentialPath)
-	if err != nil {
-		s.logger.Warn("persist refreshed token: ", err)
-	}
-
-	return newCredentials.getAccessToken(), nil
-}
-
-func (s *Service) getAccountID() string {
-	s.accessMutex.RLock()
-	defer s.accessMutex.RUnlock()
-	return s.credentials.getAccountID()
-}
-
-func (s *Service) isAPIKeyMode() bool {
-	s.accessMutex.RLock()
-	defer s.accessMutex.RUnlock()
-	return s.credentials.isAPIKeyMode()
-}
-
-func (s *Service) getBaseURL() string {
-	if s.isAPIKeyMode() {
-		return openaiAPIBaseURL
-	}
-	return chatGPTBackendURL
+	return provider, nil
 }
 
 func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	ctx := log.ContextWithNewID(r.Context())
+	if r.URL.Path == "/ocm/v1/status" {
+		s.handleStatusEndpoint(w, r)
+		return
+	}
+
+	if r.URL.Path == "/ocm/v1/reverse" {
+		s.handleReverseConnect(ctx, w, r)
+		return
+	}
+
 	path := r.URL.Path
 	if !strings.HasPrefix(path, "/v1/") {
 		writeJSONError(w, r, http.StatusNotFound, "invalid_request_error", "path must start with /v1/")
 		return
 	}
 
-	var proxyPath string
-	if s.isAPIKeyMode() {
-		proxyPath = path
-	} else {
-		if path == "/v1/chat/completions" {
-			writeJSONError(w, r, http.StatusBadRequest, "invalid_request_error",
-				"chat completions endpoint is only available in API key mode")
-			return
-		}
-		proxyPath = strings.TrimPrefix(path, "/v1")
-	}
-
 	var username string
-	if len(s.users) > 0 {
+	if len(s.options.Users) > 0 {
 		authHeader := r.Header.Get("Authorization")
 		if authHeader == "" {
-			s.logger.Warn("authentication failed for request from ", r.RemoteAddr, ": missing Authorization header")
+			s.logger.WarnContext(ctx, "authentication failed for request from ", r.RemoteAddr, ": missing Authorization header")
 			writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "missing api key")
 			return
 		}
 		clientToken := strings.TrimPrefix(authHeader, "Bearer ")
 		if clientToken == authHeader {
-			s.logger.Warn("authentication failed for request from ", r.RemoteAddr, ": invalid Authorization format")
+			s.logger.WarnContext(ctx, "authentication failed for request from ", r.RemoteAddr, ": invalid Authorization format")
 			writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key format")
 			return
 		}
 		var ok bool
 		username, ok = s.userManager.Authenticate(clientToken)
 		if !ok {
-			s.logger.Warn("authentication failed for request from ", r.RemoteAddr, ": unknown key: ", clientToken)
+			s.logger.WarnContext(ctx, "authentication failed for request from ", r.RemoteAddr, ": unknown key: ", clientToken)
 			writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key")
 			return
 		}
 	}
 
-	if strings.EqualFold(r.Header.Get("Upgrade"), "websocket") && strings.HasPrefix(path, "/v1/responses") {
-		s.handleWebSocket(w, r, proxyPath, username)
+	sessionID := r.Header.Get("session_id")
+
+	// Resolve credential provider and user config
+	var provider credentialProvider
+	var userConfig *option.OCMUser
+	if len(s.options.Users) > 0 {
+		userConfig = s.userConfigMap[username]
+		var err error
+		provider, err = credentialForUser(s.userConfigMap, s.providers, s.legacyProvider, username)
+		if err != nil {
+			s.logger.ErrorContext(ctx, "resolve credential: ", err)
+			writeJSONError(w, r, http.StatusInternalServerError, "api_error", err.Error())
+			return
+		}
+	} else {
+		provider = noUserCredentialProvider(s.providers, s.legacyProvider, s.options)
+	}
+	if provider == nil {
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "no credential available")
 		return
 	}
 
-	var requestModel string
+	provider.pollIfStale(s.ctx)
 
-	if s.usageTracker != nil && r.Body != nil {
-		bodyBytes, err := io.ReadAll(r.Body)
-		if err == nil {
-			var request struct {
-				Model string `json:"model"`
-			}
-			err := json.Unmarshal(bodyBytes, &request)
-			if err == nil {
-				requestModel = request.Model
-			}
-			r.Body = io.NopCloser(bytes.NewBuffer(bodyBytes))
+	var credentialFilter func(credential) bool
+	if userConfig != nil && !userConfig.AllowExternalUsage {
+		credentialFilter = func(c credential) bool { return !c.isExternal() }
+	}
+
+	selectedCredential, isNew, err := provider.selectCredential(sessionID, credentialFilter)
+	if err != nil {
+		writeNonRetryableCredentialError(w, unavailableCredentialMessage(provider, err.Error()))
+		return
+	}
+
+	if strings.EqualFold(r.Header.Get("Upgrade"), "websocket") && strings.HasPrefix(path, "/v1/responses") {
+		s.handleWebSocket(ctx, w, r, path, username, sessionID, userConfig, provider, selectedCredential, credentialFilter, isNew)
+		return
+	}
+
+	if !selectedCredential.isExternal() && selectedCredential.ocmIsAPIKeyMode() {
+		// API key mode path handling
+	} else if !selectedCredential.isExternal() {
+		if path == "/v1/chat/completions" {
+			writeJSONError(w, r, http.StatusBadRequest, "invalid_request_error",
+				"chat completions endpoint is only available in API key mode")
+			return
 		}
 	}
 
-	accessToken, err := s.getAccessToken()
-	if err != nil {
-		s.logger.Error("get access token: ", err)
-		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "Authentication failed")
-		return
+	shouldTrackUsage := selectedCredential.usageTrackerOrNil() != nil &&
+		(path == "/v1/chat/completions" || strings.HasPrefix(path, "/v1/responses"))
+	canRetryRequest := len(provider.allCredentials()) > 1
+
+	// Read body for model extraction and retry buffer when JSON replay is useful.
+	var bodyBytes []byte
+	var requestModel string
+	var requestServiceTier string
+	if r.Body != nil && (shouldTrackUsage || canRetryRequest) {
+		mediaType, _, parseErr := mime.ParseMediaType(r.Header.Get("Content-Type"))
+		isJSONRequest := parseErr == nil && (mediaType == "application/json" || strings.HasSuffix(mediaType, "+json"))
+		if isJSONRequest {
+			bodyBytes, err = io.ReadAll(r.Body)
+			if err != nil {
+				s.logger.ErrorContext(ctx, "read request body: ", err)
+				writeJSONError(w, r, http.StatusInternalServerError, "api_error", "failed to read request body")
+				return
+			}
+			var request struct {
+				Model       string `json:"model"`
+				ServiceTier string `json:"service_tier"`
+			}
+			if json.Unmarshal(bodyBytes, &request) == nil {
+				requestModel = request.Model
+				requestServiceTier = request.ServiceTier
+			}
+			r.Body = io.NopCloser(bytes.NewReader(bodyBytes))
+		}
 	}
 
-	proxyURL := s.getBaseURL() + proxyPath
-	if r.URL.RawQuery != "" {
-		proxyURL += "?" + r.URL.RawQuery
+	if isNew {
+		logParts := []any{"assigned credential ", selectedCredential.tagName()}
+		if sessionID != "" {
+			logParts = append(logParts, " for session ", sessionID)
+		}
+		if username != "" {
+			logParts = append(logParts, " by user ", username)
+		}
+		if requestModel != "" {
+			logParts = append(logParts, ", model=", requestModel)
+		}
+		if requestServiceTier == "priority" {
+			logParts = append(logParts, ", fast")
+		}
+		s.logger.DebugContext(ctx, logParts...)
 	}
-	proxyRequest, err := http.NewRequestWithContext(r.Context(), r.Method, proxyURL, r.Body)
+
+	requestContext := selectedCredential.wrapRequestContext(r.Context())
+	defer func() {
+		requestContext.cancelRequest()
+	}()
+	proxyRequest, err := selectedCredential.buildProxyRequest(requestContext, r, bodyBytes, s.httpHeaders)
 	if err != nil {
-		s.logger.Error("create proxy request: ", err)
+		s.logger.ErrorContext(ctx, "create proxy request: ", err)
 		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "Internal server error")
 		return
 	}
 
-	for key, values := range r.Header {
-		if !isHopByHopHeader(key) && key != "Authorization" {
-			proxyRequest.Header[key] = values
-		}
-	}
-
-	for key, values := range s.httpHeaders {
-		proxyRequest.Header.Del(key)
-		proxyRequest.Header[key] = values
-	}
-
-	proxyRequest.Header.Set("Authorization", "Bearer "+accessToken)
-
-	if accountID := s.getAccountID(); accountID != "" {
-		proxyRequest.Header.Set("ChatGPT-Account-Id", accountID)
-	}
-
-	response, err := s.httpClient.Do(proxyRequest)
+	response, err := selectedCredential.httpTransport().Do(proxyRequest)
 	if err != nil {
+		if r.Context().Err() != nil {
+			return
+		}
+		if requestContext.Err() != nil {
+			writeCredentialUnavailableError(w, r, provider, selectedCredential, credentialFilter, "credential became unavailable while processing the request")
+			return
+		}
 		writeJSONError(w, r, http.StatusBadGateway, "api_error", err.Error())
 		return
 	}
+	requestContext.releaseCredentialInterrupt()
+
+	// Transparent 429 retry
+	for response.StatusCode == http.StatusTooManyRequests {
+		resetAt := parseOCMRateLimitResetFromHeaders(response.Header)
+		nextCredential := provider.onRateLimited(sessionID, selectedCredential, resetAt, credentialFilter)
+		needsBodyReplay := r.Method != http.MethodGet && r.Method != http.MethodHead && r.Method != http.MethodDelete
+		selectedCredential.updateStateFromHeaders(response.Header)
+		if (needsBodyReplay && bodyBytes == nil) || nextCredential == nil {
+			response.Body.Close()
+			writeCredentialUnavailableError(w, r, provider, selectedCredential, credentialFilter, "all credentials rate-limited")
+			return
+		}
+		response.Body.Close()
+		s.logger.InfoContext(ctx, "retrying with credential ", nextCredential.tagName(), " after 429 from ", selectedCredential.tagName())
+		requestContext.cancelRequest()
+		requestContext = nextCredential.wrapRequestContext(r.Context())
+		retryRequest, buildErr := nextCredential.buildProxyRequest(requestContext, r, bodyBytes, s.httpHeaders)
+		if buildErr != nil {
+			s.logger.ErrorContext(ctx, "retry request: ", buildErr)
+			writeJSONError(w, r, http.StatusBadGateway, "api_error", buildErr.Error())
+			return
+		}
+		retryResponse, retryErr := nextCredential.httpTransport().Do(retryRequest)
+		if retryErr != nil {
+			if r.Context().Err() != nil {
+				return
+			}
+			if requestContext.Err() != nil {
+				writeCredentialUnavailableError(w, r, provider, nextCredential, credentialFilter, "credential became unavailable while retrying the request")
+				return
+			}
+			s.logger.ErrorContext(ctx, "retry request: ", retryErr)
+			writeJSONError(w, r, http.StatusBadGateway, "api_error", retryErr.Error())
+			return
+		}
+		requestContext.releaseCredentialInterrupt()
+		response = retryResponse
+		selectedCredential = nextCredential
+	}
 	defer response.Body.Close()
 
+	selectedCredential.updateStateFromHeaders(response.Header)
+
+	if response.StatusCode != http.StatusOK && response.StatusCode != http.StatusTooManyRequests {
+		body, _ := io.ReadAll(response.Body)
+		s.logger.ErrorContext(ctx, "upstream error from ", selectedCredential.tagName(), ": status ", response.StatusCode, " ", string(body))
+		go selectedCredential.pollUsage(s.ctx)
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error",
+			"proxy request (status "+strconv.Itoa(response.StatusCode)+"): "+string(body))
+		return
+	}
+
+	// Rewrite response headers for external users
+	if userConfig != nil && userConfig.ExternalCredential != "" {
+		s.rewriteResponseHeadersForExternalUser(response.Header, userConfig)
+	}
+
 	for key, values := range response.Header {
-		if !isHopByHopHeader(key) {
+		if !isHopByHopHeader(key) && !isReverseProxyHeader(key) {
 			w.Header()[key] = values
 		}
 	}
 	w.WriteHeader(response.StatusCode)
 
-	trackUsage := s.usageTracker != nil && response.StatusCode == http.StatusOK &&
-		(path == "/v1/chat/completions" || strings.HasPrefix(path, "/v1/responses"))
-	if trackUsage {
-		s.handleResponseWithTracking(w, response, path, requestModel, username)
+	usageTracker := selectedCredential.usageTrackerOrNil()
+	if usageTracker != nil && response.StatusCode == http.StatusOK &&
+		(path == "/v1/chat/completions" || strings.HasPrefix(path, "/v1/responses")) {
+		s.handleResponseWithTracking(ctx, w, response, usageTracker, path, requestModel, username)
 	} else {
 		mediaType, _, err := mime.ParseMediaType(response.Header.Get("Content-Type"))
 		if err == nil && mediaType != "text/event-stream" {
@@ -443,7 +599,7 @@ func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 		flusher, ok := w.(http.Flusher)
 		if !ok {
-			s.logger.Error("streaming not supported")
+			s.logger.ErrorContext(ctx, "streaming not supported")
 			return
 		}
 		buffer := make([]byte, buf.BufferSize)
@@ -452,7 +608,7 @@ func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			if n > 0 {
 				_, writeError := w.Write(buffer[:n])
 				if writeError != nil {
-					s.logger.Error("write streaming response: ", writeError)
+					s.logger.ErrorContext(ctx, "write streaming response: ", writeError)
 					return
 				}
 				flusher.Flush()
@@ -464,7 +620,7 @@ func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, response *http.Response, path string, requestModel string, username string) {
+func (s *Service) handleResponseWithTracking(ctx context.Context, writer http.ResponseWriter, response *http.Response, usageTracker *AggregatedUsage, path string, requestModel string, username string) {
 	isChatCompletions := path == "/v1/chat/completions"
 	weeklyCycleHint := extractWeeklyCycleHint(response.Header)
 	mediaType, _, err := mime.ParseMediaType(response.Header.Get("Content-Type"))
@@ -475,7 +631,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 	if !isStreaming {
 		bodyBytes, err := io.ReadAll(response.Body)
 		if err != nil {
-			s.logger.Error("read response body: ", err)
+			s.logger.ErrorContext(ctx, "read response body: ", err)
 			return
 		}
 
@@ -508,7 +664,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 			}
 			if responseModel != "" {
 				contextWindow := detectContextWindow(responseModel, serviceTier, inputTokens)
-				s.usageTracker.AddUsageWithCycleHint(
+				usageTracker.AddUsageWithCycleHint(
 					responseModel,
 					contextWindow,
 					inputTokens,
@@ -528,7 +684,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 
 	flusher, ok := writer.(http.Flusher)
 	if !ok {
-		s.logger.Error("streaming not supported")
+		s.logger.ErrorContext(ctx, "streaming not supported")
 		return
 	}
 
@@ -605,7 +761,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 
 			_, writeError := writer.Write(buffer[:n])
 			if writeError != nil {
-				s.logger.Error("write streaming response: ", writeError)
+				s.logger.ErrorContext(ctx, "write streaming response: ", writeError)
 				return
 			}
 			flusher.Flush()
@@ -619,7 +775,7 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 			if inputTokens > 0 || outputTokens > 0 {
 				if responseModel != "" {
 					contextWindow := detectContextWindow(responseModel, serviceTier, inputTokens)
-					s.usageTracker.AddUsageWithCycleHint(
+					usageTracker.AddUsageWithCycleHint(
 						responseModel,
 						contextWindow,
 						inputTokens,
@@ -637,6 +793,124 @@ func (s *Service) handleResponseWithTracking(writer http.ResponseWriter, respons
 	}
 }
 
+func (s *Service) handleStatusEndpoint(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		writeJSONError(w, r, http.StatusMethodNotAllowed, "invalid_request_error", "method not allowed")
+		return
+	}
+
+	if len(s.options.Users) == 0 {
+		writeJSONError(w, r, http.StatusForbidden, "authentication_error", "status endpoint requires user authentication")
+		return
+	}
+
+	authHeader := r.Header.Get("Authorization")
+	if authHeader == "" {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "missing api key")
+		return
+	}
+	clientToken := strings.TrimPrefix(authHeader, "Bearer ")
+	if clientToken == authHeader {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key format")
+		return
+	}
+	username, ok := s.userManager.Authenticate(clientToken)
+	if !ok {
+		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "invalid api key")
+		return
+	}
+
+	userConfig := s.userConfigMap[username]
+	if userConfig == nil {
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", "user config not found")
+		return
+	}
+
+	provider, err := credentialForUser(s.userConfigMap, s.providers, s.legacyProvider, username)
+	if err != nil {
+		writeJSONError(w, r, http.StatusInternalServerError, "api_error", err.Error())
+		return
+	}
+
+	provider.pollIfStale(r.Context())
+	avgFiveHour, avgWeekly, totalWeight := s.computeAggregatedUtilization(provider, userConfig)
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(map[string]float64{
+		"five_hour_utilization": avgFiveHour,
+		"weekly_utilization":    avgWeekly,
+		"plan_weight":           totalWeight,
+	})
+}
+
+func (s *Service) computeAggregatedUtilization(provider credentialProvider, userConfig *option.OCMUser) (float64, float64, float64) {
+	var totalWeightedRemaining5h, totalWeightedRemainingWeekly, totalWeight float64
+	for _, cred := range provider.allCredentials() {
+		if !cred.isAvailable() {
+			continue
+		}
+		if userConfig.ExternalCredential != "" && cred.tagName() == userConfig.ExternalCredential {
+			continue
+		}
+		if !userConfig.AllowExternalUsage && cred.isExternal() {
+			continue
+		}
+		weight := cred.planWeight()
+		remaining5h := cred.fiveHourCap() - cred.fiveHourUtilization()
+		if remaining5h < 0 {
+			remaining5h = 0
+		}
+		remainingWeekly := cred.weeklyCap() - cred.weeklyUtilization()
+		if remainingWeekly < 0 {
+			remainingWeekly = 0
+		}
+		totalWeightedRemaining5h += remaining5h * weight
+		totalWeightedRemainingWeekly += remainingWeekly * weight
+		totalWeight += weight
+	}
+	if totalWeight == 0 {
+		return 100, 100, 0
+	}
+	return 100 - totalWeightedRemaining5h/totalWeight,
+		100 - totalWeightedRemainingWeekly/totalWeight,
+		totalWeight
+}
+
+func (s *Service) rewriteResponseHeadersForExternalUser(headers http.Header, userConfig *option.OCMUser) {
+	provider, err := credentialForUser(s.userConfigMap, s.providers, s.legacyProvider, userConfig.Name)
+	if err != nil {
+		return
+	}
+
+	avgFiveHour, avgWeekly, totalWeight := s.computeAggregatedUtilization(provider, userConfig)
+
+	activeLimitIdentifier := normalizeRateLimitIdentifier(headers.Get("x-codex-active-limit"))
+	if activeLimitIdentifier == "" {
+		activeLimitIdentifier = "codex"
+	}
+
+	headers.Set("x-"+activeLimitIdentifier+"-primary-used-percent", strconv.FormatFloat(avgFiveHour, 'f', 2, 64))
+	headers.Set("x-"+activeLimitIdentifier+"-secondary-used-percent", strconv.FormatFloat(avgWeekly, 'f', 2, 64))
+	if totalWeight > 0 {
+		headers.Set("X-OCM-Plan-Weight", strconv.FormatFloat(totalWeight, 'f', -1, 64))
+	}
+}
+
+func (s *Service) InterfaceUpdated() {
+	for _, cred := range s.allCredentials {
+		extCred, ok := cred.(*externalCredential)
+		if !ok {
+			continue
+		}
+		if extCred.reverse && extCred.connectorURL != nil {
+			extCred.reverseService = s
+			extCred.resetReverseContext()
+			go extCred.connectorLoop()
+		}
+	}
+}
+
 func (s *Service) Close() error {
 	webSocketSessions := s.startWebSocketShutdown()
 
@@ -650,12 +924,8 @@ func (s *Service) Close() error {
 	}
 	s.webSocketGroup.Wait()
 
-	if s.usageTracker != nil {
-		s.usageTracker.cancelPendingSave()
-		saveErr := s.usageTracker.Save()
-		if saveErr != nil {
-			s.logger.Error("save usage statistics: ", saveErr)
-		}
+	for _, cred := range s.allCredentials {
+		cred.close()
 	}
 
 	return err
@@ -693,6 +963,20 @@ func (s *Service) isShuttingDown() bool {
 	return s.shuttingDown
 }
 
+func (s *Service) interruptWebSocketSessionsForCredential(tag string) {
+	s.webSocketMutex.Lock()
+	var toClose []*webSocketSession
+	for session := range s.webSocketConns {
+		if session.credentialTag == tag {
+			toClose = append(toClose, session)
+		}
+	}
+	s.webSocketMutex.Unlock()
+	for _, session := range toClose {
+		session.Close()
+	}
+}
+
 func (s *Service) startWebSocketShutdown() []*webSocketSession {
 	s.webSocketMutex.Lock()
 	defer s.webSocketMutex.Unlock()

service/ocm/service_websocket.go

@@ -1,17 +1,21 @@
 package ocm
 
 import (
+	"bufio"
 	"context"
 	stdTLS "crypto/tls"
 	"encoding/json"
 	"io"
 	"net"
 	"net/http"
+	"net/textproto"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
 
 	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/option"
 	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
 	"github.com/sagernet/sing/common/ntp"
@@ -22,9 +26,10 @@ import (
 )
 
 type webSocketSession struct {
-	clientConn   net.Conn
-	upstreamConn net.Conn
-	closeOnce    sync.Once
+	clientConn    net.Conn
+	upstreamConn  net.Conn
+	credentialTag string
+	closeOnce     sync.Once
 }
 
 func (s *webSocketSession) Close() {
@@ -61,7 +66,7 @@ func isForwardableResponseHeader(key string) bool {
 }
 
 func isForwardableWebSocketRequestHeader(key string) bool {
-	if isHopByHopHeader(key) {
+	if isHopByHopHeader(key) || isReverseProxyHeader(key) {
 		return false
 	}
 
@@ -76,65 +81,141 @@ func isForwardableWebSocketRequestHeader(key string) bool {
 	}
 }
 
-func (s *Service) handleWebSocket(w http.ResponseWriter, r *http.Request, proxyPath string, username string) {
-	accessToken, err := s.getAccessToken()
-	if err != nil {
-		s.logger.Error("get access token for websocket: ", err)
-		writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "authentication failed")
-		return
-	}
+func (s *Service) handleWebSocket(
+	ctx context.Context,
+	w http.ResponseWriter,
+	r *http.Request,
+	path string,
+	username string,
+	sessionID string,
+	userConfig *option.OCMUser,
+	provider credentialProvider,
+	selectedCredential credential,
+	credentialFilter func(credential) bool,
+	isNew bool,
+) {
+	var (
+		err                     error
+		upstreamConn            net.Conn
+		upstreamBufferedReader  *bufio.Reader
+		upstreamResponseHeaders http.Header
+		statusCode              int
+		statusResponseBody      string
+	)
 
-	upstreamURL := buildUpstreamWebSocketURL(s.getBaseURL(), proxyPath)
-	if r.URL.RawQuery != "" {
-		upstreamURL += "?" + r.URL.RawQuery
-	}
+	for {
+		accessToken, accessErr := selectedCredential.getAccessToken()
+		if accessErr != nil {
+			s.logger.ErrorContext(ctx, "get access token for websocket: ", accessErr)
+			writeJSONError(w, r, http.StatusUnauthorized, "authentication_error", "authentication failed")
+			return
+		}
 
-	upstreamHeaders := make(http.Header)
-	for key, values := range r.Header {
-		if isForwardableWebSocketRequestHeader(key) {
+		var proxyPath string
+		if selectedCredential.ocmIsAPIKeyMode() || selectedCredential.isExternal() {
+			proxyPath = path
+		} else {
+			proxyPath = strings.TrimPrefix(path, "/v1")
+		}
+
+		upstreamURL := buildUpstreamWebSocketURL(selectedCredential.ocmGetBaseURL(), proxyPath)
+		if r.URL.RawQuery != "" {
+			upstreamURL += "?" + r.URL.RawQuery
+		}
+
+		upstreamHeaders := make(http.Header)
+		for key, values := range r.Header {
+			if isForwardableWebSocketRequestHeader(key) {
+				upstreamHeaders[key] = values
+			}
+		}
+		for key, values := range s.httpHeaders {
+			upstreamHeaders.Del(key)
 			upstreamHeaders[key] = values
 		}
-	}
-	for key, values := range s.httpHeaders {
-		upstreamHeaders.Del(key)
-		upstreamHeaders[key] = values
-	}
-	upstreamHeaders.Set("Authorization", "Bearer "+accessToken)
-	if accountID := s.getAccountID(); accountID != "" {
-		upstreamHeaders.Set("ChatGPT-Account-Id", accountID)
-	}
+		upstreamHeaders.Set("Authorization", "Bearer "+accessToken)
+		if accountID := selectedCredential.ocmGetAccountID(); accountID != "" {
+			upstreamHeaders.Set("ChatGPT-Account-Id", accountID)
+		}
+		if upstreamHeaders.Get("OpenAI-Beta") == "" {
+			upstreamHeaders.Set("OpenAI-Beta", "responses_websockets=2026-02-06")
+		}
 
-	upstreamResponseHeaders := make(http.Header)
-	upstreamDialer := ws.Dialer{
-		NetDial: func(ctx context.Context, network, addr string) (net.Conn, error) {
-			return s.dialer.DialContext(ctx, network, M.ParseSocksaddr(addr))
-		},
-		TLSConfig: &stdTLS.Config{
-			RootCAs: adapter.RootPoolFromContext(s.ctx),
-			Time:    ntp.TimeFuncFromContext(s.ctx),
-		},
-		Header: ws.HandshakeHeaderHTTP(upstreamHeaders),
-		OnHeader: func(key, value []byte) error {
-			upstreamResponseHeaders.Add(string(key), string(value))
-			return nil
-		},
-	}
+		upstreamResponseHeaders = make(http.Header)
+		statusCode = 0
+		statusResponseBody = ""
+		upstreamDialer := ws.Dialer{
+			NetDial: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				return selectedCredential.ocmDialer().DialContext(ctx, network, M.ParseSocksaddr(addr))
+			},
+			TLSConfig: &stdTLS.Config{
+				RootCAs: adapter.RootPoolFromContext(s.ctx),
+				Time:    ntp.TimeFuncFromContext(s.ctx),
+			},
+			Header: ws.HandshakeHeaderHTTP(upstreamHeaders),
+			// gobwas/ws@v1.4.0: the response io.Reader is
+			// MultiReader(statusLine_without_CRLF, "\r\n", bufferedConn).
+			// ReadString('\n') consumes the status line, then ReadMIMEHeader
+			// parses the remaining headers.
+			OnStatusError: func(status int, reason []byte, response io.Reader) {
+				statusCode = status
+				bufferedResponse := bufio.NewReader(response)
+				_, readErr := bufferedResponse.ReadString('\n')
+				if readErr != nil {
+					return
+				}
+				mimeHeader, readErr := textproto.NewReader(bufferedResponse).ReadMIMEHeader()
+				if readErr == nil {
+					upstreamResponseHeaders = http.Header(mimeHeader)
+				}
+				body, readErr := io.ReadAll(io.LimitReader(bufferedResponse, 4096))
+				if readErr == nil && len(body) > 0 {
+					statusResponseBody = string(body)
+				}
+			},
+			OnHeader: func(key, value []byte) error {
+				upstreamResponseHeaders.Add(string(key), string(value))
+				return nil
+			},
+		}
 
-	upstreamConn, upstreamBufferedReader, _, err := upstreamDialer.Dial(r.Context(), upstreamURL)
-	if err != nil {
-		s.logger.Error("dial upstream websocket: ", err)
+		upstreamConn, upstreamBufferedReader, _, err = upstreamDialer.Dial(s.ctx, upstreamURL)
+		if err == nil {
+			break
+		}
+		if statusCode == http.StatusTooManyRequests {
+			resetAt := parseOCMRateLimitResetFromHeaders(upstreamResponseHeaders)
+			nextCredential := provider.onRateLimited(sessionID, selectedCredential, resetAt, credentialFilter)
+			selectedCredential.updateStateFromHeaders(upstreamResponseHeaders)
+			if nextCredential == nil {
+				writeCredentialUnavailableError(w, r, provider, selectedCredential, credentialFilter, "all credentials rate-limited")
+				return
+			}
+			s.logger.InfoContext(ctx, "retrying websocket with credential ", nextCredential.tagName(), " after 429 from ", selectedCredential.tagName())
+			selectedCredential = nextCredential
+			continue
+		}
+		if statusCode > 0 && statusResponseBody != "" {
+			s.logger.ErrorContext(ctx, "dial upstream websocket: status ", statusCode, " body: ", statusResponseBody)
+		} else {
+			s.logger.ErrorContext(ctx, "dial upstream websocket: ", err)
+		}
 		writeJSONError(w, r, http.StatusBadGateway, "api_error", "upstream websocket connection failed")
 		return
 	}
 
+	selectedCredential.updateStateFromHeaders(upstreamResponseHeaders)
 	weeklyCycleHint := extractWeeklyCycleHint(upstreamResponseHeaders)
 
 	clientResponseHeaders := make(http.Header)
 	for key, values := range upstreamResponseHeaders {
 		if isForwardableResponseHeader(key) {
-			clientResponseHeaders[key] = values
+			clientResponseHeaders[key] = append([]string(nil), values...)
 		}
 	}
+	if userConfig != nil && userConfig.ExternalCredential != "" {
+		s.rewriteResponseHeadersForExternalUser(clientResponseHeaders, userConfig)
+	}
 
 	clientUpgrader := ws.HTTPUpgrader{
 		Header: clientResponseHeaders,
@@ -146,13 +227,14 @@ func (s *Service) handleWebSocket(w http.ResponseWriter, r *http.Request, proxyP
 	}
 	clientConn, _, _, err := clientUpgrader.Upgrade(r, w)
 	if err != nil {
-		s.logger.Error("upgrade client websocket: ", err)
+		s.logger.ErrorContext(ctx, "upgrade client websocket: ", err)
 		upstreamConn.Close()
 		return
 	}
 	session := &webSocketSession{
-		clientConn:   clientConn,
-		upstreamConn: upstreamConn,
+		clientConn:    clientConn,
+		upstreamConn:  upstreamConn,
+		credentialTag: selectedCredential.tagName(),
 	}
 	if !s.registerWebSocketSession(session) {
 		session.Close()
@@ -177,35 +259,54 @@ func (s *Service) handleWebSocket(w http.ResponseWriter, r *http.Request, proxyP
 	go func() {
 		defer waitGroup.Done()
 		defer session.Close()
-		s.proxyWebSocketClientToUpstream(clientConn, upstreamConn, modelChannel)
+		s.proxyWebSocketClientToUpstream(ctx, clientConn, upstreamConn, selectedCredential, modelChannel, isNew, username, sessionID)
 	}()
 	go func() {
 		defer waitGroup.Done()
 		defer session.Close()
-		s.proxyWebSocketUpstreamToClient(upstreamReadWriter, clientConn, modelChannel, username, weeklyCycleHint)
+		s.proxyWebSocketUpstreamToClient(ctx, upstreamReadWriter, clientConn, selectedCredential, userConfig, provider, modelChannel, username, weeklyCycleHint)
 	}()
 	waitGroup.Wait()
 }
 
-func (s *Service) proxyWebSocketClientToUpstream(clientConn net.Conn, upstreamConn net.Conn, modelChannel chan<- string) {
+func (s *Service) proxyWebSocketClientToUpstream(ctx context.Context, clientConn net.Conn, upstreamConn net.Conn, selectedCredential credential, modelChannel chan<- string, isNew bool, username string, sessionID string) {
+	logged := false
 	for {
 		data, opCode, err := wsutil.ReadClientData(clientConn)
 		if err != nil {
 			if !E.IsClosedOrCanceled(err) {
-				s.logger.Debug("read client websocket: ", err)
+				s.logger.DebugContext(ctx, "read client websocket: ", err)
 			}
 			return
 		}
 
-		if opCode == ws.OpText && s.usageTracker != nil {
+		if opCode == ws.OpText {
 			var request struct {
-				Type  string `json:"type"`
-				Model string `json:"model"`
+				Type        string `json:"type"`
+				Model       string `json:"model"`
+				ServiceTier string `json:"service_tier"`
 			}
 			if json.Unmarshal(data, &request) == nil && request.Type == "response.create" && request.Model != "" {
-				select {
-				case modelChannel <- request.Model:
-				default:
+				if isNew && !logged {
+					logged = true
+					logParts := []any{"assigned credential ", selectedCredential.tagName()}
+					if sessionID != "" {
+						logParts = append(logParts, " for session ", sessionID)
+					}
+					if username != "" {
+						logParts = append(logParts, " by user ", username)
+					}
+					logParts = append(logParts, ", model=", request.Model)
+					if request.ServiceTier == "priority" {
+						logParts = append(logParts, ", fast")
+					}
+					s.logger.DebugContext(ctx, logParts...)
+				}
+				if selectedCredential.usageTrackerOrNil() != nil {
+					select {
+					case modelChannel <- request.Model:
+					default:
+					}
 				}
 			}
 		}
@@ -213,62 +314,52 @@ func (s *Service) proxyWebSocketClientToUpstream(clientConn net.Conn, upstreamCo
 		err = wsutil.WriteClientMessage(upstreamConn, opCode, data)
 		if err != nil {
 			if !E.IsClosedOrCanceled(err) {
-				s.logger.Debug("write upstream websocket: ", err)
+				s.logger.DebugContext(ctx, "write upstream websocket: ", err)
 			}
 			return
 		}
 	}
 }
 
-func (s *Service) proxyWebSocketUpstreamToClient(upstreamReadWriter io.ReadWriter, clientConn net.Conn, modelChannel <-chan string, username string, weeklyCycleHint *WeeklyCycleHint) {
+func (s *Service) proxyWebSocketUpstreamToClient(ctx context.Context, upstreamReadWriter io.ReadWriter, clientConn net.Conn, selectedCredential credential, userConfig *option.OCMUser, provider credentialProvider, modelChannel <-chan string, username string, weeklyCycleHint *WeeklyCycleHint) {
+	usageTracker := selectedCredential.usageTrackerOrNil()
 	var requestModel string
 	for {
 		data, opCode, err := wsutil.ReadServerData(upstreamReadWriter)
 		if err != nil {
 			if !E.IsClosedOrCanceled(err) {
-				s.logger.Debug("read upstream websocket: ", err)
+				s.logger.DebugContext(ctx, "read upstream websocket: ", err)
 			}
 			return
 		}
 
-		if opCode == ws.OpText && s.usageTracker != nil {
-			select {
-			case model := <-modelChannel:
-				requestModel = model
-			default:
-			}
-
+		if opCode == ws.OpText {
 			var event struct {
-				Type string `json:"type"`
+				Type       string `json:"type"`
+				StatusCode int    `json:"status_code"`
 			}
-			if json.Unmarshal(data, &event) == nil && event.Type == "response.completed" {
-				var streamEvent responses.ResponseStreamEventUnion
-				if json.Unmarshal(data, &streamEvent) == nil {
-					completedEvent := streamEvent.AsResponseCompleted()
-					responseModel := string(completedEvent.Response.Model)
-					serviceTier := string(completedEvent.Response.ServiceTier)
-					inputTokens := completedEvent.Response.Usage.InputTokens
-					outputTokens := completedEvent.Response.Usage.OutputTokens
-					cachedTokens := completedEvent.Response.Usage.InputTokensDetails.CachedTokens
-
-					if inputTokens > 0 || outputTokens > 0 {
-						if responseModel == "" {
-							responseModel = requestModel
+			if json.Unmarshal(data, &event) == nil {
+				switch event.Type {
+				case "codex.rate_limits":
+					s.handleWebSocketRateLimitsEvent(data, selectedCredential)
+					if userConfig != nil && userConfig.ExternalCredential != "" {
+						rewritten, rewriteErr := s.rewriteWebSocketRateLimitsForExternalUser(data, provider, userConfig)
+						if rewriteErr == nil {
+							data = rewritten
 						}
-						if responseModel != "" {
-							contextWindow := detectContextWindow(responseModel, serviceTier, inputTokens)
-							s.usageTracker.AddUsageWithCycleHint(
-								responseModel,
-								contextWindow,
-								inputTokens,
-								outputTokens,
-								cachedTokens,
-								serviceTier,
-								username,
-								time.Now(),
-								weeklyCycleHint,
-							)
+					}
+				case "error":
+					if event.StatusCode == http.StatusTooManyRequests {
+						s.handleWebSocketErrorRateLimited(data, selectedCredential)
+					}
+				case "response.completed":
+					if usageTracker != nil {
+						select {
+						case model := <-modelChannel:
+							requestModel = model
+						default:
 						}
+						s.handleWebSocketResponseCompleted(data, usageTracker, requestModel, username, weeklyCycleHint)
 					}
 				}
 			}
@@ -277,9 +368,175 @@ func (s *Service) proxyWebSocketUpstreamToClient(upstreamReadWriter io.ReadWrite
 		err = wsutil.WriteServerMessage(clientConn, opCode, data)
 		if err != nil {
 			if !E.IsClosedOrCanceled(err) {
-				s.logger.Debug("write client websocket: ", err)
+				s.logger.DebugContext(ctx, "write client websocket: ", err)
 			}
 			return
 		}
 	}
 }
+
+func (s *Service) handleWebSocketRateLimitsEvent(data []byte, selectedCredential credential) {
+	var rateLimitsEvent struct {
+		RateLimits struct {
+			Primary *struct {
+				UsedPercent float64 `json:"used_percent"`
+				ResetAt     int64   `json:"reset_at"`
+			} `json:"primary"`
+			Secondary *struct {
+				UsedPercent float64 `json:"used_percent"`
+				ResetAt     int64   `json:"reset_at"`
+			} `json:"secondary"`
+		} `json:"rate_limits"`
+		LimitName        string  `json:"limit_name"`
+		MeteredLimitName string  `json:"metered_limit_name"`
+		PlanWeight       float64 `json:"plan_weight"`
+	}
+	err := json.Unmarshal(data, &rateLimitsEvent)
+	if err != nil {
+		return
+	}
+	identifier := rateLimitsEvent.MeteredLimitName
+	if identifier == "" {
+		identifier = rateLimitsEvent.LimitName
+	}
+	if identifier == "" {
+		identifier = "codex"
+	}
+	identifier = normalizeRateLimitIdentifier(identifier)
+
+	headers := make(http.Header)
+	headers.Set("x-codex-active-limit", identifier)
+	if w := rateLimitsEvent.RateLimits.Primary; w != nil {
+		headers.Set("x-"+identifier+"-primary-used-percent", strconv.FormatFloat(w.UsedPercent, 'f', -1, 64))
+		if w.ResetAt > 0 {
+			headers.Set("x-"+identifier+"-primary-reset-at", strconv.FormatInt(w.ResetAt, 10))
+		}
+	}
+	if w := rateLimitsEvent.RateLimits.Secondary; w != nil {
+		headers.Set("x-"+identifier+"-secondary-used-percent", strconv.FormatFloat(w.UsedPercent, 'f', -1, 64))
+		if w.ResetAt > 0 {
+			headers.Set("x-"+identifier+"-secondary-reset-at", strconv.FormatInt(w.ResetAt, 10))
+		}
+	}
+	if rateLimitsEvent.PlanWeight > 0 {
+		headers.Set("X-OCM-Plan-Weight", strconv.FormatFloat(rateLimitsEvent.PlanWeight, 'f', -1, 64))
+	}
+	selectedCredential.updateStateFromHeaders(headers)
+}
+
+func (s *Service) handleWebSocketErrorRateLimited(data []byte, selectedCredential credential) {
+	var errorEvent struct {
+		Headers map[string]string `json:"headers"`
+	}
+	err := json.Unmarshal(data, &errorEvent)
+	if err != nil {
+		return
+	}
+	headers := make(http.Header)
+	for key, value := range errorEvent.Headers {
+		headers.Set(key, value)
+	}
+	selectedCredential.updateStateFromHeaders(headers)
+	resetAt := parseOCMRateLimitResetFromHeaders(headers)
+	selectedCredential.markRateLimited(resetAt)
+}
+
+func (s *Service) rewriteWebSocketRateLimitsForExternalUser(data []byte, provider credentialProvider, userConfig *option.OCMUser) ([]byte, error) {
+	var event map[string]json.RawMessage
+	err := json.Unmarshal(data, &event)
+	if err != nil {
+		return nil, err
+	}
+
+	rateLimitsData, exists := event["rate_limits"]
+	if !exists || len(rateLimitsData) == 0 || string(rateLimitsData) == "null" {
+		return data, nil
+	}
+
+	var rateLimits map[string]json.RawMessage
+	err = json.Unmarshal(rateLimitsData, &rateLimits)
+	if err != nil {
+		return nil, err
+	}
+
+	averageFiveHour, averageWeekly, totalWeight := s.computeAggregatedUtilization(provider, userConfig)
+
+	if totalWeight > 0 {
+		event["plan_weight"], _ = json.Marshal(totalWeight)
+	}
+
+	primaryData, err := rewriteWebSocketRateLimitWindow(rateLimits["primary"], averageFiveHour)
+	if err != nil {
+		return nil, err
+	}
+	if primaryData != nil {
+		rateLimits["primary"] = primaryData
+	}
+
+	secondaryData, err := rewriteWebSocketRateLimitWindow(rateLimits["secondary"], averageWeekly)
+	if err != nil {
+		return nil, err
+	}
+	if secondaryData != nil {
+		rateLimits["secondary"] = secondaryData
+	}
+
+	event["rate_limits"], err = json.Marshal(rateLimits)
+	if err != nil {
+		return nil, err
+	}
+
+	return json.Marshal(event)
+}
+
+func rewriteWebSocketRateLimitWindow(data json.RawMessage, usedPercent float64) (json.RawMessage, error) {
+	if len(data) == 0 || string(data) == "null" {
+		return nil, nil
+	}
+
+	var window map[string]json.RawMessage
+	err := json.Unmarshal(data, &window)
+	if err != nil {
+		return nil, err
+	}
+
+	window["used_percent"], err = json.Marshal(usedPercent)
+	if err != nil {
+		return nil, err
+	}
+
+	return json.Marshal(window)
+}
+
+func (s *Service) handleWebSocketResponseCompleted(data []byte, usageTracker *AggregatedUsage, requestModel string, username string, weeklyCycleHint *WeeklyCycleHint) {
+	var streamEvent responses.ResponseStreamEventUnion
+	if json.Unmarshal(data, &streamEvent) != nil {
+		return
+	}
+	completedEvent := streamEvent.AsResponseCompleted()
+	responseModel := string(completedEvent.Response.Model)
+	serviceTier := string(completedEvent.Response.ServiceTier)
+	inputTokens := completedEvent.Response.Usage.InputTokens
+	outputTokens := completedEvent.Response.Usage.OutputTokens
+	cachedTokens := completedEvent.Response.Usage.InputTokensDetails.CachedTokens
+
+	if inputTokens > 0 || outputTokens > 0 {
+		if responseModel == "" {
+			responseModel = requestModel
+		}
+		if responseModel != "" {
+			contextWindow := detectContextWindow(responseModel, serviceTier, inputTokens)
+			usageTracker.AddUsageWithCycleHint(
+				responseModel,
+				contextWindow,
+				inputTokens,
+				outputTokens,
+				cachedTokens,
+				serviceTier,
+				username,
+				time.Now(),
+				weeklyCycleHint,
+			)
+		}
+	}
+}

service/ssmapi/server.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/go-chi/chi/v5"
 	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/h2c"
 )
 
 func RegisterService(registry *boxService.Registry) {
@@ -59,7 +60,7 @@ func NewService(ctx context.Context, logger log.ContextLogger, tag string, optio
 			Listen:  options.ListenOptions,
 		}),
 		httpServer: &http.Server{
-			Handler: chiRouter,
+			Handler: h2c.NewHandler(chiRouter, &http2.Server{}),
 		},
 		traffics:  make(map[string]*TrafficManager),
 		users:     make(map[string]*UserManager),