fix: track fork versions for update checks

CODEX_OVERDRAFT_DEPLOYMENT_CN.md

@@ -11,6 +11,7 @@
 - 探测请求和透支期请求都可能产生真实上游用量和费用。
 - 此行为可能不符合上游服务条款。部署者必须自行确认合规性，并承担账号限制、服务中断等风险。
 - 官方 Sub2API 安装脚本和 `weishaw/sub2api:latest` 镜像不包含本 Fork 的透支功能。
+- 本 Fork 的后台更新检查读取 `DeanZFC/sub2api-overdraft`，不会把官方 Sub2API Release 当作本项目更新。
 
 ## 功能范围
 
@@ -358,6 +359,8 @@ sudo systemctl reload nginx
 
 ## 日常升级本 Fork
 
+源码镜像的当前版本来自仓库根目录的 `FORK_VERSION`。后台检查更新时读取 GitHub 上 `codex-overdraft` 分支的同名文件：远端版本更高时显示更新提示，版本一致时显示最新。源码构建不会执行二进制在线更新或在线回退，以免官方程序覆盖 Fork 功能。
+
 运行数据均位于被 Git 忽略的目录中，正常 `git pull` 不会覆盖：
 
 ```text
@@ -384,6 +387,14 @@ docker compose \
 
 如果服务器目录是 `/opt/sub2api`，只需替换第一条路径。升级完成后重新执行“判断功能是否生效”中的镜像、环境变量和日志检查。
 
+更新后可在管理后台点击刷新，版本应显示为类似 `v0.1.176-overdraft.1`，更新方式应提示源码构建使用 `git pull`。也可以直接检查容器内二进制版本：
+
+```bash
+docker exec sub2api /app/sub2api -version
+```
+
+维护者发布新的源码版本时必须递增 `FORK_VERSION`，例如从 `0.1.176-overdraft.1` 改为 `0.1.176-overdraft.2`。同步到新的上游 Sub2API 版本时，使用 `0.1.177-overdraft.1` 这样的版本号。
+
 ## 合并 Sub2API 官方更新
 
 本仓库保留两个分支角色：

CODEX_QUOTA_OVERDRAFT_CUSTOMIZATION.md

@@ -9,6 +9,14 @@
 - 参考实现：<https://github.com/Mxucc/cpa-account-config-manager>
 - 功能开关：`gateway.codex_quota_overdraft_enabled`
 - 代码默认值：关闭；`deploy/config.example.yaml` 部署示例默认开启
+- Fork 版本文件：`FORK_VERSION`
+- 更新源：`DeanZFC/sub2api-overdraft` 的 `codex-overdraft` 分支
+
+## Fork 更新检查
+
+源码 Docker 构建会读取根目录的 `FORK_VERSION`，并以 `BuildType=source` 写入二进制。后台更新服务通过 GitHub Contents API 读取 Fork 分支上的同名文件，使用语义化版本比较判断是否有新版本。Redis 缓存同时记录仓库和构建类型，因此旧的官方更新缓存不会继续生效。
+
+源码构建仅显示 `git pull` 更新提示，`PerformUpdate`、指定版本回退和在线回退列表均被禁用，防止官方二进制覆盖透支功能。维护者每次发布 Fork 更新都必须递增 `FORK_VERSION`；普通补丁使用 `0.1.176-overdraft.2`，同步上游版本后使用 `0.1.177-overdraft.1`。
 
 ## 后台测试连接与残留限流修复
 

Dockerfile

@@ -56,6 +56,7 @@ FROM --platform=${BUILDPLATFORM} ${GOLANG_IMAGE} AS backend-builder
 ARG VERSION=
 ARG COMMIT=docker
 ARG DATE
+ARG BUILD_TYPE=source
 ARG GOPROXY
 ARG GOSUMDB
 # Populated by buildx from the --platform target (e.g. linux/amd64).
@@ -79,20 +80,22 @@ RUN --mount=type=cache,id=sub2api-gomod,target=/go/pkg/mod \
 
 # Copy backend source first
 COPY backend/ ./
+COPY FORK_VERSION /app/FORK_VERSION
 
 # Copy frontend dist from previous stage (must be after backend copy to avoid being overwritten)
 COPY --from=frontend-builder /app/backend/internal/web/dist ./internal/web/dist
 
-# Build the binary (BuildType=release for CI builds, embed frontend)
-# Version precedence: build arg VERSION > exact git tag > cmd/server/VERSION
+# Build the binary and embed the frontend. Fork source builds read FORK_VERSION;
+# CI release builds still override VERSION and BUILD_TYPE explicitly.
 RUN --mount=type=cache,id=sub2api-gomod,target=/go/pkg/mod \
     --mount=type=cache,id=sub2api-gobuild,target=/root/.cache/go-build \
     VERSION_VALUE="${VERSION}" && \
+    if [ -z "${VERSION_VALUE}" ] && [ -s /app/FORK_VERSION ]; then VERSION_VALUE="$(tr -d '\r\n' < /app/FORK_VERSION)"; fi && \
     if [ -z "${VERSION_VALUE}" ]; then VERSION_VALUE="$(./scripts/resolve-version.sh)"; fi && \
     DATE_VALUE="${DATE:-$(date -u +%Y-%m-%dT%H:%M:%SZ)}" && \
     CGO_ENABLED=0 GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} go build \
     -tags embed \
-    -ldflags="-s -w -X main.Version=${VERSION_VALUE} -X main.Commit=${COMMIT} -X main.Date=${DATE_VALUE} -X main.BuildType=release" \
+    -ldflags="-s -w -X main.Version=${VERSION_VALUE} -X main.Commit=${COMMIT} -X main.Date=${DATE_VALUE} -X main.BuildType=${BUILD_TYPE}" \
     -trimpath \
     -o /app/sub2api \
     ./cmd/server

FORK_VERSION

@@ -0,0 +1 @@
+0.1.176-overdraft.1

README_CN.md

@@ -27,6 +27,7 @@
 - 网络、超时、5xx 和普通瞬时 429 不会被误判为额度耗尽；401/403、账号禁用和其他风控仍使用原有策略。
 - 多实例通过 PostgreSQL 原子领取（atomic claim）去重；状态保存在现有 `accounts.extra`，无需新增数据表。
 - 可通过一个配置开关立即关闭，恢复上游 Sub2API 的调度和请求行为。
+- 管理后台从 `DeanZFC/sub2api-overdraft` 的 `codex-overdraft` 分支检查更新，不再使用官方 Sub2API 的版本结果。
 
 ## 快速部署
 
@@ -58,6 +59,8 @@ gateway:
 
 公开的 `docker-compose.overdraft.yml` 已通过环境变量默认开启该功能。
 
+源码镜像会把根目录的 `FORK_VERSION` 写入版本信息。管理后台检测到 Fork 新版本后只提示使用 `git pull` 更新源码，不会下载官方二进制覆盖透支功能。完整更新命令见部署指南的“日常升级本 Fork”。
+
 ## 如何确认透支成功
 
 账号额度达到 100% 后检查日志：
@@ -332,12 +335,9 @@ sudo systemctl enable sub2api
 
 #### 升级
 
-可以直接在 **管理后台** 左上角点击 **检测更新** 按钮进行在线升级。
+官方发行版可以直接在管理后台进行二进制在线升级。本 Fork 使用源码构建，管理后台会读取 `DeanZFC/sub2api-overdraft` 的 `FORK_VERSION` 检测新版本，并提示使用 `git pull` 后重新构建；不会在线替换二进制。
 
-网页升级功能支持：
-- 自动检测新版本
-- 一键下载并应用更新
-- 支持回滚
+本 Fork 的升级命令见 [日常升级本 Fork](CODEX_OVERDRAFT_DEPLOYMENT_CN.md#日常升级本-fork)。源码构建不支持页面内一键升级和在线回退，避免误装官方二进制而丢失透支功能。
 
 #### 常用命令
 

backend/internal/repository/github_release_service.go

@@ -2,6 +2,7 @@ package repository
 
 import (
 	"context"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -112,6 +113,10 @@ func (c *githubReleaseClientError) FetchRecentReleases(ctx context.Context, repo
 	return nil, c.err
 }
 
+func (c *githubReleaseClientError) FetchRepositoryFile(ctx context.Context, repo, ref, filePath string) ([]byte, error) {
+	return nil, c.err
+}
+
 func (c *githubReleaseClientError) DownloadFile(ctx context.Context, url, dest string, maxSize int64) error {
 	return c.err
 }
@@ -178,6 +183,56 @@ func (c *githubReleaseClient) FetchRecentReleases(ctx context.Context, repo stri
 	return releases, nil
 }
 
+func (c *githubReleaseClient) FetchRepositoryFile(ctx context.Context, repo, ref, filePath string) ([]byte, error) {
+	repo = strings.Trim(strings.TrimSpace(repo), "/")
+	ref = strings.TrimSpace(ref)
+	filePath = strings.Trim(strings.TrimSpace(filePath), "/")
+	if repo == "" || ref == "" || filePath == "" || strings.Contains(filePath, "..") {
+		return nil, fmt.Errorf("invalid GitHub repository file reference")
+	}
+
+	endpoint := fmt.Sprintf("https://api.github.com/repos/%s/contents/%s", repo, filePath)
+	parsed, err := url.Parse(endpoint)
+	if err != nil {
+		return nil, err
+	}
+	query := parsed.Query()
+	query.Set("ref", ref)
+	parsed.RawQuery = query.Encode()
+	req, err := c.newAPIRequest(ctx, parsed.String())
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = resp.Body.Close() }()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GitHub API returned %d", resp.StatusCode)
+	}
+
+	var payload struct {
+		Encoding string `json:"encoding"`
+		Content  string `json:"content"`
+	}
+	if err := json.NewDecoder(io.LimitReader(resp.Body, 256<<10)).Decode(&payload); err != nil {
+		return nil, err
+	}
+	if payload.Encoding != "base64" {
+		return nil, fmt.Errorf("unsupported GitHub file encoding %q", payload.Encoding)
+	}
+	decoded, err := base64.StdEncoding.DecodeString(strings.ReplaceAll(payload.Content, "\n", ""))
+	if err != nil {
+		return nil, fmt.Errorf("decode GitHub repository file: %w", err)
+	}
+	if len(decoded) > 64<<10 {
+		return nil, fmt.Errorf("GitHub repository file is too large")
+	}
+	return decoded, nil
+}
+
 func (c *githubReleaseClient) DownloadFile(ctx context.Context, url, dest string, maxSize int64) error {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {

backend/internal/repository/github_release_service_test.go

@@ -3,6 +3,7 @@ package repository
 import (
 	"bytes"
 	"context"
+	"encoding/base64"
 	"io"
 	"net/http"
 	"net/http/httptest"
@@ -393,6 +394,39 @@ func (s *GitHubReleaseServiceSuite) TestFetchRecentReleases_Success() {
 	require.Equal(s.T(), "v1.0.0", releases[2].TagName)
 }
 
+func (s *GitHubReleaseServiceSuite) TestFetchRepositoryFile_Success() {
+	encoded := base64.StdEncoding.EncodeToString([]byte("0.1.176-overdraft.1\n"))
+	s.srv = newLocalTestServer(s.T(), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(s.T(), "/repos/DeanZFC/sub2api-overdraft/contents/FORK_VERSION", r.URL.Path)
+		require.Equal(s.T(), "codex-overdraft", r.URL.Query().Get("ref"))
+		require.Equal(s.T(), "application/vnd.github.v3+json", r.Header.Get("Accept"))
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"encoding":"base64","content":"` + encoded + `"}`))
+	}))
+	s.client = &githubReleaseClient{
+		httpClient:         &http.Client{Transport: &testTransport{testServerURL: s.srv.URL}},
+		downloadHTTPClient: &http.Client{},
+	}
+
+	content, err := s.client.FetchRepositoryFile(
+		context.Background(),
+		"DeanZFC/sub2api-overdraft",
+		"codex-overdraft",
+		"FORK_VERSION",
+	)
+
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "0.1.176-overdraft.1\n", string(content))
+}
+
+func (s *GitHubReleaseServiceSuite) TestFetchRepositoryFile_RejectsTraversal() {
+	s.client = newTestGitHubReleaseClient()
+
+	_, err := s.client.FetchRepositoryFile(context.Background(), "test/repo", "main", "../secret")
+
+	require.Error(s.T(), err)
+}
+
 func (s *GitHubReleaseServiceSuite) TestFetchRecentReleases_Non200() {
 	s.srv = newLocalTestServer(s.T(), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusForbidden)

backend/internal/service/update_service.go

@@ -20,17 +20,21 @@ import (
 	"time"
 
 	infraerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
+	"golang.org/x/mod/semver"
 )
 
 var (
 	ErrNoUpdateAvailable         = infraerrors.Conflict("ALREADY_UP_TO_DATE", "no update available; current version is latest")
 	ErrRollbackVersionNotAllowed = infraerrors.BadRequest("ROLLBACK_VERSION_NOT_ALLOWED", "version is not in the allowed rollback list")
+	ErrSourceBuildUpdateRequired = infraerrors.Conflict("SOURCE_BUILD_UPDATE_REQUIRED", "source builds must be updated with git pull and rebuilt")
 )
 
 const (
-	updateCacheKey = "update_check_cache"
-	updateCacheTTL = 1200 // 20 minutes
-	githubRepo     = "Wei-Shaw/sub2api"
+	updateCacheTTL        = 1200 // 20 minutes
+	githubRepo            = "DeanZFC/sub2api-overdraft"
+	githubSourceBranch    = "codex-overdraft"
+	githubForkVersionFile = "FORK_VERSION"
+	githubSourceUpdateURL = "https://github.com/DeanZFC/sub2api-overdraft/commits/codex-overdraft"
 
 	// Security: allowed download domains for updates
 	allowedDownloadHost = "github.com"
@@ -55,6 +59,7 @@ type UpdateCache interface {
 type GitHubReleaseClient interface {
 	FetchLatestRelease(ctx context.Context, repo string) (*GitHubRelease, error)
 	FetchRecentReleases(ctx context.Context, repo string, perPage int) ([]*GitHubRelease, error)
+	FetchRepositoryFile(ctx context.Context, repo, ref, filePath string) ([]byte, error)
 	DownloadFile(ctx context.Context, url, dest string, maxSize int64) error
 	FetchChecksumFile(ctx context.Context, url string) ([]byte, error)
 }
@@ -138,8 +143,15 @@ func (s *UpdateService) CheckUpdate(ctx context.Context, force bool) (*UpdateInf
 		}
 	}
 
-	// Fetch from GitHub
-	info, err := s.fetchLatestRelease(ctx)
+	// Source builds track the Fork branch version file. Release builds track the
+	// Fork's GitHub Releases and remain eligible for binary replacement.
+	var info *UpdateInfo
+	var err error
+	if s.isSourceBuild() {
+		info, err = s.fetchLatestSourceVersion(ctx)
+	} else {
+		info, err = s.fetchLatestRelease(ctx)
+	}
 	if err != nil {
 		// Return cached on error
 		if cached, cacheErr := s.getFromCache(ctx); cacheErr == nil && cached != nil {
@@ -163,6 +175,9 @@ func (s *UpdateService) CheckUpdate(ctx context.Context, force bool) (*UpdateInf
 // PerformUpdate downloads and applies the update
 // Uses atomic file replacement pattern for safe in-place updates
 func (s *UpdateService) PerformUpdate(ctx context.Context) error {
+	if s.isSourceBuild() {
+		return ErrSourceBuildUpdateRequired
+	}
 	info, err := s.CheckUpdate(ctx, true)
 	if err != nil {
 		return err
@@ -307,6 +322,9 @@ func (s *UpdateService) Rollback() error {
 // strictly older than the current version (the current version itself is excluded),
 // newest first. Draft and prerelease entries are skipped.
 func (s *UpdateService) ListRollbackVersions(ctx context.Context) ([]RollbackVersion, error) {
+	if s.isSourceBuild() {
+		return []RollbackVersion{}, nil
+	}
 	releases, err := s.fetchRollbackCandidates(ctx)
 	if err != nil {
 		return nil, err
@@ -327,6 +345,9 @@ func (s *UpdateService) ListRollbackVersions(ctx context.Context) ([]RollbackVer
 // The target must be one of the versions returned by ListRollbackVersions;
 // anything else (including the current version) is rejected.
 func (s *UpdateService) RollbackToVersion(ctx context.Context, version string) error {
+	if s.isSourceBuild() {
+		return ErrSourceBuildUpdateRequired
+	}
 	target := strings.TrimPrefix(strings.TrimSpace(version), "v")
 	if target == "" {
 		return ErrRollbackVersionNotAllowed
@@ -432,6 +453,33 @@ func (s *UpdateService) fetchLatestRelease(ctx context.Context) (*UpdateInfo, er
 	}, nil
 }
 
+func (s *UpdateService) fetchLatestSourceVersion(ctx context.Context) (*UpdateInfo, error) {
+	raw, err := s.githubClient.FetchRepositoryFile(ctx, githubRepo, githubSourceBranch, githubForkVersionFile)
+	if err != nil {
+		return nil, err
+	}
+	latestVersion := strings.TrimSpace(string(raw))
+	if canonicalVersion(latestVersion) == "" {
+		return nil, fmt.Errorf("Fork version file contains invalid semantic version %q", latestVersion)
+	}
+
+	return &UpdateInfo{
+		CurrentVersion: s.currentVersion,
+		LatestVersion:  latestVersion,
+		HasUpdate:      compareVersions(s.currentVersion, latestVersion) < 0,
+		ReleaseInfo: &ReleaseInfo{
+			Name:    "sub2api-overdraft " + latestVersion,
+			HTMLURL: githubSourceUpdateURL,
+		},
+		Cached:    false,
+		BuildType: s.buildType,
+	}, nil
+}
+
+func (s *UpdateService) isSourceBuild() bool {
+	return strings.EqualFold(strings.TrimSpace(s.buildType), "source")
+}
+
 func (s *UpdateService) downloadFile(ctx context.Context, downloadURL, dest string) error {
 	return s.githubClient.DownloadFile(ctx, downloadURL, dest, maxDownloadSize)
 }
@@ -603,6 +651,8 @@ func (s *UpdateService) getFromCache(ctx context.Context) (*UpdateInfo, error) {
 		Latest      string       `json:"latest"`
 		ReleaseInfo *ReleaseInfo `json:"release_info"`
 		Timestamp   int64        `json:"timestamp"`
+		Repository  string       `json:"repository"`
+		BuildType   string       `json:"build_type"`
 	}
 	if err := json.Unmarshal([]byte(data), &cached); err != nil {
 		return nil, err
@@ -611,6 +661,9 @@ func (s *UpdateService) getFromCache(ctx context.Context) (*UpdateInfo, error) {
 	if time.Now().Unix()-cached.Timestamp > updateCacheTTL {
 		return nil, fmt.Errorf("cache expired")
 	}
+	if cached.Repository != githubRepo || cached.BuildType != s.buildType {
+		return nil, fmt.Errorf("cache belongs to a different update source")
+	}
 
 	return &UpdateInfo{
 		CurrentVersion: s.currentVersion,
@@ -627,10 +680,14 @@ func (s *UpdateService) saveToCache(ctx context.Context, info *UpdateInfo) {
 		Latest      string       `json:"latest"`
 		ReleaseInfo *ReleaseInfo `json:"release_info"`
 		Timestamp   int64        `json:"timestamp"`
+		Repository  string       `json:"repository"`
+		BuildType   string       `json:"build_type"`
 	}{
 		Latest:      info.LatestVersion,
 		ReleaseInfo: info.ReleaseInfo,
 		Timestamp:   time.Now().Unix(),
+		Repository:  githubRepo,
+		BuildType:   s.buildType,
 	}
 
 	data, _ := json.Marshal(cacheData)
@@ -639,6 +696,12 @@ func (s *UpdateService) saveToCache(ctx context.Context, info *UpdateInfo) {
 
 // compareVersions compares two semantic versions
 func compareVersions(current, latest string) int {
+	currentSemver := canonicalVersion(current)
+	latestSemver := canonicalVersion(latest)
+	if currentSemver != "" && latestSemver != "" {
+		return semver.Compare(currentSemver, latestSemver)
+	}
+
 	currentParts := parseVersion(current)
 	latestParts := parseVersion(latest)
 
@@ -653,6 +716,20 @@ func compareVersions(current, latest string) int {
 	return 0
 }
 
+func canonicalVersion(value string) string {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return ""
+	}
+	if !strings.HasPrefix(value, "v") {
+		value = "v" + value
+	}
+	if !semver.IsValid(value) {
+		return ""
+	}
+	return value
+}
+
 func parseVersion(v string) [3]int {
 	v = strings.TrimPrefix(v, "v")
 	parts := strings.Split(v, ".")

backend/internal/service/update_service_test.go

@@ -28,12 +28,20 @@ func (s *updateServiceCacheStub) SetUpdateInfo(_ context.Context, data string, _
 }
 
 type updateServiceGitHubClientStub struct {
-	release        *GitHubRelease
-	recentReleases []*GitHubRelease
-	recentErr      error
+	release           *GitHubRelease
+	recentReleases    []*GitHubRelease
+	recentErr         error
+	repositoryFile    []byte
+	repositoryFileErr error
+	latestRepo        string
+	fileRepo          string
+	fileRef           string
+	filePath          string
+	fileCalls         int
 }
 
-func (s *updateServiceGitHubClientStub) FetchLatestRelease(context.Context, string) (*GitHubRelease, error) {
+func (s *updateServiceGitHubClientStub) FetchLatestRelease(_ context.Context, repo string) (*GitHubRelease, error) {
+	s.latestRepo = repo
 	return s.release, nil
 }
 
@@ -41,6 +49,14 @@ func (s *updateServiceGitHubClientStub) FetchRecentReleases(context.Context, str
 	return s.recentReleases, s.recentErr
 }
 
+func (s *updateServiceGitHubClientStub) FetchRepositoryFile(_ context.Context, repo, ref, filePath string) ([]byte, error) {
+	s.fileCalls++
+	s.fileRepo = repo
+	s.fileRef = ref
+	s.filePath = filePath
+	return s.repositoryFile, s.repositoryFileErr
+}
+
 func (s *updateServiceGitHubClientStub) DownloadFile(context.Context, string, string, int64) error {
 	panic("DownloadFile should not be called when no update is available")
 }
@@ -69,6 +85,72 @@ func TestUpdateServicePerformUpdateNoUpdateReturnsSentinel(t *testing.T) {
 	require.ErrorIs(t, err, ErrNoUpdateAvailable)
 }
 
+func TestUpdateServiceSourceBuildTracksForkVersionFile(t *testing.T) {
+	client := &updateServiceGitHubClientStub{repositoryFile: []byte("0.1.176-overdraft.2\n")}
+	svc := NewUpdateService(
+		&updateServiceCacheStub{},
+		client,
+		"0.1.176-overdraft.1",
+		"source",
+	)
+
+	info, err := svc.CheckUpdate(context.Background(), true)
+
+	require.NoError(t, err)
+	require.Equal(t, "0.1.176-overdraft.1", info.CurrentVersion)
+	require.Equal(t, "0.1.176-overdraft.2", info.LatestVersion)
+	require.True(t, info.HasUpdate)
+	require.Equal(t, "source", info.BuildType)
+	require.Equal(t, githubSourceUpdateURL, info.ReleaseInfo.HTMLURL)
+	require.Equal(t, githubRepo, client.fileRepo)
+	require.Equal(t, githubSourceBranch, client.fileRef)
+	require.Equal(t, githubForkVersionFile, client.filePath)
+	require.Empty(t, client.latestRepo, "源码构建不能查询官方或 Fork 的二进制 Release")
+}
+
+func TestUpdateServiceSourceBuildIgnoresLegacyOfficialCache(t *testing.T) {
+	cache := &updateServiceCacheStub{data: `{"latest":"0.1.176","timestamp":4102444800}`}
+	client := &updateServiceGitHubClientStub{repositoryFile: []byte("0.1.176-overdraft.1\n")}
+	svc := NewUpdateService(cache, client, "0.1.176-overdraft.1", "source")
+
+	info, err := svc.CheckUpdate(context.Background(), false)
+
+	require.NoError(t, err)
+	require.False(t, info.HasUpdate)
+	require.Equal(t, "0.1.176-overdraft.1", info.LatestVersion)
+	require.Equal(t, 1, client.fileCalls)
+}
+
+func TestUpdateServiceSourceBuildRejectsBinaryUpdate(t *testing.T) {
+	svc := NewUpdateService(
+		&updateServiceCacheStub{},
+		&updateServiceGitHubClientStub{},
+		"0.1.176-overdraft.1",
+		"source",
+	)
+
+	err := svc.PerformUpdate(context.Background())
+
+	require.ErrorIs(t, err, ErrSourceBuildUpdateRequired)
+}
+
+func TestUpdateServiceReleaseBuildUsesForkRepository(t *testing.T) {
+	client := &updateServiceGitHubClientStub{release: &GitHubRelease{TagName: "v0.1.177-overdraft.1"}}
+	svc := NewUpdateService(&updateServiceCacheStub{}, client, "0.1.176-overdraft.1", "release")
+
+	info, err := svc.CheckUpdate(context.Background(), true)
+
+	require.NoError(t, err)
+	require.True(t, info.HasUpdate)
+	require.Equal(t, githubRepo, client.latestRepo)
+}
+
+func TestCompareVersionsSupportsForkPrereleaseRevisions(t *testing.T) {
+	require.Less(t, compareVersions("0.1.176-overdraft.1", "0.1.176-overdraft.2"), 0)
+	require.Zero(t, compareVersions("v0.1.176-overdraft.2", "0.1.176-overdraft.2"))
+	require.Greater(t, compareVersions("0.1.177-overdraft.1", "0.1.176-overdraft.9"), 0)
+}
+
 func newRollbackTestService(current string, releases []*GitHubRelease) *UpdateService {
 	return NewUpdateService(
 		&updateServiceCacheStub{},

deploy/docker-compose.overdraft.yml

@@ -9,7 +9,8 @@ services:
       context: ..
       dockerfile: Dockerfile
       args:
-        VERSION: ${BUILD_VERSION:-codex-overdraft}
+        VERSION: ${BUILD_VERSION:-}
         COMMIT: ${BUILD_COMMIT:-local}
+        BUILD_TYPE: source
     environment:
       - GATEWAY_CODEX_QUOTA_OVERDRAFT_ENABLED=${GATEWAY_CODEX_QUOTA_OVERDRAFT_ENABLED:-true}

frontend/src/components/common/VersionBadge.vue

@@ -651,7 +651,7 @@ import {
 import { useClipboard } from '@/composables/useClipboard'
 import Icon from '@/components/icons/Icon.vue'
 
-const GITHUB_REPO = 'Wei-Shaw/sub2api'
+const GITHUB_REPO = 'DeanZFC/sub2api-overdraft'
 // Docker Hub image published by CI (tags carry no "v" prefix, e.g. weishaw/sub2api:0.1.146)
 const DOCKER_IMAGE = 'weishaw/sub2api'