update: add Go module spec updater

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/charmbracelet/glamour v0.10.0
 	github.com/mattn/go-isatty v0.0.20
 	github.com/sandrolain/httpcache v1.4.0
+	golang.org/x/mod v0.29.0
 	golang.org/x/net v0.47.0
 )
 

go.sum

@@ -60,6 +60,8 @@ github.com/yuin/goldmark-emoji v1.0.5 h1:EMVWyCGPlXJfUXBXpuMu+ii3TIaxbVBnEX9uaDC
 github.com/yuin/goldmark-emoji v1.0.5/go.mod h1:tTkZEbwu5wkPmgTcitqddVxY9osFZiavD+r4AzQrh1U=
 golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561 h1:MDc5xs78ZrZr3HMQugiXOAkSZtfTpbJLDr/lwfgO53E=
 golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561/go.mod h1:cyybsKvd6eL0RnXn6p/Grxp8F5bW7iYuBgsNCOHpMYE=
+golang.org/x/mod v0.29.0 h1:HV8lRxZC4l2cr3Zq1LvtOsi/ThTgWnUk/y64QSs8GwA=
+golang.org/x/mod v0.29.0/go.mod h1:NyhrlYXJ2H4eJiRy/WDBO6HMqZQ6q9nk4JzS3NuCK+w=
 golang.org/x/net v0.47.0 h1:Mx+4dIFzqraBXUugkia1OOvlD6LemFo1ALMHjrXDOhY=
 golang.org/x/net v0.47.0/go.mod h1:/jNxtkgq5yWUGYkaZGqo27cfGZ1c5Nen03aYrrKpVRU=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

main.go

@@ -16,6 +16,7 @@ Usage:
 
 Available Commands:
   pack        Package the Go modules into an RPM spec file
+  update      Check existing Go module spec files for updates
   help        Show this help message
 
 Use "go2spec [command] --help" for more information about a command.
@@ -46,6 +47,8 @@ func main() {
 		println("Executing 'pack' command...")
 		// Actual packing logic would go here
 		mainPack(args[1:], nil)
+	case "update":
+		os.Exit(mainUpdate(args[1:]))
 	default:
 		// Default to 'pack' command if no command is provided
 		println("No command provided. Defaulting to 'pack' command...")

pack.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -48,6 +50,7 @@ type upstream struct {
 	hasGodeps    bool     // whether the Godeps/_workspace directory exists
 	hasRelease   bool     // whether any release tags exist, for debian/watch
 	isRelease    bool     // whether what we end up packaging is a tagged release
+	sha256       string   // SHA256 checksum of the source tarball
 }
 
 var errUnsupportedHoster = errors.New("unsupported hoster")
@@ -124,6 +127,24 @@ func downloadFile(filename, url string) error {
 	return nil
 }
 
+// fetchText fetches the content of a URL and returns it as a string.
+// Returns an error if the HTTP status is not 200.
+func fetchText(url string) (string, error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return "", fmt.Errorf("http get: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		return "", fmt.Errorf("response: %s", resp.Status)
+	}
+	body, err := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	if err != nil {
+		return "", fmt.Errorf("read body: %w", err)
+	}
+	return string(body), nil
+}
+
 // get downloads the source module into the provided GOPATH,
 // checking out the specified revision if non-empty.
 func (u *upstream) get(gopath, sourceRepo, requestedPath, rev string) error {
@@ -364,7 +385,131 @@ func (u *upstream) tarballFromHoster() error {
 
 	close(done)
 
-	return err
+	if err != nil {
+		return err
+	}
+
+	u.sha256 = u.fetchChecksumFromReleasePage()
+	if u.sha256 == "" {
+		sum, err := fileSHA256(u.tarPath)
+		if err != nil {
+			log.Printf("INFO: Could not compute source tarball sha256: %v", err)
+		} else {
+			u.sha256 = sum
+		}
+	}
+
+	return nil
+}
+
+// fetchChecksumFromReleasePage fetches the GitHub/GitLab release page and
+// attempts to extract a SHA-256 checksum for the source tarball from the
+// page content. Some projects include the checksum in the release body
+// markdown, e.g. "sha256: <hex>" or "SHA256: <hex>".
+func (u *upstream) fetchChecksumFromReleasePage() string {
+	releaseURL := u.releasePageURL()
+	if releaseURL == "" {
+		return ""
+	}
+
+	log.Printf("Fetching release page %s for checksum", releaseURL)
+	content, err := fetchText(releaseURL)
+	if err != nil {
+		log.Printf("INFO: Could not fetch release page: %v", err)
+		return ""
+	}
+
+	return extractSHA256FromHTML(content, u.tag)
+}
+
+// releasePageURL constructs the release page URL for the current tag.
+// For GitHub: https://github.com/{owner}/{repo}/releases/tag/{tag}
+// For GitLab: https://gitlab.com/{owner}/{repo}/-/releases/{tag}
+func (u *upstream) releasePageURL() string {
+	repo := strings.TrimSuffix(u.repoURL, ".git")
+	if repo == "" || u.tag == "" {
+		return ""
+	}
+	repoU, err := url.Parse(repo)
+	if err != nil {
+		return ""
+	}
+
+	switch repoU.Host {
+	case "github.com":
+		return fmt.Sprintf("%s/releases/tag/%s", repo, u.tag)
+	case "gitlab.com", "salsa.debian.org":
+		return fmt.Sprintf("%s/-/releases/%s", repo, u.tag)
+	default:
+		return ""
+	}
+}
+
+// extractSHA256FromHTML searches HTML content for a SHA-256 checksum
+// associated with the tarball for the given tag. It looks for patterns like:
+//
+//	sha256: <64-hex-chars>
+//	SHA256: <64-hex-chars>
+//	sha256sum: <64-hex-chars>
+//
+// It also tries to match checksums near tarball-related filenames.
+func extractSHA256FromHTML(html, tag string) string {
+	lower := strings.ToLower(html)
+
+	patterns := []*regexp.Regexp{
+		regexp.MustCompile(`sha-?256(?:sum)?[:\s]+([a-f0-9]{64})`),
+		regexp.MustCompile(`sha-?256(?:sum)?[:\s]*([a-f0-9]{64})`),
+	}
+
+	for _, re := range patterns {
+		if m := re.FindStringSubmatch(lower); len(m) > 1 && isValidSHA256(m[1]) {
+			return m[1]
+		}
+	}
+
+	// Fallback: look for a 64-char hex string near "tar" or "source" keywords
+	tarRe := regexp.MustCompile(`(?:tar|source)[^a-f0-9]{0,80}([a-f0-9]{64})`)
+	if m := tarRe.FindStringSubmatch(lower); len(m) > 1 {
+		if isValidSHA256(m[1]) {
+			return m[1]
+		}
+	}
+	revTarRe := regexp.MustCompile(`([a-f0-9]{64})[^a-f0-9]{0,80}(?:tar|source)`)
+	if m := revTarRe.FindStringSubmatch(lower); len(m) > 1 {
+		if isValidSHA256(m[1]) {
+			return m[1]
+		}
+	}
+
+	return ""
+}
+
+// isValidSHA256 reports whether s is a valid lowercase hexadecimal string
+// of exactly 64 characters (the length of a SHA-256 digest).
+func isValidSHA256(s string) bool {
+	if len(s) != 64 {
+		return false
+	}
+	for _, c := range s {
+		if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f')) {
+			return false
+		}
+	}
+	return true
+}
+
+func fileSHA256(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", fmt.Errorf("open: %w", err)
+	}
+	defer f.Close()
+
+	sum := sha256.New()
+	if _, err := io.Copy(sum, f); err != nil {
+		return "", fmt.Errorf("hash: %w", err)
+	}
+	return hex.EncodeToString(sum.Sum(nil)), nil
 }
 
 func (u *upstream) tar(gopath, repo string) error {

pkgsite.go

@@ -14,13 +14,14 @@ import (
 	"time"
 )
 
-const pkgsiteAPIBase = "https://pkg.go.dev/v1beta"
 const pkgsiteMaxResponseBytes = 20 << 20
 
 var (
+	pkgsiteAPIBase    = "https://pkg.go.dev/v1beta"
 	pkgsiteHTTPClient = http.DefaultClient
 	pkgsiteMu         sync.Mutex
 	pkgsiteInfoCache  = make(map[string]*pkgsiteInfo)
+	pkgsiteRetryLog   func(string)
 )
 
 type pkgsiteInfo struct {
@@ -105,8 +106,6 @@ func pkgsiteURL(endpoint, importPath string, values url.Values) string {
 	return u
 }
 
-// pkgsiteGetJSON performs a pkg.go.dev v1beta GET with up to 3 attempts and
-// linear backoff for transport errors, HTTP 429, and 5xx responses.
 func pkgsiteGetJSON(ctx context.Context, endpoint, importPath string, values url.Values, v any) error {
 	client := pkgsiteHTTPClient
 	if client == nil {
@@ -114,7 +113,7 @@ func pkgsiteGetJSON(ctx context.Context, endpoint, importPath string, values url
 	}
 
 	var lastErr error
-	for attempt := 1; attempt <= 3; attempt++ {
+	for attempt := 1; attempt <= 5; attempt++ {
 		req, err := http.NewRequestWithContext(ctx, http.MethodGet, pkgsiteURL(endpoint, importPath, values), nil)
 		if err != nil {
 			return fmt.Errorf("create pkgsite request: %w", err)
@@ -124,8 +123,13 @@ func pkgsiteGetJSON(ctx context.Context, endpoint, importPath string, values url
 		resp, err := client.Do(req)
 		if err != nil {
 			lastErr = fmt.Errorf("pkgsite request: %w", err)
-			if attempt < 3 {
+			if attempt < 5 {
-				time.Sleep(time.Duration(attempt) * time.Second)
+				backoff := time.Duration(attempt*2) * time.Second
+				reportPkgsiteRetry("  RETRY:  pkgsite %s %s request failed (%v), retry %d/5 in %s",
+					endpoint, importPath, err, attempt+1, backoff)
+				if err := sleepWithContext(ctx, backoff); err != nil {
+					return err
+				}
 				continue
 			}
 			return lastErr
@@ -148,8 +152,12 @@ func pkgsiteGetJSON(ctx context.Context, endpoint, importPath string, values url
 			apiErr.Code = resp.StatusCode
 			apiErr.Status = resp.Status
 			lastErr = &apiErr
-			if attempt < 3 && (resp.StatusCode == http.StatusTooManyRequests || resp.StatusCode >= 500) {
+			if attempt < 5 && (resp.StatusCode == http.StatusTooManyRequests || resp.StatusCode >= 500) {
-				time.Sleep(time.Duration(attempt) * time.Second)
+				backoff := pkgsiteRetryBackoff(resp, attempt)
+				reportPkgsiteStatusRetry(endpoint, importPath, resp.StatusCode, &apiErr, attempt+1, backoff)
+				if err := sleepWithContext(ctx, backoff); err != nil {
+					return err
+				}
 				continue
 			}
 			return lastErr
@@ -163,6 +171,75 @@ func pkgsiteGetJSON(ctx context.Context, endpoint, importPath string, values url
 	return lastErr
 }
 
+func sleepWithContext(ctx context.Context, d time.Duration) error {
+	if d <= 0 {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+			return nil
+		}
+	}
+
+	timer := time.NewTimer(d)
+	defer timer.Stop()
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-timer.C:
+		return nil
+	}
+}
+
+func pkgsiteRetryBackoff(resp *http.Response, attempt int) time.Duration {
+	if resp != nil && resp.StatusCode == http.StatusTooManyRequests {
+		if retryAfter, ok := parseRetryAfter(resp.Header.Get("Retry-After")); ok {
+			return retryAfter
+		}
+		return time.Duration(attempt*10) * time.Second
+	}
+	return time.Duration(attempt*5) * time.Second
+}
+
+func parseRetryAfter(v string) (time.Duration, bool) {
+	v = strings.TrimSpace(v)
+	if v == "" {
+		return 0, false
+	}
+	if seconds, err := time.ParseDuration(v + "s"); err == nil && seconds > 0 {
+		return seconds, true
+	}
+	for _, layout := range []string{time.RFC1123, time.RFC1123Z, time.RFC850, time.ANSIC} {
+		t, err := time.Parse(layout, v)
+		if err == nil {
+			delay := time.Until(t)
+			if delay > 0 {
+				return delay, true
+			}
+			return time.Second, true
+		}
+	}
+	return 0, false
+}
+
+func reportPkgsiteRetry(format string, args ...any) {
+	if pkgsiteRetryLog != nil {
+		pkgsiteRetryLog(fmt.Sprintf(format, args...))
+	}
+}
+
+func reportPkgsiteStatusRetry(endpoint, importPath string, statusCode int, apiErr *pkgsiteAPIError, nextAttempt int, backoff time.Duration) {
+	switch statusCode {
+	case http.StatusTooManyRequests:
+		reportPkgsiteRetry("  RATE:   %s limited on %s, retry %d/5 in %s",
+			importPath, endpoint, nextAttempt, backoff)
+	default:
+		reportPkgsiteRetry("  RETRY:  %s %s HTTP %d, retry %d/5 in %s",
+			importPath, endpoint, statusCode, nextAttempt, backoff)
+	}
+}
+
 func getPkgsitePackage(ctx context.Context, gopkg, modulePath string) (pkgsitePackage, error) {
 	values := url.Values{}
 	values.Set("imports", "true")

pkgsite_test.go

@@ -1,12 +1,16 @@
 package main
 
 import (
+	"context"
 	"io"
 	"net/http"
+	"net/http/httptest"
+	"net/url"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 )
@@ -62,6 +66,22 @@ func TestPkgsiteLicenseExpression(t *testing.T) {
 	}
 }
 
+func TestFileSHA256(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "archive.tar.gz")
+	if err := os.WriteFile(path, []byte("source archive"), 0o644); err != nil {
+		t.Fatalf("write archive: %v", err)
+	}
+
+	got, err := fileSHA256(path)
+	if err != nil {
+		t.Fatalf("fileSHA256: %v", err)
+	}
+	want := "6ad189ace456a83fade855d5a647cd8ad9e7966da4404b1187218dca3d9eddaa"
+	if got != want {
+		t.Fatalf("fileSHA256() = %q, want %q", got, want)
+	}
+}
+
 func TestPkgsiteLicenseFilePaths(t *testing.T) {
 	licenses := []pkgsiteLicense{
 		{FilePath: "License", Types: []string{"MIT"}},
@@ -538,3 +558,55 @@ func runGit(t *testing.T, dir string, env []string, args ...string) string {
 	}
 	return string(out)
 }
+
+func TestPkgsiteGetJSONLogsRateLimitRetry(t *testing.T) {
+	var mu sync.Mutex
+	var logs []string
+	attempts := 0
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.Header().Set("Retry-After", "1")
+			w.WriteHeader(http.StatusTooManyRequests)
+			_, _ = w.Write([]byte(`{"message":"slow down"}`))
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"path":"example.com/mod","version":"v1.2.3"}`))
+	}))
+	defer srv.Close()
+
+	oldBase := pkgsiteAPIBase
+	oldClient := pkgsiteHTTPClient
+	oldLog := pkgsiteRetryLog
+	t.Cleanup(func() {
+		pkgsiteAPIBase = oldBase
+		pkgsiteHTTPClient = oldClient
+		pkgsiteRetryLog = oldLog
+	})
+
+	pkgsiteAPIBase = srv.URL
+	pkgsiteHTTPClient = srv.Client()
+	pkgsiteRetryLog = func(msg string) {
+		mu.Lock()
+		defer mu.Unlock()
+		logs = append(logs, msg)
+	}
+
+	var mod pkgsiteModule
+	if err := pkgsiteGetJSON(context.Background(), "module", "example.com/mod", url.Values{}, &mod); err != nil {
+		t.Fatalf("pkgsiteGetJSON: %v", err)
+	}
+	if attempts != 2 {
+		t.Fatalf("expected 2 attempts, got %d", attempts)
+	}
+	mu.Lock()
+	defer mu.Unlock()
+	if len(logs) == 0 {
+		t.Fatal("expected rate limit log message")
+	}
+	if !strings.Contains(logs[0], "example.com/mod limited on module") || !strings.Contains(logs[0], "retry 2/5 in 1s") {
+		t.Fatalf("unexpected log message: %q", logs[0])
+	}
+}

spec.go

@@ -148,7 +148,11 @@ func writeSpec(dir, gopkg, openRuyiSrc, openRuyiLib, openRuyiProgram, version st
 	fmt.Fprintf(f, "Summary:        %s\n", description)
 	fmt.Fprintf(f, "License:        %s\n", license)
 	fmt.Fprintf(f, "URL:            %s\n", repoURL)
-	fmt.Fprintf(f, "#!RemoteAsset\n")
+	if u.sha256 != "" {
+		fmt.Fprintf(f, "#!RemoteAsset:  sha256:%s\n", u.sha256)
+	} else {
+		fmt.Fprintf(f, "#!RemoteAsset\n")
+	}
 	sourceModulePath := u.modulePath
 	if sourceModulePath == "" {
 		sourceModulePath = gopkg

update.go

@@ -0,0 +1,625 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"regexp"
+	"strings"
+	"time"
+
+	"golang.org/x/mod/semver"
+)
+
+var downloadRetryLog func(string)
+
+var errRemoteAssetSkip = errors.New("skip remote asset sha256")
+
+type downloadCandidate struct {
+	source string
+	url    string
+}
+
+func repoRefForVersion(version string) string {
+	v := strings.TrimSpace(version)
+	if !strings.HasPrefix(v, "v") {
+		v = "v" + v
+	}
+	if canonical := semver.Canonical(v); canonical != "" {
+		return canonical
+	}
+	return v
+}
+
+func specVersionForVersion(version string) string {
+	return strings.TrimPrefix(repoRefForVersion(version), "v")
+}
+
+func verifyDownload(ctx context.Context, spec *specInfo) error {
+	if spec.GoImportPath == "" {
+		return fmt.Errorf("no go_import_path")
+	}
+	if spec.LatestVersion == "" {
+		return fmt.Errorf("no latest version")
+	}
+
+	info, err := getPkgsiteInfo(ctx, spec.GoImportPath)
+	if err != nil {
+		return fmt.Errorf("get pkgsite info: %w", err)
+	}
+
+	candidates, archiveErr, err := downloadCandidatesForSpec(spec, info)
+	if err != nil {
+		return err
+	}
+	if archiveErr != nil {
+		reportDownloadRetry("  FALLBACK: %s repo archive unavailable (%v), trying module proxy",
+			spec.GoImportPath, archiveErr)
+	}
+	return verifyDownloadCandidates(ctx, spec.GoImportPath, candidates)
+}
+
+func downloadCandidatesForSpec(spec *specInfo, info *pkgsiteInfo) ([]downloadCandidate, error, error) {
+	repoURL := gitCloneURLFromRepoURL(info.Module.RepoURL)
+	if repoURL == "" {
+		return nil, nil, fmt.Errorf("no repository URL")
+	}
+
+	version := spec.LatestVersion
+	if !strings.HasPrefix(version, "v") {
+		version = "v" + version
+	}
+	repoRef := repoRefForVersion(version)
+	sourceModulePath := sourceImportPathForPackage(spec.GoImportPath, info)
+	proxyURL := fmt.Sprintf("https://proxy.golang.org/%s/@v/%s.zip",
+		moduleProxyEscapedPath(sourceModulePath),
+		moduleProxyVersionForSpec(version))
+
+	if moduleUsesRepoSubdir(sourceModulePath, repoURL) {
+		return []downloadCandidate{
+			{source: "proxy", url: proxyURL},
+		}, nil, nil
+	}
+
+	tarURL, err := (&upstream{repoURL: repoURL}).tarballURLForRef(repoRef, "gz")
+	if err != nil {
+		return []downloadCandidate{
+			{source: "proxy", url: proxyURL},
+		}, err, nil
+	}
+
+	return []downloadCandidate{
+		{source: "repo", url: tarURL},
+		{source: "proxy", url: proxyURL},
+	}, nil, nil
+}
+
+func remoteAssetSHA256(ctx context.Context, spec *specInfo, newVersion string) (string, error) {
+	sourceURL, err := resolvedSource0URL(spec.FilePath, sourceVersionForSpec(newVersion))
+	if err != nil {
+		return "", err
+	}
+	releaseURL, tag := releasePageURLForSource(sourceURL)
+	if releaseURL == "" {
+		reportDownloadRetry("  HASH:   %s no release checksum page, downloading Source0", spec.GoImportPath)
+		return downloadAssetSHA256(ctx, sourceURL)
+	}
+	content, err := fetchTextContext(ctx, releaseURL)
+	if err == nil {
+		if sum := extractSHA256FromHTML(content, tag); sum != "" {
+			return sum, nil
+		}
+	}
+	reportDownloadRetry("  HASH:   %s release checksum unavailable, downloading Source0", spec.GoImportPath)
+	return downloadAssetSHA256(ctx, sourceURL)
+}
+
+func sourceVersionForSpec(version string) string {
+	return specVersionForVersion(version)
+}
+
+func verifyDownloadCandidates(ctx context.Context, importPath string, candidates []downloadCandidate) error {
+	var errs []string
+	for i, candidate := range candidates {
+		err := verifyHTTPRequest(ctx, candidate.url)
+		if err == nil {
+			if i > 0 {
+				reportDownloadRetry("  OK:     %s verified via %s after fallback", importPath, candidate.source)
+			}
+			return nil
+		}
+		errs = append(errs, fmt.Sprintf("%s: %v", candidate.source, err))
+		if i+1 < len(candidates) {
+			reportDownloadRetry("  FALLBACK: %s %s probe failed (%v), trying %s",
+				importPath, candidate.source, err, candidates[i+1].source)
+		}
+	}
+	return errors.New(strings.Join(errs, "; "))
+}
+
+func verifyHTTPRequest(ctx context.Context, downloadURL string) error {
+	var lastErr error
+	for attempt := 1; attempt <= 3; attempt++ {
+		if err := verifyHTTPHead(ctx, downloadURL); err == nil {
+			return nil
+		} else {
+			lastErr = err
+		}
+		if err := verifyHTTPRangeGet(ctx, downloadURL); err == nil {
+			return nil
+		} else {
+			lastErr = err
+		}
+		if attempt < 3 && isRetryableDownloadError(lastErr) {
+			backoff := time.Duration(attempt*2) * time.Second
+			reportDownloadRetry("  RETRY:  download probe %s failed (%v), retry %d/3 in %s",
+				downloadURL, lastErr, attempt+1, backoff)
+			if err := sleepWithContext(ctx, backoff); err != nil {
+				return err
+			}
+			continue
+		}
+		break
+	}
+	return lastErr
+}
+
+func verifyHTTPHead(ctx context.Context, downloadURL string) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodHead, downloadURL, nil)
+	if err != nil {
+		return fmt.Errorf("create HEAD request: %w", err)
+	}
+
+	client := &http.Client{Timeout: 30 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("HEAD request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
+		return fmt.Errorf("HTTP %d from %s", resp.StatusCode, downloadURL)
+	}
+
+	if resp.ContentLength == 0 {
+		return fmt.Errorf("HEAD response has no content length from %s", downloadURL)
+	}
+
+	return nil
+}
+
+func verifyHTTPRangeGet(ctx context.Context, downloadURL string) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, nil)
+	if err != nil {
+		return fmt.Errorf("create GET request: %w", err)
+	}
+	req.Header.Set("Range", "bytes=0-0")
+
+	client := &http.Client{Timeout: 30 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("GET request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
+		return fmt.Errorf("HTTP %d from %s", resp.StatusCode, downloadURL)
+	}
+
+	buf := make([]byte, 1)
+	n, err := resp.Body.Read(buf)
+	if err != nil && err != io.EOF {
+		return fmt.Errorf("read download probe: %w", err)
+	}
+	if n == 0 {
+		return fmt.Errorf("empty download from %s", downloadURL)
+	}
+
+	return nil
+}
+
+func isRetryableDownloadError(err error) bool {
+	if err == nil {
+		return false
+	}
+	var netErr net.Error
+	if errors.As(err, &netErr) && (netErr.Timeout() || netErr.Temporary()) {
+		return true
+	}
+	msg := err.Error()
+	return strings.Contains(msg, "context deadline exceeded") ||
+		strings.Contains(msg, "Client.Timeout exceeded") ||
+		strings.Contains(msg, "connection reset by peer") ||
+		strings.Contains(msg, "EOF") ||
+		strings.Contains(msg, "HTTP 408") ||
+		strings.Contains(msg, "HTTP 425") ||
+		strings.Contains(msg, "HTTP 429") ||
+		strings.Contains(msg, "HTTP 500") ||
+		strings.Contains(msg, "HTTP 502") ||
+		strings.Contains(msg, "HTTP 503") ||
+		strings.Contains(msg, "HTTP 504")
+}
+
+func reportDownloadRetry(format string, args ...any) {
+	if downloadRetryLog != nil {
+		downloadRetryLog(fmt.Sprintf(format, args...))
+	}
+}
+
+func readSpecLines(path string) ([]string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var lines []string
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+	return lines, scanner.Err()
+}
+
+func writeSpecLines(path string, lines []string) error {
+	f, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	w := bufio.NewWriter(f)
+	for i, line := range lines {
+		if _, err := w.WriteString(line); err != nil {
+			return err
+		}
+		if i < len(lines)-1 {
+			if _, err := w.WriteString("\n"); err != nil {
+				return err
+			}
+		}
+	}
+	if len(lines) > 0 {
+		if _, err := w.WriteString("\n"); err != nil {
+			return err
+		}
+	}
+	return w.Flush()
+}
+
+func updateSpecVersion(spec *specInfo, newVersion, remoteSHA256 string, updateRemoteAsset bool) error {
+	lines, err := readSpecLines(spec.FilePath)
+	if err != nil {
+		return err
+	}
+
+	versionLineRe := regexp.MustCompile(`^(\s*Version:\s*)(\S+)(.*)$`)
+	autoChangelogRe := regexp.MustCompile(`^(\s*)%\{\?autochangelog\}(\s*)$`)
+	remoteAssetHashRe := regexp.MustCompile(`^(\s*)#!RemoteAsset(?::\s*sha256:[0-9a-fA-F]+)?(\s*)$`)
+	source0LineRe := regexp.MustCompile(`^(\s*Source0:\s*)(\S+)(.*)$`)
+	updated := false
+	source0Index := -1
+	source0RemoteAssetIndex := -1
+	for i, line := range lines {
+		matches := versionLineRe.FindStringSubmatch(line)
+		if len(matches) == 4 {
+			lines[i] = matches[1] + newVersion + matches[3]
+			updated = true
+		}
+		matches = autoChangelogRe.FindStringSubmatch(line)
+		if len(matches) == 3 {
+			lines[i] = matches[1] + "%autochangelog" + matches[2]
+		}
+		if source0Index < 0 && source0LineRe.MatchString(line) {
+			source0Index = i
+			if i > 0 && remoteAssetHashRe.MatchString(lines[i-1]) {
+				source0RemoteAssetIndex = i - 1
+			}
+		}
+	}
+	if !updated {
+		return fmt.Errorf("Version line not found in %s", spec.FilePath)
+	}
+	if !updateRemoteAsset {
+		return writeSpecLines(spec.FilePath, lines)
+	}
+	if source0RemoteAssetIndex >= 0 {
+		matches := remoteAssetHashRe.FindStringSubmatch(lines[source0RemoteAssetIndex])
+		if remoteSHA256 != "" {
+			lines[source0RemoteAssetIndex] = matches[1] + "#!RemoteAsset:  sha256:" + remoteSHA256 + matches[2]
+		} else {
+			lines[source0RemoteAssetIndex] = matches[1] + "#!RemoteAsset" + matches[2]
+		}
+	} else if source0Index >= 0 {
+		insert := "#!RemoteAsset"
+		if remoteSHA256 != "" {
+			insert = "#!RemoteAsset:  sha256:" + remoteSHA256
+		}
+		lines = append(lines[:source0Index], append([]string{insert}, lines[source0Index:]...)...)
+	}
+
+	return writeSpecLines(spec.FilePath, lines)
+}
+
+type downloadResult struct {
+	spec *specInfo
+	err  error
+}
+
+func verifyAndUpdateSpec(ctx context.Context, spec *specInfo, dryRun bool) error {
+	err := verifyDownload(ctx, spec)
+	if err != nil {
+		return fmt.Errorf("download verification failed: %w", err)
+	}
+
+	if !dryRun {
+		newVer := specVersionForVersion(spec.LatestVersion)
+		remoteSHA256, err := remoteAssetSHA256(ctx, spec, newVer)
+		updateRemoteAsset := true
+		if errors.Is(err, errRemoteAssetSkip) {
+			updateRemoteAsset = false
+			err = nil
+		}
+		if err != nil {
+			return fmt.Errorf("compute remote asset sha256: %w", err)
+		}
+
+		if err := updateSpecVersion(spec, newVer, remoteSHA256, updateRemoteAsset); err != nil {
+			return fmt.Errorf("update spec file: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func processUpdate(ctx context.Context, spec *specInfo, dryRun bool) error {
+	err := verifyDownload(ctx, spec)
+	if err != nil {
+		return err
+	}
+
+	if !dryRun {
+		newVer := specVersionForVersion(spec.LatestVersion)
+		remoteSHA256, err := remoteAssetSHA256(ctx, spec, newVer)
+		updateRemoteAsset := true
+		if errors.Is(err, errRemoteAssetSkip) {
+			updateRemoteAsset = false
+			err = nil
+		}
+		if err != nil {
+			return fmt.Errorf("compute remote asset sha256: %w", err)
+		}
+
+		if err := updateSpecVersion(spec, newVer, remoteSHA256, updateRemoteAsset); err != nil {
+			return fmt.Errorf("update spec file: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func resolvedSource0URL(path, newVersion string) (string, error) {
+	lines, err := readSpecLines(path)
+	if err != nil {
+		return "", err
+	}
+
+	macros := make(map[string]string)
+	defineRe := regexp.MustCompile(`^%(?:define|global)\s+(\S+)\s+(.+)$`)
+	fieldRe := regexp.MustCompile(`^(Name|Version):\s+(\S+)`)
+	source0Re := regexp.MustCompile(`^Source0:\s+(\S+)`)
+
+	for _, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		if matches := defineRe.FindStringSubmatch(trimmed); len(matches) == 3 {
+			macros[matches[1]] = strings.TrimSpace(matches[2])
+			continue
+		}
+		if matches := fieldRe.FindStringSubmatch(trimmed); len(matches) == 3 {
+			switch matches[1] {
+			case "Name":
+				macros["name"] = matches[2]
+			case "Version":
+				macros["version"] = newVersion
+			}
+			continue
+		}
+		if matches := source0Re.FindStringSubmatch(trimmed); len(matches) == 2 {
+			if source0UsesPinnedCommit(matches[1]) {
+				return "", fmt.Errorf("%w: Source0 uses pinned commit_id", errRemoteAssetSkip)
+			}
+			macros["version"] = newVersion
+			resolved := expandRPMMacros(matches[1], macros, 16)
+			if strings.Contains(resolved, "%{") {
+				return "", fmt.Errorf("unresolved Source0 macros in %s: %s", path, resolved)
+			}
+			return strings.SplitN(resolved, "#", 2)[0], nil
+		}
+	}
+
+	return "", fmt.Errorf("Source0 line not found in %s", path)
+}
+
+func source0UsesPinnedCommit(source string) bool {
+	return strings.Contains(source, "%{commit_id}") || strings.Contains(source, "%{?commit_id}")
+}
+
+func expandRPMMacros(s string, macros map[string]string, limit int) string {
+	re := regexp.MustCompile(`%\{(\??)([^}]+)\}`)
+	expanded := s
+	for i := 0; i < limit; i++ {
+		changed := false
+		next := re.ReplaceAllStringFunc(expanded, func(match string) string {
+			parts := re.FindStringSubmatch(match)
+			if len(parts) != 3 {
+				return match
+			}
+			optional := parts[1] == "?"
+			name := parts[2]
+			value, ok := macros[name]
+			if !ok {
+				if optional {
+					changed = true
+					return ""
+				}
+				return match
+			}
+			changed = true
+			return value
+		})
+		expanded = next
+		if !changed {
+			break
+		}
+	}
+	return expanded
+}
+
+func releasePageURLForSource(sourceURL string) (releaseURL, tag string) {
+	u, err := url.Parse(sourceURL)
+	if err != nil {
+		return "", ""
+	}
+
+	tag = sourceTagFromURLPath(u.Path)
+	if tag == "" {
+		return "", ""
+	}
+
+	parts := strings.Split(strings.Trim(u.Path, "/"), "/")
+	switch u.Host {
+	case "github.com":
+		if len(parts) < 2 {
+			return "", ""
+		}
+		repo := fmt.Sprintf("%s://%s/%s/%s", u.Scheme, u.Host, parts[0], parts[1])
+		return fmt.Sprintf("%s/releases/tag/%s", repo, tag), tag
+	case "gitlab.com", "salsa.debian.org":
+		dashArchive := -1
+		for i := 0; i+1 < len(parts); i++ {
+			if parts[i] == "-" && parts[i+1] == "archive" {
+				dashArchive = i
+				break
+			}
+		}
+		if dashArchive <= 0 {
+			return "", ""
+		}
+		repo := fmt.Sprintf("%s://%s/%s", u.Scheme, u.Host, strings.Join(parts[:dashArchive], "/"))
+		return fmt.Sprintf("%s/-/releases/%s", repo, tag), tag
+	default:
+		return "", ""
+	}
+}
+
+func sourceTagFromURLPath(path string) string {
+	path, err := url.PathUnescape(path)
+	if err != nil {
+		return ""
+	}
+
+	const refsPrefix = "refs/tags/"
+	parts := strings.Split(strings.Trim(path, "/"), "/")
+	for i, part := range parts {
+		if part != "archive" || i+1 >= len(parts) {
+			continue
+		}
+		rest := strings.Join(parts[i+1:], "/")
+		if strings.HasPrefix(rest, refsPrefix) {
+			return trimArchiveSuffix(strings.TrimPrefix(rest, refsPrefix))
+		}
+		if idx := strings.Index(rest, "/"); idx >= 0 {
+			rest = rest[:idx]
+		}
+		return trimArchiveSuffix(rest)
+	}
+	return ""
+}
+
+func trimArchiveSuffix(s string) string {
+	for _, suffix := range []string{".tar.gz", ".tar.xz", ".tar.bz2", ".tgz", ".zip"} {
+		if strings.HasSuffix(s, suffix) {
+			return strings.TrimSuffix(s, suffix)
+		}
+	}
+	return s
+}
+
+func fetchTextContext(ctx context.Context, fetchURL string) (string, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fetchURL, nil)
+	if err != nil {
+		return "", fmt.Errorf("create GET request: %w", err)
+	}
+
+	client := &http.Client{Timeout: 30 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("GET request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("HTTP %d from %s", resp.StatusCode, fetchURL)
+	}
+
+	body, err := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	if err != nil {
+		return "", fmt.Errorf("read response: %w", err)
+	}
+	return string(body), nil
+}
+
+func downloadAssetSHA256(ctx context.Context, downloadURL string) (string, error) {
+	var lastErr error
+	for attempt := 1; attempt <= 3; attempt++ {
+		sum, err := fetchSHA256(ctx, downloadURL)
+		if err == nil {
+			return sum, nil
+		}
+		lastErr = err
+		if attempt < 3 && isRetryableDownloadError(lastErr) {
+			backoff := time.Duration(attempt*2) * time.Second
+			reportDownloadRetry("  RETRY:  asset hash %s failed (%v), retry %d/3 in %s",
+				downloadURL, lastErr, attempt+1, backoff)
+			if err := sleepWithContext(ctx, backoff); err != nil {
+				return "", err
+			}
+			continue
+		}
+		break
+	}
+	return "", lastErr
+}
+
+func fetchSHA256(ctx context.Context, downloadURL string) (string, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, nil)
+	if err != nil {
+		return "", fmt.Errorf("create GET request: %w", err)
+	}
+
+	client := &http.Client{Timeout: 120 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("GET request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
+		return "", fmt.Errorf("HTTP %d from %s", resp.StatusCode, downloadURL)
+	}
+
+	sum := sha256.New()
+	if _, err := io.Copy(sum, resp.Body); err != nil {
+		return "", fmt.Errorf("read download for sha256: %w", err)
+	}
+
+	return hex.EncodeToString(sum.Sum(nil)), nil
+}

update_cli.go

@@ -0,0 +1,492 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"flag"
+	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/mattn/go-isatty"
+	"github.com/sandrolain/httpcache"
+	"golang.org/x/mod/semver"
+)
+
+type specInfo struct {
+	FilePath      string
+	GoImportPath  string
+	Version       string
+	Name          string
+	Source0       string
+	LatestVersion string
+	HasUpdate     bool
+	Error         string
+}
+
+func parseSpecFile(path string) (*specInfo, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	info := &specInfo{FilePath: path}
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if strings.HasPrefix(line, "#") {
+			continue
+		}
+		if strings.HasPrefix(line, "%define go_import_path") || strings.HasPrefix(line, "%global go_import_path") {
+			parts := strings.Fields(line)
+			if len(parts) >= 3 {
+				info.GoImportPath = parts[2]
+			}
+		}
+		if strings.HasPrefix(line, "%define _name") || strings.HasPrefix(line, "%global _name") {
+			parts := strings.Fields(line)
+			if len(parts) >= 3 {
+				info.Name = parts[2]
+			}
+		}
+		if strings.HasPrefix(line, "Version:") {
+			parts := strings.Fields(line)
+			if len(parts) >= 2 {
+				info.Version = parts[1]
+			}
+		}
+		if strings.HasPrefix(line, "Source0:") {
+			parts := strings.Fields(line)
+			if len(parts) >= 2 {
+				info.Source0 = parts[1]
+			}
+		}
+	}
+	return info, scanner.Err()
+}
+
+func normalizeVersion(v string) string {
+	v = strings.TrimSpace(v)
+	if !strings.HasPrefix(v, "v") {
+		v = "v" + v
+	}
+	if semver.IsValid(v) {
+		return v
+	}
+	return ""
+}
+
+func checkLatestVersion(ctx context.Context, spec *specInfo) {
+	if spec.GoImportPath == "" {
+		spec.Error = "no go_import_path"
+		return
+	}
+	info, err := getPkgsiteInfo(ctx, spec.GoImportPath)
+	if err != nil {
+		spec.Error = fmt.Sprintf("pkgsite error: %v", err)
+		return
+	}
+	latestPkgVer := info.Package.Version
+	latestModVer := info.Module.Version
+	latestVer := latestPkgVer
+	if latestModVer != "" && (latestVer == "" || semver.Compare(normalizeVersion(latestModVer), normalizeVersion(latestVer)) > 0) {
+		latestVer = latestModVer
+	}
+	spec.LatestVersion = latestVer
+	currentNorm := normalizeVersion(spec.Version)
+	latestNorm := normalizeVersion(latestVer)
+	if currentNorm == "" || latestNorm == "" {
+		spec.HasUpdate = false
+		return
+	}
+	spec.HasUpdate = semver.Compare(latestNorm, currentNorm) > 0
+}
+
+func scanSpecDir(specDir string) ([]*specInfo, error) {
+	entries, err := os.ReadDir(specDir)
+	if err != nil {
+		return nil, err
+	}
+	var specs []*specInfo
+	for _, entry := range entries {
+		if !entry.IsDir() || !strings.HasPrefix(entry.Name(), "go-") {
+			continue
+		}
+		specFiles, err := filepath.Glob(filepath.Join(specDir, entry.Name(), "*.spec"))
+		if err != nil {
+			continue
+		}
+		for _, sf := range specFiles {
+			spec, err := parseSpecFile(sf)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Warning: failed to parse %s: %v\n", sf, err)
+				continue
+			}
+			if spec.GoImportPath != "" {
+				specs = append(specs, spec)
+			}
+		}
+	}
+	return specs, nil
+}
+
+func printBox(title string, lines []string) {
+	width := 56
+	contentWidth := width - 4
+	fmt.Println("+" + strings.Repeat("-", width) + "+")
+	if title != "" {
+		padding := width - len(title)
+		left := padding / 2
+		right := padding - left
+		fmt.Printf("|%s%s%s|\n", strings.Repeat(" ", left), title, strings.Repeat(" ", right))
+		fmt.Println("+" + strings.Repeat("-", width) + "+")
+	}
+	for _, line := range lines {
+		if len(line) > contentWidth {
+			line = line[:contentWidth-3] + "..."
+		}
+		fmt.Printf("|  %-*s  |\n", contentWidth, line)
+	}
+	fmt.Println("+" + strings.Repeat("-", width) + "+")
+}
+
+type outputMsg struct {
+	text string
+}
+
+type counters struct {
+	scanned    int32
+	withUpdate int32
+	scanErrors int32
+	modified   int32
+	processed  int32
+	dlErrors   int32
+	upErrors   int32
+	total      int
+}
+
+type outputLoop struct {
+	ch             chan outputMsg
+	counts         *counters
+	done           chan struct{}
+	exited         chan struct{}
+	lastProgress   []string
+	interactiveTTY bool
+	progressShown  int
+}
+
+func newOutputLoop(c *counters) *outputLoop {
+	return &outputLoop{
+		ch:             make(chan outputMsg, 64),
+		counts:         c,
+		done:           make(chan struct{}),
+		exited:         make(chan struct{}),
+		interactiveTTY: isatty.IsTerminal(os.Stdout.Fd()) || isatty.IsCygwinTerminal(os.Stdout.Fd()),
+	}
+}
+
+func (o *outputLoop) start() {
+	go o.loop()
+}
+
+func (o *outputLoop) loop() {
+	defer close(o.exited)
+	ticker := time.NewTicker(200 * time.Millisecond)
+	defer ticker.Stop()
+	for {
+		select {
+		case msg := <-o.ch:
+			o.printMessage(msg.text)
+		case <-ticker.C:
+			o.maybePrintProgress()
+		case <-o.done:
+			for {
+				select {
+				case msg := <-o.ch:
+					o.printMessage(msg.text)
+				default:
+					o.clearProgress()
+					return
+				}
+			}
+		}
+	}
+}
+
+func (o *outputLoop) maybePrintProgress() {
+	progress := o.currentProgressLines()
+	if sameProgressLines(progress, o.lastProgress) {
+		return
+	}
+	o.lastProgress = append(o.lastProgress[:0], progress...)
+
+	if o.interactiveTTY {
+		o.renderProgress(progress)
+		return
+	}
+
+	for _, line := range progress {
+		fmt.Println(line)
+	}
+}
+
+func (o *outputLoop) currentProgressLines() []string {
+	c := o.counts
+	scanned := atomic.LoadInt32(&c.scanned)
+	withUpdate := atomic.LoadInt32(&c.withUpdate)
+	scanErrors := atomic.LoadInt32(&c.scanErrors)
+	processed := atomic.LoadInt32(&c.processed)
+	modified := atomic.LoadInt32(&c.modified)
+	dlErrors := atomic.LoadInt32(&c.dlErrors)
+	upErrors := atomic.LoadInt32(&c.upErrors)
+
+	return []string{
+		fmt.Sprintf("  [scan]   %d/%d  updates:%d  errors:%d",
+			scanned, c.total, withUpdate, scanErrors),
+		fmt.Sprintf("  [verify] %d/%d  modified:%d  errors:%d",
+			processed, withUpdate, modified, dlErrors+upErrors),
+	}
+}
+
+func (o *outputLoop) print(text string) {
+	o.ch <- outputMsg{text: text}
+}
+
+func (o *outputLoop) stop() {
+	close(o.done)
+	<-o.exited
+}
+
+func (o *outputLoop) printMessage(text string) {
+	o.clearProgress()
+	fmt.Println(text)
+	if o.interactiveTTY {
+		progress := o.currentProgressLines()
+		o.lastProgress = append(o.lastProgress[:0], progress...)
+		o.renderProgress(progress)
+	}
+}
+
+func (o *outputLoop) clearProgress() {
+	if o.interactiveTTY && o.progressShown > 0 {
+		fmt.Print("\r\033[2K")
+		for i := 1; i < o.progressShown; i++ {
+			fmt.Print("\033[1A\r\033[2K")
+		}
+		o.progressShown = 0
+	}
+}
+
+func (o *outputLoop) renderProgress(lines []string) {
+	o.clearProgress()
+	for i, line := range lines {
+		if i > 0 {
+			fmt.Print("\n")
+		}
+		fmt.Print(line)
+	}
+	o.progressShown = len(lines)
+}
+
+func sameProgressLines(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func mainUpdate(args []string) int {
+	fs := flag.NewFlagSet("update", flag.ContinueOnError)
+	fs.SetOutput(os.Stderr)
+	concurrency := fs.Int("j", 3, "number of concurrent checks")
+	dryRun := fs.Bool("n", false, "dry run: detect updates only, do not modify files")
+	fs.Usage = func() {
+		fmt.Fprintf(fs.Output(), "Usage: %s update [options] <SPECS_DIR>\n\n", os.Args[0])
+		fmt.Fprintf(fs.Output(), "Check Go module spec files for updates.\n\n")
+		fmt.Fprintf(fs.Output(), "Arguments:\n")
+		fmt.Fprintf(fs.Output(), "  SPECS_DIR    directory containing go-* subdirectories\n\n")
+		fmt.Fprintf(fs.Output(), "Options:\n")
+		fs.PrintDefaults()
+	}
+	if err := fs.Parse(args); err != nil {
+		if errors.Is(err, flag.ErrHelp) {
+			return 0
+		}
+		return 2
+	}
+	if *concurrency < 1 {
+		*concurrency = 1
+	}
+	if fs.NArg() != 1 {
+		fs.Usage()
+		return 1
+	}
+
+	specDir := fs.Arg(0)
+	specs, err := scanSpecDir(specDir)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error scanning spec dir: %v\n", err)
+		return 1
+	}
+	if len(specs) == 0 {
+		fmt.Fprintf(os.Stderr, "No spec files with go_import_path found in %s\n", specDir)
+		return 1
+	}
+
+	pkgsiteHTTPClient = &http.Client{
+		Timeout:   30 * time.Second,
+		Transport: httpcache.NewMemoryCacheTransport(),
+	}
+
+	ctx := context.Background()
+	total := len(specs)
+	c := &counters{total: total}
+
+	out := newOutputLoop(c)
+	out.start()
+	pkgsiteRetryLog = out.print
+	downloadRetryLog = out.print
+
+	fmt.Printf("Checking %d spec files for updates...\n", total)
+	fmt.Printf("Parameters: spec_dir=%s  concurrency=%d  dry_run=%t\n", specDir, *concurrency, *dryRun)
+
+	updateCh := make(chan *specInfo, *concurrency)
+
+	var wg2 sync.WaitGroup
+	if !*dryRun {
+		for i := 0; i < *concurrency; i++ {
+			wg2.Add(1)
+			go func() {
+				defer wg2.Done()
+				for sp := range updateCh {
+					err := verifyDownload(ctx, sp)
+					if err != nil {
+						sp.Error = err.Error()
+						out.print(fmt.Sprintf("  FAIL:   %s - %v", sp.GoImportPath, err))
+						atomic.AddInt32(&c.dlErrors, 1)
+					} else {
+						newVer := specVersionForVersion(sp.LatestVersion)
+						remoteSHA256, err := remoteAssetSHA256(ctx, sp, newVer)
+						updateRemoteAsset := true
+						if errors.Is(err, errRemoteAssetSkip) {
+							out.print(fmt.Sprintf("  SKIP:   %s remote asset sha256 - %v", sp.GoImportPath, err))
+							updateRemoteAsset = false
+							err = nil
+						}
+						if err != nil {
+							sp.Error = err.Error()
+							out.print(fmt.Sprintf("  FAIL:   %s - %v", sp.GoImportPath, err))
+							atomic.AddInt32(&c.upErrors, 1)
+						} else if err := updateSpecVersion(sp, newVer, remoteSHA256, updateRemoteAsset); err != nil {
+							sp.Error = err.Error()
+							out.print(fmt.Sprintf("  FAIL:   %s - %v", sp.GoImportPath, err))
+							atomic.AddInt32(&c.upErrors, 1)
+						} else {
+							atomic.AddInt32(&c.modified, 1)
+							out.print(fmt.Sprintf("  OK:     %s updated to %s", sp.GoImportPath, newVer))
+						}
+					}
+					atomic.AddInt32(&c.processed, 1)
+				}
+			}()
+		}
+	}
+
+	var wg1 sync.WaitGroup
+	sem1 := make(chan struct{}, *concurrency)
+
+	for _, spec := range specs {
+		wg1.Add(1)
+		sem1 <- struct{}{}
+		go func(s *specInfo) {
+			defer wg1.Done()
+			defer func() { <-sem1 }()
+
+			checkLatestVersion(ctx, s)
+
+			atomic.AddInt32(&c.scanned, 1)
+			needSend := false
+
+			if s.Error != "" {
+				atomic.AddInt32(&c.scanErrors, 1)
+				out.print(fmt.Sprintf("  ERROR:  %s - %s", s.GoImportPath, s.Error))
+			} else if s.HasUpdate {
+				atomic.AddInt32(&c.withUpdate, 1)
+				out.print(fmt.Sprintf("  UPDATE: %-50s  %s -> %s", s.GoImportPath, s.Version, s.LatestVersion))
+				needSend = true
+			}
+
+			if needSend && !*dryRun {
+				updateCh <- s
+			}
+		}(spec)
+	}
+
+	wg1.Wait()
+	close(updateCh)
+
+	if !*dryRun {
+		wg2.Wait()
+	}
+
+	pkgsiteRetryLog = nil
+	downloadRetryLog = nil
+	out.stop()
+
+	var errSpecs []*specInfo
+	for _, s := range specs {
+		if s.Error != "" {
+			errSpecs = append(errSpecs, s)
+		}
+	}
+
+	summaryLines := []string{
+		fmt.Sprintf("%-12s  %d/%d", "Scanned:", total, total),
+		fmt.Sprintf("%-12s  %d", "Updates:", atomic.LoadInt32(&c.withUpdate)),
+		fmt.Sprintf("%-12s  %d", "Modified:", atomic.LoadInt32(&c.modified)),
+	}
+	if atomic.LoadInt32(&c.scanErrors) > 0 || atomic.LoadInt32(&c.dlErrors) > 0 || atomic.LoadInt32(&c.upErrors) > 0 {
+		totalErrors := atomic.LoadInt32(&c.scanErrors) + atomic.LoadInt32(&c.dlErrors) + atomic.LoadInt32(&c.upErrors)
+		summaryLines = append(summaryLines, fmt.Sprintf("%-12s  %d", "Errors:", totalErrors))
+	}
+	if *dryRun {
+		summaryLines = append(summaryLines, fmt.Sprintf("%-12s  %s", "Mode:", "dry run"))
+	}
+	fmt.Println()
+	printBox("SUMMARY", summaryLines)
+
+	if atomic.LoadInt32(&c.withUpdate) == 0 {
+		fmt.Println("\nAll modules are up to date.")
+	} else if *dryRun {
+		fmt.Println("\nDry run complete. No files were modified.")
+	} else {
+		fmt.Println()
+		printBox("UPDATE RESULT", []string{
+			fmt.Sprintf("%-12s  %d", "Attempted:", atomic.LoadInt32(&c.withUpdate)),
+			fmt.Sprintf("%-12s  %d", "Modified:", atomic.LoadInt32(&c.modified)),
+			fmt.Sprintf("%-12s  %d", "Dl errors:", atomic.LoadInt32(&c.dlErrors)),
+			fmt.Sprintf("%-12s  %d", "Up errors:", atomic.LoadInt32(&c.upErrors)),
+		})
+	}
+
+	if len(errSpecs) > 0 {
+		fmt.Printf("\n=== %d modules with errors ===\n", len(errSpecs))
+		for _, s := range errSpecs {
+			fmt.Printf("  %-50s  %s\n", s.GoImportPath, s.Error)
+		}
+	}
+
+	return 0
+}

update_test.go

@@ -0,0 +1,456 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"testing"
+)
+
+func TestUpdateSpecVersionPreservesFormatting(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	specPath := filepath.Join(dir, "test.spec")
+	original := strings.Join([]string{
+		"Name:           golang-test",
+		"Version:\t1.2.3  # keep-comment",
+		"Release:        1%{?dist}",
+		"%changelog",
+		"%{?autochangelog}",
+	}, "\n")
+	if err := os.WriteFile(specPath, []byte(original), 0o644); err != nil {
+		t.Fatalf("write spec: %v", err)
+	}
+
+	spec := &specInfo{FilePath: specPath}
+	if err := updateSpecVersion(spec, "2.0.0", strings.Repeat("a", 64), true); err != nil {
+		t.Fatalf("updateSpecVersion: %v", err)
+	}
+
+	updated, err := os.ReadFile(specPath)
+	if err != nil {
+		t.Fatalf("read spec: %v", err)
+	}
+
+	got := string(updated)
+	if !strings.Contains(got, "Version:\t2.0.0  # keep-comment") {
+		t.Fatalf("version line not updated as expected:\n%s", got)
+	}
+	if !strings.Contains(got, "%autochangelog\n") {
+		t.Fatalf("expected %%{{?autochangelog}} to be normalized, got:\n%s", got)
+	}
+	if strings.Contains(got, "%{?autochangelog}") {
+		t.Fatalf("expected %%{{?autochangelog}} to be removed, got:\n%s", got)
+	}
+	if !strings.HasSuffix(got, "\n") {
+		t.Fatalf("expected rewritten spec to keep trailing newline, got %q", got)
+	}
+}
+
+func TestUpdateSpecVersionReturnsErrorWhenVersionLineMissing(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	specPath := filepath.Join(dir, "test.spec")
+	if err := os.WriteFile(specPath, []byte("Name: golang-test\n"), 0o644); err != nil {
+		t.Fatalf("write spec: %v", err)
+	}
+
+	spec := &specInfo{FilePath: specPath}
+	if err := updateSpecVersion(spec, "2.0.0", strings.Repeat("a", 64), true); err == nil {
+		t.Fatal("expected updateSpecVersion to fail when Version line is missing")
+	}
+}
+
+func TestParseSpecFileAcceptsGlobalMacros(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	specPath := filepath.Join(dir, "test.spec")
+	original := strings.Join([]string{
+		"%global go_import_path github.com/example/project/cmd/tool",
+		"%global _name golang-github-example-project",
+		"Version:        1.2.3",
+		"Source0:        https://example.invalid/source.tar.gz",
+	}, "\n")
+	if err := os.WriteFile(specPath, []byte(original), 0o644); err != nil {
+		t.Fatalf("write spec: %v", err)
+	}
+
+	spec, err := parseSpecFile(specPath)
+	if err != nil {
+		t.Fatalf("parseSpecFile: %v", err)
+	}
+	if spec.GoImportPath != "github.com/example/project/cmd/tool" {
+		t.Fatalf("GoImportPath = %q", spec.GoImportPath)
+	}
+	if spec.Name != "golang-github-example-project" {
+		t.Fatalf("Name = %q", spec.Name)
+	}
+}
+
+func TestDownloadCandidatesUseModulePathForPackageImport(t *testing.T) {
+	t.Parallel()
+
+	spec := &specInfo{
+		GoImportPath:  "github.com/example/project/cmd/tool",
+		LatestVersion: "v1.2.3",
+	}
+	info := &pkgsiteInfo{
+		Package: pkgsitePackage{ModulePath: "github.com/example/project"},
+		Module: pkgsiteModule{
+			Path:    "github.com/example/project",
+			RepoURL: "https://github.com/example/project",
+		},
+	}
+
+	candidates, archiveErr, err := downloadCandidatesForSpec(spec, info)
+	if err != nil {
+		t.Fatalf("downloadCandidatesForSpec: %v", err)
+	}
+	if archiveErr != nil {
+		t.Fatalf("archiveErr = %v", archiveErr)
+	}
+	if len(candidates) != 2 {
+		t.Fatalf("len(candidates) = %d, want 2", len(candidates))
+	}
+	if got, want := candidates[0].url, "https://github.com/example/project/archive/v1.2.3.tar.gz"; got != want {
+		t.Fatalf("repo candidate = %q, want %q", got, want)
+	}
+	if got, want := candidates[1].url, "https://proxy.golang.org/github.com/example/project/@v/v1.2.3.zip"; got != want {
+		t.Fatalf("proxy candidate = %q, want %q", got, want)
+	}
+}
+
+func TestVerifyHTTPRequestFallsBackToRangeGet(t *testing.T) {
+	t.Parallel()
+
+	var sawHead atomic.Bool
+	var sawGet atomic.Bool
+	var gotRange atomic.Value
+	gotRange.Store("")
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodHead:
+			sawHead.Store(true)
+			w.WriteHeader(http.StatusMethodNotAllowed)
+		case http.MethodGet:
+			sawGet.Store(true)
+			gotRange.Store(r.Header.Get("Range"))
+			w.WriteHeader(http.StatusPartialContent)
+			_, _ = w.Write([]byte("x"))
+		default:
+			w.WriteHeader(http.StatusMethodNotAllowed)
+		}
+	}))
+	defer srv.Close()
+
+	if err := verifyHTTPRequest(context.Background(), srv.URL); err != nil {
+		t.Fatalf("verifyHTTPRequest: %v", err)
+	}
+	if !sawHead.Load() {
+		t.Fatal("expected HEAD request to be attempted first")
+	}
+	if !sawGet.Load() {
+		t.Fatal("expected GET fallback to be attempted")
+	}
+	if gotRange.Load().(string) != "bytes=0-0" {
+		t.Fatalf("unexpected Range header: %q", gotRange.Load().(string))
+	}
+}
+
+func TestRepoRefForVersionStripsBuildMetadata(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		in   string
+		want string
+	}{
+		{in: "v2.74.0+incompatible", want: "v2.74.0"},
+		{in: "2.74.0+incompatible", want: "v2.74.0"},
+		{in: "v1.2.3-rc.1", want: "v1.2.3-rc.1"},
+		{in: "release-2026-06-12", want: "vrelease-2026-06-12"},
+	}
+
+	for _, tc := range tests {
+		if got := repoRefForVersion(tc.in); got != tc.want {
+			t.Fatalf("repoRefForVersion(%q) = %q, want %q", tc.in, got, tc.want)
+		}
+	}
+}
+
+func TestSourceVersionForSpecStripsBuildMetadata(t *testing.T) {
+	t.Parallel()
+
+	if got := sourceVersionForSpec("v2.74.0+incompatible"); got != "2.74.0" {
+		t.Fatalf("sourceVersionForSpec() = %q, want %q", got, "2.74.0")
+	}
+}
+
+func TestSpecVersionForVersionStripsIncompatible(t *testing.T) {
+	t.Parallel()
+
+	if got := specVersionForVersion("v2.74.0+incompatible"); got != "2.74.0" {
+		t.Fatalf("specVersionForVersion() = %q, want %q", got, "2.74.0")
+	}
+}
+
+func TestUpdateSpecVersionOnlyUpdatesSource0RemoteAsset(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	specPath := filepath.Join(dir, "test.spec")
+	source1Hash := strings.Repeat("b", 64)
+	source0Hash := strings.Repeat("c", 64)
+	original := strings.Join([]string{
+		"Name:           golang-test",
+		"Version:        1.0.0",
+		"#!RemoteAsset:  sha256:" + source1Hash,
+		"Source1:        https://example.invalid/extra.tar.gz",
+		"Source0:        https://example.invalid/source.tar.gz",
+	}, "\n")
+	if err := os.WriteFile(specPath, []byte(original), 0o644); err != nil {
+		t.Fatalf("write spec: %v", err)
+	}
+
+	spec := &specInfo{FilePath: specPath}
+	if err := updateSpecVersion(spec, "2.0.0", source0Hash, true); err != nil {
+		t.Fatalf("updateSpecVersion: %v", err)
+	}
+
+	updated, err := os.ReadFile(specPath)
+	if err != nil {
+		t.Fatalf("read spec: %v", err)
+	}
+	got := string(updated)
+
+	if !strings.Contains(got, "#!RemoteAsset:  sha256:"+source1Hash+"\nSource1:") {
+		t.Fatalf("Source1 RemoteAsset was unexpectedly changed:\n%s", got)
+	}
+	if !strings.Contains(got, "#!RemoteAsset:  sha256:"+source0Hash+"\nSource0:") {
+		t.Fatalf("Source0 RemoteAsset was not inserted correctly:\n%s", got)
+	}
+}
+
+func TestUpdateSpecVersionClearsRemoteAssetWhenHashEmpty(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	specPath := filepath.Join(dir, "test.spec")
+	sourceHash := strings.Repeat("d", 64)
+	original := strings.Join([]string{
+		"Name:           golang-test",
+		"Version:        1.0.0",
+		"#!RemoteAsset:  sha256:" + sourceHash,
+		"Source0:        https://example.invalid/%{commit_id}.tar.gz",
+	}, "\n")
+	if err := os.WriteFile(specPath, []byte(original), 0o644); err != nil {
+		t.Fatalf("write spec: %v", err)
+	}
+
+	spec := &specInfo{FilePath: specPath}
+	if err := updateSpecVersion(spec, "2.0.0", "", true); err != nil {
+		t.Fatalf("updateSpecVersion: %v", err)
+	}
+
+	updated, err := os.ReadFile(specPath)
+	if err != nil {
+		t.Fatalf("read spec: %v", err)
+	}
+	got := string(updated)
+
+	if !strings.Contains(got, "Version:        2.0.0") {
+		t.Fatalf("version was not updated:\n%s", got)
+	}
+	if strings.Contains(got, "sha256:"+sourceHash) {
+		t.Fatalf("RemoteAsset hash should be cleared:\n%s", got)
+	}
+	if !strings.Contains(got, "#!RemoteAsset\nSource0:") {
+		t.Fatalf("RemoteAsset marker should be kept without hash:\n%s", got)
+	}
+}
+
+func TestUpdateSpecVersionKeepsRemoteAssetWhenUpdateDisabled(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	specPath := filepath.Join(dir, "test.spec")
+	sourceHash := strings.Repeat("d", 64)
+	original := strings.Join([]string{
+		"Name:           golang-test",
+		"Version:        1.0.0",
+		"#!RemoteAsset:  sha256:" + sourceHash,
+		"Source0:        https://example.invalid/%{commit_id}.tar.gz",
+	}, "\n")
+	if err := os.WriteFile(specPath, []byte(original), 0o644); err != nil {
+		t.Fatalf("write spec: %v", err)
+	}
+
+	spec := &specInfo{FilePath: specPath}
+	if err := updateSpecVersion(spec, "2.0.0", "", false); err != nil {
+		t.Fatalf("updateSpecVersion: %v", err)
+	}
+
+	updated, err := os.ReadFile(specPath)
+	if err != nil {
+		t.Fatalf("read spec: %v", err)
+	}
+	got := string(updated)
+
+	if !strings.Contains(got, "Version:        2.0.0") {
+		t.Fatalf("version was not updated:\n%s", got)
+	}
+	if !strings.Contains(got, "#!RemoteAsset:  sha256:"+sourceHash) {
+		t.Fatalf("RemoteAsset hash should be unchanged:\n%s", got)
+	}
+}
+
+func TestResolvedSource0URLSkipsPinnedCommit(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	specPath := filepath.Join(dir, "test.spec")
+	original := strings.Join([]string{
+		"%define commit_id abcdef123456",
+		"Name:           golang-test",
+		"Version:        1.0.0",
+		"Source0:        https://example.invalid/%{commit_id}.tar.gz",
+	}, "\n")
+	if err := os.WriteFile(specPath, []byte(original), 0o644); err != nil {
+		t.Fatalf("write spec: %v", err)
+	}
+
+	_, err := resolvedSource0URL(specPath, "2.0.0")
+	if !errors.Is(err, errRemoteAssetSkip) {
+		t.Fatalf("resolvedSource0URL error = %v, want errRemoteAssetSkip", err)
+	}
+}
+
+func TestReleasePageURLForSource(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		source  string
+		wantURL string
+		wantTag string
+	}{
+		{
+			source:  "https://github.com/apache/beam/archive/refs/tags/v2.74.0.tar.gz",
+			wantURL: "https://github.com/apache/beam/releases/tag/v2.74.0",
+			wantTag: "v2.74.0",
+		},
+		{
+			source:  "https://github.com/charmbracelet/x/archive/refs/tags/term/v0.2.2.tar.gz",
+			wantURL: "https://github.com/charmbracelet/x/releases/tag/term/v0.2.2",
+			wantTag: "term/v0.2.2",
+		},
+		{
+			source:  "https://gitlab.com/group/project/-/archive/v1.2.3/project-v1.2.3.tar.gz",
+			wantURL: "https://gitlab.com/group/project/-/releases/v1.2.3",
+			wantTag: "v1.2.3",
+		},
+	}
+
+	for _, tc := range tests {
+		gotURL, gotTag := releasePageURLForSource(tc.source)
+		if gotURL != tc.wantURL || gotTag != tc.wantTag {
+			t.Fatalf("releasePageURLForSource(%q) = (%q, %q), want (%q, %q)",
+				tc.source, gotURL, gotTag, tc.wantURL, tc.wantTag)
+		}
+	}
+}
+
+func TestExtractSHA256FromHTML(t *testing.T) {
+	t.Parallel()
+
+	want := strings.Repeat("a", 64)
+	html := "Release notes\nSHA256: " + want
+	if got := extractSHA256FromHTML(html, "v1.2.3"); got != want {
+		t.Fatalf("extractSHA256FromHTML() = %q, want %q", got, want)
+	}
+}
+
+func TestDownloadAssetSHA256(t *testing.T) {
+	t.Parallel()
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("source archive"))
+	}))
+	defer srv.Close()
+
+	got, err := downloadAssetSHA256(context.Background(), srv.URL)
+	if err != nil {
+		t.Fatalf("downloadAssetSHA256: %v", err)
+	}
+	want := "6ad189ace456a83fade855d5a647cd8ad9e7966da4404b1187218dca3d9eddaa"
+	if got != want {
+		t.Fatalf("downloadAssetSHA256() = %q, want %q", got, want)
+	}
+}
+
+func TestVerifyDownloadCandidatesFallsBackToProxy(t *testing.T) {
+	t.Parallel()
+
+	var logsMu sync.Mutex
+	var logs []string
+	oldLog := downloadRetryLog
+	downloadRetryLog = func(msg string) {
+		logsMu.Lock()
+		defer logsMu.Unlock()
+		logs = append(logs, msg)
+	}
+	defer func() { downloadRetryLog = oldLog }()
+
+	repoSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusGatewayTimeout)
+	}))
+	defer repoSrv.Close()
+
+	proxySrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusPartialContent)
+		_, _ = w.Write([]byte("x"))
+	}))
+	defer proxySrv.Close()
+
+	err := verifyDownloadCandidates(context.Background(), "codeberg.org/go-fonts/liberation", []downloadCandidate{
+		{source: "repo", url: repoSrv.URL},
+		{source: "proxy", url: proxySrv.URL},
+	})
+	if err != nil {
+		t.Fatalf("verifyDownloadCandidates: %v", err)
+	}
+
+	logsMu.Lock()
+	defer logsMu.Unlock()
+	joined := strings.Join(logs, "\n")
+	if !strings.Contains(joined, "trying proxy") {
+		t.Fatalf("expected fallback log, got: %s", joined)
+	}
+	if !strings.Contains(joined, "verified via proxy after fallback") {
+		t.Fatalf("expected fallback success log, got: %s", joined)
+	}
+}
+
+func TestIsRetryableDownloadErrorRecognizesTimeout(t *testing.T) {
+	t.Parallel()
+
+	timeoutErr := &net.DNSError{IsTimeout: true}
+	if !isRetryableDownloadError(timeoutErr) {
+		t.Fatal("expected timeout net error to be retryable")
+	}
+	if !isRetryableDownloadError(errors.New("HTTP 504 from example")) {
+		t.Fatal("expected HTTP 504 to be retryable")
+	}
+	if isRetryableDownloadError(fmt.Errorf("HTTP 404 from example")) {
+		t.Fatal("did not expect HTTP 404 to be retryable")
+	}
+}