hub v0.29.0: Day-0 artifact manifest — version dropdowns + auto-derived sha

Operator picks a version from a Gitea-populated dropdown; the hub reads that
version's sha256 from Gitea itself (files-metadata API, no artifact download) and
vouches it — no hand-copied checksums. New internal/gitea read-only client
(ListVersions + FileSHA256, unit-tested). Configuration UI: version <select>s +
read-only sha display; handleSetArtifacts derives the sha authoritatively and
refuses the save on a Gitea lookup failure. Degrades to manual text entry without
registry creds. go build/vet/test clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

hub/CHANGELOG.md

@@ -1,5 +1,29 @@
 # Felhom Hub — Changelog
 
+## v0.29.0 — Day-0 artifact manifest: version dropdowns + auto-derived sha (2026-07-01)
+
+Removes the hand-copied sha256 from the Day-0 artifact manifest. The operator now **picks a version**
+from a dropdown of what's actually in Gitea (olders get pruned), and the hub **reads that version's
+sha256 from Gitea itself** — no transcription, no stale checksums. Keeps the human-in-the-loop trust
+gate (the operator still deliberately chooses the version; "latest" is never auto-promoted) while the
+hub stays the checksum trust root.
+
+- **`internal/gitea`** (new): a minimal read-only Gitea packages client — `ListVersions` (generic
+  package versions, newest-semver first) + `FileSHA256` (a version's file sha256 via the files-metadata
+  API, **without downloading** the artifact — important for the ~GB golden). Basic-auth with the
+  registry creds the hub already holds. Unit-tested against an httptest server (filter+sort, preferred
+  file match + fallback, non-200 → error).
+- **Configuration → Day-0 artifacts:** the two version text inputs are now `<select>` dropdowns
+  populated from Gitea; the sha256 fields are **read-only, displayed** (mirrored from the picked
+  version via a tiny inline script). Choosing "— none —" clears an artifact.
+- **`handleSetArtifacts`:** derives each chosen version's sha256 from Gitea **authoritatively** (a
+  client-submitted sha is ignored); a Gitea lookup failure REFUSES the save (never stores a version
+  with a wrong/blank checksum) rather than corrupting the manifest.
+- **Graceful degradation:** with no registry creds (`web.SetGiteaClient` not wired) the form falls back
+  to the previous manual text-entry path. `main.go` enables the Gitea browser when `REGISTRY_USERNAME`
+  /`REGISTRY_TOKEN` are set.
+- `go build`/`vet`/`test ./...` clean.
+
 ## v0.28.0 — global settings → Configuration tab + online setup command (2026-07-01)
 
 Three operator-requested improvements (companion: host-install script v1.2.0).

hub/cmd/hub/main.go

@@ -14,6 +14,7 @@ import (
 
 	"gitea.dooplex.hu/admin/felhom-hub/internal/api"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/assets"
+	"gitea.dooplex.hu/admin/felhom-hub/internal/gitea"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/mailrelay"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/monitor"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/notify"
@@ -254,6 +255,13 @@ func main() {
 	webServer := web.New(dataStore, cfg.Auth.PasswordHash, cfg.API.ReportAPIKey, Version, staleThreshold, logger)
 	webServer.SetTemplateFetcher(templateFetcher)
 	webServer.SetAssetManager(assetsMgr)
+	// Day-0 artifact version dropdowns: let the operator pick a version and have the hub derive the
+	// sha256 from Gitea (no hand-copied checksums). Reuses the registry creds; degrades to manual text
+	// entry when they're absent.
+	if cfg.Registry.Username != "" && cfg.Registry.Token != "" {
+		webServer.SetGiteaClient(gitea.New("https://gitea.dooplex.hu", "admin", cfg.Registry.Username, cfg.Registry.Token))
+		logger.Printf("[INFO] Gitea artifact browser enabled (Day-0 version dropdowns)")
+	}
 
 	// Build HTTP mux
 	mux := http.NewServeMux()

hub/internal/gitea/gitea.go

@@ -0,0 +1,134 @@
+// Package gitea is a minimal read-only client for the Gitea generic-package API. It lets the hub
+// discover which artifact versions currently exist (olders get pruned) and read each file's sha256
+// WITHOUT downloading the artifact — so the operator picks a version in the UI and the hub derives and
+// vouches the checksum itself, instead of the operator pasting a 64-hex sha by hand.
+package gitea
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Client talks to the Gitea packages API with basic auth (the registry username + token the hub
+// already holds for the controller image pull).
+type Client struct {
+	baseURL string // e.g. https://gitea.dooplex.hu (no trailing slash)
+	owner   string // package owner, e.g. admin
+	user    string
+	token   string
+	http    *http.Client
+}
+
+// New builds a client. baseURL/owner/user/token come from the hub's registry config.
+func New(baseURL, owner, user, token string) *Client {
+	return &Client{
+		baseURL: strings.TrimRight(baseURL, "/"),
+		owner:   owner,
+		user:    user,
+		token:   token,
+		http:    &http.Client{Timeout: 10 * time.Second},
+	}
+}
+
+type pkgEntry struct {
+	Name    string `json:"name"`
+	Version string `json:"version"`
+	Type    string `json:"type"`
+}
+
+// ListVersions returns the versions of a generic package, newest-semver first. Non-semver versions
+// (if any) sort after the semver ones so nothing is silently dropped.
+func (c *Client) ListVersions(ctx context.Context, pkgName string) ([]string, error) {
+	u := fmt.Sprintf("%s/api/v1/packages/%s?type=generic&q=%s&limit=100",
+		c.baseURL, c.owner, pkgName)
+	var pkgs []pkgEntry
+	if err := c.getJSON(ctx, u, &pkgs); err != nil {
+		return nil, err
+	}
+	var vers []string
+	for _, p := range pkgs {
+		if p.Name == pkgName && p.Version != "" {
+			vers = append(vers, p.Version)
+		}
+	}
+	sort.SliceStable(vers, func(i, j int) bool { return compareSemver(vers[i], vers[j]) > 0 })
+	return vers, nil
+}
+
+type pkgFile struct {
+	Name   string `json:"name"`
+	SHA256 string `json:"sha256"`
+}
+
+// FileSHA256 returns the sha256 of a file inside a generic package version. When the version holds
+// multiple files it prefers an exact match to preferredFile (e.g. "golden.tar.zst"); otherwise it uses
+// the first file. This is a cheap metadata call — the artifact bytes are never downloaded.
+func (c *Client) FileSHA256(ctx context.Context, pkgName, version, preferredFile string) (string, error) {
+	u := fmt.Sprintf("%s/api/v1/packages/%s/generic/%s/%s/files",
+		c.baseURL, c.owner, pkgName, version)
+	var files []pkgFile
+	if err := c.getJSON(ctx, u, &files); err != nil {
+		return "", err
+	}
+	if len(files) == 0 {
+		return "", fmt.Errorf("no files listed for %s/%s", pkgName, version)
+	}
+	if preferredFile != "" {
+		for _, f := range files {
+			if f.Name == preferredFile && f.SHA256 != "" {
+				return f.SHA256, nil
+			}
+		}
+	}
+	if files[0].SHA256 == "" {
+		return "", fmt.Errorf("no sha256 for %s/%s file %q", pkgName, version, files[0].Name)
+	}
+	return files[0].SHA256, nil
+}
+
+func (c *Client) getJSON(ctx context.Context, url string, out interface{}) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+	req.SetBasicAuth(c.user, c.token)
+	req.Header.Set("Accept", "application/json")
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("gitea GET %s: HTTP %d", url, resp.StatusCode)
+	}
+	return json.NewDecoder(resp.Body).Decode(out)
+}
+
+// compareSemver returns >0 if a>b, 0 if equal, <0 if a<b. Falls back to a lexical compare on a
+// non-"X.Y.Z" input (mirrors web.compareVersions; kept local to avoid an import cycle).
+func compareSemver(a, b string) int {
+	a = strings.TrimPrefix(a, "v")
+	b = strings.TrimPrefix(b, "v")
+	ap := strings.SplitN(a, ".", 3)
+	bp := strings.SplitN(b, ".", 3)
+	if len(ap) != 3 || len(bp) != 3 {
+		return strings.Compare(a, b)
+	}
+	for i := 0; i < 3; i++ {
+		ai, e1 := strconv.Atoi(ap[i])
+		bi, e2 := strconv.Atoi(bp[i])
+		if e1 != nil || e2 != nil {
+			return strings.Compare(a, b)
+		}
+		if ai != bi {
+			return ai - bi
+		}
+	}
+	return 0
+}

hub/internal/gitea/gitea_test.go

@@ -0,0 +1,88 @@
+package gitea
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// ListVersions filters to the requested package name and returns versions newest-semver first.
+func TestListVersions_FilterAndSort(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.HasPrefix(r.URL.Path, "/api/v1/packages/admin") {
+			http.NotFound(w, r)
+			return
+		}
+		// Intentionally unsorted + a foreign package that must be filtered out.
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte(`[
+			{"name":"felhom-agent","version":"0.43.0","type":"generic"},
+			{"name":"felhom-agent","version":"0.52.0","type":"generic"},
+			{"name":"felhom-golden","version":"0.85.1","type":"generic"},
+			{"name":"felhom-agent","version":"0.9.0","type":"generic"}
+		]`))
+	}))
+	defer srv.Close()
+
+	c := New(srv.URL, "admin", "u", "t")
+	vers, err := c.ListVersions(context.Background(), "felhom-agent")
+	if err != nil {
+		t.Fatalf("ListVersions: %v", err)
+	}
+	// Only felhom-agent, newest semver first (0.52.0 > 0.43.0 > 0.9.0 — numeric, not lexical).
+	want := []string{"0.52.0", "0.43.0", "0.9.0"}
+	if len(vers) != len(want) {
+		t.Fatalf("got %v, want %v", vers, want)
+	}
+	for i := range want {
+		if vers[i] != want[i] {
+			t.Fatalf("got %v, want %v", vers, want)
+		}
+	}
+}
+
+// FileSHA256 prefers an exact filename match; otherwise it falls back to the first file.
+func TestFileSHA256_PreferredAndFallback(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		switch {
+		case strings.Contains(r.URL.Path, "/felhom-golden/0.85.1/files"):
+			w.Write([]byte(`[
+				{"name":"stray.txt","sha256":"aaaa"},
+				{"name":"golden.tar.zst","sha256":"f87031cc"}
+			]`))
+		case strings.Contains(r.URL.Path, "/felhom-agent/0.52.0/files"):
+			w.Write([]byte(`[{"name":"felhom-agent","sha256":"5bfc690c"}]`))
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer srv.Close()
+
+	c := New(srv.URL, "admin", "u", "t")
+
+	// preferred-file match among multiple files
+	sha, err := c.FileSHA256(context.Background(), "felhom-golden", "0.85.1", "golden.tar.zst")
+	if err != nil || sha != "f87031cc" {
+		t.Fatalf("golden sha: got %q err %v, want f87031cc", sha, err)
+	}
+	// single-file version resolves regardless of preferred name (fallback to first)
+	sha, err = c.FileSHA256(context.Background(), "felhom-agent", "0.52.0", "felhom-agent")
+	if err != nil || sha != "5bfc690c" {
+		t.Fatalf("agent sha: got %q err %v, want 5bfc690c", sha, err)
+	}
+}
+
+// A non-200 from Gitea surfaces as an error (so a save refuses rather than storing a blank sha).
+func TestGetJSON_ErrorOnNon200(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "nope", http.StatusInternalServerError)
+	}))
+	defer srv.Close()
+	c := New(srv.URL, "admin", "u", "t")
+	if _, err := c.ListVersions(context.Background(), "felhom-agent"); err == nil {
+		t.Fatal("expected an error on HTTP 500")
+	}
+}

hub/internal/web/configs.go

@@ -1,6 +1,7 @@
 package web
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"html/template"
@@ -635,22 +636,24 @@ func normalizeSHA256(raw string) (string, bool) {
 }
 
 // handleSetArtifacts records the operator-vouched current artifact set (agent binary + golden
-// archive: version + sha256 each) into hub_settings. This is the checksum TRUST ROOT the
-// host-bootstrap script verifies fetched artifacts against. Versions are validated as bare semver
-// (reusing the floor validator); sha256s as 64-hex. Empty fields are allowed (clears that field).
+// archive) into hub_settings — the checksum TRUST ROOT the host-bootstrap script verifies fetched
+// artifacts against. The operator picks a VERSION (from the Gitea-populated dropdown); the hub DERIVES
+// that version's sha256 from Gitea itself (never trusting a client-supplied checksum), so there is no
+// hand-copied sha to get wrong. When no Gitea client is configured (no registry creds) it falls back
+// to the submitted sha256 (legacy manual path). Empty version clears that artifact.
 func (s *Server) handleSetArtifacts(w http.ResponseWriter, r *http.Request) {
 	if err := r.ParseForm(); err != nil {
 		http.Error(w, "Bad request", http.StatusBadRequest)
 		return
 	}
 	agentVer, okAV := normalizeFloorInput(r.FormValue("agent_version"))
-	agentSHA, okAS := normalizeSHA256(r.FormValue("agent_sha256"))
 	goldenVer, okGV := normalizeFloorInput(r.FormValue("golden_version"))
-	goldenSHA, okGS := normalizeSHA256(r.FormValue("golden_sha256"))
 	if !okAV || !okGV {
 		http.Redirect(w, r, "/configuration?flash=artifact_ver_invalid", http.StatusSeeOther)
 		return
 	}
+	agentSHA, okAS := s.resolveArtifactSHA(r.Context(), pkgAgent, fileAgent, agentVer, r.FormValue("agent_sha256"))
+	goldenSHA, okGS := s.resolveArtifactSHA(r.Context(), pkgGolden, fileGolden, goldenVer, r.FormValue("golden_sha256"))
 	if !okAS || !okGS {
 		http.Redirect(w, r, "/configuration?flash=artifact_sha_invalid", http.StatusSeeOther)
 		return
@@ -669,6 +672,26 @@ func (s *Server) handleSetArtifacts(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, "/configuration?flash=artifacts_set", http.StatusSeeOther)
 }
 
+// resolveArtifactSHA determines the sha256 to store for a chosen artifact version. An empty version
+// clears the artifact (returns "",true). With a Gitea client it fetches the sha AUTHORITATIVELY from
+// Gitea (the submitted value is ignored — nothing hand-typed to trust); a fetch failure returns
+// (_,false) so the caller refuses the save rather than storing a version with a wrong/blank checksum.
+// Without a Gitea client it validates + uses the submitted sha (legacy manual path).
+func (s *Server) resolveArtifactSHA(ctx context.Context, pkg, file, version, submittedSHA string) (string, bool) {
+	if version == "" {
+		return "", true
+	}
+	if s.gitea != nil {
+		sha, err := s.gitea.FileSHA256(ctx, pkg, version, file)
+		if err != nil {
+			s.logger.Printf("[WARN] artifact sha resolve (%s/%s): %v", pkg, version, err)
+			return "", false
+		}
+		return sha, true
+	}
+	return normalizeSHA256(submittedSHA)
+}
+
 // handleSetCustomerFloor sets (or clears) a customer's per-customer controller-version floor
 // override. Empty clears the override (the customer then uses the global floor).
 func (s *Server) handleSetCustomerFloor(w http.ResponseWriter, r *http.Request, customerID string) {

hub/internal/web/server.go

@@ -17,10 +17,27 @@ import (
 	"time"
 
 	"gitea.dooplex.hu/admin/felhom-hub/internal/assets"
+	"gitea.dooplex.hu/admin/felhom-hub/internal/gitea"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
 	"golang.org/x/crypto/bcrypt"
 )
 
+// Generic-package names + the artifact filename inside each version (used to resolve version lists +
+// sha256 from Gitea for the Day-0 artifact manifest UI).
+const (
+	pkgAgent   = "felhom-agent"
+	fileAgent  = "felhom-agent"
+	pkgGolden  = "felhom-golden"
+	fileGolden = "golden.tar.zst"
+)
+
+// artifactChoice is one selectable artifact version + its Gitea-resolved sha256 (for the dropdown +
+// the read-only sha display).
+type artifactChoice struct {
+	Version string
+	SHA256  string
+}
+
 // hubSession holds per-session auth and CSRF data.
 type hubSession struct {
 	expiresAt time.Time
@@ -39,6 +56,7 @@ type Server struct {
 	versionChecker  *VersionChecker
 	templateFetcher *TemplateFetcher
 	assetsMgr       *assets.Manager
+	gitea           *gitea.Client // optional; enables the Day-0 artifact version dropdowns
 
 	sessions   map[string]*hubSession
 	sessionsMu sync.RWMutex
@@ -125,6 +143,42 @@ func (s *Server) SetAssetManager(am *assets.Manager) {
 	s.assetsMgr = am
 }
 
+// SetGiteaClient enables the Day-0 artifact version dropdowns (optional). Without it the artifact form
+// degrades to manual text entry.
+func (s *Server) SetGiteaClient(c *gitea.Client) {
+	s.gitea = c
+}
+
+// artifactChoices resolves the currently-available versions of a generic package + each one's sha256
+// from Gitea, newest first, for the Day-0 artifact dropdown. Returns nil (→ manual text-entry
+// fallback) when no Gitea client is configured or Gitea is unreachable. A failed sha lookup for a
+// single version drops just that version, not the whole list.
+func (s *Server) artifactChoices(ctx context.Context, pkg, file string) []artifactChoice {
+	if s.gitea == nil {
+		return nil
+	}
+	vers, err := s.gitea.ListVersions(ctx, pkg)
+	if err != nil {
+		s.logger.Printf("[WARN] artifact versions (%s): %v", pkg, err)
+		return nil
+	}
+	const maxChoices = 20
+	if len(vers) > maxChoices {
+		s.logger.Printf("[INFO] artifact versions (%s): showing newest %d of %d", pkg, maxChoices, len(vers))
+		vers = vers[:maxChoices]
+	}
+	out := make([]artifactChoice, 0, len(vers))
+	for _, v := range vers {
+		sha, err := s.gitea.FileSHA256(ctx, pkg, v, file)
+		if err != nil {
+			s.logger.Printf("[WARN] artifact sha (%s/%s): %v", pkg, v, err)
+			continue
+		}
+		out = append(out, artifactChoice{Version: v, SHA256: sha})
+	}
+	return out
+}
+
 // ServeHTTP routes web requests.
 func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	path := r.URL.Path
@@ -586,6 +640,7 @@ func (s *Server) handleConfiguration(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	ctx := r.Context()
 	data := map[string]interface{}{
 		"CSRFToken":     csrfToken,
 		"CSRFField":     s.csrfField(r),
@@ -593,6 +648,8 @@ func (s *Server) handleConfiguration(w http.ResponseWriter, r *http.Request) {
 		"AssetLastSync": assetLastSync,
 		"GlobalFloor":   s.store.GetGlobalMinControllerVersion(),
 		"Artifacts":     s.store.GetArtifactManifest(),
+		"AgentChoices":  s.artifactChoices(ctx, pkgAgent, fileAgent),
+		"GoldenChoices": s.artifactChoices(ctx, pkgGolden, fileGolden),
 		"Flash":         r.URL.Query().Get("flash"),
 	}
 	if err := s.templates.ExecuteTemplate(w, "configuration.html", data); err != nil {

hub/internal/web/templates/configuration.html

@@ -43,7 +43,7 @@
         <div class="flash flash-error">Invalid artifact version — use X.Y.Z (or blank to clear).</div>
         {{end}}
         {{if eq .Flash "artifact_sha_invalid"}}
-        <div class="flash flash-error">Invalid sha256 — use 64 hex chars (or blank to clear).</div>
+        <div class="flash flash-error">Couldn't set the checksum — the Gitea sha lookup failed (version missing / Gitea unreachable) or the manually-entered sha is invalid. Manifest unchanged.</div>
         {{end}}
 
         <!-- Phase 2 managed updates: global controller-version floor (moved from the Customers page —
@@ -71,20 +71,49 @@
             <p class="text-muted" style="margin: 0 0 0.75rem; font-size: 0.85em;">
                 The current agent binary + golden archive the host-bootstrap script fetches from Gitea and
                 verifies (sha256) before installing. The hub vouches for these checksums (a different trust
-                root than Gitea). Paste the version + sha256 printed by <code>publish-agent.sh</code> /
-                <code>build-golden.sh</code>. Blank a field to clear it.
+                root than Gitea). Pick a version — the sha256 is read from Gitea automatically (no manual
+                copy). Choose <em>— none —</em> to clear an artifact.
             </p>
-            <form method="POST" action="/configuration/artifacts" style="display: grid; grid-template-columns: auto 8em 1fr; gap: 0.5rem; align-items: center; max-width: 56em;">
+            <form method="POST" action="/configuration/artifacts" style="display: grid; grid-template-columns: auto 12em 1fr; gap: 0.5rem; align-items: center; max-width: 56em;">
                 {{.CSRFField}}
                 <label style="font-size: 0.9em; color: #cbd5e1;">Agent</label>
-                <input type="text" name="agent_version" value="{{.Artifacts.AgentVersion}}" placeholder="0.43.0" style="padding: 0.3em 0.5em;">
-                <input type="text" name="agent_sha256" value="{{.Artifacts.AgentSHA256}}" placeholder="64-hex sha256 (blank = none)" style="padding: 0.3em 0.5em; font-family: monospace;">
+                {{if .AgentChoices}}
+                <select name="agent_version" id="agent_version" onchange="syncArtifactSha('agent')" style="padding: 0.3em 0.5em;">
+                    <option value="" data-sha="">— none —</option>
+                    {{range .AgentChoices}}
+                    <option value="{{.Version}}" data-sha="{{.SHA256}}" {{if eq .Version $.Artifacts.AgentVersion}}selected{{end}}>{{.Version}}</option>
+                    {{end}}
+                </select>
+                {{else}}
+                <input type="text" name="agent_version" value="{{.Artifacts.AgentVersion}}" placeholder="0.52.0" style="padding: 0.3em 0.5em;">
+                {{end}}
+                <input type="text" name="agent_sha256" id="agent_sha256" value="{{.Artifacts.AgentSHA256}}" {{if .AgentChoices}}readonly{{end}} placeholder="64-hex sha256 (blank = none)" style="padding: 0.3em 0.5em; font-family: monospace; {{if .AgentChoices}}opacity: 0.7;{{end}}">
                 <label style="font-size: 0.9em; color: #cbd5e1;">Golden</label>
+                {{if .GoldenChoices}}
+                <select name="golden_version" id="golden_version" onchange="syncArtifactSha('golden')" style="padding: 0.3em 0.5em;">
+                    <option value="" data-sha="">— none —</option>
+                    {{range .GoldenChoices}}
+                    <option value="{{.Version}}" data-sha="{{.SHA256}}" {{if eq .Version $.Artifacts.GoldenVersion}}selected{{end}}>{{.Version}}</option>
+                    {{end}}
+                </select>
+                {{else}}
                 <input type="text" name="golden_version" value="{{.Artifacts.GoldenVersion}}" placeholder="0.85.1" style="padding: 0.3em 0.5em;">
-                <input type="text" name="golden_sha256" value="{{.Artifacts.GoldenSHA256}}" placeholder="64-hex sha256 (blank = none)" style="padding: 0.3em 0.5em; font-family: monospace;">
+                {{end}}
+                <input type="text" name="golden_sha256" id="golden_sha256" value="{{.Artifacts.GoldenSHA256}}" {{if .GoldenChoices}}readonly{{end}} placeholder="64-hex sha256 (blank = none)" style="padding: 0.3em 0.5em; font-family: monospace; {{if .GoldenChoices}}opacity: 0.7;{{end}}">
                 <span></span><span></span>
                 <button class="btn btn-sm" type="submit" style="justify-self: start;">Save artifact manifest</button>
             </form>
+            <script>
+            // When a version is picked, mirror that option's Gitea-resolved sha256 into the read-only
+            // display field. The hub re-derives the sha authoritatively on save regardless of this value.
+            function syncArtifactSha(kind) {
+                var sel = document.getElementById(kind + '_version');
+                var sha = document.getElementById(kind + '_sha256');
+                if (!sel || !sha) return;
+                var opt = sel.options[sel.selectedIndex];
+                sha.value = (opt && opt.getAttribute('data-sha')) || '';
+            }
+            </script>
         </section>
 
         <!-- Assets section -->