Show the build in a footer, linked to its release or commit

The version moves from the header to a "Powered by Jarl" footer. A build
of a release tag (HEAD tagged v<VERSION>, no tracked changes; the release
workflow sets RELEASE_TAG) shows and links the release; any other build
shows and links its commit, marked -modified with uncommitted changes.
jarld version, jarl --version, /status and /auth/whoami report the same.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/types.go

@@ -8,6 +8,7 @@ import (
 
 	"jarl/internal/model"
 	"jarl/internal/nscheck"
+	"jarl/internal/version"
 )
 
 // Version is the API path prefix.
@@ -92,6 +93,8 @@ type Whoami struct {
 	Permissions []string `json:"permissions"`
 	Admin       bool     `json:"admin"`
 	Version     string   `json:"version"`
+	// Build is what the server was built from (release or commit).
+	Build version.Build `json:"build"`
 }
 
 // LoginRequest logs in.
@@ -156,6 +159,7 @@ type Changeset struct {
 // StatusResponse is GET /status.
 type StatusResponse struct {
 	Version string          `json:"version"`
+	Build   version.Build   `json:"build"`
 	Engine  json.RawMessage `json:"engine"`
 	Time    time.Time       `json:"time"`
 	// ExpiringTokens are tokens that expire within TokenExpiryWarning or

internal/server/h_changes.go

@@ -13,6 +13,7 @@ import (
 	"jarl/internal/engine"
 	"jarl/internal/model"
 	"jarl/internal/store"
+	"jarl/internal/version"
 )
 
 func toRequests(in []api.ChangeRequest) []engine.Request {
@@ -273,7 +274,7 @@ func (s *Server) status(w http.ResponseWriter, r *http.Request, p *auth.Principa
 		}
 	}
 	now := time.Now()
-	resp := api.StatusResponse{Version: s.cfg.Version, Engine: raw(st), Time: now, ExpiringTokens: s.expiringTokens(r.Context(), p, now)}
+	resp := api.StatusResponse{Version: s.cfg.Version, Build: version.Info(), Engine: raw(st), Time: now, ExpiringTokens: s.expiringTokens(r.Context(), p, now)}
 	if p.IsAdmin() {
 		resp.Backup = s.backupStatus(r.Context(), now)
 	}

internal/server/present.go

@@ -9,6 +9,7 @@ import (
 	"jarl/internal/model"
 	"jarl/internal/render"
 	"jarl/internal/rr"
+	"jarl/internal/version"
 )
 
 func (s *Server) presentZone(st *model.State, z *model.Zone, counts map[int64]int) api.Zone {
@@ -132,7 +133,7 @@ func presentToken(t *model.Token) api.Token {
 }
 
 func (s *Server) whoamiOf(p *auth.Principal, se *model.Session) api.Whoami {
-	out := api.Whoami{User: presentUser(p.User), Method: p.Method, Permissions: p.Summary(), Admin: p.IsAdmin(), Version: s.cfg.Version}
+	out := api.Whoami{User: presentUser(p.User), Method: p.Method, Permissions: p.Summary(), Admin: p.IsAdmin(), Version: s.cfg.Version, Build: version.Info()}
 	if p.Token != nil {
 		t := presentToken(p.Token)
 		out.Token = &t

internal/version/version.go

@@ -1,7 +1,94 @@
 // Package version holds Jarl's version, set at build time with
 //
-//	go build -ldflags "-X jarl/internal/version.Version=1.2.3"
+//	go build -ldflags "-X jarl/internal/version.Version=1.2.3 -X jarl/internal/version.Tag=v1.2.3"
+//
+// The Makefile sets Version from the VERSION file, and Tag only when the
+// build is of that release: HEAD is the tag v<VERSION> and no tracked file
+// is changed. Other builds are identified by their commit, which Go
+// records from git by itself.
 package version
 
-// Version is the Jarl version.
+import (
+	"runtime/debug"
+	"sync"
+)
+
+// Version is the Jarl version (the VERSION file).
 var Version = "0.1.0-dev"
+
+// Tag is the release tag the build is of ("" when it isn't a release).
+var Tag = ""
+
+// Commit is the git commit the build is of. It is read from the build
+// information when not set at build time.
+var Commit = ""
+
+// Repo is Jarl's source repository.
+const Repo = "https://gitea.adbraun.lol/adam/jarl"
+
+// Build describes what a binary was built from.
+type Build struct {
+	Version  string `json:"version"`
+	Tag      string `json:"tag,omitempty"`
+	Commit   string `json:"commit,omitempty"`
+	Modified bool   `json:"modified,omitempty"` // built with uncommitted changes
+	// Label is the short form to show: the tag of a release, otherwise
+	// the abbreviated commit (or the version when the commit is unknown).
+	Label string `json:"label"`
+	// URL is the release or commit in the repository.
+	URL string `json:"url"`
+}
+
+var info = sync.OnceValue(func() Build {
+	commit, modified := Commit, false
+	if bi, ok := debug.ReadBuildInfo(); ok {
+		for _, s := range bi.Settings {
+			switch s.Key {
+			case "vcs.revision":
+				if commit == "" {
+					commit = s.Value
+				}
+			case "vcs.modified":
+				modified = s.Value == "true"
+			}
+		}
+	}
+	return describe(Version, Tag, commit, modified)
+})
+
+func describe(version, tag, commit string, modified bool) Build {
+	b := Build{Version: version, Tag: tag, Commit: commit, Modified: modified}
+	switch {
+	case tag != "":
+		b.Modified = false // the Makefile only sets Tag for clean trees
+		b.Label, b.URL = tag, Repo+"/releases/tag/"+tag
+	case commit != "":
+		b.Label, b.URL = short(commit), Repo+"/commit/"+commit
+		if modified {
+			b.Label += "-modified"
+		}
+	default:
+		b.Label, b.URL = version, Repo
+	}
+	return b
+}
+
+// Info describes this build.
+func Info() Build { return info() }
+
+// String is the version for logs and 'version' commands: "0.2.0" for a
+// release, otherwise the version and the commit ("0.2.0-dev (a1b2c3d4e5f6)").
+func String() string {
+	b := Info()
+	if b.Tag != "" || b.Commit == "" {
+		return b.Version
+	}
+	return b.Version + " (" + b.Label + ")"
+}
+
+func short(commit string) string {
+	if len(commit) > 12 {
+		return commit[:12]
+	}
+	return commit
+}

internal/version/version_test.go

@@ -0,0 +1,22 @@
+package version
+
+import "testing"
+
+func TestDescribe(t *testing.T) {
+	const c = "4d00be5e1f0a9b8c7d6e5f4a3b2c1d0e9f8a7b6c"
+	for _, tc := range []struct {
+		tag, commit string
+		modified    bool
+		label, url  string
+	}{
+		{"v0.1.0", c, true, "v0.1.0", Repo + "/releases/tag/v0.1.0"},
+		{"", c, false, "4d00be5e1f0a", Repo + "/commit/" + c},
+		{"", c, true, "4d00be5e1f0a-modified", Repo + "/commit/" + c},
+		{"", "", false, "0.1.0", Repo},
+	} {
+		b := describe("0.1.0", tc.tag, tc.commit, tc.modified)
+		if b.Label != tc.label || b.URL != tc.url {
+			t.Errorf("describe(%q, %q, %v) = %q %q, want %q %q", tc.tag, tc.commit, tc.modified, b.Label, b.URL, tc.label, tc.url)
+		}
+	}
+}

internal/web/static/assets/app.js

@@ -93,8 +93,7 @@ function layout() {
   const header = h("header", { class: "top" },
     h("a", { class: "brand", href: "#/", title: "Dashboard" },
       logo(30),
-      wordmark({ rule: false, height: 19, cls: "brand-name" }),
-      h("span", { class: "brand-version" }, me.version)),
+      wordmark({ rule: false, height: 19, cls: "brand-name" })),
     navEl,
     h("div", { class: "spacer" }),
     modeEl = h("span"),
@@ -102,7 +101,7 @@ function layout() {
     h("a", { href: "#/account", class: "user", title: (me.permissions || []).join("\n") }, me.user.username),
     me.admin ? h("a", { href: "#/users" }, "Users") : null,
     h("button", { class: "small", onclick: logout }, "Log out"));
-  mount(app, header, barEl, mainEl);
+  mount(app, h("div", { class: "shell" }, header, barEl, mainEl, footer(me.build)));
   modeHolder = modeEl;
   renderNav();
   renderBar();
@@ -110,6 +109,16 @@ function layout() {
 
 let modeHolder;
 
+// footer names the Jarl build: the release, or the commit for other
+// builds, linked to it in the repository.
+function footer(b) {
+  if (!b) return null;
+  const what = b.tag ? "release " + b.tag
+    : b.commit ? "commit " + b.commit + (b.modified ? ", with uncommitted changes" : "") : "version " + b.version;
+  return h("footer", { class: "site" }, "Powered by ",
+    h("a", { href: b.url, target: "_blank", rel: "noopener", title: "Jarl " + b.version + ", built from " + what }, "Jarl " + b.label));
+}
+
 function renderNav() {
   mount(navEl, navItems.map(([key, href, label]) => h("a", { href, class: current.nav === key ? "active" : "" }, label)));
 }

internal/web/static/assets/style.css

@@ -97,7 +97,6 @@ header.top {
 header.top .brand { display: inline-flex; align-items: center; gap: 8px; color: var(--text); text-decoration: none; }
 header.top .brand .logo { display: block; transition: transform 0.15s; }
 header.top .brand .brand-name { display: block; color: var(--text); }
-header.top .brand .brand-version { color: var(--muted); font-size: 12px; align-self: flex-end; padding-bottom: 2px; }
 header.top .brand:hover { text-decoration: none; }
 header.top .brand:hover .brand-name { color: var(--accent); }
 header.top .brand:hover .logo { transform: scale(1.06); }
@@ -403,3 +402,10 @@ button.chip:hover { background: var(--accent-soft); border-color: var(--accent);
 .swatch.selected { box-shadow: 0 0 0 2px currentColor; }
 .swatch:focus-visible { outline: 2px solid var(--text); outline-offset: 2px; }
 tr.selected td { background: var(--accent-soft); }
+
+/* the page footer with the Jarl build */
+.shell { min-height: 100vh; display: flex; flex-direction: column; }
+.shell > main { flex: 1; width: 100%; }
+footer.site { padding: 12px 16px 16px; text-align: center; font-size: 12px; color: var(--muted); }
+footer.site a { color: var(--muted); text-decoration: underline; text-decoration-color: var(--border); text-underline-offset: 2px; }
+footer.site a:hover { color: var(--accent); text-decoration-color: currentColor; }