feat(agentgit): register members' SSH keys + enable git push over SSH

Make git.profullstack.com a real, key-authenticated git host for every BBS
member ("BBS membership is the git account", SSH-key auth end to end):

- forgejo.EnsureKey: register a member's SSH public key on their Forgejo
  account (idempotent, ignores the key comment). So the key they sign in to
  the BBS with is also their git push key.
- provisionGit now takes the session public key and registers it after
  ensuring the account; called on email verification AND (newly) on every
  member login, so members who predate AgentGit — or whose key wasn't
  registered yet — are backfilled automatically and off the hot path.
- setup.sh:
  - admin token scopes write:admin,read:user,write:user (the old write:admin
    alone failed userExists' /users lookup, so provisioning never worked).
  - REQUIRE_SIGNIN_VIEW=false so member profiles + public repos are viewable
    at git.profullstack.com/<name> (private repos stay private; accounts are
    still created only by agentbbs).
  - Enable Forgejo's built-in SSH server (port 2222, BUILTIN_SSH_SERVER_USER=git)
    and open the firewall, so members push to git@git.profullstack.com:2222.

Verified live: all members provisioned, git.profullstack.com/chovy serves the
profile, and a push over ssh://git@host:2222 with a registered key succeeds.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cmd/agentbbs/main.go

@@ -400,6 +400,13 @@ func (a *app) teaHandler(s ssh.Session) (tea.Model, []tea.ProgramOption) {
 		// provisions their @host email alias on the transition).
 		a.ensurePremium(&su)
 		u = auth.User{Name: su.Name, Kind: auth.Kind(su.Kind), PubKeyFP: fp, StoreID: su.ID}
+		// Backfill the git.profullstack.com account + SSH key on login. Idempotent
+		// and off the hot path: members who verified before AgentGit existed (or
+		// before their key was registered) get provisioned on their next visit.
+		if su.EmailVerified {
+			suCopy, key := su, authorizedKey(s)
+			go a.provisionGit(&suCopy, key)
+		}
 	}
 
 	sessID, _ := a.st.RecordSession(u.StoreID, s.User(), remoteIP(s), "hub")
@@ -779,7 +786,7 @@ func (a *app) verifyEmailInteractive(s ssh.Session, in *bufio.Reader, u *store.U
 		}
 		if ok {
 			*u = vu
-			a.provisionGit(u)
+			a.provisionGit(u, authorizedKey(s))
 			wish.Println(s, "  Email confirmed ✓")
 			return true
 		}
@@ -954,7 +961,7 @@ func (a *app) handleVerify(w http.ResponseWriter, r *http.Request) {
 			"Run <code>ssh join@"+a.host+"</code> to get a fresh confirmation link.")))
 		return
 	}
-	a.provisionGit(&u)
+	a.provisionGit(&u, "") // web flow: no SSH session key; key is added on next BBS login
 	_, _ = w.Write([]byte(verifyPage("Email confirmed ✓",
 		"Welcome, "+u.Name+". Your account is active — <code>ssh "+u.Name+"@"+a.host+"</code>.")))
 }
@@ -964,7 +971,7 @@ func (a *app) handleVerify(w http.ResponseWriter, r *http.Request) {
 // alike; plan only affects quotas, enforced by AgentGit, not account existence.
 // Failures are logged but never block BBS verification, and it is a no-op when
 // Forgejo is unconfigured.
-func (a *app) provisionGit(u *store.User) {
+func (a *app) provisionGit(u *store.User, pubKey string) {
 	if u == nil || !a.forgejo.Configured() || u.Name == "" || u.Email == "" {
 		return
 	}
@@ -976,6 +983,25 @@ func (a *app) provisionGit(u *store.User) {
 	if created {
 		log.Info("provisioned git account", "user", u.Name, "host", a.forgejo.BaseURL)
 	}
+	// Register the BBS SSH key so the member can push with the same key they sign
+	// in with. No-op when called without a session key (e.g. the web verify flow).
+	if pubKey != "" {
+		if added, err := a.forgejo.EnsureKey(u.Name, "agentbbs", pubKey); err != nil {
+			log.Error("forgejo ssh key", "user", u.Name, "err", err)
+		} else if added {
+			log.Info("registered git ssh key", "user", u.Name)
+		}
+	}
+}
+
+// authorizedKey renders the session's public key as a single authorized_keys
+// line, or "" when the session has no key (guests / keyboard-interactive).
+func authorizedKey(s ssh.Session) string {
+	pk := s.PublicKey()
+	if pk == nil {
+		return ""
+	}
+	return strings.TrimSpace(string(gossh.MarshalAuthorizedKey(pk)))
 }
 
 // verifyPage renders the minimal confirmation result page.

internal/forgejo/forgejo.go

@@ -84,6 +84,58 @@ func (c Config) EnsureUser(username, email string) (created bool, err error) {
 	return true, nil
 }
 
+// EnsureKey registers an SSH public key on the member's Forgejo account so the
+// key they use for the BBS is also their git push key ("BBS membership is the
+// git account"). It is idempotent: added is false when the same key material is
+// already present. A blank key is a no-op. title labels the key in Forgejo.
+func (c Config) EnsureKey(username, title, pubKey string) (added bool, err error) {
+	if !c.Configured() {
+		return false, fmt.Errorf("forgejo not configured")
+	}
+	pubKey = strings.TrimSpace(pubKey)
+	if pubKey == "" {
+		return false, nil
+	}
+
+	// Skip if this key (ignoring the trailing comment) is already on the account.
+	if status, resp, e := c.do(http.MethodGet, "/users/"+username+"/keys", nil); e == nil && status == http.StatusOK {
+		var keys []struct {
+			Key string `json:"key"`
+		}
+		if json.Unmarshal([]byte(resp), &keys) == nil {
+			want := keyMaterial(pubKey)
+			for _, k := range keys {
+				if keyMaterial(k.Key) == want {
+					return false, nil
+				}
+			}
+		}
+	}
+
+	body, _ := json.Marshal(map[string]any{"title": title, "key": pubKey, "read_only": false})
+	status, resp, err := c.do(http.MethodPost, "/admin/users/"+username+"/keys", body)
+	if err != nil {
+		return false, err
+	}
+	if status == http.StatusUnprocessableEntity {
+		return false, nil // key already exists (raced or comment differs)
+	}
+	if status < 200 || status >= 300 {
+		return false, fmt.Errorf("forgejo add key %q: %d: %s", username, status, truncate(resp, 200))
+	}
+	return true, nil
+}
+
+// keyMaterial returns the type+base64 of an authorized-key line, dropping the
+// optional comment so the same key compares equal regardless of how it's labeled.
+func keyMaterial(authorizedKey string) string {
+	f := strings.Fields(strings.TrimSpace(authorizedKey))
+	if len(f) >= 2 {
+		return f[0] + " " + f[1]
+	}
+	return strings.TrimSpace(authorizedKey)
+}
+
 // userExists reports whether a Forgejo user with this name is present.
 func (c Config) userExists(username string) (bool, error) {
 	status, resp, err := c.do(http.MethodGet, "/users/"+username, nil)

internal/forgejo/forgejo_test.go

@@ -93,3 +93,65 @@ func TestEnsureUserNoOpWhenExists(t *testing.T) {
 		t.Fatal("must not POST when the user already exists")
 	}
 }
+
+const aliceKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAITESTKEY alice@bbs"
+
+func TestEnsureKeyAddsWhenMissing(t *testing.T) {
+	var posted map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case r.Method == http.MethodGet && r.URL.Path == "/api/v1/users/alice/keys":
+			_, _ = w.Write([]byte(`[]`))
+		case r.Method == http.MethodPost && r.URL.Path == "/api/v1/admin/users/alice/keys":
+			_ = json.NewDecoder(r.Body).Decode(&posted)
+			w.WriteHeader(http.StatusCreated)
+			_, _ = w.Write([]byte(`{"id":1}`))
+		default:
+			t.Errorf("unexpected %s %s", r.Method, r.URL.Path)
+		}
+	}))
+	defer srv.Close()
+
+	c := Config{BaseURL: srv.URL, Token: "secret"}
+	added, err := c.EnsureKey("alice", "agentbbs", aliceKey)
+	if err != nil {
+		t.Fatalf("EnsureKey: %v", err)
+	}
+	if !added {
+		t.Fatal("expected added=true")
+	}
+	if posted["key"] != aliceKey {
+		t.Errorf("posted key = %v", posted["key"])
+	}
+}
+
+func TestEnsureKeyIdempotentIgnoringComment(t *testing.T) {
+	posted := false
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodPost {
+			posted = true
+		}
+		// Same key material, different comment — must be treated as already present.
+		_, _ = w.Write([]byte(`[{"key":"ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAITESTKEY different-comment"}]`))
+	}))
+	defer srv.Close()
+
+	c := Config{BaseURL: srv.URL, Token: "secret"}
+	added, err := c.EnsureKey("alice", "agentbbs", aliceKey)
+	if err != nil {
+		t.Fatalf("EnsureKey: %v", err)
+	}
+	if added {
+		t.Fatal("expected added=false when key material already present")
+	}
+	if posted {
+		t.Fatal("must not POST when the key already exists")
+	}
+}
+
+func TestEnsureKeyBlankIsNoOp(t *testing.T) {
+	c := Config{BaseURL: "https://git.example.com", Token: "t"}
+	if added, err := c.EnsureKey("alice", "agentbbs", "  "); err != nil || added {
+		t.Fatalf("blank key should be a silent no-op, got added=%v err=%v", added, err)
+	}
+}

setup.sh

@@ -53,6 +53,7 @@ MAIL_DOMAIN="${MAIL_DOMAIN:-mail.${DOMAIN#*.}}"  # mail host (default: mail.<roo
 FORGEJO_HTTP_ADDR="${FORGEJO_HTTP_ADDR:-127.0.0.1:3000}"  # Forgejo loopback HTTP (Caddy fronts it)
 FORGEJO_DATA="${FORGEJO_DATA:-/var/lib/forgejo}"  # Forgejo state dir (repos, db)
 FORGEJO_ADMIN_USER="${FORGEJO_ADMIN_USER:-agentgit-admin}"  # Forgejo admin used to provision members
+FORGEJO_SSH_PORT="${FORGEJO_SSH_PORT:-2222}"  # Forgejo built-in SSH server port (git push); host :22 is agentbbs, :2202 admin
 
 log()  { printf '\033[1;36m==>\033[0m %s\n' "$*"; }
 warn() { printf '\033[1;33m[warn]\033[0m %s\n' "$*" >&2; }
@@ -838,8 +839,15 @@ HTTP_ADDR = ${FORGEJO_HTTP_ADDR%%:*}
 HTTP_PORT = ${FORGEJO_HTTP_ADDR##*:}
 DOMAIN = ${GIT_DOMAIN}
 ROOT_URL = https://${GIT_DOMAIN}/
-DISABLE_SSH = true
+SSH_DOMAIN = ${GIT_DOMAIN}
-START_SSH_SERVER = false
+# Built-in SSH server (in-process, runs as the forgejo user) so members can push
+# with the same key they use for the BBS. Host :22 is agentbbs and :2202 is the
+# admin OpenSSH, so Forgejo gets its own port; clones use ssh://git@host:PORT/.
+DISABLE_SSH = false
+START_SSH_SERVER = true
+SSH_USER = git
+SSH_PORT = ${FORGEJO_SSH_PORT}
+SSH_LISTEN_PORT = ${FORGEJO_SSH_PORT}
 
 [database]
 DB_TYPE = sqlite3
@@ -850,7 +858,10 @@ ROOT = ${FORGEJO_DATA}/repos
 
 [service]
 DISABLE_REGISTRATION = true
-REQUIRE_SIGNIN_VIEW = true
+# Public read: member profiles (git.${DOMAIN#*.}/<name>) and public repos are
+# viewable without signing in; private repos stay private. Accounts are created
+# only by agentbbs (DISABLE_REGISTRATION), never self-serve.
+REQUIRE_SIGNIN_VIEW = false
 DEFAULT_KEEP_EMAIL_PRIVATE = true
 
 [security]
@@ -896,6 +907,9 @@ UNIT
   systemctl is-active --quiet forgejo \
     || warn "forgejo failed to start — check: journalctl -u forgejo -n50"
 
+  # Open the Forgejo SSH port so members can push (git@${GIT_DOMAIN}:${FORGEJO_SSH_PORT}).
+  ufw allow "${FORGEJO_SSH_PORT}/tcp" >/dev/null 2>&1 || true
+
   # First-run: create the admin agentbbs uses to mint member accounts, and store
   # an admin-scoped token in agentbbs.env. Guarded on the token being empty so
   # reruns never create duplicate tokens.
@@ -906,7 +920,7 @@ UNIT
       --password "$FJ_ADMIN_PW" --must-change-password=false --config "$FORGEJO_CONF" >/dev/null 2>&1 \
       || true
     FJ_TOKEN=$(sudo -u forgejo GITEA_WORK_DIR="$FORGEJO_DATA" /usr/local/bin/forgejo admin user generate-access-token \
-      --username "$FORGEJO_ADMIN_USER" --token-name "agentbbs-$(date +%s)" --scopes write:admin \
+      --username "$FORGEJO_ADMIN_USER" --token-name "agentbbs-$(date +%s)" --scopes write:admin,read:user,write:user \
       --config "$FORGEJO_CONF" 2>/dev/null | grep -oE '[0-9a-f]{40}' | head -1)
     if [ -n "$FJ_TOKEN" ]; then
       upsert_env AGENTBBS_FORGEJO_URL "https://${GIT_DOMAIN}"