README.md

@@ -445,6 +445,20 @@ Authorization: Bearer <api-key>
 or the web UI's session cookie. A request that carries an `Authorization` header
 is judged on that header alone.
 
+Two kinds of user exist. An **administrator** manages accounts: creating and
+deleting users, setting anybody's password, minting keys for anybody, and
+granting the flag itself. Everybody else works incidents — acknowledging,
+assigning, snoozing, resolving, noting — and manages their own account and
+nobody else's. An API key carries exactly the rights of the user it belongs to.
+
+The first user, from `/api/bootstrap`, is an administrator. Users created
+afterwards are not, until an administrator says so. An install always keeps at
+least one: the last administrator can be neither deleted nor demoted, and
+nobody can delete or demote themselves.
+
+Endpoints that require the flag answer `403` with
+`{"error":"administrator access required"}`.
+
 | Method | Path | Description |
 |---|---|---|
 | `POST` | `/api/login` | `{"username","password"}` → sets the session cookie, returns `{user, has_password}`. `429` after too many failures |
@@ -455,14 +469,21 @@ is judged on that header alone.
 
 | Method | Path | Description |
 |---|---|---|
-| `POST` | `/api/bootstrap` | Create first user + API key `{"username","email","password"?}` (only works on empty DB) |
-| `GET` | `/api/users` | List users |
-| `POST` | `/api/users` | Create user `{"username","email"}` |
-| `DELETE` | `/api/users/{id}` | Delete user (cascades to keys) |
-| `PUT` | `/api/users/{id}/notify` | Set push notification target `{"ntfy_topic"}` — empty string clears it |
-| `PUT` | `/api/users/{id}/password` | Set web UI password `{"password","current_password"}`. `current_password` is required only when changing your own existing password. Ends the user's other sessions |
-| `POST` | `/api/users/{id}/api-keys` | Issue API key `{"name"}` — key shown once |
-| `DELETE` | `/api/users/{id}/api-keys/{keyID}` | Revoke API key |
+**admin** marks an endpoint that requires the administrator flag; **self or
+admin** marks one you may use on your own account and an administrator may use
+on anybody's.
+
+| Method | Path | Who | Description |
+|---|---|---|---|
+| `POST` | `/api/bootstrap` | — | Create first user + API key `{"username","email","password"?}` (only works on empty DB). The user is an administrator |
+| `GET` | `/api/users` | any | List users. Open to everybody: the queue's assignment control and the schedule both have to name people |
+| `POST` | `/api/users` | **admin** | Create user `{"username","email"}`. Not an administrator |
+| `DELETE` | `/api/users/{id}` | **admin** | Delete user (cascades to keys). `409` for yourself or the last administrator |
+| `PUT` | `/api/users/{id}/admin` | **admin** | Grant or revoke the administrator flag `{"is_admin"}`. `409` for yourself or the last administrator |
+| `PUT` | `/api/users/{id}/notify` | self or admin | Set push notification target `{"ntfy_topic"}` — empty string clears it |
+| `PUT` | `/api/users/{id}/password` | self or admin | Set web UI password `{"password","current_password"}`. `current_password` is required only when changing your own existing password. Ends the user's other sessions |
+| `POST` | `/api/users/{id}/api-keys` | self or admin | Issue API key `{"name"}` — key shown once |
+| `DELETE` | `/api/users/{id}/api-keys/{keyID}` | self or admin | Revoke API key |
 
 ### Alert ingestion
 
@@ -678,6 +699,28 @@ averages over incidents that have actually been acknowledged or resolved, and ar
 
 ---
 
+## Upgrading to roles
+
+Before this release every authenticated caller could create and delete users,
+set anybody's password and mint anybody's API keys. That is now the
+administrator flag, and the migration **makes every existing user an
+administrator** — they already held those powers, so nobody's access changes on
+upgrade and demotion is a deliberate act afterwards. Promoting only the first
+user would have silently stripped the rest, and could leave an install whose
+only administrator is an account nobody has a password for.
+
+Users created after the upgrade are not administrators. Hand the flag out with:
+
+```bash
+curl -X PUT https://terdut.example.com/api/users/7/admin \
+  -H "Authorization: Bearer $TERDUT_API_KEY" \
+  -H 'Content-Type: application/json' \
+  -d '{"is_admin": true}'
+```
+
+Nothing in the API changed shape, so terdut-tui needs no new version — but a
+non-administrator now gets `403` where a `200` used to come back.
+
 ## Upgrading from SQLite
 
 Versions up to v0.10.2 stored everything in a SQLite file. From the Postgres release onwards

internal/api/admin_test.go

@@ -0,0 +1,255 @@
+package api_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strconv"
+	"testing"
+)
+
+// The bootstrap user is an administrator; everybody it creates afterwards is
+// not. These tests are about the line between them.
+
+// id64 spells an id into a path segment.
+func id64(n int64) string { return strconv.FormatInt(n, 10) }
+
+// member creates an ordinary user and an API key for it, and returns a caller
+// that authenticates as them. Minting the key goes through the admin's own
+// credentials, which is how a real install hands one out.
+func member(t *testing.T, s *ts, username string) (id int64, call func(method, path string, body any) *http.Response) {
+	t.Helper()
+
+	resp := s.req(t, http.MethodPost, "/api/users",
+		map[string]string{"username": username, "email": username + "@test.com"})
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("create %s: %d", username, resp.StatusCode)
+	}
+	var user struct {
+		ID      int64 `json:"id"`
+		IsAdmin bool  `json:"is_admin"`
+	}
+	decode(t, resp, &user)
+	if user.IsAdmin {
+		t.Fatalf("a created user must not be an administrator")
+	}
+
+	resp = s.req(t, http.MethodPost, "/api/users/"+id64(user.ID)+"/api-keys",
+		map[string]string{"name": "test"})
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("mint key for %s: %d", username, resp.StatusCode)
+	}
+	var key struct {
+		Key string `json:"key"`
+	}
+	decode(t, resp, &key)
+
+	return user.ID, func(method, path string, body any) *http.Response {
+		t.Helper()
+		var r io.Reader
+		if body != nil {
+			data, _ := json.Marshal(body)
+			r = bytes.NewReader(data)
+		}
+		req, _ := http.NewRequest(method, s.URL+path, r)
+		req.Header.Set("Authorization", "Bearer "+key.Key)
+		if body != nil {
+			req.Header.Set("Content-Type", "application/json")
+		}
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatalf("%s %s: %v", method, path, err)
+		}
+		return resp
+	}
+}
+
+// The whole point of the release: a user who is not an administrator cannot
+// manage other people's accounts. Every one of these was open to any
+// authenticated caller before.
+func TestAdmin_MemberIsRefusedAdministration(t *testing.T) {
+	s := newTS(t)
+	memberID, call := member(t, s, "member")
+
+	cases := []struct {
+		name   string
+		method string
+		path   string
+		body   any
+	}{
+		{"create a user", http.MethodPost, "/api/users",
+			map[string]string{"username": "sneaky", "email": "sneaky@test.com"}},
+		{"delete the admin", http.MethodDelete, "/api/users/1", nil},
+		{"grant themselves admin", http.MethodPut, "/api/users/" + id64(memberID) + "/admin",
+			map[string]bool{"is_admin": true}},
+		{"set the admin's password", http.MethodPut, "/api/users/1/password",
+			map[string]string{"password": "hunter2-hunter2"}},
+		{"mint a key for the admin", http.MethodPost, "/api/users/1/api-keys",
+			map[string]string{"name": "borrowed"}},
+		{"retarget the admin's notifications", http.MethodPut, "/api/users/1/notify",
+			map[string]string{"ntfy_topic": "attacker-topic"}},
+	}
+
+	for _, c := range cases {
+		resp := call(c.method, c.path, c.body)
+		resp.Body.Close()
+		if resp.StatusCode != http.StatusForbidden {
+			t.Errorf("%s: expected 403, got %d", c.name, resp.StatusCode)
+		}
+	}
+}
+
+// Being refused other people's accounts must not cost a user their own.
+func TestAdmin_MemberKeepsTheirOwnAccount(t *testing.T) {
+	s := newTS(t)
+	memberID, call := member(t, s, "member")
+	self := "/api/users/" + id64(memberID)
+
+	resp := call(http.MethodPut, self+"/notify", map[string]string{"ntfy_topic": "terdut-member"})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("own notify target: %d", resp.StatusCode)
+	}
+
+	resp = call(http.MethodPut, self+"/password", map[string]string{"password": "correct-horse-battery"})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusNoContent {
+		t.Errorf("own password: %d", resp.StatusCode)
+	}
+
+	// An API key carries exactly the rights of its owner, so minting your own
+	// is no more than signing in again.
+	resp = call(http.MethodPost, self+"/api-keys", map[string]string{"name": "laptop"})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusCreated {
+		t.Errorf("own API key: %d", resp.StatusCode)
+	}
+
+	// And the queue still has to be able to name people.
+	resp = call(http.MethodGet, "/api/users", nil)
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("list users: %d", resp.StatusCode)
+	}
+}
+
+// Incident work is everybody's job; none of it is administration.
+func TestAdmin_MemberCanWorkIncidents(t *testing.T) {
+	s := newTS(t)
+	_, call := member(t, s, "responder")
+	postWebhook(t, s, []map[string]any{
+		amAlert("fp-admin", "DiskFull", "firing", "2026-09-20T10:00:00Z", zeroTime, nil),
+	})
+
+	for _, c := range []struct {
+		name   string
+		method string
+		path   string
+	}{
+		{"list", http.MethodGet, "/api/incidents"},
+		{"acknowledge", http.MethodPost, "/api/incidents/1/acknowledge"},
+		{"resolve", http.MethodPost, "/api/incidents/1/resolve"},
+	} {
+		resp := call(c.method, c.path, nil)
+		resp.Body.Close()
+		if resp.StatusCode != http.StatusOK {
+			t.Errorf("%s: expected 200, got %d", c.name, resp.StatusCode)
+		}
+	}
+}
+
+// An install must never be left with nobody who can administer it.
+func TestAdmin_LastAdministratorIsProtected(t *testing.T) {
+	s := newTS(t)
+
+	resp := s.req(t, http.MethodPut, "/api/users/1/admin", map[string]bool{"is_admin": false})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusConflict {
+		t.Errorf("self-demotion: expected 409, got %d", resp.StatusCode)
+	}
+
+	resp = s.req(t, http.MethodDelete, "/api/users/1", nil)
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusConflict {
+		t.Errorf("deleting yourself: expected 409, got %d", resp.StatusCode)
+	}
+
+	// With a second administrator the first may stand down, but not while they
+	// are the only one — which is the same rule from the other side.
+	otherID, _ := member(t, s, "second")
+	resp = s.req(t, http.MethodPut, "/api/users/"+id64(otherID)+"/admin", map[string]bool{"is_admin": true})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("granting admin: %d", resp.StatusCode)
+	}
+
+	resp = s.req(t, http.MethodDelete, "/api/users/"+id64(otherID), nil)
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusNoContent {
+		t.Errorf("deleting the second admin: expected 204, got %d", resp.StatusCode)
+	}
+}
+
+// A promoted user gets the powers with the flag, and loses them with it.
+func TestAdmin_GrantAndRevokeChangeWhatIsAllowed(t *testing.T) {
+	s := newTS(t)
+	memberID, call := member(t, s, "promotee")
+	admin := "/api/users/" + id64(memberID) + "/admin"
+
+	resp := call(http.MethodPost, "/api/users", map[string]string{"username": "a", "email": "a@test.com"})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusForbidden {
+		t.Fatalf("before the grant: %d", resp.StatusCode)
+	}
+
+	resp = s.req(t, http.MethodPut, admin, map[string]bool{"is_admin": true})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("grant: %d", resp.StatusCode)
+	}
+
+	resp = call(http.MethodPost, "/api/users", map[string]string{"username": "b", "email": "b@test.com"})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusCreated {
+		t.Errorf("after the grant: expected 201, got %d", resp.StatusCode)
+	}
+
+	resp = s.req(t, http.MethodPut, admin, map[string]bool{"is_admin": false})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("revoke: %d", resp.StatusCode)
+	}
+
+	resp = call(http.MethodPost, "/api/users", map[string]string{"username": "c", "email": "c@test.com"})
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusForbidden {
+		t.Errorf("after the revoke: expected 403, got %d", resp.StatusCode)
+	}
+}
+
+// The flag has to reach the client, or the web UI cannot decide what to show.
+func TestAdmin_MeReportsTheFlag(t *testing.T) {
+	s := newTS(t)
+
+	var me struct {
+		User struct {
+			IsAdmin bool `json:"is_admin"`
+		} `json:"user"`
+	}
+	decode(t, s.req(t, http.MethodGet, "/api/me", nil), &me)
+	if !me.User.IsAdmin {
+		t.Error("the bootstrap user should be an administrator")
+	}
+
+	_, call := member(t, s, "plain")
+	var theirs struct {
+		User struct {
+			IsAdmin bool `json:"is_admin"`
+		} `json:"user"`
+	}
+	decode(t, call(http.MethodGet, "/api/me", nil), &theirs)
+	if theirs.User.IsAdmin {
+		t.Error("a created user should not be an administrator")
+	}
+}

internal/api/auth.go

@@ -266,8 +266,9 @@ func handleMe(db *sql.DB) http.HandlerFunc {
 //
 // Changing your own password takes the current one, when there is one, so an
 // unattended signed-in browser cannot be used to take the account over. Setting
-// somebody else's is how an admin gives a user their first password, and like
-// the other user endpoints it is open to any authenticated caller.
+// somebody else's is how an admin gives a user their first password, and is
+// restricted to administrators: it hands over an account outright, without
+// knowing the password it replaces.
 //
 // Every other session of the target is ended: a password change is what you
 // do when you think someone else is signed in.
@@ -278,6 +279,9 @@ func handleSetPassword(db *sql.DB) http.HandlerFunc {
 			respond(w, http.StatusBadRequest, errResp("invalid user id"))
 			return
 		}
+		if !requireSelfOrAdmin(w, r, id) {
+			return
+		}
 		var req struct {
 			Password        string `json:"password"`
 			CurrentPassword string `json:"current_password"`

internal/api/middleware.go

@@ -66,6 +66,39 @@ func AuthMiddleware(db *sql.DB) func(http.Handler) http.Handler {
 	}
 }
 
+// AdminOnly rejects a caller who is not a system administrator. It runs inside
+// AuthMiddleware's group, so by the time it sees a request the caller is known.
+//
+// 403 and not 404: the route exists and the caller is authenticated, they are
+// simply not allowed. Hiding the endpoint would buy nothing — every one of them
+// is in the README.
+func AdminOnly(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		caller, ok := userFromContext(r.Context())
+		if !ok || !caller.IsAdmin {
+			respond(w, http.StatusForbidden, errResp("administrator access required"))
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+// requireSelfOrAdmin guards the endpoints that are self-service for your own
+// account and administration for anybody else's: your password, your ntfy
+// topic, your API keys. Reports whether the request may proceed, and answers it
+// if not.
+//
+// An API key is not an escalation: it carries exactly the rights of the user it
+// belongs to, so minting your own is no more than signing in again.
+func requireSelfOrAdmin(w http.ResponseWriter, r *http.Request, targetID int64) bool {
+	caller, ok := userFromContext(r.Context())
+	if !ok || (caller.ID != targetID && !caller.IsAdmin) {
+		respond(w, http.StatusForbidden, errResp("administrator access required"))
+		return false
+	}
+	return true
+}
+
 // apiKeyUser resolves an API key to its user and stamps its last use.
 func apiKeyUser(ctx context.Context, db *sql.DB, token string) (int64, bool) {
 	var keyID, userID int64
@@ -111,8 +144,8 @@ func serveAs(w http.ResponseWriter, r *http.Request, next http.Handler, db *sql.
 	var u models.User
 	var createdUnix int64
 	if err := db.QueryRowContext(r.Context(),
-		"SELECT id, username, email, created_at FROM users WHERE id = $1", userID,
-	).Scan(&u.ID, &u.Username, &u.Email, &createdUnix); err != nil {
+		"SELECT id, username, email, created_at, is_admin FROM users WHERE id = $1", userID,
+	).Scan(&u.ID, &u.Username, &u.Email, &createdUnix, &u.IsAdmin); err != nil {
 		respond(w, http.StatusUnauthorized, errResp("unauthorized"))
 		return
 	}

internal/api/router.go

@@ -40,14 +40,30 @@ func NewRouter(db *sql.DB, notify NotifyConfig, deadman DeadmanConfig) http.Hand
 		r.Use(AuthMiddleware(db))
 
 		r.Get("/api/me", handleMe(db))
+
+		// Readable by anyone signed in: the queue's assignment control and the
+		// on-call schedule both need to name people.
 		r.Get("/api/users", handleListUsers(db))
-		r.Post("/api/users", handleCreateUser(db))
-		r.Delete("/api/users/{id}", handleDeleteUser(db))
+
+		// Your own account, or anybody's if you are an admin. The handlers call
+		// requireSelfOrAdmin rather than sitting behind AdminOnly, because
+		// which rule applies depends on the {id} in the path.
 		r.Put("/api/users/{id}/notify", handleSetNotifyTarget(db))
 		r.Put("/api/users/{id}/password", handleSetPassword(db))
 		r.Post("/api/users/{id}/api-keys", handleCreateAPIKey(db))
 		r.Delete("/api/users/{id}/api-keys/{keyID}", handleDeleteAPIKey(db))
 
+		// Administration: who exists, and who is an administrator. Until #3
+		// these were open to any authenticated caller, which meant every user
+		// could delete every other one.
+		r.Group(func(r chi.Router) {
+			r.Use(AdminOnly)
+
+			r.Post("/api/users", handleCreateUser(db))
+			r.Delete("/api/users/{id}", handleDeleteUser(db))
+			r.Put("/api/users/{id}/admin", handleSetAdmin(db))
+		})
+
 		// Alerts are read-only: they are Alertmanager's record, not a work
 		// queue. Everything a person does happens on the incident instead.
 		r.Get("/api/alerts", handleListAlerts(db))

internal/api/users.go

@@ -58,7 +58,7 @@ func handleBootstrap(db *sql.DB) http.HandlerFunc {
 
 		var userID int64
 		if err := db.QueryRowContext(r.Context(),
-			"INSERT INTO users (username, email, password_hash) VALUES ($1, $2, $3) RETURNING id",
+			"INSERT INTO users (username, email, password_hash, is_admin) VALUES ($1, $2, $3, true) RETURNING id",
 			req.Username, req.Email, passwordHash).Scan(&userID); err != nil {
 			respond(w, http.StatusInternalServerError, errResp("internal error"))
 			return
@@ -86,7 +86,7 @@ func handleBootstrap(db *sql.DB) http.HandlerFunc {
 func handleListUsers(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		rows, err := db.QueryContext(r.Context(),
-			"SELECT id, username, email, created_at, ntfy_topic FROM users ORDER BY id")
+			"SELECT id, username, email, created_at, ntfy_topic, is_admin FROM users ORDER BY id")
 		if err != nil {
 			respond(w, http.StatusInternalServerError, errResp("internal error"))
 			return
@@ -97,7 +97,7 @@ func handleListUsers(db *sql.DB) http.HandlerFunc {
 		for rows.Next() {
 			var u models.User
 			var ts int64
-			if err := rows.Scan(&u.ID, &u.Username, &u.Email, &ts, &u.NtfyTopic); err != nil {
+			if err := rows.Scan(&u.ID, &u.Username, &u.Email, &ts, &u.NtfyTopic, &u.IsAdmin); err != nil {
 				respond(w, http.StatusInternalServerError, errResp("internal error"))
 				return
 			}
@@ -150,6 +150,9 @@ func handleSetNotifyTarget(db *sql.DB) http.HandlerFunc {
 			respond(w, http.StatusBadRequest, errResp("invalid user id"))
 			return
 		}
+		if !requireSelfOrAdmin(w, r, id) {
+			return
+		}
 		var req struct {
 			NtfyTopic string `json:"ntfy_topic"`
 		}
@@ -190,6 +193,21 @@ func handleDeleteUser(db *sql.DB) http.HandlerFunc {
 			respond(w, http.StatusBadRequest, errResp("invalid user id"))
 			return
 		}
+		// Deleting yourself is how an install ends up with no administrator at
+		// all, and it is never what somebody meant to do.
+		caller, _ := userFromContext(r.Context())
+		if caller.ID == id {
+			respond(w, http.StatusConflict, errResp("cannot delete your own account"))
+			return
+		}
+		if last, err := isLastAdmin(r.Context(), db, id); err != nil {
+			respond(w, http.StatusInternalServerError, errResp("internal error"))
+			return
+		} else if last {
+			respond(w, http.StatusConflict, errResp("cannot delete the last administrator"))
+			return
+		}
+
 		res, err := db.ExecContext(r.Context(), "DELETE FROM users WHERE id = $1", id)
 		if err != nil {
 			respond(w, http.StatusInternalServerError, errResp("internal error"))
@@ -211,6 +229,9 @@ func handleCreateAPIKey(db *sql.DB) http.HandlerFunc {
 			respond(w, http.StatusBadRequest, errResp("invalid user id"))
 			return
 		}
+		if !requireSelfOrAdmin(w, r, userID) {
+			return
+		}
 
 		var req struct {
 			Name string `json:"name"`
@@ -254,6 +275,9 @@ func handleDeleteAPIKey(db *sql.DB) http.HandlerFunc {
 			respond(w, http.StatusBadRequest, errResp("invalid user id"))
 			return
 		}
+		if !requireSelfOrAdmin(w, r, userID) {
+			return
+		}
 		keyID, err := strconv.ParseInt(chi.URLParam(r, "keyID"), 10, 64)
 		if err != nil {
 			respond(w, http.StatusBadRequest, errResp("invalid key id"))
@@ -292,11 +316,77 @@ func fetchUser(ctx context.Context, db *sql.DB, id int64) (models.User, error) {
 	var u models.User
 	var ts int64
 	err := db.QueryRowContext(ctx,
-		"SELECT id, username, email, created_at, ntfy_topic FROM users WHERE id = $1", id).
-		Scan(&u.ID, &u.Username, &u.Email, &ts, &u.NtfyTopic)
+		"SELECT id, username, email, created_at, ntfy_topic, is_admin FROM users WHERE id = $1", id).
+		Scan(&u.ID, &u.Username, &u.Email, &ts, &u.NtfyTopic, &u.IsAdmin)
 	if err != nil {
 		return u, err
 	}
 	u.CreatedAt = time.Unix(ts, 0).UTC()
 	return u, nil
 }
+
+// handleSetAdmin grants or revokes the system administrator flag.
+//
+// Revoking is guarded twice: an install must keep at least one administrator,
+// and you cannot demote yourself. The first stops the flag being lost
+// altogether; the second stops the likelier accident, where the only admin
+// clears their own flag while tidying up and locks the door behind them.
+func handleSetAdmin(db *sql.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
+		if err != nil {
+			respond(w, http.StatusBadRequest, errResp("invalid user id"))
+			return
+		}
+		var req struct {
+			IsAdmin *bool `json:"is_admin"`
+		}
+		if err := decodeJSON(r, &req); err != nil || req.IsAdmin == nil {
+			respond(w, http.StatusBadRequest, errResp("is_admin is required"))
+			return
+		}
+
+		if !*req.IsAdmin {
+			caller, _ := userFromContext(r.Context())
+			if caller.ID == id {
+				respond(w, http.StatusConflict, errResp("cannot revoke your own administrator access"))
+				return
+			}
+			if last, err := isLastAdmin(r.Context(), db, id); err != nil {
+				respond(w, http.StatusInternalServerError, errResp("internal error"))
+				return
+			} else if last {
+				respond(w, http.StatusConflict, errResp("cannot revoke the last administrator"))
+				return
+			}
+		}
+
+		res, err := db.ExecContext(r.Context(),
+			"UPDATE users SET is_admin = $1 WHERE id = $2", *req.IsAdmin, id)
+		if err != nil {
+			respond(w, http.StatusInternalServerError, errResp("internal error"))
+			return
+		}
+		if n, _ := res.RowsAffected(); n == 0 {
+			respond(w, http.StatusNotFound, errResp("user not found"))
+			return
+		}
+
+		user, err := fetchUser(r.Context(), db, id)
+		if err != nil {
+			respond(w, http.StatusInternalServerError, errResp("internal error"))
+			return
+		}
+		respond(w, http.StatusOK, user)
+	}
+}
+
+// isLastAdmin reports whether id is an administrator and no other user is one.
+// A non-admin id is never the last one, so removing them is always allowed.
+func isLastAdmin(ctx context.Context, db *sql.DB, id int64) (bool, error) {
+	var last bool
+	err := db.QueryRowContext(ctx, `
+		SELECT EXISTS (SELECT 1 FROM users WHERE id = $1 AND is_admin)
+		   AND NOT EXISTS (SELECT 1 FROM users WHERE id <> $1 AND is_admin)`, id).Scan(&last)
+	return last, err
+}

internal/db/migrations/002_admin_role.sql

@@ -0,0 +1,25 @@
+-- A system administrator role, and the first thing in this server that one user
+-- can do and another cannot.
+--
+-- Until now every authenticated caller could create and delete users, set
+-- anybody's password and mint API keys for anybody — auth.go said so in a
+-- comment. That was defensible with one operator and a hand-made account; it is
+-- not once people sign themselves up (see #7).
+--
+-- EVERY EXISTING USER BECOMES AN ADMIN. They already hold these powers, so
+-- this migration changes nobody's access: it names what is already true, and
+-- leaves demotion as a deliberate act somebody performs afterwards. The
+-- alternative — promoting only user 1 — would silently strip the others, and
+-- could leave an install whose only admin is an account nobody has a password
+-- for.
+--
+-- New users are not admins: the column defaults to false, and the only ways to
+-- become one are this backfill, the bootstrap endpoint, or an existing admin
+-- granting it.
+ALTER TABLE users ADD COLUMN is_admin BOOLEAN NOT NULL DEFAULT false;
+
+UPDATE users SET is_admin = true;
+
+-- The queue's assignment dropdown and the on-call schedule read every user, and
+-- the admin screens in #5 will filter on this.
+CREATE INDEX users_is_admin_idx ON users(is_admin) WHERE is_admin;

internal/models/user.go

@@ -12,6 +12,12 @@ type User struct {
 	// none of their own; incidents assigned to them fall back to the configured
 	// fallback topic instead.
 	NtfyTopic *string `json:"ntfy_topic,omitempty"`
+
+	// IsAdmin is the system administrator flag: managing users and API keys.
+	// Not omitempty — a client has to be able to tell "false" from "this server
+	// is too old to have the field", and the web UI decides what to show from
+	// it.
+	IsAdmin bool `json:"is_admin"`
 }
 
 type APIKey struct {