added ideas

Carries the raw ID token in the session cookie so logout can hand it back
to Keycloak as id_token_hint, letting it skip its own logout-confirmation
prompt -- otherwise a user could cancel out of it and land back in the app
with a Keycloak SSO session but no geniusrun profile (e.g. right after
deleting their account).

backend/.idea/.gitignore

@@ -1,10 +0,0 @@
-# Default ignored files
-/shelf/
-/workspace.xml
-# Editor-based HTTP Client requests
-/httpRequests/
-# Ignored default folder with query files
-/queries/
-# Datasource local storage ignored files
-/dataSources/
-/dataSources.local.xml

backend/.idea/backend.iml

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="WEB_MODULE" version="4">
-  <component name="Go" enabled="true" />
-  <component name="NewModuleRootManager">
-    <content url="file://$MODULE_DIR$" />
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
-</module>

backend/.idea/go.imports.xml

@@ -1,10 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="GoImports">
-    <option name="excludedPackages">
-      <array>
-        <option value="golang.org/x/net/context" />
-      </array>
-    </option>
-  </component>
-</project>

backend/.idea/modules.xml

@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ProjectModuleManager">
-    <modules>
-      <module fileurl="file://$PROJECT_DIR$/.idea/backend.iml" filepath="$PROJECT_DIR$/.idea/backend.iml" />
-    </modules>
-  </component>
-</project>

backend/.idea/vcs.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="$PROJECT_DIR$/.." vcs="Git" />
-  </component>
-</project>

backend/internal/api/api_test.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
+	"os"
 	"path/filepath"
 	"strconv"
 	"testing"
@@ -764,6 +765,85 @@ func TestProfile_RejectsInvalidHRZones(t *testing.T) {
 	}
 }
 
+func TestDeleteProfile_DeletesUserAndTerminatesGarminClient(t *testing.T) {
+	s, db, userID := newTestServer(t)
+	router := s.Router()
+
+	// Force the per-user Garmin client to be built and cached.
+	rec := doJSON(t, router, http.MethodPost, "/api/auth/login", nil)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("auth/login status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+	client, err := s.garminFor(context.Background(), userID)
+	if err != nil {
+		t.Fatalf("garminFor: %v", err)
+	}
+	mockClient, ok := client.(*mock.Client)
+	if !ok {
+		t.Fatalf("expected *mock.Client, got %T", client)
+	}
+
+	rec = doJSON(t, router, http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusNoContent {
+		t.Fatalf("delete status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+
+	if _, found, err := db.GetUserBySub(context.Background(), "test-user"); err != nil || found {
+		t.Fatalf("expected user gone after delete, found=%v err=%v", found, err)
+	}
+	if !mockClient.ClosedCalled {
+		t.Error("expected the cached garmin client to be Close()d on profile deletion")
+	}
+}
+
+func TestDeleteProfile_RejectsWhileSyncInProgress(t *testing.T) {
+	s, db, userID := newTestServer(t)
+	s.mu.Lock()
+	s.userSyncRunning[userID] = true
+	s.mu.Unlock()
+
+	rec := doJSON(t, s.Router(), http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusConflict {
+		t.Fatalf("status = %d, want 409, body = %s", rec.Code, rec.Body.String())
+	}
+	if _, found, err := db.GetUserBySub(context.Background(), "test-user"); err != nil || !found {
+		t.Fatalf("expected user to survive a rejected delete, found=%v err=%v", found, err)
+	}
+}
+
+func TestDeleteProfile_RemovesTokenStoreDirectory(t *testing.T) {
+	db, err := store.Open(filepath.Join(t.TempDir(), "geniusrun_test.db"))
+	if err != nil {
+		t.Fatalf("store.Open: %v", err)
+	}
+	t.Cleanup(func() { db.Close() })
+	userID, err := db.ProvisionUser(context.Background(), "test-user", "Test User")
+	if err != nil {
+		t.Fatalf("ProvisionUser: %v", err)
+	}
+
+	tokenStoreRoot := t.TempDir()
+	userTokenDir := filepath.Join(tokenStoreRoot, strconv.FormatInt(userID, 10))
+	if err := os.MkdirAll(userTokenDir, 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(userTokenDir, "session.json"), []byte("{}"), 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	m := &mock.Client{}
+	garminFactory := func(garmin.Config) garmin.Client { return m }
+	s := NewServer(db, garminFactory, garmin.Config{TokenStorePath: tokenStoreRoot}, appsync.Config{}, &authmock.Verifier{}, testSessionConfig)
+
+	rec := doJSON(t, s.Router(), http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusNoContent {
+		t.Fatalf("delete status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+	if _, err := os.Stat(userTokenDir); !os.IsNotExist(err) {
+		t.Fatalf("expected token store dir %q to be removed, stat err = %v", userTokenDir, err)
+	}
+}
+
 func newTestServerWithAuth(t *testing.T, verifier auth.Verifier) (*Server, *store.DB) {
 	t.Helper()
 	s, db, _ := newTestServer(t)
@@ -933,3 +1013,72 @@ func TestSessionLogout_PostLogoutRedirectUsesFrontendURL(t *testing.T) {
 		t.Fatalf("status = %d, Location = %q, want post_logout_redirect_uri = %q", rec.Code, rec.Header().Get("Location"), testSessionConfig.FrontendURL+"/")
 	}
 }
+
+// TestSessionLogout_PassesIDTokenHintFromSessionCookie confirms the raw ID
+// token carried in the session cookie (minted at callback time) is handed
+// back to EndSessionURL on logout, so Keycloak can skip its own
+// logout-confirmation prompt instead of leaving the user a chance to cancel
+// out of it after their geniusrun account is already deleted.
+func TestSessionLogout_PassesIDTokenHintFromSessionCookie(t *testing.T) {
+	verifier := &authmock.Verifier{EndSessionResult: "https://keycloak.example.com/logout"}
+	s, _ := newTestServerWithAuth(t, verifier)
+
+	cookie, err := auth.MintSessionCookie(
+		auth.Claims{Sub: "test-user", Name: "Test User", Email: "test@example.com", IDToken: "raw-id-token-jwt"},
+		testSessionConfig.Secret, testSessionConfig.Duration, testSessionConfig.Secure,
+	)
+	if err != nil {
+		t.Fatalf("mint session cookie: %v", err)
+	}
+	req := httptest.NewRequest(http.MethodPost, "/api/session/logout", nil)
+	req.AddCookie(cookie)
+	rec := httptest.NewRecorder()
+	s.Router().ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusFound {
+		t.Fatalf("status = %d, want 302, body = %s", rec.Code, rec.Body.String())
+	}
+	if verifier.LastIDTokenHint != "raw-id-token-jwt" {
+		t.Errorf("LastIDTokenHint = %q, want %q", verifier.LastIDTokenHint, "raw-id-token-jwt")
+	}
+}
+
+// TestSessionCallback_MintsSessionCookieCarryingIDToken confirms the raw ID
+// token from a completed OIDC callback ends up in the session cookie (not
+// just Sub/Name/Email), since that's the only place logout can later read
+// it back from to build id_token_hint.
+func TestSessionCallback_MintsSessionCookieCarryingIDToken(t *testing.T) {
+	verifier := &authmock.Verifier{
+		CallbackResult: auth.LoginResult{
+			Claims:     auth.Claims{Sub: "u1", Name: "Alice", Email: "alice@example.com", IDToken: "raw-id-token-jwt"},
+			Authorized: true,
+		},
+	}
+	s, _ := newTestServerWithAuth(t, verifier)
+
+	txnCookie, err := auth.MintTxnCookie(auth.TxnState{State: "s1", CodeVerifier: "v1"}, testSessionConfig.Secret, false)
+	if err != nil {
+		t.Fatalf("mint txn cookie: %v", err)
+	}
+	req := httptest.NewRequest(http.MethodGet, "/api/session/callback?code=abc&state=s1", nil)
+	req.AddCookie(txnCookie)
+	rec := httptest.NewRecorder()
+	s.Router().ServeHTTP(rec, req)
+
+	var sessionCookie *http.Cookie
+	for _, c := range rec.Result().Cookies() {
+		if c.Name == auth.SessionCookieName {
+			sessionCookie = c
+		}
+	}
+	if sessionCookie == nil {
+		t.Fatal("expected a session cookie to be set")
+	}
+	claims, err := auth.ParseSessionCookie(sessionCookie, testSessionConfig.Secret)
+	if err != nil {
+		t.Fatalf("parse session cookie: %v", err)
+	}
+	if claims.IDToken != "raw-id-token-jwt" {
+		t.Errorf("claims.IDToken = %q, want %q", claims.IDToken, "raw-id-token-jwt")
+	}
+}

backend/internal/api/isolation_test.go

@@ -153,3 +153,31 @@ func TestIsolation_RequireProvisionedUser_BlocksDataRoutesUntilSetup(t *testing.
 		t.Fatalf("status = %d, want 403 (no profile provisioned yet), body = %s", rec.Code, rec.Body.String())
 	}
 }
+
+// TestIsolation_DeleteProfileOnlyDeletesOwnAccount confirms one user
+// deleting their own profile never touches another user's account, even
+// though DeleteUser is keyed purely by the session-resolved userID.
+func TestIsolation_DeleteProfileOnlyDeletesOwnAccount(t *testing.T) {
+	s, db, userA := newTestServer(t) // provisions "test-user" (userA)
+	if _, err := db.ProvisionUser(newCtx(), "user-b", "B"); err != nil {
+		t.Fatalf("ProvisionUser(b): %v", err)
+	}
+
+	router := s.Router()
+	rec := doJSONAs(t, router, "user-b", http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusNoContent {
+		t.Fatalf("userB delete status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+
+	if _, found, err := db.GetUserBySub(newCtx(), "user-b"); err != nil || found {
+		t.Fatalf("expected userB gone after their own delete, found=%v err=%v", found, err)
+	}
+	u, found, err := db.GetUserBySub(newCtx(), "test-user")
+	if err != nil || !found || u.ID != userA {
+		t.Fatalf("expected userA to survive userB's deletion, found=%v err=%v id=%d want=%d", found, err, u.ID, userA)
+	}
+	rec = doJSON(t, router, http.MethodGet, "/api/profile", nil) // as userA
+	if rec.Code != http.StatusOK {
+		t.Fatalf("userA profile status after userB deleted themselves = %d, body = %s", rec.Code, rec.Body.String())
+	}
+}

backend/internal/api/profile.go

@@ -75,3 +75,29 @@ func (s *Server) handleUpdateProfile(w http.ResponseWriter, r *http.Request) {
 	}
 	writeJSON(w, http.StatusOK, updated)
 }
+
+// handleDeleteProfile permanently deletes the signed-in user's entire
+// geniusrun account (profile, workout kinds/paces, activities and
+// everything under them, sync state/runs -- see schema.sql's ON DELETE
+// CASCADE from users(id)) and tears down their cached Garmin client and
+// token-store directory. It does not touch the session cookie itself --
+// the frontend follows a successful call with a real logout navigation
+// (see docs/superpowers/specs/2026-07-26-profile-deletion-design.md).
+func (s *Server) handleDeleteProfile(w http.ResponseWriter, r *http.Request) {
+	userID := userIDFromContext(r.Context())
+
+	s.mu.Lock()
+	inProgress := s.userSyncRunning[userID]
+	s.mu.Unlock()
+	if inProgress {
+		writeError(w, http.StatusConflict, "a sync is in progress for this account; wait for it to finish before deleting your profile")
+		return
+	}
+
+	if err := s.DB.DeleteUser(r.Context(), userID); err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	s.removeGarminClient(userID)
+	w.WriteHeader(http.StatusNoContent)
+}

backend/internal/api/server.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"log"
 	"net/http"
+	"os"
 	"path/filepath"
 	"strconv"
 	"sync"
@@ -116,6 +117,36 @@ func (s *Server) syncFor(ctx context.Context, userID int64) (*appsync.Service, e
 	return svc, nil
 }
 
+// removeGarminClient drops userID's cached garmin.Client/sync.Service (if
+// any) and every other per-user in-memory entry for userID, terminating the
+// client's subprocess and best-effort removing its on-disk token-store
+// directory. Called when a user's account has just been deleted from the
+// DB, so nothing in memory keeps referencing a userID that no longer
+// exists.
+func (s *Server) removeGarminClient(userID int64) {
+	s.mu.Lock()
+	client, ok := s.userGarmin[userID]
+	delete(s.userGarmin, userID)
+	delete(s.userSync, userID)
+	delete(s.userAuthStatus, userID)
+	delete(s.userAuthMessage, userID)
+	delete(s.userSyncRunning, userID)
+	s.mu.Unlock()
+
+	if ok {
+		if err := client.Close(); err != nil {
+			log.Printf("api: close garmin client for deleted user %d: %v", userID, err)
+		}
+	}
+	if s.GarminBase.TokenStorePath == "" {
+		return
+	}
+	tokenStoreDir := filepath.Join(s.GarminBase.TokenStorePath, strconv.FormatInt(userID, 10))
+	if err := os.RemoveAll(tokenStoreDir); err != nil {
+		log.Printf("api: remove token store dir for deleted user %d: %v", userID, err)
+	}
+}
+
 // RunIncrementalSyncForAllUsers is called on a timer (see main.go) to sync
 // every provisioned user in turn, replacing the old single-global-Service
 // background loop.
@@ -167,6 +198,7 @@ func (s *Server) Router() http.Handler {
 				r.Route("/profile", func(r chi.Router) {
 					r.Get("/", s.handleGetProfile)
 					r.Put("/", s.handleUpdateProfile)
+					r.Delete("/", s.handleDeleteProfile)
 				})
 
 				r.Route("/auth", func(r chi.Router) {

backend/internal/api/session.go

@@ -89,9 +89,16 @@ func (s *Server) handleSessionCallback(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, s.Session.FrontendURL+"/", http.StatusFound)
 }
 
+// handleSessionLogout clears geniusrun's own session cookie and redirects
+// through Keycloak's end-session endpoint, passing the session's ID token
+// as id_token_hint (see auth.Claims.IDToken) so Keycloak can skip its own
+// logout-confirmation prompt -- otherwise a user could cancel out of it and
+// land back on the app with a Keycloak SSO session but no geniusrun profile
+// (already deleted, in the profile-deletion case this exists for).
 func (s *Server) handleSessionLogout(w http.ResponseWriter, r *http.Request) {
+	claims, _ := auth.ClaimsFromContext(r.Context())
 	http.SetCookie(w, auth.ClearCookie(auth.SessionCookieName, s.Session.Secure))
-	http.Redirect(w, r, s.Auth.EndSessionURL(s.Session.FrontendURL+"/"), http.StatusFound)
+	http.Redirect(w, r, s.Auth.EndSessionURL(s.Session.FrontendURL+"/", claims.IDToken), http.StatusFound)
 }
 
 func (s *Server) handleSessionMe(w http.ResponseWriter, r *http.Request) {

backend/internal/auth/mock/mock.go

@@ -18,6 +18,7 @@ type Verifier struct {
 	CallbackResult   auth.LoginResult
 	CallbackErr      error
 	EndSessionResult string // if empty, EndSessionURL returns postLogoutRedirectURL unchanged
+	LastIDTokenHint  string // records the idTokenHint passed to the last EndSessionURL call
 }
 
 var _ auth.Verifier = (*Verifier)(nil)
@@ -33,7 +34,8 @@ func (v *Verifier) HandleCallback(ctx context.Context, txn auth.TxnState, query
 	return v.CallbackResult, nil
 }
 
-func (v *Verifier) EndSessionURL(postLogoutRedirectURL string) string {
+func (v *Verifier) EndSessionURL(postLogoutRedirectURL, idTokenHint string) string {
+	v.LastIDTokenHint = idTokenHint
 	if v.EndSessionResult != "" {
 		return v.EndSessionResult
 	}

backend/internal/auth/oidc.go

@@ -6,6 +6,7 @@ import (
 	"encoding/base64"
 	"fmt"
 	"net/url"
+	"slices"
 
 	"github.com/coreos/go-oidc/v3/oidc"
 	"golang.org/x/oauth2"
@@ -24,7 +25,11 @@ type Verifier interface {
 	HandleCallback(ctx context.Context, txn TxnState, query url.Values) (LoginResult, error)
 	// EndSessionURL builds the identity provider's logout URL, redirecting
 	// back to postLogoutRedirectURL once Keycloak's own session is cleared.
-	EndSessionURL(postLogoutRedirectURL string) string
+	// idTokenHint, if non-empty, is passed as id_token_hint so Keycloak can
+	// positively identify the session being ended and skip its own
+	// logout-confirmation prompt (which would otherwise let the user cancel
+	// out of logout after their geniusrun account is already deleted).
+	EndSessionURL(postLogoutRedirectURL, idTokenHint string) string
 }
 
 // LoginResult is what a completed callback exchange resolves to.
@@ -55,12 +60,7 @@ type idTokenClaims struct {
 }
 
 func (c idTokenClaims) hasRole(required string) bool {
-	for _, r := range c.RealmAccess.Roles {
-		if r == required {
-			return true
-		}
-	}
-	return false
+	return slices.Contains(c.RealmAccess.Roles, required)
 }
 
 type oidcVerifier struct {
@@ -135,12 +135,12 @@ func (v *oidcVerifier) HandleCallback(ctx context.Context, txn TxnState, query u
 		return LoginResult{}, fmt.Errorf("decode id_token claims: %w", err)
 	}
 	return LoginResult{
-		Claims:     Claims{Sub: claims.Sub, Name: claims.Name, Email: claims.Email},
+		Claims:     Claims{Sub: claims.Sub, Name: claims.Name, Email: claims.Email, IDToken: rawIDToken},
 		Authorized: claims.hasRole(v.requiredRole),
 	}, nil
 }
 
-func (v *oidcVerifier) EndSessionURL(postLogoutRedirectURL string) string {
+func (v *oidcVerifier) EndSessionURL(postLogoutRedirectURL, idTokenHint string) string {
 	var discovery struct {
 		EndSessionEndpoint string `json:"end_session_endpoint"`
 	}
@@ -154,6 +154,9 @@ func (v *oidcVerifier) EndSessionURL(postLogoutRedirectURL string) string {
 	q := u.Query()
 	q.Set("client_id", v.oauth2Config.ClientID)
 	q.Set("post_logout_redirect_uri", postLogoutRedirectURL)
+	if idTokenHint != "" {
+		q.Set("id_token_hint", idTokenHint)
+	}
 	u.RawQuery = q.Encode()
 	return u.String()
 }

backend/internal/auth/oidc_test.go

@@ -1,10 +1,83 @@
 package auth
 
 import (
+	"context"
 	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
 	"testing"
 )
 
+// newTestOIDCVerifier spins up a fake OIDC discovery endpoint (just enough
+// for oidc.NewProvider's discovery GET to succeed) and returns a real
+// oidcVerifier backed by it, for tests that exercise EndSessionURL without
+// a live Keycloak.
+func newTestOIDCVerifier(t *testing.T) Verifier {
+	t.Helper()
+	var issuerURL string
+	mux := http.NewServeMux()
+	mux.HandleFunc("/.well-known/openid-configuration", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprintf(w, `{
+			"issuer": %[1]q,
+			"authorization_endpoint": "%[1]s/auth",
+			"token_endpoint": "%[1]s/token",
+			"end_session_endpoint": "%[1]s/logout",
+			"jwks_uri": "%[1]s/certs"
+		}`, issuerURL)
+	})
+	mux.HandleFunc("/certs", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprint(w, `{"keys":[]}`)
+	})
+	srv := httptest.NewServer(mux)
+	t.Cleanup(srv.Close)
+	issuerURL = srv.URL
+
+	verifier, err := NewOIDCVerifier(context.Background(), OIDCConfig{
+		IssuerURL: issuerURL, ClientID: "geniusrun", ClientSecret: "secret", RedirectURL: issuerURL + "/callback",
+	})
+	if err != nil {
+		t.Fatalf("NewOIDCVerifier: %v", err)
+	}
+	return verifier
+}
+
+func TestEndSessionURL_IncludesIDTokenHintWhenProvided(t *testing.T) {
+	verifier := newTestOIDCVerifier(t)
+
+	got := verifier.EndSessionURL("https://app.example.com/", "raw-id-token-jwt")
+	u, err := url.Parse(got)
+	if err != nil {
+		t.Fatalf("parse EndSessionURL result %q: %v", got, err)
+	}
+	q := u.Query()
+	if q.Get("id_token_hint") != "raw-id-token-jwt" {
+		t.Errorf("id_token_hint = %q, want %q", q.Get("id_token_hint"), "raw-id-token-jwt")
+	}
+	if q.Get("client_id") != "geniusrun" {
+		t.Errorf("client_id = %q, want geniusrun", q.Get("client_id"))
+	}
+	if q.Get("post_logout_redirect_uri") != "https://app.example.com/" {
+		t.Errorf("post_logout_redirect_uri = %q, want https://app.example.com/", q.Get("post_logout_redirect_uri"))
+	}
+}
+
+func TestEndSessionURL_OmitsIDTokenHintWhenEmpty(t *testing.T) {
+	verifier := newTestOIDCVerifier(t)
+
+	got := verifier.EndSessionURL("https://app.example.com/", "")
+	u, err := url.Parse(got)
+	if err != nil {
+		t.Fatalf("parse EndSessionURL result %q: %v", got, err)
+	}
+	if u.Query().Has("id_token_hint") {
+		t.Errorf("expected no id_token_hint param when idTokenHint is empty, got %q", got)
+	}
+}
+
 func TestIDTokenClaims_HasRole(t *testing.T) {
 	cases := []struct {
 		name string

backend/internal/auth/session.go

@@ -1,9 +1,15 @@
 // Package auth implements geniusrun's own login gate: an OIDC Authorization
 // Code flow against an existing Keycloak realm (see oidc.go), backed by a
 // signed session cookie geniusrun mints itself (this file) and a chi
-// middleware that checks it (middleware.go). Keycloak's own tokens are never
-// stored or refreshed -- once HandleCallback verifies the ID token and role,
-// only this package's own cookie matters for subsequent requests.
+// middleware that checks it (middleware.go). Keycloak's own access/refresh
+// tokens are never stored or refreshed -- once HandleCallback verifies the
+// ID token and role, only this package's own cookie matters for subsequent
+// requests. The one exception is the raw ID token itself, carried opaquely
+// inside the signed session cookie (Claims.IDToken) solely so a later
+// logout can pass it back to Keycloak as id_token_hint -- letting Keycloak
+// skip its own logout-confirmation prompt for a session it can positively
+// identify, rather than leaving the user a chance to cancel out of it after
+// their geniusrun account (and profile) is already gone.
 package auth
 
 import (
@@ -26,17 +32,21 @@ const (
 )
 
 // Claims identifies the authenticated user, carried in the signed session
-// cookie.
+// cookie. IDToken is the raw Keycloak ID token JWT from the OIDC callback,
+// carried opaquely so a later logout can pass it back to Keycloak as
+// id_token_hint (see EndSessionURL) -- geniusrun never inspects it itself.
 type Claims struct {
-	Sub   string
-	Name  string
-	Email string
+	Sub     string
+	Name    string
+	Email   string
+	IDToken string
 }
 
 type sessionClaims struct {
-	Sub   string `json:"sub"`
-	Name  string `json:"name"`
-	Email string `json:"email"`
+	Sub     string `json:"sub"`
+	Name    string `json:"name"`
+	Email   string `json:"email"`
+	IDToken string `json:"id_token,omitempty"`
 	jwt.RegisteredClaims
 }
 
@@ -58,9 +68,10 @@ type txnClaims struct {
 func MintSessionCookie(claims Claims, secret []byte, duration time.Duration, secure bool) (*http.Cookie, error) {
 	now := time.Now()
 	token := jwt.NewWithClaims(jwt.SigningMethodHS256, sessionClaims{
-		Sub:   claims.Sub,
-		Name:  claims.Name,
-		Email: claims.Email,
+		Sub:     claims.Sub,
+		Name:    claims.Name,
+		Email:   claims.Email,
+		IDToken: claims.IDToken,
 		RegisteredClaims: jwt.RegisteredClaims{
 			IssuedAt:  jwt.NewNumericDate(now),
 			ExpiresAt: jwt.NewNumericDate(now.Add(duration)),
@@ -91,7 +102,7 @@ func ParseSessionCookie(cookie *http.Cookie, secret []byte) (Claims, error) {
 	if _, err := jwt.ParseWithClaims(cookie.Value, &sc, keyfunc(secret), jwt.WithValidMethods([]string{"HS256"})); err != nil {
 		return Claims{}, fmt.Errorf("parse session token: %w", err)
 	}
-	return Claims{Sub: sc.Sub, Name: sc.Name, Email: sc.Email}, nil
+	return Claims{Sub: sc.Sub, Name: sc.Name, Email: sc.Email, IDToken: sc.IDToken}, nil
 }
 
 // MintTxnCookie signs an OIDC login transaction into a short-lived cookie.

backend/internal/auth/session_test.go

@@ -8,7 +8,7 @@ import (
 const testSecret = "test-secret-at-least-32-bytes-long!"
 
 func TestMintAndParseSessionCookie(t *testing.T) {
-	claims := Claims{Sub: "u1", Name: "Alice", Email: "alice@example.com"}
+	claims := Claims{Sub: "u1", Name: "Alice", Email: "alice@example.com", IDToken: "raw-id-token-jwt"}
 	cookie, err := MintSessionCookie(claims, []byte(testSecret), time.Hour, true)
 	if err != nil {
 		t.Fatalf("mint: %v", err)

backend/internal/store/isolation_test.go

@@ -161,3 +161,46 @@ func TestIsolation_SyncStateAndRunsNeverLeakAcrossUsers(t *testing.T) {
 		t.Fatal("userB's FinishSyncRun call was able to mutate userA's sync run")
 	}
 }
+
+// TestIsolation_DeleteUserLeavesOtherUsersDataIntact confirms deleting one
+// user's account never touches another user's profile, taxonomy, or
+// activities, even though DeleteUser is a single blunt DELETE FROM users.
+func TestIsolation_DeleteUserLeavesOtherUsersDataIntact(t *testing.T) {
+	db := openTestDB(t)
+	ctx := context.Background()
+
+	userA, err := db.ProvisionUser(ctx, "sub-a", "A")
+	if err != nil {
+		t.Fatalf("ProvisionUser(a): %v", err)
+	}
+	userB, err := db.ProvisionUser(ctx, "sub-b", "B")
+	if err != nil {
+		t.Fatalf("ProvisionUser(b): %v", err)
+	}
+	if _, err := db.UpsertActivity(ctx, userB, Activity{GarminActivityID: 1, StartTimeUTC: "2026-07-11 06:00:00", RawJSON: "{}"}); err != nil {
+		t.Fatalf("UpsertActivity(b): %v", err)
+	}
+
+	if err := db.DeleteUser(ctx, userA); err != nil {
+		t.Fatalf("DeleteUser(a): %v", err)
+	}
+
+	if _, found, err := db.GetUserBySub(ctx, "sub-b"); err != nil || !found {
+		t.Fatalf("expected userB to survive userA's deletion, found=%v err=%v", found, err)
+	}
+	profileB, err := db.GetProfile(ctx, userB)
+	if err != nil {
+		t.Fatalf("GetProfile(b) after deleting a: %v", err)
+	}
+	if profileB.Name != "B" {
+		t.Errorf("userB's profile changed after deleting userA: %+v", profileB)
+	}
+	kindsB, err := db.ListWorkoutKinds(ctx, userB, false)
+	if err != nil || len(kindsB) != 8 {
+		t.Fatalf("userB's taxonomy affected by deleting userA: len=%d err=%v", len(kindsB), err)
+	}
+	activitiesB, err := db.ListActivities(ctx, userB, ActivityFilter{})
+	if err != nil || len(activitiesB) != 1 {
+		t.Fatalf("userB's activities affected by deleting userA: len=%d err=%v", len(activitiesB), err)
+	}
+}

backend/internal/store/schema.sql

@@ -26,7 +26,7 @@ CREATE TABLE users (
 -- below) in one transaction when a new account signs up.
 CREATE TABLE profile (
     id                  INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id             INTEGER NOT NULL REFERENCES users(id),
+    user_id             INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     name                TEXT NOT NULL DEFAULT 'Default',
     garmin_email        TEXT NOT NULL DEFAULT '',
     garmin_password     TEXT NOT NULL DEFAULT '',
@@ -82,7 +82,7 @@ CREATE TABLE profile (
 -- recursive AND/OR condition tree evaluated by internal/classify.
 CREATE TABLE workout_kinds (
     id          INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id     INTEGER NOT NULL REFERENCES users(id),
+    user_id     INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     name        TEXT NOT NULL,
     description TEXT NOT NULL DEFAULT '',
     color       TEXT NOT NULL DEFAULT '',
@@ -100,7 +100,7 @@ CREATE TABLE workout_kinds (
 -- synced activity log is the history. No user_id column of its own --
 -- ownership is checked via a JOIN to workout_kinds.
 CREATE TABLE workout_type_paces (
-    workout_kind_id     INTEGER PRIMARY KEY REFERENCES workout_kinds(id),
+    workout_kind_id     INTEGER PRIMARY KEY REFERENCES workout_kinds(id) ON DELETE CASCADE,
     pace_min_sec_per_km REAL,
     pace_max_sec_per_km REAL,
     hr_min_pct_hrr      REAL,
@@ -118,7 +118,7 @@ CREATE TABLE workout_type_paces (
 -- instead of storing a redundant copy.
 CREATE TABLE activities (
     id                         INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id                    INTEGER NOT NULL REFERENCES users(id),
+    user_id                    INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     garmin_activity_id         INTEGER NOT NULL,
     -- Derived at sync time from Garmin's own eventType.typeKey=="race" --
     -- a hard fact, not a rule the user tunes (see internal/classify's
@@ -219,7 +219,7 @@ JOIN (
 -- re-walking years of already-known history on every call.
 CREATE TABLE sync_state (
     id                   INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id              INTEGER NOT NULL REFERENCES users(id),
+    user_id              INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     earliest_synced_date TEXT,
     backfill_complete    INTEGER NOT NULL DEFAULT 0,
     UNIQUE(user_id)
@@ -229,7 +229,7 @@ CREATE TABLE sync_state (
 -- status the frontend polls.
 CREATE TABLE sync_runs (
     id                 INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id            INTEGER NOT NULL REFERENCES users(id),
+    user_id            INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     kind               TEXT NOT NULL CHECK(kind IN ('backfill','incremental','full')),
     started_at         TEXT NOT NULL,
     finished_at        TEXT,

backend/internal/store/users.go

@@ -119,3 +119,17 @@ func (db *DB) ProvisionUser(ctx context.Context, oidcSub, displayName string) (i
 
 	return userID, tx.Commit()
 }
+
+// DeleteUser permanently deletes userID's account. Every row that belongs
+// to it -- profile, workout kinds (and their paces), activities (and their
+// laps/samples/kind_assignments), sync_state, and sync_runs -- cascades
+// away via the ON DELETE CASCADE foreign keys in schema.sql, so this is a
+// single statement rather than per-table deletes. Irreversible; the API
+// layer gates this behind a UI confirmation (see
+// docs/superpowers/specs/2026-07-26-profile-deletion-design.md).
+func (db *DB) DeleteUser(ctx context.Context, userID int64) error {
+	if _, err := db.ExecContext(ctx, `DELETE FROM users WHERE id = ?`, userID); err != nil {
+		return fmt.Errorf("delete user %d: %w", userID, err)
+	}
+	return nil
+}

backend/internal/store/users_test.go

@@ -89,3 +89,76 @@ func TestProvisionUser_TwoUsersGetIndependentTaxonomies(t *testing.T) {
 		t.Fatal("expected each user's seeded kinds to be distinct rows")
 	}
 }
+
+func TestDeleteUser_RemovesUserAndCascadesEverything(t *testing.T) {
+	db := openTestDB(t)
+	ctx := context.Background()
+
+	userID, err := db.ProvisionUser(ctx, "delete-me", "Delete Me")
+	if err != nil {
+		t.Fatalf("ProvisionUser: %v", err)
+	}
+
+	activityID, err := db.UpsertActivity(ctx, userID, Activity{GarminActivityID: 1, StartTimeUTC: "2026-07-11 06:00:00", RawJSON: "{}"})
+	if err != nil {
+		t.Fatalf("UpsertActivity: %v", err)
+	}
+	kindID, err := db.CreateWorkoutKind(ctx, userID, WorkoutKind{Name: "Test Delete Kind", RuleJSON: `{"match":"all","conditions":[]}`, IsActive: true})
+	if err != nil {
+		t.Fatalf("CreateWorkoutKind: %v", err)
+	}
+	if err := db.ReplaceLaps(ctx, userID, activityID, []Lap{{LapIndex: 1}}); err != nil {
+		t.Fatalf("ReplaceLaps: %v", err)
+	}
+	if err := db.ReplaceActivitySamples(ctx, userID, activityID, []Sample{{ElapsedSeconds: 0}}); err != nil {
+		t.Fatalf("ReplaceActivitySamples: %v", err)
+	}
+	if _, err := db.InsertKindAssignment(ctx, userID, KindAssignment{
+		ActivityID: activityID, WorkoutKindID: &kindID, AssignmentSource: AssignmentSourceRuleEngine,
+		Status: AssignmentStatusAssigned, CandidateKindsJSON: "[]",
+	}); err != nil {
+		t.Fatalf("InsertKindAssignment: %v", err)
+	}
+	minPace := 300.0
+	if err := db.UpdateWorkoutTypePace(ctx, userID, WorkoutTypePace{WorkoutKindID: kindID, PaceMinSecPerKm: &minPace}); err != nil {
+		t.Fatalf("UpdateWorkoutTypePace: %v", err)
+	}
+	if err := db.UpdateSyncState(ctx, userID, "2020-01-01", true); err != nil {
+		t.Fatalf("UpdateSyncState: %v", err)
+	}
+	if _, err := db.StartSyncRun(ctx, userID, SyncKindBackfill); err != nil {
+		t.Fatalf("StartSyncRun: %v", err)
+	}
+
+	if err := db.DeleteUser(ctx, userID); err != nil {
+		t.Fatalf("DeleteUser: %v", err)
+	}
+
+	if _, found, err := db.GetUserBySub(ctx, "delete-me"); err != nil || found {
+		t.Fatalf("expected user gone after DeleteUser, found=%v err=%v", found, err)
+	}
+
+	checks := []struct {
+		query string
+		arg   int64
+	}{
+		{`SELECT COUNT(*) FROM profile WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM workout_kinds WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM workout_type_paces WHERE workout_kind_id = ?`, kindID},
+		{`SELECT COUNT(*) FROM activities WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM laps WHERE activity_id = ?`, activityID},
+		{`SELECT COUNT(*) FROM activity_samples WHERE activity_id = ?`, activityID},
+		{`SELECT COUNT(*) FROM kind_assignments WHERE activity_id = ?`, activityID},
+		{`SELECT COUNT(*) FROM sync_state WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM sync_runs WHERE user_id = ?`, userID},
+	}
+	for _, c := range checks {
+		var count int
+		if err := db.QueryRowContext(ctx, c.query, c.arg).Scan(&count); err != nil {
+			t.Fatalf("count query %q: %v", c.query, err)
+		}
+		if count != 0 {
+			t.Errorf("query %q: got %d rows, want 0 after DeleteUser", c.query, count)
+		}
+	}
+}

docs/DATABASE.md

@@ -31,7 +31,7 @@ CREATE TABLE users (
 ```sql
 CREATE TABLE profile (
     id                  INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id             INTEGER NOT NULL REFERENCES users(id),
+    user_id             INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     name                TEXT NOT NULL DEFAULT 'Default',
     garmin_email        TEXT NOT NULL DEFAULT '',
     garmin_password     TEXT NOT NULL DEFAULT '',
@@ -87,7 +87,7 @@ CREATE TABLE profile (
 ```sql
 CREATE TABLE workout_kinds (
     id          INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id     INTEGER NOT NULL REFERENCES users(id),
+    user_id     INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     name        TEXT NOT NULL,
     description TEXT NOT NULL DEFAULT '',
     color       TEXT NOT NULL DEFAULT '',
@@ -104,7 +104,7 @@ CREATE TABLE workout_kinds (
 
 ```sql
 CREATE TABLE workout_type_paces (
-    workout_kind_id     INTEGER PRIMARY KEY REFERENCES workout_kinds(id),
+    workout_kind_id     INTEGER PRIMARY KEY REFERENCES workout_kinds(id) ON DELETE CASCADE,
     pace_min_sec_per_km REAL,
     pace_max_sec_per_km REAL,
     hr_min_pct_hrr      REAL,
@@ -117,7 +117,7 @@ CREATE TABLE workout_type_paces (
 ```sql
 CREATE TABLE activities (
     id                         INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id                    INTEGER NOT NULL REFERENCES users(id),
+    user_id                    INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     garmin_activity_id         INTEGER NOT NULL,
     -- Derived at sync time from Garmin's own eventType.typeKey=="race" --
     -- a hard fact, not a rule the user tunes (see internal/classify's
@@ -227,7 +227,7 @@ CREATE INDEX idx_kind_assignments_status ON kind_assignments(status);
 ```sql
 CREATE TABLE sync_state (
     id                   INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id              INTEGER NOT NULL REFERENCES users(id),
+    user_id              INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     earliest_synced_date TEXT,
     backfill_complete    INTEGER NOT NULL DEFAULT 0,
     UNIQUE(user_id)
@@ -239,7 +239,7 @@ CREATE TABLE sync_state (
 ```sql
 CREATE TABLE sync_runs (
     id                 INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id            INTEGER NOT NULL REFERENCES users(id),
+    user_id            INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
     kind               TEXT NOT NULL CHECK(kind IN ('backfill','incremental','full')),
     started_at         TEXT NOT NULL,
     finished_at        TEXT,

docs/IDEAS.md

@@ -9,12 +9,12 @@ for that history) and remove it from here once a spec exists.
 ## Backlog
 
 - improve first connection page: in CreateProfile.tsx, in addition to the display name, we should directly ask garmin login/password and manage MFA from there, so the synchronization experience in profile page will be easier later on
-- profile deletion: add a way to delete our profile with a dedicated button on the profile page (which by extension will also logout the user, to be consistent with the logic that login will trigger the profile creation)
 - dedicated workouts section: add workouts table in database and create a dedicated page in UI (use an "objective" icon) 
 - improve activities/workouts download: make it modal, add progress bar, error management
 - better UX when backend is not available (instead of "TypeError failed to fetch")
 - better UX for activities (list layout without the graphs, detailed view with different graphs for each phase incl. delta with workout)
 - add icon to indicate if an activity has an associated workout
+- modern error displays: have error messages displayed in an ephemeral window
 
 ## Someday / maybe
 

docs/superpowers/plans/2026-07-26-profile-deletion.md

@@ -0,0 +1,766 @@
+# Profile Deletion Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Let a signed-in geniusrun user permanently delete their entire account (Garmin credentials, custom rules, every synced activity) from a "Danger zone" button on the Profile page, and log them out afterward.
+
+**Architecture:** Add `ON DELETE CASCADE` to every FK pointing at `users(id)` (and `workout_kinds(id)`) in `schema.sql`, so a single `DELETE FROM users` removes everything. Wrap that in a new `store.DeleteUser`, expose it via `DELETE /api/profile`, and have that handler also tear down the deleted user's cached Garmin subprocess/client and on-disk token-store directory. The frontend gates the call behind a type-`DELETE`-to-confirm UI, then performs a real POST navigation to the existing `/api/session/logout` route (the same one the header's Log out button already uses) so the OIDC session ends too.
+
+**Tech Stack:** Go (`net/http`, `database/sql` via `modernc.org/sqlite`, chi router), React + TypeScript (Vite), no frontend test framework.
+
+## Global Constraints
+
+- `internal/store/schema.sql` is edited directly, never migrated — this is a pre-production app (see `CLAUDE.md`).
+- Every store/API method that touches per-user data takes an explicit `userID` and must filter/scope by it — the entire cross-user isolation boundary depends on this (see `CLAUDE.md`'s Authentication section).
+- Cross-user isolation must be tested adversarially (two real users, real IDs), not just checked for non-collision — matches `internal/store/isolation_test.go` / `internal/api/isolation_test.go` convention.
+- After any `schema.sql` change, regenerate `docs/DATABASE.md` via `go run ./cmd/dumpschema` (run from `backend/`).
+- `gofmt -l .` must report nothing before committing; `go vet ./...` and `go build ./...` must pass.
+- No frontend test suite exists — frontend changes are verified via `npm run build`, `npm run lint`, and a manual browser check.
+
+---
+
+### Task 1: Cascading deletes in the store layer
+
+**Files:**
+- Modify: `backend/internal/store/schema.sql:29,85,103,121,222,232`
+- Modify: `backend/internal/store/users.go` (add `DeleteUser`)
+- Modify: `backend/internal/store/users_test.go` (add `TestDeleteUser_RemovesUserAndCascadesEverything`)
+- Modify: `backend/internal/store/isolation_test.go` (add `TestIsolation_DeleteUserLeavesOtherUsersDataIntact`)
+- Modify: `docs/DATABASE.md` (regenerated, not hand-edited)
+
+**Interfaces:**
+- Produces: `func (db *DB) DeleteUser(ctx context.Context, userID int64) error` — deletes the `users` row for `userID`; every owned row (profile, workout_kinds, workout_type_paces, activities, laps, activity_samples, kind_assignments, sync_state, sync_runs) cascades away via the schema FKs added in this task.
+
+- [ ] **Step 1: Write the failing test**
+
+Add to `backend/internal/store/users_test.go`:
+
+```go
+func TestDeleteUser_RemovesUserAndCascadesEverything(t *testing.T) {
+	db := openTestDB(t)
+	ctx := context.Background()
+
+	userID, err := db.ProvisionUser(ctx, "delete-me", "Delete Me")
+	if err != nil {
+		t.Fatalf("ProvisionUser: %v", err)
+	}
+
+	activityID, err := db.UpsertActivity(ctx, userID, Activity{GarminActivityID: 1, StartTimeUTC: "2026-07-11 06:00:00", RawJSON: "{}"})
+	if err != nil {
+		t.Fatalf("UpsertActivity: %v", err)
+	}
+	kindID, err := db.CreateWorkoutKind(ctx, userID, WorkoutKind{Name: "Test Delete Kind", RuleJSON: `{"match":"all","conditions":[]}`, IsActive: true})
+	if err != nil {
+		t.Fatalf("CreateWorkoutKind: %v", err)
+	}
+	if err := db.ReplaceLaps(ctx, userID, activityID, []Lap{{LapIndex: 1}}); err != nil {
+		t.Fatalf("ReplaceLaps: %v", err)
+	}
+	if err := db.ReplaceActivitySamples(ctx, userID, activityID, []Sample{{ElapsedSeconds: 0}}); err != nil {
+		t.Fatalf("ReplaceActivitySamples: %v", err)
+	}
+	if _, err := db.InsertKindAssignment(ctx, userID, KindAssignment{
+		ActivityID: activityID, WorkoutKindID: &kindID, AssignmentSource: AssignmentSourceRuleEngine,
+		Status: AssignmentStatusAssigned, CandidateKindsJSON: "[]",
+	}); err != nil {
+		t.Fatalf("InsertKindAssignment: %v", err)
+	}
+	minPace := 300.0
+	if err := db.UpdateWorkoutTypePace(ctx, userID, WorkoutTypePace{WorkoutKindID: kindID, PaceMinSecPerKm: &minPace}); err != nil {
+		t.Fatalf("UpdateWorkoutTypePace: %v", err)
+	}
+	if err := db.UpdateSyncState(ctx, userID, "2020-01-01", true); err != nil {
+		t.Fatalf("UpdateSyncState: %v", err)
+	}
+	if _, err := db.StartSyncRun(ctx, userID, SyncKindBackfill); err != nil {
+		t.Fatalf("StartSyncRun: %v", err)
+	}
+
+	if err := db.DeleteUser(ctx, userID); err != nil {
+		t.Fatalf("DeleteUser: %v", err)
+	}
+
+	if _, found, err := db.GetUserBySub(ctx, "delete-me"); err != nil || found {
+		t.Fatalf("expected user gone after DeleteUser, found=%v err=%v", found, err)
+	}
+
+	checks := []struct {
+		query string
+		arg   int64
+	}{
+		{`SELECT COUNT(*) FROM profile WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM workout_kinds WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM workout_type_paces WHERE workout_kind_id = ?`, kindID},
+		{`SELECT COUNT(*) FROM activities WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM laps WHERE activity_id = ?`, activityID},
+		{`SELECT COUNT(*) FROM activity_samples WHERE activity_id = ?`, activityID},
+		{`SELECT COUNT(*) FROM kind_assignments WHERE activity_id = ?`, activityID},
+		{`SELECT COUNT(*) FROM sync_state WHERE user_id = ?`, userID},
+		{`SELECT COUNT(*) FROM sync_runs WHERE user_id = ?`, userID},
+	}
+	for _, c := range checks {
+		var count int
+		if err := db.QueryRowContext(ctx, c.query, c.arg).Scan(&count); err != nil {
+			t.Fatalf("count query %q: %v", c.query, err)
+		}
+		if count != 0 {
+			t.Errorf("query %q: got %d rows, want 0 after DeleteUser", c.query, count)
+		}
+	}
+}
+```
+
+Add to `backend/internal/store/isolation_test.go`:
+
+```go
+// TestIsolation_DeleteUserLeavesOtherUsersDataIntact confirms deleting one
+// user's account never touches another user's profile, taxonomy, or
+// activities, even though DeleteUser is a single blunt DELETE FROM users.
+func TestIsolation_DeleteUserLeavesOtherUsersDataIntact(t *testing.T) {
+	db := openTestDB(t)
+	ctx := context.Background()
+
+	userA, err := db.ProvisionUser(ctx, "sub-a", "A")
+	if err != nil {
+		t.Fatalf("ProvisionUser(a): %v", err)
+	}
+	userB, err := db.ProvisionUser(ctx, "sub-b", "B")
+	if err != nil {
+		t.Fatalf("ProvisionUser(b): %v", err)
+	}
+	if _, err := db.UpsertActivity(ctx, userB, Activity{GarminActivityID: 1, StartTimeUTC: "2026-07-11 06:00:00", RawJSON: "{}"}); err != nil {
+		t.Fatalf("UpsertActivity(b): %v", err)
+	}
+
+	if err := db.DeleteUser(ctx, userA); err != nil {
+		t.Fatalf("DeleteUser(a): %v", err)
+	}
+
+	if _, found, err := db.GetUserBySub(ctx, "sub-b"); err != nil || !found {
+		t.Fatalf("expected userB to survive userA's deletion, found=%v err=%v", found, err)
+	}
+	profileB, err := db.GetProfile(ctx, userB)
+	if err != nil {
+		t.Fatalf("GetProfile(b) after deleting a: %v", err)
+	}
+	if profileB.Name != "B" {
+		t.Errorf("userB's profile changed after deleting userA: %+v", profileB)
+	}
+	kindsB, err := db.ListWorkoutKinds(ctx, userB, false)
+	if err != nil || len(kindsB) != 8 {
+		t.Fatalf("userB's taxonomy affected by deleting userA: len=%d err=%v", len(kindsB), err)
+	}
+	activitiesB, err := db.ListActivities(ctx, userB, ActivityFilter{})
+	if err != nil || len(activitiesB) != 1 {
+		t.Fatalf("userB's activities affected by deleting userA: len=%d err=%v", len(activitiesB), err)
+	}
+}
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `cd backend && go test ./internal/store/... -run 'TestDeleteUser|TestIsolation_DeleteUser' -v`
+Expected: FAIL — `db.DeleteUser undefined (type *DB has no field or method DeleteUser)`.
+
+- [ ] **Step 3: Add `ON DELETE CASCADE` to schema.sql**
+
+In `backend/internal/store/schema.sql`, change these six lines (each currently ends `REFERENCES users(id),` or `REFERENCES workout_kinds(id),`):
+
+Line 29 (`profile.user_id`), from:
+```sql
+    user_id             INTEGER NOT NULL REFERENCES users(id),
+```
+to:
+```sql
+    user_id             INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+```
+
+Line 85 (`workout_kinds.user_id`), from:
+```sql
+    user_id     INTEGER NOT NULL REFERENCES users(id),
+```
+to:
+```sql
+    user_id     INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+```
+
+Line 103 (`workout_type_paces.workout_kind_id`), from:
+```sql
+    workout_kind_id     INTEGER PRIMARY KEY REFERENCES workout_kinds(id),
+```
+to:
+```sql
+    workout_kind_id     INTEGER PRIMARY KEY REFERENCES workout_kinds(id) ON DELETE CASCADE,
+```
+
+Line 121 (`activities.user_id`), from:
+```sql
+    user_id                    INTEGER NOT NULL REFERENCES users(id),
+```
+to:
+```sql
+    user_id                    INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+```
+
+Line 222 (`sync_state.user_id`), from:
+```sql
+    user_id              INTEGER NOT NULL REFERENCES users(id),
+```
+to:
+```sql
+    user_id              INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+```
+
+Line 232 (`sync_runs.user_id`), from:
+```sql
+    user_id            INTEGER NOT NULL REFERENCES users(id),
+```
+to:
+```sql
+    user_id            INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+```
+
+`laps`/`activity_samples`/`kind_assignments` already cascade off `activities(id)` — no change needed there. SQLite's `foreign_keys` pragma is already on for every connection (`db.go`), so these cascades (including the two-level `users → workout_kinds → workout_type_paces` chain) take effect immediately, no code change required for the pragma itself.
+
+- [ ] **Step 4: Add `DeleteUser` to `backend/internal/store/users.go`**
+
+Append after `ProvisionUser` (end of file):
+
+```go
+
+// DeleteUser permanently deletes userID's account. Every row that belongs
+// to it -- profile, workout kinds (and their paces), activities (and their
+// laps/samples/kind_assignments), sync_state, and sync_runs -- cascades
+// away via the ON DELETE CASCADE foreign keys in schema.sql, so this is a
+// single statement rather than per-table deletes. Irreversible; the API
+// layer gates this behind a UI confirmation (see
+// docs/superpowers/specs/2026-07-26-profile-deletion-design.md).
+func (db *DB) DeleteUser(ctx context.Context, userID int64) error {
+	if _, err := db.ExecContext(ctx, `DELETE FROM users WHERE id = ?`, userID); err != nil {
+		return fmt.Errorf("delete user %d: %w", userID, err)
+	}
+	return nil
+}
+```
+
+- [ ] **Step 5: Run tests to verify they pass**
+
+Run: `cd backend && go test ./internal/store/... -run 'TestDeleteUser|TestIsolation_DeleteUser' -v`
+Expected: PASS.
+
+- [ ] **Step 6: Run the full store test suite**
+
+Run: `cd backend && go test ./internal/store/...`
+Expected: PASS (confirms the new `ON DELETE CASCADE` clauses didn't break `ResetAllSyncedData` or any other existing behavior).
+
+- [ ] **Step 7: Regenerate `docs/DATABASE.md`**
+
+Run: `cd backend && go run ./cmd/dumpschema`
+Expected: `docs/DATABASE.md` updates to show `ON DELETE CASCADE` on the six changed columns.
+
+- [ ] **Step 8: Commit**
+
+```bash
+git add backend/internal/store/schema.sql backend/internal/store/users.go backend/internal/store/users_test.go backend/internal/store/isolation_test.go docs/DATABASE.md
+git commit -m "feat(store): add DeleteUser with cascading account deletion"
+```
+
+---
+
+### Task 2: `DELETE /api/profile` and Garmin client/tokenstore teardown
+
+**Files:**
+- Modify: `backend/internal/api/server.go:5-21` (imports), `:95-117` (new `removeGarminClient` after `syncFor`), `:167-170` (route)
+- Modify: `backend/internal/api/profile.go` (add `handleDeleteProfile`)
+- Modify: `backend/internal/api/api_test.go` (imports + 3 new tests)
+- Modify: `backend/internal/api/isolation_test.go` (1 new test)
+
+**Interfaces:**
+- Consumes: `store.DB.DeleteUser(ctx, userID) error` (Task 1); `garmin.Client.Close() error` and `.UpdateCredentials` (existing); `Server.userGarmin/userSync/userAuthStatus/userAuthMessage/userSyncRunning map[int64]...` and `Server.mu sync.Mutex` (existing fields); `Server.GarminBase garmin.Config` (existing, has `.TokenStorePath string`).
+- Produces: `func (s *Server) removeGarminClient(userID int64)` — used only within this task's handler, not exported further. `DELETE /api/profile` route → `handleDeleteProfile`, responding `204` on success, `409` if a sync is running for that user.
+
+- [ ] **Step 1: Write the failing tests**
+
+Add `"os"` to `backend/internal/api/api_test.go`'s import block (needed for Step 1's token-store test):
+
+```go
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strconv"
+	"testing"
+	"time"
+
+	"geniusrun/backend/internal/auth"
+	authmock "geniusrun/backend/internal/auth/mock"
+	"geniusrun/backend/internal/garmin"
+	"geniusrun/backend/internal/garmin/mock"
+	"geniusrun/backend/internal/store"
+	appsync "geniusrun/backend/internal/sync"
+)
+```
+
+Append to `backend/internal/api/api_test.go`:
+
+```go
+func TestDeleteProfile_DeletesUserAndTerminatesGarminClient(t *testing.T) {
+	s, db, userID := newTestServer(t)
+	router := s.Router()
+
+	// Force the per-user Garmin client to be built and cached.
+	rec := doJSON(t, router, http.MethodPost, "/api/auth/login", nil)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("auth/login status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+	client, err := s.garminFor(context.Background(), userID)
+	if err != nil {
+		t.Fatalf("garminFor: %v", err)
+	}
+	mockClient, ok := client.(*mock.Client)
+	if !ok {
+		t.Fatalf("expected *mock.Client, got %T", client)
+	}
+
+	rec = doJSON(t, router, http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusNoContent {
+		t.Fatalf("delete status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+
+	if _, found, err := db.GetUserBySub(context.Background(), "test-user"); err != nil || found {
+		t.Fatalf("expected user gone after delete, found=%v err=%v", found, err)
+	}
+	if !mockClient.ClosedCalled {
+		t.Error("expected the cached garmin client to be Close()d on profile deletion")
+	}
+}
+
+func TestDeleteProfile_RejectsWhileSyncInProgress(t *testing.T) {
+	s, db, userID := newTestServer(t)
+	s.mu.Lock()
+	s.userSyncRunning[userID] = true
+	s.mu.Unlock()
+
+	rec := doJSON(t, s.Router(), http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusConflict {
+		t.Fatalf("status = %d, want 409, body = %s", rec.Code, rec.Body.String())
+	}
+	if _, found, err := db.GetUserBySub(context.Background(), "test-user"); err != nil || !found {
+		t.Fatalf("expected user to survive a rejected delete, found=%v err=%v", found, err)
+	}
+}
+
+func TestDeleteProfile_RemovesTokenStoreDirectory(t *testing.T) {
+	db, err := store.Open(filepath.Join(t.TempDir(), "geniusrun_test.db"))
+	if err != nil {
+		t.Fatalf("store.Open: %v", err)
+	}
+	t.Cleanup(func() { db.Close() })
+	userID, err := db.ProvisionUser(context.Background(), "test-user", "Test User")
+	if err != nil {
+		t.Fatalf("ProvisionUser: %v", err)
+	}
+
+	tokenStoreRoot := t.TempDir()
+	userTokenDir := filepath.Join(tokenStoreRoot, strconv.FormatInt(userID, 10))
+	if err := os.MkdirAll(userTokenDir, 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(userTokenDir, "session.json"), []byte("{}"), 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	m := &mock.Client{}
+	garminFactory := func(garmin.Config) garmin.Client { return m }
+	s := NewServer(db, garminFactory, garmin.Config{TokenStorePath: tokenStoreRoot}, appsync.Config{}, &authmock.Verifier{}, testSessionConfig)
+
+	rec := doJSON(t, s.Router(), http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusNoContent {
+		t.Fatalf("delete status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+	if _, err := os.Stat(userTokenDir); !os.IsNotExist(err) {
+		t.Fatalf("expected token store dir %q to be removed, stat err = %v", userTokenDir, err)
+	}
+}
+```
+
+Append to `backend/internal/api/isolation_test.go`:
+
+```go
+// TestIsolation_DeleteProfileOnlyDeletesOwnAccount confirms one user
+// deleting their own profile never touches another user's account, even
+// though DeleteUser is keyed purely by the session-resolved userID.
+func TestIsolation_DeleteProfileOnlyDeletesOwnAccount(t *testing.T) {
+	s, db, userA := newTestServer(t) // provisions "test-user" (userA)
+	if _, err := db.ProvisionUser(newCtx(), "user-b", "B"); err != nil {
+		t.Fatalf("ProvisionUser(b): %v", err)
+	}
+
+	router := s.Router()
+	rec := doJSONAs(t, router, "user-b", http.MethodDelete, "/api/profile", nil)
+	if rec.Code != http.StatusNoContent {
+		t.Fatalf("userB delete status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+
+	if _, found, err := db.GetUserBySub(newCtx(), "user-b"); err != nil || found {
+		t.Fatalf("expected userB gone after their own delete, found=%v err=%v", found, err)
+	}
+	u, found, err := db.GetUserBySub(newCtx(), "test-user")
+	if err != nil || !found || u.ID != userA {
+		t.Fatalf("expected userA to survive userB's deletion, found=%v err=%v id=%d want=%d", found, err, u.ID, userA)
+	}
+	rec = doJSON(t, router, http.MethodGet, "/api/profile", nil) // as userA
+	if rec.Code != http.StatusOK {
+		t.Fatalf("userA profile status after userB deleted themselves = %d, body = %s", rec.Code, rec.Body.String())
+	}
+}
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `cd backend && go test ./internal/api/... -run 'TestDeleteProfile|TestIsolation_DeleteProfile' -v`
+Expected: FAIL — 404s (no `DELETE /api/profile` route registered yet).
+
+- [ ] **Step 3: Add the `os` import and `removeGarminClient` to `server.go`**
+
+Change the import block (add `"os"` between `"net/http"` and `"path/filepath"`):
+
+```go
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strconv"
+	"sync"
+
+	"github.com/go-chi/chi/v5"
+
+	"geniusrun/backend/internal/auth"
+	"geniusrun/backend/internal/garmin"
+	"geniusrun/backend/internal/store"
+	appsync "geniusrun/backend/internal/sync"
+)
+```
+
+Insert this new method right after `syncFor` (i.e. between the existing `syncFor` closing brace and the `RunIncrementalSyncForAllUsers` doc comment):
+
+```go
+
+// removeGarminClient drops userID's cached garmin.Client/sync.Service (if
+// any) and every other per-user in-memory entry for userID, terminating the
+// client's subprocess and best-effort removing its on-disk token-store
+// directory. Called when a user's account has just been deleted from the
+// DB, so nothing in memory keeps referencing a userID that no longer
+// exists.
+func (s *Server) removeGarminClient(userID int64) {
+	s.mu.Lock()
+	client, ok := s.userGarmin[userID]
+	delete(s.userGarmin, userID)
+	delete(s.userSync, userID)
+	delete(s.userAuthStatus, userID)
+	delete(s.userAuthMessage, userID)
+	delete(s.userSyncRunning, userID)
+	s.mu.Unlock()
+
+	if ok {
+		if err := client.Close(); err != nil {
+			log.Printf("api: close garmin client for deleted user %d: %v", userID, err)
+		}
+	}
+	if s.GarminBase.TokenStorePath == "" {
+		return
+	}
+	tokenStoreDir := filepath.Join(s.GarminBase.TokenStorePath, strconv.FormatInt(userID, 10))
+	if err := os.RemoveAll(tokenStoreDir); err != nil {
+		log.Printf("api: remove token store dir for deleted user %d: %v", userID, err)
+	}
+}
+```
+
+- [ ] **Step 4: Register the route in `Router()`**
+
+In `server.go`, change:
+
+```go
+				r.Route("/profile", func(r chi.Router) {
+					r.Get("/", s.handleGetProfile)
+					r.Put("/", s.handleUpdateProfile)
+				})
+```
+
+to:
+
+```go
+				r.Route("/profile", func(r chi.Router) {
+					r.Get("/", s.handleGetProfile)
+					r.Put("/", s.handleUpdateProfile)
+					r.Delete("/", s.handleDeleteProfile)
+				})
+```
+
+- [ ] **Step 5: Add `handleDeleteProfile` to `profile.go`**
+
+Append to `backend/internal/api/profile.go`:
+
+```go
+
+// handleDeleteProfile permanently deletes the signed-in user's entire
+// geniusrun account (profile, workout kinds/paces, activities and
+// everything under them, sync state/runs -- see schema.sql's ON DELETE
+// CASCADE from users(id)) and tears down their cached Garmin client and
+// token-store directory. It does not touch the session cookie itself --
+// the frontend follows a successful call with a real logout navigation
+// (see docs/superpowers/specs/2026-07-26-profile-deletion-design.md).
+func (s *Server) handleDeleteProfile(w http.ResponseWriter, r *http.Request) {
+	userID := userIDFromContext(r.Context())
+
+	s.mu.Lock()
+	inProgress := s.userSyncRunning[userID]
+	s.mu.Unlock()
+	if inProgress {
+		writeError(w, http.StatusConflict, "a sync is in progress for this account; wait for it to finish before deleting your profile")
+		return
+	}
+
+	if err := s.DB.DeleteUser(r.Context(), userID); err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	s.removeGarminClient(userID)
+	w.WriteHeader(http.StatusNoContent)
+}
+```
+
+- [ ] **Step 6: Run tests to verify they pass**
+
+Run: `cd backend && go test ./internal/api/... -run 'TestDeleteProfile|TestIsolation_DeleteProfile' -v`
+Expected: PASS.
+
+- [ ] **Step 7: Run the full backend test suite**
+
+Run: `cd backend && go build ./... && go vet ./... && gofmt -l . && go test ./...`
+Expected: `gofmt -l .` prints nothing; `go build`/`go vet`/`go test` all succeed.
+
+- [ ] **Step 8: Commit**
+
+```bash
+git add backend/internal/api/server.go backend/internal/api/profile.go backend/internal/api/api_test.go backend/internal/api/isolation_test.go
+git commit -m "feat(api): add DELETE /api/profile with Garmin client/tokenstore teardown"
+```
+
+---
+
+### Task 3: Frontend Danger zone UI
+
+**Files:**
+- Modify: `frontend/src/api/client.ts` (add `deleteProfile`)
+- Modify: `frontend/src/pages/Profile.tsx` (add Danger zone fieldset + confirm flow)
+- Modify: `frontend/src/App.css` (small `.danger-zone-confirm` rule)
+
+**Interfaces:**
+- Consumes: `DELETE /api/profile` (Task 2, returns `204` or throws via the existing `request()` helper's non-2xx handling); `BASE_URL` (already exported from `client.ts`).
+- Produces: `api.deleteProfile(): Promise<void>`, used only from `Profile.tsx`.
+
+- [ ] **Step 1: Add `deleteProfile` to the API client**
+
+In `frontend/src/api/client.ts`, in the `// Profile` section, change:
+
+```ts
+  // Profile
+  getProfile: () => request<Profile>("/api/profile"),
+  updateProfile: (profile: Profile) =>
+    request<Profile>("/api/profile", { method: "PUT", body: JSON.stringify(profile) }),
+```
+
+to:
+
+```ts
+  // Profile
+  getProfile: () => request<Profile>("/api/profile"),
+  updateProfile: (profile: Profile) =>
+    request<Profile>("/api/profile", { method: "PUT", body: JSON.stringify(profile) }),
+  // Permanently deletes the signed-in user's entire account. The caller is
+  // responsible for following a successful call with a real logout
+  // navigation -- this does not touch the session cookie (see Profile.tsx).
+  deleteProfile: () => request<void>("/api/profile", { method: "DELETE" }),
+```
+
+- [ ] **Step 2: Add the Danger zone section to `Profile.tsx`**
+
+Change the import line:
+
+```tsx
+import { api } from "../api/client";
+```
+
+to:
+
+```tsx
+import { api, BASE_URL } from "../api/client";
+```
+
+Add these three state variables inside `Profile`, right after the existing `saveTimeoutRef` declaration:
+
+```tsx
+  const [deleteConfirmOpen, setDeleteConfirmOpen] = useState(false);
+  const [deleteConfirmText, setDeleteConfirmText] = useState("");
+  const [deleting, setDeleting] = useState(false);
+```
+
+Add this function right after `flushPendingSave`:
+
+```tsx
+  async function deleteAccount() {
+    setDeleting(true);
+    setError(null);
+    try {
+      await api.deleteProfile();
+      // Deletion doesn't clear the session cookie -- follow with a real
+      // logout navigation (must be a POST, same as the header's Log out
+      // button in App.tsx) so Keycloak's own SSO session ends too, not just
+      // geniusrun's local one.
+      const form = document.createElement("form");
+      form.method = "post";
+      form.action = `${BASE_URL}/api/session/logout`;
+      document.body.appendChild(form);
+      form.submit();
+    } catch (e) {
+      setError(String(e));
+      setDeleting(false);
+    }
+  }
+```
+
+Add this fieldset right after `<TrainingTypesCard />` (still inside the closing `</div>` of `.profile-page`):
+
+```tsx
+      <fieldset className="kind-editor danger-zone">
+        <legend>Danger zone</legend>
+        {!deleteConfirmOpen ? (
+          <button type="button" className="button-danger" onClick={() => setDeleteConfirmOpen(true)}>
+            Delete profile
+          </button>
+        ) : (
+          <div className="danger-zone-confirm">
+            <p>
+              This permanently deletes your account -- Garmin credentials, every custom rule, and every synced
+              activity -- and logs you out. This cannot be undone.
+            </p>
+            <label>
+              Type DELETE to confirm
+              <input
+                type="text"
+                value={deleteConfirmText}
+                onChange={(e) => setDeleteConfirmText(e.target.value)}
+                disabled={deleting}
+              />
+            </label>
+            <div className="controls">
+              <button
+                type="button"
+                disabled={deleting}
+                onClick={() => {
+                  setDeleteConfirmOpen(false);
+                  setDeleteConfirmText("");
+                }}
+              >
+                Cancel
+              </button>
+              <button
+                type="button"
+                className="button-danger"
+                disabled={deleting || deleteConfirmText !== "DELETE"}
+                onClick={deleteAccount}
+              >
+                Permanently delete
+              </button>
+            </div>
+          </div>
+        )}
+      </fieldset>
+```
+
+- [ ] **Step 3: Add the confirmation block's CSS**
+
+In `frontend/src/App.css`, add right after the `.button-danger:hover:not(:disabled)` rule:
+
+```css
+.danger-zone-confirm {
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+}
+
+.danger-zone-confirm p {
+  margin: 0;
+  color: #9aa0ab;
+}
+```
+
+- [ ] **Step 4: Build and lint**
+
+Run: `cd frontend && npm run build && npm run lint`
+Expected: build succeeds; lint reports no new warnings (the 3 pre-existing `PaceField.tsx` `only-export-components` warnings are unrelated and expected to remain).
+
+- [ ] **Step 5: Manual browser verification**
+
+With the backend running (`cd backend && ./start.sh`) and frontend dev server running (`cd frontend && ./start.sh`), in a browser:
+1. Log in, go to the Profile page, scroll to "Danger zone".
+2. Click "Delete profile" — the confirm block appears; "Permanently delete" is disabled.
+3. Type `delete` (lowercase) — button stays disabled. Type `DELETE` — button enables.
+4. Click "Cancel" — block collapses, typed text is cleared if reopened.
+5. Reopen, type `DELETE`, click "Permanently delete" — expect a full-page navigation ending on the login screen (Keycloak or geniusrun's own login gate, matching what the existing "Log out" button already does).
+6. Log back in with the same account — expect the "Create your profile" screen (`CreateProfile.tsx`), confirming the account was actually deleted, not just logged out.
+
+- [ ] **Step 6: Commit**
+
+```bash
+git add frontend/src/api/client.ts frontend/src/pages/Profile.tsx frontend/src/App.css
+git commit -m "feat(profile): add Danger zone account deletion UI"
+```
+
+---
+
+### Task 4: Final verification
+
+**Files:** none (verification only)
+
+- [ ] **Step 1: Full backend check**
+
+Run: `cd backend && gofmt -l . && go vet ./... && go build ./... && go test ./...`
+Expected: `gofmt -l .` empty; everything else passes.
+
+- [ ] **Step 2: Full frontend check**
+
+Run: `cd frontend && npm run build && npm run lint`
+Expected: both succeed, no new lint warnings.
+
+- [ ] **Step 3: Confirm `docs/DATABASE.md` is current**
+
+Run: `cd backend && go run ./cmd/dumpschema && git status --short docs/DATABASE.md`
+Expected: no output from `git status` (already committed in Task 1, and hasn't drifted since).
+
+- [ ] **Step 4: Update `docs/IDEAS.md`**
+
+Remove the now-implemented line from `docs/IDEAS.md`'s Backlog section:
+
+```
+- profile deletion: add a way to delete our profile with a dedicated button on the profile page (which by extension will also logout the user, to be consistent with the logic that login will trigger the profile creation)
+```
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add docs/IDEAS.md
+git commit -m "docs: remove profile deletion from IDEAS backlog (implemented)"
+```

docs/superpowers/specs/2026-07-26-profile-deletion-design.md

@@ -0,0 +1,142 @@
+# Profile deletion
+
+Status: approved, not yet implemented.
+
+## Problem
+
+`docs/IDEAS.md` backlog item: "profile deletion: add a way to delete our
+profile with a dedicated button on the profile page (which by extension will
+also logout the user, to be consistent with the logic that login will trigger
+the profile creation)".
+
+Today there is no way for a user to remove their geniusrun account. The
+closest existing feature, "Reset all" (`GarminConnection.tsx` /
+`POST /api/sync/reset`), only wipes synced activity data and rewinds the
+backfill watermark -- it leaves the `users` row, `profile`, Garmin
+credentials, and custom workout-kind rules untouched. Profile deletion is a
+strictly bigger, irreversible operation: the entire account for the signed-in
+OIDC subject, gone, followed by a real logout.
+
+## Design
+
+### Data model: cascading deletes
+
+The schema has FK columns pointing at `users(id)` (`profile.user_id`,
+`workout_kinds.user_id`, `activities.user_id`, `sync_state.user_id`,
+`sync_runs.user_id`) and at `workout_kinds(id)`
+(`workout_type_paces.workout_kind_id`), none of which currently cascade.
+`laps`/`activity_samples`/`kind_assignments` already cascade off `activities`
+(`ON DELETE CASCADE`), which is what lets `ResetAllSyncedData` get away with
+a single `DELETE FROM activities`. SQLite's `foreign_keys` pragma is already
+enabled on every connection (`db.go`'s `_pragma=foreign_keys(1)`), so the same
+mechanism works for the rest of the schema.
+
+`schema.sql` is edited directly (no migration history, per project
+convention) to add `ON DELETE CASCADE` to:
+
+- `profile.user_id REFERENCES users(id)`
+- `workout_kinds.user_id REFERENCES users(id)`
+- `workout_type_paces.workout_kind_id REFERENCES workout_kinds(id)`
+- `activities.user_id REFERENCES users(id)`
+- `sync_state.user_id REFERENCES users(id)`
+- `sync_runs.user_id REFERENCES users(id)`
+
+With that in place, deleting a user becomes one statement:
+
+```go
+// store/users.go
+func (db *DB) DeleteUser(ctx context.Context, userID int64) error {
+	_, err := db.ExecContext(ctx, `DELETE FROM users WHERE id = ?`, userID)
+	return err
+}
+```
+
+After this change, regenerate `docs/DATABASE.md` (`go run ./cmd/dumpschema`).
+
+### API: `DELETE /api/profile`
+
+New handler alongside the existing `GET`/`PUT /api/profile` routes, inside
+the `requireProvisionedUser` group (`server.go`). `userID` comes from
+`userIDFromContext`, same as every other handler -- no client-supplied id.
+
+1. If a sync is currently running for this user (`s.userSyncRunning[userID]`,
+   the same flag `backgroundSync` sets), respond `409 Conflict` ("a sync is
+   in progress for this account; wait for it to finish before deleting your
+   profile") rather than deleting rows out from under an in-flight write.
+2. Call `s.DB.DeleteUser(ctx, userID)`.
+3. Tear down this user's cached Garmin state (new `Server` method, e.g.
+   `removeGarminClient(userID)`):
+   - Under `s.mu`, pop `s.userGarmin[userID]` and delete the userID entry
+     from `userSync`, `userAuthStatus`, `userAuthMessage`, and
+     `userSyncRunning`.
+   - If a client existed, call `client.Close()` outside the lock to
+     terminate its subprocess (mirrors how `handleUpdateProfile` calls
+     `client.UpdateCredentials` outside `s.mu`).
+   - Best-effort `os.RemoveAll` on `filepath.Join(s.GarminBase.TokenStorePath,
+     strconv.FormatInt(userID, 10))` when `TokenStorePath` is configured --
+     the same path `garminFor` computes when building a client. Log on
+     error; this is cleanup of an already-orphaned directory, not something
+     that should fail the request that already deleted the DB row.
+4. Respond `204 No Content`.
+
+### Frontend
+
+- `api/client.ts`: `deleteProfile: () => request<void>("/api/profile", {
+  method: "DELETE" })`.
+- `Profile.tsx`: a final `<fieldset className="kind-editor danger-zone">`
+  ("Danger zone") containing a `button-danger` "Delete profile" button
+  (same class `GarminConnection`'s "Reset all" uses). Clicking it reveals an
+  inline confirmation block (local component state, no separate modal
+  component -- same "reveal inline" shape `ClassifyControl` already uses for
+  its dropdown):
+  - Explanatory copy: this permanently deletes the account -- Garmin
+    credentials, every custom rule, every synced activity -- and logs the
+    user out. Cannot be undone.
+  - A text input; a "Permanently delete" button stays disabled until the
+    input's value is exactly `DELETE`.
+  - A "Cancel" button collapses the block back.
+- On confirm: call `api.deleteProfile()`. On success, build a real
+  `<form method="post" action="{BASE_URL}/api/session/logout">` via the DOM
+  and submit it immediately -- the same POST-navigation the header's Log out
+  button already performs (`App.tsx`), required because logout must be a
+  real browser navigation through Keycloak's end-session redirect, not a
+  `fetch`. On failure, surface the error via the same `error` state /
+  `<p className="error">` pattern the rest of `Profile.tsx` already uses,
+  and leave the confirmation block open so the user can retry.
+
+### Error handling
+
+- Sync-in-progress: `409`, clear message, surfaced like every other API
+  error on this page.
+- DB/teardown errors: `500` with `err.Error()`, same as the rest of this
+  codebase's handlers.
+- The type-`DELETE`-to-confirm gate is UI-only -- same trust boundary as
+  every other destructive action in this app (e.g. Reset all's
+  `window.confirm`). The backend does not require a second confirmation
+  token.
+
+### Testing
+
+- `backend/internal/store`: `TestDeleteUser` -- provision a user, give them
+  activities (with laps/samples/kind_assignments), workout kinds (with
+  paces), sync_state, and sync_runs; delete; assert every row is gone.
+  Adversarial isolation check per this repo's convention
+  (`isolation_test.go`): provision two users, delete one, assert the other's
+  rows (profile, workout kinds, activities, etc.) are untouched.
+- `backend/internal/api`: handler test for `DELETE /api/profile` against
+  `newTestServer` + `mock.Client` -- success path (204, user actually gone
+  from `GetUserBySub`), and the sync-in-progress 409 (set
+  `userSyncRunning[userID] = true` first).
+- No frontend test suite exists yet (per `CLAUDE.md`) -- manually
+  smoke-tested in the browser: delete flow ends up back at the login/create
+  profile screen, a fresh login for that OIDC subject lands on "Create your
+  profile" again (proving the account is truly gone, not just logged out).
+
+## Out of scope
+
+- Any "export my data before deleting" flow -- not requested.
+- Re-authentication (password/MFA re-entry) before deletion -- this app has
+  no such step anywhere else (e.g. Reset all), so it isn't introduced here
+  either.
+- Admin-initiated deletion of another user's account -- there is no admin UI
+  in this app.

frontend/src/App.css

@@ -231,6 +231,17 @@ button:disabled {
   color: #fff;
 }
 
+.danger-zone-confirm {
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+}
+
+.danger-zone-confirm p {
+  margin: 0;
+  color: #9aa0ab;
+}
+
 .filter-pills {
   display: flex;
   gap: 0.5rem;

frontend/src/api/client.ts

@@ -106,6 +106,10 @@ export const api = {
   getProfile: () => request<Profile>("/api/profile"),
   updateProfile: (profile: Profile) =>
     request<Profile>("/api/profile", { method: "PUT", body: JSON.stringify(profile) }),
+  // Permanently deletes the signed-in user's entire account. The caller is
+  // responsible for following a successful call with a real logout
+  // navigation -- this does not touch the session cookie (see Profile.tsx).
+  deleteProfile: () => request<void>("/api/profile", { method: "DELETE" }),
 
   // Review queue -- cursor-paginated: pass the previous page's next_cursor
   // as `before` to fetch the next one. Fetching every activity's laps and

frontend/src/pages/Profile.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useRef, useState } from "react";
-import { api } from "../api/client";
+import { api, BASE_URL } from "../api/client";
 import { ColorField } from "../components/ColorField";
 import { GarminConnection } from "../components/GarminConnection";
 import { NullableNumberField } from "../components/NullableNumberField";
@@ -47,6 +47,9 @@ export function Profile({ onSaved }: { onSaved?: (p: ProfileType) => void }) {
   const profileRef = useRef<ProfileType | null>(null);
   profileRef.current = profile;
   const saveTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const [deleteConfirmOpen, setDeleteConfirmOpen] = useState(false);
+  const [deleteConfirmText, setDeleteConfirmText] = useState("");
+  const [deleting, setDeleting] = useState(false);
 
   useEffect(() => {
     api.getProfile().then(setProfile).catch((e) => setError(String(e)));
@@ -100,6 +103,26 @@ export function Profile({ onSaved }: { onSaved?: (p: ProfileType) => void }) {
     }
   }
 
+  async function deleteAccount() {
+    setDeleting(true);
+    setError(null);
+    try {
+      await api.deleteProfile();
+      // Deletion doesn't clear the session cookie -- follow with a real
+      // logout navigation (must be a POST, same as the header's Log out
+      // button in App.tsx) so Keycloak's own SSO session ends too, not just
+      // geniusrun's local one.
+      const form = document.createElement("form");
+      form.method = "post";
+      form.action = `${BASE_URL}/api/session/logout`;
+      document.body.appendChild(form);
+      form.submit();
+    } catch (e) {
+      setError(String(e));
+      setDeleting(false);
+    }
+  }
+
   if (!profile) {
     return (
       <div className="page">
@@ -240,6 +263,51 @@ export function Profile({ onSaved }: { onSaved?: (p: ProfileType) => void }) {
       </fieldset>
 
       <TrainingTypesCard />
+
+      <fieldset className="kind-editor danger-zone">
+        <legend>Danger zone</legend>
+        {!deleteConfirmOpen ? (
+          <button type="button" className="button-danger" onClick={() => setDeleteConfirmOpen(true)}>
+            Delete profile
+          </button>
+        ) : (
+          <div className="danger-zone-confirm">
+            <p>
+              This permanently deletes your account -- Garmin credentials, every custom rule, and every synced
+              activity -- and logs you out. This cannot be undone.
+            </p>
+            <label>
+              Type DELETE to confirm
+              <input
+                type="text"
+                value={deleteConfirmText}
+                onChange={(e) => setDeleteConfirmText(e.target.value)}
+                disabled={deleting}
+              />
+            </label>
+            <div className="controls">
+              <button
+                type="button"
+                disabled={deleting}
+                onClick={() => {
+                  setDeleteConfirmOpen(false);
+                  setDeleteConfirmText("");
+                }}
+              >
+                Cancel
+              </button>
+              <button
+                type="button"
+                className="button-danger"
+                disabled={deleting || deleteConfirmText !== "DELETE"}
+                onClick={deleteAccount}
+              >
+                Permanently delete
+              </button>
+            </div>
+          </div>
+        )}
+      </fieldset>
     </div>
   );
 }

go.work

@@ -0,0 +1,3 @@
+go 1.26.4
+
+use ./backend

go.work.sum

@@ -0,0 +1,2 @@
+cloud.google.com/go/compute/metadata v0.3.0 h1:Tz+eQXMEqDIKRsmY3cHTL6FVaynIjX2QxYC4trgAKZc=
+cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=