diff --git a/NEXT_SESSION.md b/NEXT_SESSION.md
index 3d8feda7..a84a89e3 100644
--- a/NEXT_SESSION.md
+++ b/NEXT_SESSION.md
@@ -33,8 +33,16 @@ architecture and conventions. Delete this file when the list is done.
   fallback in gc.login (main() parks it as .bak first).
 - DB after sync: 385 activities (→ 2026-06-02), all ISO timestamps on new
   rows, 356 FITs linked, 364 TIZ rows, wellness through 2026-06-12.
-  The 18 legacy epoch-ms rows remain (P2). Web Sync page still uses the
-  garth login flow — port it to the gc backend (or hide login) later.
+  The 18 legacy epoch-ms rows remain (P2).
+- **Web Sync page ported to the gc backend** (same session): login + MFA
+  round-trip + sync button all run on garminconnect; verified headlessly via
+  streamlit AppTest (login restore, button click, full sync, no exceptions).
+  `openrun.ingest.auth` (garth) remains only for `--backend=garth`.
+- **New goal (user, 2026-06-12): shareable web UI** — let others run the
+  openrun web app against their own Garmin account. Known gaps: per-user
+  token store + DB (everything is cwd-relative single-user today), per-user
+  openrun.toml (zones/races — openrun-init helps), and deploy story
+  (`streamlit run` is single-process; secrets must stay server-side).
 - `race_plan` table is EMPTY and `manual_activities` empty, but openrun.toml
   has races: 30K 2026-06-13, 50K 2026-07-25, 50 MILE 2026-09-12.
 - Known bugs: 18 activities have epoch-ms floats in `start_time_local`
diff --git a/src/openrun/ingest/garminconnect_backend.py b/src/openrun/ingest/garminconnect_backend.py
index eddab802..f9f467c9 100644
--- a/src/openrun/ingest/garminconnect_backend.py
+++ b/src/openrun/ingest/garminconnect_backend.py
@@ -19,19 +19,86 @@ from pathlib import Path
 from typing import Any
 
 
+def token_dir() -> Path:
+    """Token store: `.secrets/` relative to the current working directory."""
+    return Path.cwd() / ".secrets"
+
+
 def has_tokens(token_dir: Path) -> bool:
     return (token_dir / "garmin_tokens.json").exists()
 
 
+def resume(td: Path | None = None) -> Any | None:
+    """Restore an authenticated Garmin client from saved tokens, else None.
+
+    Validates against the API (refreshing the DI token if needed), so a dead
+    tokenstore returns None rather than failing later mid-sync.
+    """
+    from garminconnect import Garmin
+
+    td = td or token_dir()
+    if not has_tokens(td):
+        return None
+    try:
+        gc = Garmin()
+        gc.login(tokenstore=str(td))
+        return gc
+    except Exception:  # noqa: BLE001 — expired/rejected tokens → logged out
+        return None
+
+
+def begin_login(email: str, password: str, td: Path | None = None) -> tuple[str, Any]:
+    """Start a fresh credential login (web flow, no input()). Returns:
+
+    * ``("ok", gc)``        — logged in; tokens saved.
+    * ``("needs_mfa", gc)`` — hold ``gc`` (e.g. in st.session_state) and pass
+                              it with the emailed/app code to ``complete_mfa``.
+
+    Raises garminconnect's typed errors on bad credentials / rate limits.
+    """
+    from garminconnect import Garmin
+
+    gc = Garmin(email=email, password=password, return_on_mfa=True)
+    status, _ = gc.login()  # cascading strategies; early-returns pre-dump
+    if status == "needs_mfa":
+        return "needs_mfa", gc
+    return "ok", _finish_login(gc, td)
+
+
+def complete_mfa(gc: Any, code: str, td: Path | None = None) -> Any:
+    """Finish an MFA login started by ``begin_login``. Returns the client."""
+    gc.client.resume_login(None, code.strip())
+    return _finish_login(gc, td)
+
+
+def _finish_login(gc: Any, td: Path | None = None) -> Any:
+    """Persist tokens and load the profile (skipped in return_on_mfa mode)."""
+    td = td or token_dir()
+    td.mkdir(parents=True, exist_ok=True)
+    gc.client.dump(str(td))
+    gc._load_profile_and_settings()  # noqa: SLF001 — wrapper has no public hook
+    return gc
+
+
+def user_label(gc: Any) -> str:
+    """Human-readable account label for UI display."""
+    return gc.full_name or gc.username or gc.display_name or "Garmin user"
+
+
 def activate(token_dir: Path) -> str:
     """Authenticate from `token_dir` and patch garth. Returns the username."""
-    import garth
-    from garth.http import Client as GarthClient
-    from garth.http import client as garth_singleton
     from garminconnect import Garmin
 
     gc = Garmin()
     gc.login(tokenstore=str(token_dir))  # loads DI tokens; auto-refreshes + re-saves
+    return patch_garth(gc)
+
+
+def patch_garth(gc: Any) -> str:
+    """Route garth's API surface through an authenticated garminconnect client."""
+    import garth
+    from garth.http import Client as GarthClient
+    from garth.http import client as garth_singleton
 
     def connectapi(path: str, **kwargs: Any) -> Any:
         return gc.connectapi(path, **kwargs)
diff --git a/src/openrun/web/pages/5_Sync.py b/src/openrun/web/pages/5_Sync.py
index 80f29f8b..0d69efe3 100644
--- a/src/openrun/web/pages/5_Sync.py
+++ b/src/openrun/web/pages/5_Sync.py
@@ -19,7 +19,7 @@ import streamlit as st
 
 from openrun.config import default_config
 from openrun.db import get_state
-from openrun.ingest import auth as gauth
+from openrun.ingest import garminconnect_backend as gauth
 from openrun.ingest.garmin_api import run_sync
 from openrun.ingest.garmin_export import ingest_path
 from openrun.web._helpers import get_conn, show_sidebar
@@ -45,10 +45,14 @@ st.write(
 st.divider()
 st.subheader("Live sync (Garmin Connect)")
 
-_user = gauth.current_user()
+# Resume validates tokens against the API (one round-trip), so cache the
+# result for the browser session instead of re-checking on every rerun.
+if "garmin_client" not in st.session_state:
+    st.session_state["garmin_client"] = gauth.resume()
+_gc = st.session_state["garmin_client"]
 
-if _user:
-    st.success(f"Logged in as **{_user}**.")
+if _gc is not None:
+    st.success(f"Logged in as **{gauth.user_label(_gc)}**.")
 
     c1, c2 = st.columns(2)
     full = c1.checkbox(
@@ -77,34 +81,33 @@ if _user:
         fit_limit = int(_lim) or None
 
     if st.button("🔄 Sync now from Garmin", type="primary"):
-        if not gauth.resume():
-            st.error("Session expired — log in again below.")
-        else:
-            summary = None
-            with st.status("Syncing from Garmin…", expanded=True) as status:
-                try:
-                    summary = run_sync(
-                        get_conn(),
-                        full=full,
-                        fetch_fit=want_fit,
-                        fit_backfill=fit_backfill,
-                        fit_type=fit_type,
-                        fit_limit=fit_limit,
-                        progress=status.write,
-                    )
-                    status.update(label="Sync complete", state="complete")
-                except Exception as exc:  # noqa: BLE001 — surface any garth/HTTP error
-                    status.update(label="Sync failed", state="error")
-                    st.error(str(exc))
-            if summary is not None:
-                st.cache_data.clear()
-                st.success("Synced from Garmin Connect.")
-                st.json(summary)
+        summary = None
+        with st.status("Syncing from Garmin…", expanded=True) as status:
+            try:
+                gauth.patch_garth(_gc)
+                summary = run_sync(
+                    get_conn(),
+                    full=full,
+                    fetch_fit=want_fit,
+                    fit_backfill=fit_backfill,
+                    fit_type=fit_type,
+                    fit_limit=fit_limit,
+                    progress=status.write,
+                )
+                status.update(label="Sync complete", state="complete")
+            except Exception as exc:  # noqa: BLE001 — surface any API/HTTP error
+                status.update(label="Sync failed", state="error")
+                st.error(str(exc))
+        if summary is not None:
+            st.cache_data.clear()
+            st.success("Synced from Garmin Connect.")
+            st.json(summary)
 
     with st.expander("Log out"):
         st.caption("Removes the saved OAuth tokens in `.secrets/`. You'll need to log in again to sync.")
         if st.button("Forget saved tokens"):
             shutil.rmtree(gauth.token_dir(), ignore_errors=True)
+            st.session_state.pop("garmin_client", None)
             st.rerun()
 
 else:
@@ -123,7 +126,8 @@ else:
             st.warning("Enter both email and password.")
         else:
             try:
-                kind, payload = gauth.begin_login(email, password)
+                with st.spinner("Logging in to Garmin…"):
+                    kind, payload = gauth.begin_login(email, password)
             except Exception as exc:  # noqa: BLE001
                 st.error(f"Login failed: {exc}")
             else:
@@ -131,7 +135,7 @@ else:
                     st.session_state["garmin_mfa_state"] = payload
                     st.rerun()
                 else:
-                    st.success(f"Logged in as {payload}.")
+                    st.session_state["garmin_client"] = payload
                     st.rerun()
 
     if "garmin_mfa_state" in st.session_state:
@@ -141,12 +145,12 @@ else:
             mfa_submitted = st.form_submit_button("Verify", type="primary")
         if mfa_submitted:
             try:
-                user = gauth.complete_mfa(st.session_state["garmin_mfa_state"], code)
+                gc = gauth.complete_mfa(st.session_state["garmin_mfa_state"], code)
             except Exception as exc:  # noqa: BLE001
                 st.error(f"Verification failed: {exc}")
             else:
                 del st.session_state["garmin_mfa_state"]
-                st.success(f"Logged in as {user}.")
+                st.session_state["garmin_client"] = gc
                 st.rerun()
 
 st.divider()