navi-offroute: Auto Valhalla bypass for road↔road (#46)

Co-authored-by: mj <mj@k7zvx.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/services/navi_offroute/router.py

@@ -838,6 +838,30 @@ class OffrouteRouter:
         end_eligible = self._auto_eligible_modes(end_lat, end_lon, end_category, snap_cache)
         seed_set = sorted(start_eligible | end_eligible)
 
+        # === Valhalla bypass: pure road↔road skips the raster pipeline entirely ===
+        # When BOTH endpoints are tagged with a vehicle-eligible category (only _MODES_ALL
+        # contains "vehicle"), the trip is on-road end-to-end -> hand it straight to the same
+        # inline-Valhalla path explicit vehicle requests use, saving the ~7.5s raster build +
+        # unified A*. Untagged endpoints (category -> None) and any non-paved category fall
+        # through to the unified flow. Boundary-mode MVUM exclusions are not applied here (urban
+        # roads aren't MVUM-gated); this matches a pragmatic in-town vehicle route.
+        bp_start = self._eligible_modes_from_category(start_category)
+        bp_end = self._eligible_modes_from_category(end_category)
+        if (bp_start is not None and bp_end is not None
+                and "vehicle" in bp_start and "vehicle" in bp_end):
+            _bt0 = time.perf_counter()
+            bypass = self._route_D_network_only(start_lat, start_lon, end_lat, end_lon, "vehicle")
+            if bypass.get("status") == "ok":
+                bypass["selected_mode"] = "vehicle"
+                bypass["selected_mode_set"] = ["vehicle"]
+                bypass.setdefault("summary", {})["auto_bypass"] = True
+                logger.info("auto bypass: vehicle road↔road via Valhalla in %.3fs",
+                            time.perf_counter() - _bt0)
+                return bypass
+            logger.warning("auto bypass attempted but Valhalla returned %s; falling through to unified",
+                           bypass.get("status"))
+        # === end bypass ===
+
         # 2-3. bbox covering both endpoints + the shared rasters (one fetch, all modes).
         try:
             (elevation, friction_mult, friction_raw, trails, barriers,

backend/services/navi_offroute/tests/test_offroute.py

@@ -1292,3 +1292,83 @@ def test_route_auto_perf_under_5s(monkeypatch):
     assert out["status"] == "ok", out
     assert out["selected_mode_set"] == ["foot"]
     assert elapsed <= 5.0, f"_route_auto on ~50 km grid took {elapsed:.2f}s > 5.0s"
+
+
+# ── Auto Valhalla bypass: pure road↔road skips the raster pipeline ────────────
+import logging as _bp_logging
+
+
+class _BypassOKResp:
+    status_code = 200
+    def json(self):
+        return {"trip": {"legs": [{"shape": "", "maneuvers": []}],
+                         "summary": {"length": 1.2, "time": 90}}}
+
+
+class _BypassErrResp:
+    status_code = 500
+    text = "valhalla boom"
+
+
+def _bp_fetch_should_not_run(*a, **k):
+    raise AssertionError("_fetch_auto_rasters must NOT run when the bypass fires")
+
+
+def _bp_fetch_sentinel(*a, **k):
+    raise RuntimeError("FETCH_REACHED")   # proves we fell through to the unified flow
+
+
+def test_route_auto_road_road_uses_valhalla_bypass(monkeypatch):
+    r = object.__new__(OffrouteRouter)
+    monkeypatch.setattr(OffrouteRouter, "_fetch_auto_rasters", _bp_fetch_should_not_run)
+    calls = []
+    real_D = OffrouteRouter._route_D_network_only
+    monkeypatch.setattr(OffrouteRouter, "_route_D_network_only",
+                        lambda self, *a, **k: (calls.append(a) or real_D(self, *a, **k)))
+    monkeypatch.setattr(_p4router.requests, "post", lambda *a, **k: _BypassOKResp())
+
+    out = r._route_auto(42.5558, -114.4701, 42.5644, -114.4631, "pragmatic",
+                        start_category="highway:residential", end_category="highway:residential")
+    assert out["status"] == "ok"
+    assert out["selected_mode"] == "vehicle"
+    assert out["selected_mode_set"] == ["vehicle"]
+    assert out["summary"]["auto_bypass"] is True
+    assert out["summary"]["scenario"] == "D"
+    assert len(calls) == 1                              # _route_D_network_only called exactly once
+
+
+def test_route_auto_road_offroad_skips_bypass(monkeypatch):
+    r = object.__new__(OffrouteRouter)
+    monkeypatch.setattr(OffrouteRouter, "_route_D_network_only",
+                        lambda *a, **k: (_ for _ in ()).throw(AssertionError("D must not run")))
+    monkeypatch.setattr(OffrouteRouter, "_fetch_auto_rasters", _bp_fetch_sentinel)
+    # start = paved road (vehicle eligible), end = footway (foot-only, no vehicle) -> no bypass.
+    out = r._route_auto(42.5558, -114.4701, 42.5878, -114.5550, "pragmatic",
+                        start_category="highway:residential", end_category="highway:footway")
+    assert out["status"] == "error"
+    assert "Failed to load terrain" in out["message"]   # reached _fetch_auto_rasters (unified flow)
+
+
+def test_route_auto_untagged_skips_bypass(monkeypatch):
+    r = object.__new__(OffrouteRouter)
+    monkeypatch.setattr(OffrouteRouter, "_spatial_eligible_modes",
+                        lambda self, lat, lon, cache: frozenset({"foot"}))
+    monkeypatch.setattr(OffrouteRouter, "_route_D_network_only",
+                        lambda *a, **k: (_ for _ in ()).throw(AssertionError("D must not run")))
+    monkeypatch.setattr(OffrouteRouter, "_fetch_auto_rasters", _bp_fetch_sentinel)
+    out = r._route_auto(42.5558, -114.4701, 42.5644, -114.4631, "pragmatic")  # no categories
+    assert out["status"] == "error"
+    assert "Failed to load terrain" in out["message"]   # bypass skipped, unified flow reached
+
+
+def test_route_auto_bypass_falls_through_on_valhalla_error(monkeypatch, caplog):
+    r = object.__new__(OffrouteRouter)
+    monkeypatch.setattr(_p4router.requests, "post", lambda *a, **k: _BypassErrResp())
+    monkeypatch.setattr(OffrouteRouter, "_fetch_auto_rasters", _bp_fetch_sentinel)
+    with caplog.at_level(_bp_logging.WARNING, logger="navi_offroute.router"):
+        out = r._route_auto(42.5558, -114.4701, 42.5644, -114.4631, "pragmatic",
+                            start_category="highway:residential", end_category="highway:residential")
+    assert "auto bypass attempted but Valhalla returned" in caplog.text
+    assert out["status"] == "error"
+    assert "Failed to load terrain" in out["message"]   # fell through to the unified flow
+    assert "auto_bypass" not in (out.get("summary") or {})