diff --git a/packages/ludic.nav/build.ludic b/packages/ludic.nav/build.ludic
index 15fc5233..6ba8ef4e 100644
--- a/packages/ludic.nav/build.ludic
+++ b/packages/ludic.nav/build.ludic
@@ -47,8 +47,8 @@ export function nav_polygons(nav_st: NavState, kind: int) -> int {
   return nvc_polys(h)
 }
 
-# a kind's mesh written to a file, and read back. Reading holds the file's bytes for good (a slice
-# is never given back), so a mesh is loaded once per map, never per frame
+# a kind's mesh written to a file, and read back - through the asset pack when it is in one - into the
+# shim's own memory, which it frees once the tiles are made, so a map swap leaves nothing behind
 export function nav_save_file(nav_st: NavState, kind: int, path: string) -> bool {
   let h = nv_mesh(nav_st, kind)
   if h == null { return false }
@@ -59,8 +59,14 @@ export function nav_save_file(nav_st: NavState, kind: int, path: string) -> bool
   return Fs.write_bytes(path, buf, n)
 }
 export function nav_load_file(nav_st: mut NavState, kind: int, path: string) -> bool {
-  if not Fs.exists(path) { return false }
-  let buf = Fs.read_bytes(path)
-  if buf == null or len(buf) == 0 { return false }
-  return nv_set(nav_st, kind, nvc_load(buf, len(buf)))
+  let f = file_open(path, "rb")
+  if f == null { return false }
+  file_seek(f, 0, 2)
+  let n = file_tell(f)
+  file_seek(f, 0, 0)
+  let buf = nvc_stage(n)
+  var got = 0
+  if buf != null { got = file_read(f, buf, n) }
+  file_close(f)
+  return nv_set(nav_st, kind, nvc_load_staged(buf, got))
 }
diff --git a/packages/ludic.nav/lib/macos-arm64/libludicnav.dylib b/packages/ludic.nav/lib/macos-arm64/libludicnav.dylib
index 4ea3bedc..3941b8a7 100755
--- a/packages/ludic.nav/lib/macos-arm64/libludicnav.dylib
+++ b/packages/ludic.nav/lib/macos-arm64/libludicnav.dylib
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:7d2e4aa97130a76c41dfb6a6b93172e7cbab3fa6249035cc745c8eb162a8487a
-size 176736
+oid sha256:10555b7baa5958700f0ce4599e85fc4fc18b9c92afbbacfa64f04b630f42f583
+size 176816
diff --git a/packages/ludic.nav/native.ludic b/packages/ludic.nav/native.ludic
index 0d897d54..71d02ce1 100644
--- a/packages/ludic.nav/native.ludic
+++ b/packages/ludic.nav/native.ludic
@@ -13,3 +13,5 @@ extern function nvc_path(h: pointer, f: int, sx: float, sy: float, sz: float, ex
 extern function nvc_partial(h: pointer) -> int = "nav_partial"
 extern function nvc_raycast(h: pointer, f: int, sx: float, sy: float, sz: float, ex: float, ez: float) -> int = "nav_raycast"
 extern function nvc_random_near(h: pointer, f: int, x: float, y: float, z: float, r: float, seed: int, out: pointer) -> int = "nav_random_near"
+extern function nvc_stage(size: int) -> pointer = "nav_stage"
+extern function nvc_load_staged(buf: pointer, size: int) -> pointer = "nav_load_staged"
diff --git a/packages/ludic.nav/native/shim/nav_shim.cpp b/packages/ludic.nav/native/shim/nav_shim.cpp
index f31f049f..4d5b485f 100644
--- a/packages/ludic.nav/native/shim/nav_shim.cpp
+++ b/packages/ludic.nav/native/shim/nav_shim.cpp
@@ -7,6 +7,7 @@
 #include <DetourNavMeshQuery.h>
 #include <DetourCommon.h>
 #include <cstring>
+#include <cstdlib>
 #include <cmath>
 #include <vector>
 
diff --git a/packages/ludic.nav/native/shim/nav_tiles.inl b/packages/ludic.nav/native/shim/nav_tiles.inl
index 0b1b8ec4..347f7c55 100644
--- a/packages/ludic.nav/native/shim/nav_tiles.inl
+++ b/packages/ludic.nav/native/shim/nav_tiles.inl
@@ -100,3 +100,12 @@ NAV_SHIM void *nav_load(const unsigned char *buf, int size) {
   }
   return nav_open(mesh);
 }
+
+// a file read straight into the shim's own memory rather than a Ludic slice (which is never given
+// back): nav_stage hands out the room, nav_load_staged parses it and frees it, whatever the outcome
+NAV_SHIM unsigned char *nav_stage(int size) { return size > 0 ? static_cast<unsigned char *>(malloc(size)) : nullptr; }
+NAV_SHIM void *nav_load_staged(unsigned char *buf, int size) {
+  void *h = buf ? nav_load(buf, size) : nullptr;
+  free(buf);
+  return h;
+}
diff --git a/packages/ludic.npc/README.md b/packages/ludic.npc/README.md
index 31daab20..42263c87 100644
--- a/packages/ludic.npc/README.md
+++ b/packages/ludic.npc/README.md
@@ -87,10 +87,18 @@ export port NpcWorld {       # every member has a default: a flat dry field at n
   next_id: fn() -> int, body_of: fn(int) -> int      # an id across machines; a look seed's body
   taken: fn(string) -> bool                          # a name the place keeps
   born / gone: fn(NpcPerson) -> void                 # draw it, stop drawing it
+  way: fn(NpcPerson, x, z) -> bool, way_x, way_z      # the next corner of its way toward (x, z)
 }
 export port NpcTalk { say: fn(NpcPerson, int) -> string, greeting: fn(NpcPerson) -> string }
 ```
 
+**A person walks by the world's way where the world has one.** `way` is asked for the next corner
+toward where it is going - every half second, on reaching the corner, and at once for a new target -
+and the person walks corner to corner, but begins its errand only at the target itself. With no
+answer (the default) it walks straight and steps round what is in the way, as before; the step
+round and the twenty seconds' give-up stay as the fallback. Maroon Lake binds `way` to its navmesh
+by a person's taste.
+
 ## API
 
 | | |
diff --git a/packages/ludic.npc/defs.ludic b/packages/ludic.npc/defs.ludic
index 905fee0b..18e3121a 100644
--- a/packages/ludic.npc/defs.ludic
+++ b/packages/ludic.npc/defs.ludic
@@ -47,6 +47,11 @@ export property NpcPerson {
   via_on: bool = false         # a step round whatever is in the way
   vx: float = 0.0
   vz: float = 0.0
+  wx: float = 0.0              # the corner of its way it walks to now (NpcWorld.way)
+  wz: float = 0.0
+  wtx: float = 0.0             # the target that corner was asked for: a new target asks again
+  wtz: float = 0.0
+  way_t: float = 0.0           # seconds until it asks the way again
   detours: int = 0
   fails: int = 0
   stall: float = 0.0           # seconds walking without moving
diff --git a/packages/ludic.npc/index.ludic b/packages/ludic.npc/index.ludic
index ee478ac6..4cb6a00c 100644
--- a/packages/ludic.npc/index.ludic
+++ b/packages/ludic.npc/index.ludic
@@ -10,6 +10,7 @@ import "ground.ludic"
 import "spots.ludic"
 import "routine.ludic"
 import "walk.ludic"
+import "way.ludic"
 import "act.ludic"
 import "names.ludic"
 import "census.ludic"
diff --git a/packages/ludic.npc/port.ludic b/packages/ludic.npc/port.ludic
index 3448ec87..908588a4 100644
--- a/packages/ludic.npc/port.ludic
+++ b/packages/ludic.npc/port.ludic
@@ -25,6 +25,11 @@ export port NpcWorld {
   taken: fn(string) -> bool = fn nw_free                   # a name the place already uses
   born: fn(NpcPerson) -> void = fn nw_nothing              # a new one (or a slot reused): draw it
   gone: fn(NpcPerson) -> void = fn nw_nothing              # left: stop drawing it
+  # (p, x, z): the next corner of this person's way toward (x, z) into way_x / _z; false, the
+  # straight line with its steps round (a navmesh's path by a person's taste, in Maroon Lake)
+  way: fn(NpcPerson, float, float) -> bool = fn nw_no_way
+  way_x: fn() -> float = fn nw_asked_x
+  way_z: fn() -> float = fn nw_asked_z
 }
 
 # what the story says through them: the words of a line whose `fill` is set ("" when it has nothing
@@ -76,3 +81,4 @@ export function npc_near(npc_st: mut NpcState, x: float, z: float) -> float {
 }
 
 export function npc_near_i(npc_st: NpcState) -> int { return npc_st.np_near_i }
+function nw_no_way(p: NpcPerson, x: float, z: float) -> bool { return false }
diff --git a/packages/ludic.npc/tests/way_test.ludic b/packages/ludic.npc/tests/way_test.ludic
new file mode 100644
index 00000000..22b726b4
--- /dev/null
+++ b/packages/ludic.npc/tests/way_test.ludic
@@ -0,0 +1,82 @@
+# way_test.ludic - a person walks by the world's way where the world has one: round a wall the
+# straight line runs into, by the corners NpcWorld.way gives, and arrives only where it was going -
+# never at a corner
+import "ludic.npc"
+import "ludic.base"
+import "fake"
+program NpcWayTest {
+  numbers float
+  bind NpcWorld {
+    ground: fn fk_ground
+    water: fn fk_water
+    allowed: fn fk_allowed
+    push: fn fk_push
+    pushed_x: fn fk_pushed_x
+    pushed_z: fn fk_pushed_z
+    clear: fn fk_clear
+    hour: fn fk_hour_now
+    day: fn fk_day_now
+    players: fn fk_players
+    player_on: fn fk_player_on
+    player_x: fn fk_x
+    player_z: fn fk_z
+    want: fn fk_wanted
+    extra: fn fk_extra_kind
+    taken: fn fk_taken
+    born: fn fk_on_born
+    gone: fn fk_on_gone
+    way: fn wt_way
+    way_x: fn wt_x
+    way_z: fn wt_z
+  }
+  bind NpcTalk { say: fn tk_say, greeting: fn tk_greeting }
+
+  def NpcActs sit { }
+  def NpcActs fish { turns: false }
+  def NpcKinds from "kinds.lres"
+  def NpcNames from "names.lres"
+  def NpcLines from "lines.lres"
+
+  function tk_say(p: NpcPerson, line: int) -> string { return "" }
+  function tk_greeting(p: NpcPerson) -> string { return "" }
+  function tk_start(npc_st: mut NpcState, p: NpcPerson) -> void { npc_start_near(npc_st, p, 0.0, 0.0, 0.0, 10.0) }
+
+  state WayTestState {
+    wx: float = 0.0
+    wz: float = 0.0
+    asked: int = 0
+  }
+  # a wall across x = 20 for |z| < 15 (a straight walk to (38, -25) meets it): the way goes round its
+  # north end, then on to the target - which is clear of where the fake place forbids stopping
+  function wt_way(way_test_st: mut WayTestState, p: NpcPerson, x: float, z: float) -> bool {
+    way_test_st.asked += 1
+    way_test_st.wx = x
+    way_test_st.wz = z
+    if p.x < 19.0 and p.z < 16.0 {
+      way_test_st.wx = 20.0
+      way_test_st.wz = 17.0
+    }
+    return true
+  }
+  function wt_x(way_test_st: WayTestState) -> float { return way_test_st.wx }
+  function wt_z(way_test_st: WayTestState) -> float { return way_test_st.wz }
+
+  test "it walks round the wall by the corners it is given and begins only where it was going" (npc_st: mut NpcState, npc_tests_fake_st: mut NpcTestsFakeState, way_test_st: WayTestState) {
+    fk_setup(npc_st, npc_tests_fake_st)
+    npc_tests_fake_st.fk_want = 1
+    let p = npc_spawn(npc_st, NPCK_HIKER)
+    npc_set_at(p, 0.0, 0.0)
+    npc_go(npc_st, p, 38.0, -25.0, NPCA_SIT, 30.0)
+    var north = -100.0
+    var k = 0
+    while p.act == NPCA_WALK and k < 2000 {
+      npc_tick(npc_st, 0.05)
+      if p.x > 19.0 and p.x < 21.0 { north = Math.max(north, p.z) }
+      k += 1
+    }
+    expect(north > 14.0)
+    expect_eq(p.act, NPCA_SIT)
+    expect(npc_d(p.x, p.z, 38.0, -25.0) < 1.3)
+    expect(way_test_st.asked > 5)
+  }
+}
diff --git a/packages/ludic.npc/walk.ludic b/packages/ludic.npc/walk.ludic
index 230a7797..90758386 100644
--- a/packages/ludic.npc/walk.ludic
+++ b/packages/ludic.npc/walk.ludic
@@ -1,6 +1,6 @@
-# walk.ludic - walking to the target: turn toward it, step, slid round a trunk or a tent, never into
-# the water and never up a scramble - step round it instead - and give up on a target that gets no
-# closer for twenty seconds
+# walk.ludic - walking to the target by the world's way where it has one (way.ludic): turn toward the
+# next corner, step, slid round a trunk or a tent, never into the water and never up a scramble - step
+# round it instead - and give up on a target that gets no closer for twenty seconds
 const NP_BODY_R: float = 0.35      # a person's width, for the still things
 
 export function npc_walk(npc_st: mut NpcState, p: NpcPerson, dt: float) -> void {
@@ -10,12 +10,17 @@ export function npc_walk(npc_st: mut NpcState, p: NpcPerson, dt: float) -> void
     gx = p.vx
     gz = p.vz
   }
-  let dx = gx - p.x
-  let dz = gz - p.z
-  if Math.sqrt(dx * dx + dz * dz) < 1.2 {
+  if npc_d(p.x, p.z, gx, gz) < 1.2 {
     np_arrive(npc_st, p)
     return
   }
+  if not p.via_on {
+    np_way(p, dt)
+    gx = p.wx
+    gz = p.wz
+  }
+  let dx = gx - p.x
+  let dz = gz - p.z
   let dg = npc_d(p.x, p.z, p.tx, p.tz)
   if dg < p.best - 1.0 {
     p.best = dg
@@ -79,28 +84,3 @@ function np_arrive(npc_st: mut NpcState, p: NpcPerson) -> void {
   p.stall = 0.0
   if p.act != NPCA_WALK { np_fact(npc_st, NPC_F_ARRIVED, p, -1) }
 }
-
-function np_detour(p: NpcPerson, want: float) -> bool {
-  for k in 0 .. 8 {
-    let ang = want + float((k / 2 + 1) * (1 - 2 * (k % 2))) * 0.6
-    let x = p.x - Math.sin(ang) * 6.0
-    let z = p.z - Math.cos(ang) * 6.0
-    if npc_line_ok(p.x, p.z, x, z) {
-      p.via_on = true
-      p.vx = x
-      p.vz = z
-      p.yaw = ang
-      return true
-    }
-  }
-  return false
-}
-
-function np_stuck(npc_st: mut NpcState, p: NpcPerson) -> void {
-  p.fails += 1
-  p.via_on = false
-  if p.fails >= 3 {
-    p.fails = 0
-    npc_wander(npc_st, p)
-  } else { npc_plan(npc_st, p) }
-}
diff --git a/packages/ludic.npc/way.ludic b/packages/ludic.npc/way.ludic
new file mode 100644
index 00000000..1108897f
--- /dev/null
+++ b/packages/ludic.npc/way.ludic
@@ -0,0 +1,45 @@
+# way.ludic - where a person walks when the straight line will not do: the world's way (NpcWorld.way,
+# a navmesh by a person's taste in Maroon Lake), and without one a step round what is in the way,
+# and giving the target up after three tries
+
+# the next corner toward the target, asked again every half second, on reaching it, or for a new target
+const NP_WAY_EVERY: float = 0.5
+function np_way(p: NpcPerson, dt: float) -> void {
+  p.way_t = p.way_t - dt
+  let fresh = p.wtx != p.tx or p.wtz != p.tz
+  if p.way_t > 0.0 and not fresh and npc_d(p.x, p.z, p.wx, p.wz) >= 1.0 { return }
+  p.way_t = NP_WAY_EVERY
+  p.wtx = p.tx
+  p.wtz = p.tz
+  p.wx = p.tx
+  p.wz = p.tz
+  if NpcWorld.way(p, p.tx, p.tz) {
+    p.wx = NpcWorld.way_x()
+    p.wz = NpcWorld.way_z()
+  }
+}
+
+function np_detour(p: NpcPerson, want: float) -> bool {
+  for k in 0 .. 8 {
+    let ang = want + float((k / 2 + 1) * (1 - 2 * (k % 2))) * 0.6
+    let x = p.x - Math.sin(ang) * 6.0
+    let z = p.z - Math.cos(ang) * 6.0
+    if npc_line_ok(p.x, p.z, x, z) {
+      p.via_on = true
+      p.vx = x
+      p.vz = z
+      p.yaw = ang
+      return true
+    }
+  }
+  return false
+}
+
+function np_stuck(npc_st: mut NpcState, p: NpcPerson) -> void {
+  p.fails += 1
+  p.via_on = false
+  if p.fails >= 3 {
+    p.fails = 0
+    npc_wander(npc_st, p)
+  } else { npc_plan(npc_st, p) }
+}