diff --git a/pkg/arvo/sys/hoon.hoon b/pkg/arvo/sys/hoon.hoon
index 9b809933b..0e2f79efa 100644
--- a/pkg/arvo/sys/hoon.hoon
+++ b/pkg/arvo/sys/hoon.hoon
@@ -3810,6 +3810,7 @@
   --
 ::
 ++  ob
+  ~%  %ob  +  ~
   |%
   ::  +fein: conceal structure, v3.
   ::
@@ -3817,6 +3818,7 @@
   ::    trivial to tell which planet a star has spawned under.
   ::
   ++  fein
+    ~/  %fein
     |=  pyn/@  ^-  @
     ?:  &((gte pyn 0x1.0000) (lte pyn 0xffff.ffff))
       (add 0x1.0000 (feis (sub pyn 0x1.0000)))
@@ -3832,6 +3834,7 @@
   ::    Restores obfuscated values that have been enciphered with +fein.
   ::
   ++  fynd
+    ~/  %fynd
     |=  cry/@  ^-  @
     ?:  &((gte cry 0x1.0000) (lte cry 0xffff.ffff))
       (add 0x1.0000 (tail (sub cry 0x1.0000)))
@@ -3848,6 +3851,7 @@
   ::    See: Black & Rogaway (2002), Ciphers for arbitrary finite domains.
   ::
   ++  feis
+    ~/  %feis
     |=  m=@
     ^-  @
     (fee 4 0xffff 0x1.0000 (mul 0xffff 0x1.0000) eff m)
@@ -3855,6 +3859,7 @@
   ::  +tail: reverse +feis.
   ::
   ++  tail
+    ~/  %tail
     |=  m=@
     ^-  @
     (feen 4 0xffff 0x1.0000 (mul 0xffff 0x1.0000) eff m)
@@ -3871,6 +3876,7 @@
   ::    m:    an input value in the domain [0, k - 1]
   ::
   ++  fee
+    ~/  %fee
     |=  [r=@ a=@ b=@ k=@ prf=$-([j=@ r=@] @) m=@]
     ^-  @
     =/  c  (fe r a b prf m)
@@ -3884,6 +3890,7 @@
   ::    +fee.
   ::
   ++  feen
+    ~/  %feen
     |=  [r=@ a=@ b=@ k=@ prf=$-([j=@ r=@] @) m=@]
     ^-  @
     =/  c  (fen r a b prf m)
@@ -3899,6 +3906,7 @@
   ::    to support some legacy behaviour.  See urbit/arvo#1105.
   ::
   ++  fe
+    ~/  %fe
     |=  [r=@ a=@ b=@ prf=$-([j=@ r=@] @) m=@]
     =/  j  1
     =/  ell  (mod m a)
@@ -3937,6 +3945,7 @@
   ::    to support some legacy behaviour.  See urbit/arvo#1105.
   ::
   ++  fen
+    ~/  %fen
     |=  [r=@ a=@ b=@ prf=$-([j=@ r=@] @) m=@]
     =/  j  r
     ::
@@ -3985,6 +3994,7 @@
   ::  +eff: a murmur3-based pseudorandom function.  'F' in B&R (2002).
   ::
   ++  eff
+    ~/  %eff
     |=  [j=@ r=@]
     ^-  @
     (muk (snag j raku) 2 r)
diff --git a/pkg/urbit/include/jets/w.h b/pkg/urbit/include/jets/w.h
index 439c0be82..33c1610ce 100644
--- a/pkg/urbit/include/jets/w.h
+++ b/pkg/urbit/include/jets/w.h
@@ -76,6 +76,8 @@
     u3_noun u3wcp_tos(u3_noun);
     u3_noun u3wcp_tod(u3_noun);
 
+    u3_noun u3wc_ob_eff(u3_noun);
+
   /** Tier 4.
   **/
     u3_noun u3wdb_bif(u3_noun);
diff --git a/pkg/urbit/jets/c/ob.c b/pkg/urbit/jets/c/ob.c
new file mode 100644
index 000000000..539340616
--- /dev/null
+++ b/pkg/urbit/jets/c/ob.c
@@ -0,0 +1,48 @@
+/* j/3/ob.c
+**
+*/
+#include "all.h"
+
+u3_noun
+u3qc_ob_eff(u3_atom j, u3_atom r)
+{
+  c3_d found = 0;
+  switch (j) {
+    case 0:
+      found = 0xb76d5eed;
+      break;
+    case 1:
+      found = 0xee281300;
+      break;
+    case 2:
+      found = 0x85bcae01;
+      break;
+    case 3:
+      found = 0x4b387af7;
+      break;
+    default:
+      // the internal snag would have failed.
+      return u3m_bail(c3__exit);
+  }
+
+  return u3qc_muk(u3i_chubs(1, &found), 2, r);
+}
+
+u3_noun
+u3wc_ob_eff(u3_noun cor)
+{
+  u3_noun j, r;
+
+  if ( (c3n == u3r_mean(cor, u3x_sam_2, &j,
+                             u3x_sam_3, &r, 0)) ||
+       (c3n == u3ud(j)) ||
+       (c3n == u3ud(r)) )
+  {
+    fprintf(stderr, "u3wc_ob_eff failed to unpack\r\n");
+    return u3m_bail(c3__exit);
+  }
+  else {
+    return u3qc_ob_eff(j, r);
+  }
+}
+
diff --git a/pkg/urbit/jets/e/slaw.c b/pkg/urbit/jets/e/slaw.c
index f27436ccd..52cdfe690 100644
--- a/pkg/urbit/jets/e/slaw.c
+++ b/pkg/urbit/jets/e/slaw.c
@@ -49,6 +49,18 @@
     return u3nc(0, total);
   }
 
+  // parsing @p:
+  //
+  // +slaw calls +fed:ag directly. +fed:ag:
+  //
+  // - parses the text first into a number.
+  // - runs fynd:ob, which is the scrambler restore structure. And +fynd is
+  //   unjetted.
+  //
+  // The actual +po stuff, like +ins:po, is jetted but it's jetted such that it
+  // pulls the tables out of the sample, so we can't just reuse it from other
+  // jets.
+
   u3_noun
   _parse_tas(u3_noun txt) {
     // For any symbol which matches, txt will return itself as a
diff --git a/pkg/urbit/jets/tree.c b/pkg/urbit/jets/tree.c
index 75b8fc0e8..d3a3cac03 100644
--- a/pkg/urbit/jets/tree.c
+++ b/pkg/urbit/jets/tree.c
@@ -923,6 +923,14 @@ static c3_c* _141_tri__cofl_ha[] = {
   0
 };
 
+
+static u3j_harm _141_tri__ob_eff_a[] = {{".2", u3wc_ob_eff}, {}};
+static u3j_core _141_tri__ob_d[] =
+  { { "eff", 7, _141_tri__ob_eff_a, 0, 0 },
+    {}
+  };
+
+
   static u3j_harm _141_tri__rd_add_a[] = {{".2", u3wer_add}, {}};
   static c3_c* _141_tri__rd_add_ha[] = {
     "90dfaaadb2878d6d89a808ce4199e5bb239fa981e1c2edf24dc54aa3fcab55a5",
@@ -1270,6 +1278,7 @@ static c3_c* _141_tri_shal_ha[] = {
 
 static u3j_core _141_tri_d[] =
 { { "qua",  3, 0, _141_qua_d, _141_qua_ha, _141_qua_ho },
+  { "ob",   3, 0, _141_tri__ob_d, 0 },
   { "cofl", 7, 0, _141_tri__cofl_d, _141_tri__cofl_ha },
   { "rd",   7, 0, _141_tri__rd_d, _141_tri__rd_ha },
   { "rs",   7, 0, _141_tri__rs_d, _141_tri__rs_ha },
@@ -1282,6 +1291,7 @@ static u3j_core _141_tri_d[] =
   { "shay", 7, _141_tri_shay_a, 0, _141_tri_shay_ha },
   { "shas", 7, _141_tri_shas_a, 0, _141_tri_shas_ha },
   { "shal", 7, _141_tri_shal_a, 0, _141_tri_shal_ha },
+
   {}
 };
 static c3_c* _141_tri_ha[] = {