Answer prose round 1: readName and readField say one idea a sentence and name what each pick and read is, and the test's message names whose b it checks

pick.go

@@ -141,11 +141,12 @@ func (sc renderScope) frameOf(scope *nameScope) *pickFrame {
 	return nil
 }
 
-// readName reads a from its name's pick in the frame rendering the name's scope. A read entering
-// another category takes the frames of the name scopes there from the pick's memo (enter), and
-// renderFrame finds them and opens none, so every read of the pick reads one pick of each name
-// bound there: {a.street} and {a.postal-code} in data/sv_SE/address.json read one pick of the
-// name l that data/geo/SE/address.json binds.
+// readName reads the arm a from the pick of its name, held in the frame of the name's scope.
+// When the pick renders another category, enter takes that category's frames from the pick's
+// memo, and renderFrame finds them and opens no new one.
+// So every read through one pick sees one pick of each name the other category binds:
+// {a.street} and {a.postal-code} in data/sv_SE/address.json read one pick of the name l
+// that data/geo/SE/address.json binds.
 func readName(s *drawstate.State, sc renderScope, a arm) readValue {
 	f := sc.frameOf(a.named.scope)
 	if f == nil {

pick_test.go

@@ -340,7 +340,7 @@ func TestAFreshReadInsideANamedPickSharesNoValueWithIt(t *testing.T) {
 	for i := 0; i < 100; i++ {
 		got := mustRender(t, f, src)
 		if m := want.FindStringSubmatch(got); m == nil || m[1] != m[2] {
-			t.Fatalf("draw %d = %q, want p.a's c drawn afresh and its b read from p's pick", i, got)
+			t.Fatalf("draw %d = %q, want c's b from x, y or z, and p.a's b equal to {p.a.b}", i, got)
 		}
 	}
 }

render.go

@@ -142,11 +142,12 @@ func expand(s *drawstate.State, t *template, sc renderScope) string {
 	return b.String()
 }
 
-// readField renders one arm of a token. A read of a name, or of a level a read of the name
-// rendering addresses, is kept in that name's pick; every other read draws afresh, so {word}
-// {word} draws twice and {p.a} {p.b} reads two draws of p. A fresh read leaves the pick: a read
-// below it would key the pick's memo by sc.pickKey, the level the pick rendered, so it and the
-// pick would read one value for two nodes.
+// readField renders one arm of a token. A read is kept in a name's pick when it reads the name, or
+// a level that a read of the name being rendered addresses; every other read draws afresh, so
+// {word} {word} draws twice and {p.a} {p.b} reads two draws of p.
+// A fresh read clears sc.pick. Kept, a read nested in the fresh one would key the pick's memo by
+// sc.pickKey, the path from the name to what the pick renders, and share a value with a different
+// node at that path.
 func readField(s *drawstate.State, t *template, sc renderScope, a arm) readValue {
 	switch {
 	case a.kind == namedRead: