Answer architecture round 1: the read-once check back at link over uses from the compiled arms, every link step taking its inputs as arguments in link.go, a record column holding its name and datatype, and items 104 to 106 dropped from the plan with the decisions citing them reworded

name_test.go

@@ -188,6 +188,10 @@ func TestNameErrors(t *testing.T) {
 			`no field "word"; a binding names a field, or a reference`},
 		{"read once through a field", map[string]string{"card": `{"format":"{place as p}{p.x}","place":{"format":"{x}","x":["a","b"]}}`},
 			`name "p" is read once, so it keeps no pick for another read; write {place.x} where it is read`},
+		{"read once through a path that does not resolve", map[string]string{"word": `{"format":"{w}","w":["a","b"]}`, "card": `"{/word as a}{a.zz}"`},
+			`no field "zz"`},
+		{"read once through a field path that does not resolve", map[string]string{"card": `{"format":"{place as p}{p.zz}","place":{"format":"{x}","x":["a","b"]}}`},
+			`no field "zz"`},
 		{"read by nothing", map[string]string{"word": `["a","b"]`, "card": `"{/word as w}"`},
 			`nothing reads name "w"`},
 		{"read in a repeat", map[string]string{"nm.json": `{"format":"{first}","rows":"nm.tsv"}`, "nm.tsv": "first\tlast\nAda\tByron\nBo\tEk\n", "person": `{"format":"{first} {last}","first":"{/nm.first}","last":"{/nm.last}"}`, "card": `{"format":"{/person as p}{each}","each":{"format":"{p.first}","repeat":2}}`},