diff --git a/packages/compiler/src/ir/fields.generated.ts b/packages/compiler/src/ir/fields.generated.ts
index e9f5efaa3..86c6a15e5 100644
--- a/packages/compiler/src/ir/fields.generated.ts
+++ b/packages/compiler/src/ir/fields.generated.ts
@@ -2069,3 +2069,252 @@ export function walkTypeFields(node: IrType, walker: IrFieldWalker, skipType: bo
     }
   }
 }
+
+/** A field ir.ts declares that this file does not read. */
+type FieldsNotRead<T, Read extends PropertyKey> = Exclude<keyof T, Read>;
+/** The string or object values a field read as a scalar can hold. */
+type ValuesNotRead<T> = Extract<NonNullable<T>, string | object>;
+/** Fails type checking unless `T` is never: run `pnpm generate:ir-fields`. */
+type Unread<T extends never> = T;
+
+/** Every walked object type's fields as ir.ts declared them when this file
+ * was generated. */
+export type IrFieldsCurrent = [
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "arrIntrinsic" }>, "kind" | "method" | "receiver" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "arrayGet" }>, "kind" | "arr" | "index" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "arrayHas" }>, "kind" | "arr" | "index" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "arrayLit" }>, "kind" | "elems" | "spreads" | "capacity" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "arrayLit" }>["capacity"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "arrayNewLen" }>, "kind" | "length" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "arrayState" }>, "kind" | "arr" | "index" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "assignExpr" }>, "kind" | "localId" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "awaitExpr" }>, "kind" | "value" | "type" | "adopt" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "awaitExpr" }>["adopt"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "awaitUnionExpr" }>, "kind" | "value" | "promiseTag" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "awaitUnionExpr" }>["promiseTag"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "bin" }>, "kind" | "op" | "left" | "right" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "boolLit" }>, "kind" | "value" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "boolLit" }>["value"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "bytesIntrinsic" }>, "kind" | "method" | "receiver" | "args" | "type" | "loc" | "invalidNaN">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "bytesIntrinsic" }>["invalidNaN"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "bytesNew" }>, "kind" | "source" | "from" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "bytesNew" }>["from"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "call" }>, "kind" | "callee" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "callValue" }>, "kind" | "callee" | "receiver" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "caughtCheck" }>, "kind" | "value" | "className" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "caughtNarrow" }>, "kind" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "caughtTest" }>, "kind" | "value" | "test" | "className" | "negated" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "caughtTest" }>["negated"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "caughtToDyn" }>, "kind" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "chainRecv" }>, "kind" | "id" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "classRef" }>, "kind" | "className" | "captures" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "closure" }>, "kind" | "fnName" | "captures" | "adapts" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "closure" }>["adapts"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "downcast" }>, "kind" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynArrLit" }>, "kind" | "elems" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrExpr, { kind: "dynCall" }>["spreads"]>, readonly unknown[]>[number]>, object>, "arg" | "what">>,
+  Unread<ValuesNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrExpr, { kind: "dynCall" }>["spreads"]>, readonly unknown[]>[number]>, object>["arg"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynCall" }>, "kind" | "callee" | "receiver" | "calleeName" | "calleeNameValue" | "args" | "spreads" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynCheck" }>, "kind" | "value" | "preserveRefs" | "adopt" | "exact" | "inferredSite" | "origin" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynCheck" }>["preserveRefs"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynCheck" }>["adopt"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynCheck" }>["exact"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynCheck" }>["origin"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynDestrCheck" }>, "kind" | "value" | "spelling" | "firstProp" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynFrom" }>, "kind" | "value" | "fnName" | "fnLength" | "liveRef" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynFrom" }>["fnLength"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynFrom" }>["liveRef"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynHasKey" }>, "kind" | "key" | "negated" | "value" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynHasKey" }>["negated"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynInvoke" }>, "kind" | "recv" | "method" | "calleeName" | "calleeNameValue" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynIterN" }>, "kind" | "value" | "count" | "notIterableMessage" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynIterN" }>["count"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynKeyGet" }>, "kind" | "key" | "optional" | "value" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynKeyGet" }>["optional"]>>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrExpr, { kind: "dynObjLit" }>["fields"]>, readonly unknown[]>[number]>, object>, "key" | "value">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynObjLit" }>, "kind" | "fields" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynScalarEq" }>, "kind" | "left" | "right" | "negated" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynScalarEq" }>["negated"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "dynTest" }>, "kind" | "test" | "bytesElem" | "negated" | "value" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "dynTest" }>["negated"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "ffiCall" }>, "kind" | "import" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "fieldAbsent" }>, "kind" | "unionId" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "fieldGet" }>, "kind" | "obj" | "className" | "field" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "fieldIncDec" }>, "kind" | "op" | "prefix" | "obj" | "className" | "field" | "fieldDyn" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "fieldIncDec" }>["prefix"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "fieldIncDec" }>["fieldDyn"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "genResume" }>, "kind" | "mode" | "gen" | "arg" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "incDec" }>, "kind" | "op" | "prefix" | "localId" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "incDec" }>["prefix"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "instanceOf" }>, "kind" | "value" | "className" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "instanceOfValue" }>, "kind" | "value" | "classValue" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "intrinsic" }>, "kind" | "name" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "jsonStringify" }>, "kind" | "value" | "indent" | "circular" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "jsonStringify" }>["circular"]>>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<IrExpr, { kind: "libCall" }>["assertOptions"]>, object>, "diff" | "skipPrototype">>,
+  Unread<ValuesNotRead<Extract<NonNullable<Extract<IrExpr, { kind: "libCall" }>["assertOptions"]>, object>["skipPrototype"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "libCall" }>, "kind" | "fn" | "args" | "type" | "loc" | "prototypeIdentityOnly" | "realTimer" | "assertOptions">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "libCall" }>["prototypeIdentityOnly"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "libCall" }>["realTimer"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "logical" }>, "kind" | "op" | "left" | "right" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "mapIntrinsic" }>, "kind" | "method" | "receiver" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrExpr, { kind: "mapNew" }>["seed"]>, readonly unknown[]>[number]>, object>, "key" | "value">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "mapNew" }>, "kind" | "seed" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "moduleNsRef" }>, "kind" | "moduleId" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "new" }>, "kind" | "className" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "newPromise" }>, "kind" | "executor" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "newValue" }>, "kind" | "callee" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "nullish" }>, "kind" | "left" | "right" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "numLit" }>, "kind" | "value" | "spelling" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "numLit" }>["value"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "optChain" }>, "kind" | "id" | "receiver" | "body" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "orDefault" }>, "kind" | "left" | "right" | "retag" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "promiseVoidWiden" }>, "kind" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "promiseWithResolvers" }>, "kind" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrExpr, { kind: "recordClone" }>["overrides"]>, readonly unknown[]>[number]>, object>, "name" | "value">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordClone" }>, "kind" | "source" | "overrides" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordGet" }>, "kind" | "obj" | "shapeId" | "field" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordHas" }>, "kind" | "obj" | "shapeId" | "field" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordKeyGet" }>, "kind" | "obj" | "shapeId" | "key" | "overflowOnly" | "missNaN" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "recordKeyGet" }>["overflowOnly"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "recordKeyGet" }>["missNaN"]>>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrExpr, { kind: "recordLit" }>["fields"]>, readonly unknown[]>[number]>, object>, "name" | "value" | "overflow">>,
+  Unread<ValuesNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrExpr, { kind: "recordLit" }>["fields"]>, readonly unknown[]>[number]>, object>["overflow"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordLit" }>, "kind" | "fields" | "nullProto" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "recordLit" }>["nullProto"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordNullProto" }>, "kind" | "obj" | "shapeId" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordOvfHas" }>, "kind" | "obj" | "shapeId" | "key" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "recordOvfKeys" }>, "kind" | "obj" | "shapeId" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "regexIntrinsic" }>, "kind" | "method" | "receiver" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "regexLit" }>, "kind" | "pattern" | "flags" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "selfRef" }>, "kind" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "seqExpr" }>, "kind" | "stmts" | "result" | "generatorDelegate" | "diverges" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "seqExpr" }>["generatorDelegate"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "seqExpr" }>["diverges"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "setIntrinsic" }>, "kind" | "method" | "receiver" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "setNew" }>, "kind" | "seed" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "strCmp" }>, "kind" | "op" | "left" | "right" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "strConcat" }>, "kind" | "left" | "right" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "strEq" }>, "kind" | "negated" | "left" | "right" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "strEq" }>["negated"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "strIntrinsic" }>, "kind" | "method" | "receiver" | "args" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "strLit" }>, "kind" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "templateStrings" }>, "kind" | "key" | "cooked" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "ternary" }>, "kind" | "cond" | "then" | "else_" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "toBool" }>, "kind" | "operand" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "toString" }>, "kind" | "operand" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unary" }>, "kind" | "op" | "operand" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionDisc" }>, "kind" | "unionId" | "field" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionEq" }>, "kind" | "unionId" | "negated" | "sameValue" | "left" | "right" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionEq" }>["negated"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionEq" }>["sameValue"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionFuncEq" }>, "kind" | "unionId" | "tag" | "union" | "func" | "negated" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionFuncEq" }>["tag"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionFuncEq" }>["negated"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionIsTag" }>, "kind" | "unionId" | "tag" | "negated" | "value" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionIsTag" }>["tag"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionIsTag" }>["negated"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionKeyGet" }>, "kind" | "unionId" | "key" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionNarrow" }>, "kind" | "unionId" | "tag" | "value" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionNarrow" }>["tag"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionRetype" }>, "kind" | "fromId" | "unionId" | "tags" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unionWrap" }>, "kind" | "unionId" | "tag" | "value" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "unionWrap" }>["tag"]>>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "unitLit" }>, "kind" | "unit" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "upcast" }>, "kind" | "value" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "varRef" }>, "kind" | "localId" | "type" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "virtualCall" }>, "kind" | "className" | "method" | "args" | "type" | "loc" | "targets">>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<IrExpr, { kind: "yieldExpr" }>["captureCompletion"]>, object>, "returnType">>,
+  Unread<FieldsNotRead<Extract<IrExpr, { kind: "yieldExpr" }>, "kind" | "value" | "awaited" | "delegated" | "captureCompletion" | "type" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "yieldExpr" }>["awaited"]>>,
+  Unread<ValuesNotRead<Extract<IrExpr, { kind: "yieldExpr" }>["delegated"]>>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "arrayDelete" }>, "kind" | "arr" | "index" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "arraySet" }>, "kind" | "arr" | "index" | "value" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "arraySetLength" }>, "kind" | "arr" | "length" | "loc" | "pop" | "reserve">>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "arraySetLength" }>["pop"]>>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "arraySetLength" }>["reserve"]>>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "arraySetUndefined" }>, "kind" | "arr" | "index" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "assign" }>, "kind" | "localId" | "value" | "initializes" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "assign" }>["initializes"]>>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "block" }>, "kind" | "body" | "labels" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "break" }>, "kind" | "label" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "bytesSet" }>, "kind" | "arr" | "index" | "value" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "continue" }>, "kind" | "label" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "doWhile" }>, "kind" | "body" | "cond" | "labels" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "exprStmt" }>, "kind" | "expr" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "fieldSet" }>, "kind" | "obj" | "className" | "field" | "value" | "sloppy" | "define" | "attributesChecked" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "fieldSet" }>["sloppy"]>>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "fieldSet" }>["define"]>>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "fieldSet" }>["attributesChecked"]>>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "for" }>, "kind" | "init" | "cond" | "update" | "body" | "labels" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "forOf" }>, "kind" | "localId" | "iterable" | "body" | "labels" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "if" }>, "kind" | "cond" | "then" | "else_" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "recordKeyDelete" }>, "kind" | "obj" | "shapeId" | "key" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "recordKeySet" }>, "kind" | "obj" | "shapeId" | "key" | "value" | "overflowOnly" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "recordKeySet" }>["overflowOnly"]>>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "recordSet" }>, "kind" | "obj" | "shapeId" | "field" | "value" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "rethrow" }>, "kind" | "localId" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "return" }>, "kind" | "value" | "awaited" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "return" }>["awaited"]>>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "runtimeFence" }>, "kind" | "code" | "message" | "loc">>,
+  Unread<FieldsNotRead<Extract<NonNullable<Extract<NonNullable<Extract<IrStmt, { kind: "switch" }>["cases"]>, readonly unknown[]>[number]>, object>, "test" | "body">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "switch" }>, "kind" | "disc" | "cases" | "labels" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "throw" }>, "kind" | "value" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "tryCatch" }>, "kind" | "tryBody" | "catchBody" | "catchLocalId" | "finallyBody" | "suppressFinallyErrors" | "dropFinallyErrors" | "loc">>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "tryCatch" }>["suppressFinallyErrors"]>>,
+  Unread<ValuesNotRead<Extract<IrStmt, { kind: "tryCatch" }>["dropFinallyErrors"]>>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "varDecl" }>, "kind" | "localId" | "init" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrStmt, { kind: "while" }>, "kind" | "cond" | "body" | "labels" | "loc">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "array" }>, "kind" | "elem" | "optionalElements">>,
+  Unread<ValuesNotRead<Extract<IrType, { kind: "array" }>["optionalElements"]>>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "bigint" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "bool" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "bytes" }>, "kind" | "elem">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "caught" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "child" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "childStream" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "childWriter" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "classval" }>, "kind" | "className">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "cryptoHash" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "cryptoHmac" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "date" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "dgramSocket" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "dir" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "dyn" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "f64" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "fileHandle" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "fsWatcher" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "func" }>, "kind" | "params" | "ret" | "rest" | "restAbi" | "argumentsAll">>,
+  Unread<ValuesNotRead<Extract<IrType, { kind: "func" }>["rest"]>>,
+  Unread<ValuesNotRead<Extract<IrType, { kind: "func" }>["argumentsAll"]>>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "generator" }>, "kind" | "async" | "yieldT" | "retT" | "nextT">>,
+  Unread<ValuesNotRead<Extract<IrType, { kind: "generator" }>["async"]>>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "http2Session" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "http2Stream" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "httpClientReq" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "httpReq" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "httpRes" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "jsval" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "map" }>, "kind" | "key" | "value">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "moduleNs" }>, "kind" | "moduleId">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "netServer" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "netSocket" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "nullT" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "object" }>, "kind" | "className">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "procStream" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "promise" }>, "kind" | "inner">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "record" }>, "kind" | "shapeId">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "regex" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "searchParams" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "secureCtx" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "set" }>, "kind" | "elem">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "spawnRes" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "stats" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "string" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "symbol" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "testCtx" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "undefinedT" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "union" }>, "kind" | "unionId">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "url" }>, "kind">>,
+  Unread<FieldsNotRead<Extract<IrType, { kind: "void" }>, "kind">>,
+];
diff --git a/scripts/generate-ir-fields.mjs b/scripts/generate-ir-fields.mjs
index 5b5ad011a..037cb615d 100644
--- a/scripts/generate-ir-fields.mjs
+++ b/scripts/generate-ir-fields.mjs
@@ -105,9 +105,23 @@ function irKind(type) {
 }
 
 let temp = 0;
-/** Lines that walk `expr` of `type`: strings to `walker.string`, IR nodes to
- * their walkers, arrays by element and other objects by field. */
-function walkLines(expr, type, indent, depth) {
+/** The fields each walked object type declares, for the type-level check at
+ * the end of the file: `typeExpr` names the object type, `fields` every
+ * field it had when the file was generated and `scalars` the fields that held
+ * no string and no object then. */
+const checks = [];
+/** Records `property list` of `object` (named `typeExpr`) for the check. */
+function noteFields(typeExpr, properties, scalarNames) {
+  checks.push({
+    typeExpr,
+    fields: properties.map((property) => property.name),
+    scalars: scalarNames,
+  });
+}
+/** Lines that walk `expr` of `type` (named `typeExpr` in the generated file):
+ * strings to `walker.string`, IR nodes to their walkers, arrays by element and
+ * other objects by field. */
+function walkLines(expr, type, typeExpr, indent, depth) {
   if (depth > 12) throw new Error(`field type nests too deep at ${expr}`);
   const parts = type.isUnion() ? type.types : [type];
   const present = parts.filter((part) => (part.flags & nullish) === 0);
@@ -127,19 +141,28 @@ function walkLines(expr, type, indent, depth) {
       if (objects.length !== 1) throw new Error(`several array types at ${expr}`);
       const item = `item${temp++}`;
       body.push(`for (const ${item} of ${expr}) {`);
-      body.push(...walkLines(item, checker.getTypeArguments(objects[0])[0], "  ", depth + 1));
+      const itemType = `Extract<NonNullable<${typeExpr}>, readonly unknown[]>[number]`;
+      body.push(
+        ...walkLines(item, checker.getTypeArguments(objects[0])[0], itemType, "  ", depth + 1),
+      );
       body.push("}");
     } else if (kinds.has(null) && objects.length === 1) {
-      for (const property of checker.getPropertiesOfType(objects[0])) {
+      const recordType = `Extract<NonNullable<${typeExpr}>, object>`;
+      const properties = checker.getPropertiesOfType(objects[0]);
+      const scalarNames = [];
+      for (const property of properties) {
         if (property.name === "loc") continue;
         const fieldType = checker.getTypeOfSymbol(property);
         const field = `${expr}.${property.name}`;
-        const lines = walkLines(field, fieldType, "", depth + 1);
+        const fieldTypeExpr = `${recordType}[${JSON.stringify(property.name)}]`;
+        const lines = walkLines(field, fieldType, fieldTypeExpr, "", depth + 1);
+        if (lines.length === 0) scalarNames.push(property.name);
         if (lines.length === 0) continue;
         if (property.name === "type")
           body.push("if (!skipType) {", ...lines.map((l) => `  ${l}`), "}");
         else body.push(...lines);
       }
+      noteFields(recordType, properties, scalarNames);
     } else throw new Error(`mixed object types at ${expr}: ${checker.typeToString(type)}`);
   }
   let lines = body;
@@ -193,20 +216,50 @@ for (const name of ["IrExpr", "IrStmt", "IrType"]) {
   }
   for (const [kind, member] of [...byKind].sort(([a], [b]) => (a < b ? -1 : a > b ? 1 : 0))) {
     lines.push(`    case ${JSON.stringify(kind)}: {`);
+    const memberType = `Extract<${name}, { kind: ${JSON.stringify(kind)} }>`;
+    const scalarNames = [];
     for (const property of member.getProperties()) {
       if (property.name === "loc") continue;
       const fieldType = checker.getTypeOfSymbol(property);
       const field = `node.${property.name}`;
-      const walk = walkLines(field, fieldType, "", 0);
+      const fieldTypeExpr = `${memberType}[${JSON.stringify(property.name)}]`;
+      const walk = walkLines(field, fieldType, fieldTypeExpr, "", 0);
+      if (walk.length === 0) scalarNames.push(property.name);
       if (walk.length === 0) continue;
       if (property.name === "type")
         lines.push("      if (!skipType) {", ...walk.map((l) => `        ${l}`), "      }");
       else lines.push(...walk.map((l) => `      ${l}`));
     }
     lines.push("      return;", "    }");
+    noteFields(memberType, member.getProperties(), scalarNames);
   }
   lines.push("  }", "}", "");
 }
+
+// Type checking fails below when ir.ts gives a walked object a field this
+// file does not know, or lets a field that held no string and no object hold
+// one before this file is regenerated.
+const quoted = (names) => names.map((name) => JSON.stringify(name)).join(" | ");
+lines.push(
+  "/** A field ir.ts declares that this file does not read. */",
+  "type FieldsNotRead<T, Read extends PropertyKey> = Exclude<keyof T, Read>;",
+  "/** The string or object values a field read as a scalar can hold. */",
+  "type ValuesNotRead<T> = Extract<NonNullable<T>, string | object>;",
+  "/** Fails type checking unless `T` is never: run `pnpm generate:ir-fields`. */",
+  "type Unread<T extends never> = T;",
+  "",
+  "/** Every walked object type's fields as ir.ts declared them when this file",
+  " * was generated. */",
+  "export type IrFieldsCurrent = [",
+);
+for (const { typeExpr, fields, scalars } of checks) {
+  lines.push(
+    `  Unread<FieldsNotRead<${typeExpr}, ${fields.length > 0 ? quoted(fields) : "never"}>>,`,
+  );
+  for (const scalarName of scalars)
+    lines.push(`  Unread<ValuesNotRead<${typeExpr}[${JSON.stringify(scalarName)}]>>,`);
+}
+lines.push("];", "");
 const text = lines.join("\n");
 
 if (process.argv.includes("--check")) {