diff --git a/compiler/semantic/ztests/const-from-err.yaml b/compiler/semantic/ztests/const-from-err.yaml
index d930eb2a18..85d596c09d 100644
--- a/compiler/semantic/ztests/const-from-err.yaml
+++ b/compiler/semantic/ztests/const-from-err.yaml
@@ -3,6 +3,12 @@ spq: |
   values x
 
 error: |
+  file does not exist at line 1, column 41:
+  const x = [values {x:1},2 | put y[(from noa.json | bar+1)]:=1]
+                                          ~~~~~~~~
   cannot read data in constant expression at line 1, column 41:
   const x = [values {x:1},2 | put y[(from noa.json | bar+1)]:=1]
                                           ~~~~~~~~
+  no such field "bar" at line 1, column 52:
+  const x = [values {x:1},2 | put y[(from noa.json | bar+1)]:=1]
+                                                     ~~~
diff --git a/pkg/storage/internal.go b/pkg/storage/internal.go
new file mode 100644
index 0000000000..2f8bfcdf5a
--- /dev/null
+++ b/pkg/storage/internal.go
@@ -0,0 +1,60 @@
+package storage
+
+import (
+	"context"
+	"io"
+	"io/fs"
+)
+
+type InternalEngine struct {
+	files map[string]io.Reader
+}
+
+func NewInternalEngine() *InternalEngine {
+	return &InternalEngine{map[string]io.Reader{}}
+}
+
+func (i *InternalEngine) AddReader(uri string, r io.Reader) {
+	i.files[uri] = r
+}
+
+func (i *InternalEngine) Get(_ context.Context, u *URI) (Reader, error) {
+	v, ok := i.files[u.String()]
+	if !ok {
+		return nil, fs.ErrNotExist
+	}
+	return &notSupportedReaderAt{io.NopCloser(v)}, nil
+}
+
+func (*InternalEngine) Put(context.Context, *URI) (io.WriteCloser, error) {
+	return nil, ErrNotSupported
+}
+
+func (*InternalEngine) PutIfNotExists(context.Context, *URI, []byte) error {
+	return ErrNotSupported
+
+}
+func (*InternalEngine) Delete(context.Context, *URI) error {
+	return ErrNotSupported
+}
+
+func (*InternalEngine) DeleteByPrefix(context.Context, *URI) error {
+	return ErrNotSupported
+}
+
+func (i *InternalEngine) Exists(_ context.Context, u *URI) (bool, error) {
+	_, ok := i.files[u.String()]
+	return ok, nil
+}
+
+func (i *InternalEngine) Size(_ context.Context, u *URI) (int64, error) {
+	_, ok := i.files[u.String()]
+	if !ok {
+		return 0, fs.ErrNotExist
+	}
+	return 0, nil
+}
+
+func (*InternalEngine) List(context.Context, *URI) ([]Info, error) {
+	return nil, ErrNotSupported
+}
diff --git a/sio/fjsonio/ztests/parser-error.yaml b/sio/fjsonio/ztests/parser-error.yaml
index 17bab10a16..e29e4db399 100644
--- a/sio/fjsonio/ztests/parser-error.yaml
+++ b/sio/fjsonio/ztests/parser-error.yaml
@@ -9,7 +9,7 @@ input: |
   {"x":1}
 
 error: |
-  line 2: invalid JSON value
+  stdio:stdin: line 2: invalid JSON value
 
 ---
 
diff --git a/ztest/ztest.go b/ztest/ztest.go
index f09fb5a5bd..0fb63cd85d 100644
--- a/ztest/ztest.go
+++ b/ztest/ztest.go
@@ -137,6 +137,7 @@ import (
 	"github.com/brimdata/super/cli/outputflags"
 	"github.com/brimdata/super/compiler"
 	"github.com/brimdata/super/compiler/parser"
+	"github.com/brimdata/super/pkg/storage"
 	"github.com/brimdata/super/runtime"
 	"github.com/brimdata/super/runtime/exec"
 	"github.com/brimdata/super/sio"
@@ -488,30 +489,33 @@ func runInternal(ctx context.Context, query string, input *string, outputFlags,
 	if err != nil {
 		return "", err
 	}
-	sctx := super.NewContext()
-	var readers []sio.Reader
-	if input != nil {
-		zrc, err := newInputReader(sctx, *input, inputFlags)
-		if err != nil {
-			return "", err
-		}
-		defer zrc.Close()
-		readers = []sio.Reader{zrc}
-	}
 	var fs flag.FlagSet
+	var inflags inputflags.Flags
 	var outflags outputflags.Flags
+	inflags.SetFlags(&fs, true)
 	outflags.SetFlags(&fs)
-	if err := fs.Parse(outputFlags); err != nil {
+	if err := fs.Parse(append(inputFlags, outputFlags...)); err != nil {
+		return "", err
+	}
+	if err := inflags.Init(); err != nil {
 		return "", err
 	}
 	if err := outflags.Init(); err != nil {
 		return "", err
 	}
-	env := exec.NewEnvironment(nil, nil)
+	eng := storage.NewInternalEngine()
+	if input != nil {
+		ast.PrependFileScan([]string{"stdio:stdin"})
+		eng.AddReader("stdio:stdin", strings.NewReader(*input))
+	}
+	env := exec.NewEnvironment(eng, nil)
+	env.Dynamic = inflags.Dynamic
+	env.ReaderOpts = inflags.ReaderOpts
+	env.SampleSize = inflags.SampleSize
 	if vector {
 		env.Runtime = exec.RuntimeVAM
 	}
-	q, err := runtime.CompileQuery(ctx, sctx, compiler.NewCompilerWithEnv(env), ast, readers)
+	q, err := runtime.CompileQuery(ctx, super.NewContext(), compiler.NewCompilerWithEnv(env), ast, nil)
 	if err != nil {
 		return "", err
 	}
@@ -527,17 +531,3 @@ func runInternal(ctx context.Context, query string, input *string, outputFlags,
 	}
 	return outbuf.String(), err
 }
-
-func newInputReader(sctx *super.Context, input string, flags []string) (sio.ReadCloser, error) {
-	var inflags inputflags.Flags
-	var fs flag.FlagSet
-	inflags.SetFlags(&fs, true)
-	if err := fs.Parse(flags); err != nil {
-		return nil, err
-	}
-	r, err := anyio.GzipReader(strings.NewReader(input))
-	if err != nil {
-		return nil, err
-	}
-	return anyio.NewReader(sctx, r, inflags.ReaderOpts)
-}