refactor: propagate ctx into the four public constructors

CHANGELOG.md

@@ -62,6 +62,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `context.Context` as the first argument. `NewExecutableUnit` gains a leading
   `ctx` too. The Extism compiler's `WithContext` option and the FromHTTP
   loader's `GetReaderWithContext` helper are removed (now redundant).
+- **BREAKING**: `polyscript.New[E]`, `extism.FromExtismLoader`,
+  `risor.FromRisorLoader`, and `starlark.FromStarlarkLoader` now take a
+  `context.Context` as the first argument. Cancelling that ctx reaches the
+  loader's I/O and (where the parser supports it) the compile path.
 
 ### Deprecated
 - The twelve legacy top-level constructors (`FromRisorFile`,

deprecated.go

@@ -7,6 +7,7 @@
 package polyscript
 
 import (
+	"context"
 	"log/slog"
 
 	extismMachine "github.com/robbyt/go-polyscript/engines/extism"
@@ -35,7 +36,7 @@ func FromExtismFile(
 		return nil, err
 	}
 
-	return extismMachine.FromExtismLoader(l,
+	return extismMachine.FromExtismLoader(context.Background(), l,
 		extismMachine.WithLogHandler(logHandler),
 		extismMachine.WithEntryPoint(entryPoint),
 	)
@@ -57,7 +58,7 @@ func FromExtismFileWithData(
 		return nil, err
 	}
 
-	return extismMachine.FromExtismLoader(l,
+	return extismMachine.FromExtismLoader(context.Background(), l,
 		extismMachine.WithLogHandler(logHandler),
 		extismMachine.WithStaticData(staticData),
 		extismMachine.WithEntryPoint(entryPoint),
@@ -77,7 +78,7 @@ func FromExtismBytes(
 		return nil, err
 	}
 
-	return extismMachine.FromExtismLoader(l,
+	return extismMachine.FromExtismLoader(context.Background(), l,
 		extismMachine.WithLogHandler(logHandler),
 		extismMachine.WithEntryPoint(entryPoint),
 	)
@@ -99,7 +100,7 @@ func FromExtismBytesWithData(
 		return nil, err
 	}
 
-	return extismMachine.FromExtismLoader(l,
+	return extismMachine.FromExtismLoader(context.Background(), l,
 		extismMachine.WithLogHandler(logHandler),
 		extismMachine.WithStaticData(staticData),
 		extismMachine.WithEntryPoint(entryPoint),
@@ -118,7 +119,7 @@ func FromRisorFile(
 		return nil, err
 	}
 
-	return risorMachine.FromRisorLoader(l, risorMachine.WithLogHandler(logHandler))
+	return risorMachine.FromRisorLoader(context.Background(), l, risorMachine.WithLogHandler(logHandler))
 }
 
 // FromRisorFileWithData creates a Risor evaluator with both static and dynamic
@@ -135,7 +136,7 @@ func FromRisorFileWithData(
 		return nil, err
 	}
 
-	return risorMachine.FromRisorLoader(l,
+	return risorMachine.FromRisorLoader(context.Background(), l,
 		risorMachine.WithLogHandler(logHandler),
 		risorMachine.WithStaticData(staticData),
 	)
@@ -153,7 +154,7 @@ func FromRisorString(
 		return nil, err
 	}
 
-	return risorMachine.FromRisorLoader(l, risorMachine.WithLogHandler(logHandler))
+	return risorMachine.FromRisorLoader(context.Background(), l, risorMachine.WithLogHandler(logHandler))
 }
 
 // FromRisorStringWithData creates a Risor evaluator with both static and
@@ -170,7 +171,7 @@ func FromRisorStringWithData(
 		return nil, err
 	}
 
-	return risorMachine.FromRisorLoader(l,
+	return risorMachine.FromRisorLoader(context.Background(), l,
 		risorMachine.WithLogHandler(logHandler),
 		risorMachine.WithStaticData(staticData),
 	)
@@ -188,7 +189,7 @@ func FromStarlarkFile(
 		return nil, err
 	}
 
-	return starlarkMachine.FromStarlarkLoader(l, starlarkMachine.WithLogHandler(logHandler))
+	return starlarkMachine.FromStarlarkLoader(context.Background(), l, starlarkMachine.WithLogHandler(logHandler))
 }
 
 // FromStarlarkFileWithData creates a Starlark evaluator with both static and
@@ -205,7 +206,7 @@ func FromStarlarkFileWithData(
 		return nil, err
 	}
 
-	return starlarkMachine.FromStarlarkLoader(l,
+	return starlarkMachine.FromStarlarkLoader(context.Background(), l,
 		starlarkMachine.WithLogHandler(logHandler),
 		starlarkMachine.WithStaticData(staticData),
 	)
@@ -223,7 +224,7 @@ func FromStarlarkString(
 		return nil, err
 	}
 
-	return starlarkMachine.FromStarlarkLoader(l, starlarkMachine.WithLogHandler(logHandler))
+	return starlarkMachine.FromStarlarkLoader(context.Background(), l, starlarkMachine.WithLogHandler(logHandler))
 }
 
 // FromStarlarkStringWithData creates a Starlark evaluator with both static and
@@ -240,7 +241,7 @@ func FromStarlarkStringWithData(
 		return nil, err
 	}
 
-	return starlarkMachine.FromStarlarkLoader(l,
+	return starlarkMachine.FromStarlarkLoader(context.Background(), l,
 		starlarkMachine.WithLogHandler(logHandler),
 		starlarkMachine.WithStaticData(staticData),
 	)

engines/extism/new.go

@@ -69,7 +69,10 @@ var ErrEntryPointRequired = errors.New("extism: entry point is required (use Wit
 // If both [WithStaticData] and [WithDataProvider] are supplied,
 // [WithDataProvider] takes precedence — pass exactly one of them per
 // call to keep intent unambiguous.
-func FromExtismLoader(ldr loader.Loader, opts ...Option) (*evaluator.Evaluator, error) {
+//
+// The supplied ctx flows into the loader's I/O and the Extism SDK's
+// WASM compile + entry-point probe; cancelling it halts both.
+func FromExtismLoader(ctx context.Context, ldr loader.Loader, opts ...Option) (*evaluator.Evaluator, error) {
 	cfg := &config{}
 	for _, opt := range opts {
 		if opt != nil {
@@ -96,10 +99,7 @@ func FromExtismLoader(ldr loader.Loader, opts ...Option) (*evaluator.Evaluator,
 		execUnitID = u.String()
 	}
 
-	// FromExtismLoader is a one-shot startup constructor; compile uses a
-	// fresh Background context. Callers needing cancellable compile
-	// should drive script.NewExecutableUnit directly.
-	execUnit, err := script.NewExecutableUnit(context.Background(), cfg.handler, execUnitID, ldr, comp, provider)
+	execUnit, err := script.NewExecutableUnit(ctx, cfg.handler, execUnitID, ldr, comp, provider)
 	if err != nil {
 		return nil, err
 	}

engines/extism/new_test.go

@@ -2,6 +2,7 @@ package extism
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -42,7 +43,7 @@ func newErrorLoader(t *testing.T, msg string) *loaderMock {
 
 func TestFromExtismLoader_RequiresEntryPoint(t *testing.T) {
 	mockLoader := new(loaderMock)
-	eval, err := FromExtismLoader(mockLoader)
+	eval, err := FromExtismLoader(t.Context(), mockLoader)
 	require.Error(t, err)
 	require.Nil(t, eval)
 	require.ErrorIs(t, err, ErrEntryPointRequired)
@@ -53,15 +54,15 @@ func TestFromExtismLoader_RequiresEntryPoint(t *testing.T) {
 
 func TestFromExtismLoader_EmptyEntryPointStillRejected(t *testing.T) {
 	mockLoader := new(loaderMock)
-	eval, err := FromExtismLoader(mockLoader, WithEntryPoint(""))
+	eval, err := FromExtismLoader(t.Context(), mockLoader, WithEntryPoint(""))
 	require.Error(t, err)
 	require.Nil(t, eval)
 	require.ErrorIs(t, err, ErrEntryPointRequired)
 }
 
 func TestFromExtismLoader_NoOptionsBeyondEntryPoint(t *testing.T) {
 	mockLoader := newWASMLoader(t)
-	eval, err := FromExtismLoader(mockLoader, WithEntryPoint(wasmdata.EntrypointGreet))
+	eval, err := FromExtismLoader(t.Context(), mockLoader, WithEntryPoint(wasmdata.EntrypointGreet))
 	require.NoError(t, err)
 	require.NotNil(t, eval)
 	assert.Equal(t, "extism.Evaluator", eval.String())
@@ -71,7 +72,8 @@ func TestFromExtismLoader_NoOptionsBeyondEntryPoint(t *testing.T) {
 func TestFromExtismLoader_WithLogHandler(t *testing.T) {
 	mockLoader := newWASMLoader(t)
 	handler := slog.NewTextHandler(os.Stdout, nil)
-	eval, err := FromExtismLoader(mockLoader,
+	eval, err := FromExtismLoader(
+		t.Context(), mockLoader,
 		WithEntryPoint(wasmdata.EntrypointGreet),
 		WithLogHandler(handler),
 	)
@@ -82,7 +84,8 @@ func TestFromExtismLoader_WithLogHandler(t *testing.T) {
 
 func TestFromExtismLoader_NilLogHandler(t *testing.T) {
 	mockLoader := newWASMLoader(t)
-	eval, err := FromExtismLoader(mockLoader,
+	eval, err := FromExtismLoader(
+		t.Context(), mockLoader,
 		WithEntryPoint(wasmdata.EntrypointGreet),
 		WithLogHandler(nil),
 	)
@@ -93,7 +96,8 @@ func TestFromExtismLoader_NilLogHandler(t *testing.T) {
 
 func TestFromExtismLoader_WithStaticData(t *testing.T) {
 	mockLoader := newWASMLoader(t)
-	eval, err := FromExtismLoader(mockLoader,
+	eval, err := FromExtismLoader(
+		t.Context(), mockLoader,
 		WithEntryPoint(wasmdata.EntrypointGreet),
 		WithStaticData(map[string]any{"input": "World"}),
 	)
@@ -105,7 +109,8 @@ func TestFromExtismLoader_WithStaticData(t *testing.T) {
 func TestFromExtismLoader_WithDataProvider(t *testing.T) {
 	mockLoader := newWASMLoader(t)
 	provider := data.NewContextProvider("test_key")
-	eval, err := FromExtismLoader(mockLoader,
+	eval, err := FromExtismLoader(
+		t.Context(), mockLoader,
 		WithEntryPoint(wasmdata.EntrypointGreet),
 		WithDataProvider(provider),
 	)
@@ -117,7 +122,8 @@ func TestFromExtismLoader_WithDataProvider(t *testing.T) {
 func TestFromExtismLoader_DataProviderBeatsStaticData(t *testing.T) {
 	mockLoader := newWASMLoader(t)
 	provider := data.NewContextProvider("sentinel")
-	eval, err := FromExtismLoader(mockLoader,
+	eval, err := FromExtismLoader(
+		t.Context(), mockLoader,
 		WithEntryPoint(wasmdata.EntrypointGreet),
 		WithStaticData(map[string]any{"ignored": true}),
 		WithDataProvider(provider),
@@ -130,7 +136,8 @@ func TestFromExtismLoader_DataProviderBeatsStaticData(t *testing.T) {
 func TestFromExtismLoader_NilOption(t *testing.T) {
 	mockLoader := newWASMLoader(t)
 	var nilOpt Option
-	eval, err := FromExtismLoader(mockLoader,
+	eval, err := FromExtismLoader(
+		t.Context(), mockLoader,
 		nilOpt,
 		WithEntryPoint(wasmdata.EntrypointGreet),
 	)
@@ -140,7 +147,7 @@ func TestFromExtismLoader_NilOption(t *testing.T) {
 
 func TestFromExtismLoader_LoaderError(t *testing.T) {
 	mockLoader := newErrorLoader(t, "failed to load WASM")
-	eval, err := FromExtismLoader(mockLoader, WithEntryPoint(wasmdata.EntrypointGreet))
+	eval, err := FromExtismLoader(t.Context(), mockLoader, WithEntryPoint(wasmdata.EntrypointGreet))
 	require.Error(t, err)
 	require.Nil(t, eval)
 	mockLoader.AssertExpectations(t)
@@ -151,7 +158,7 @@ func TestFromExtismLoader_NilSourceURL(t *testing.T) {
 	mockLoader.On("GetSourceURL").Return(nil)
 	mockLoader.On("GetReader", mock.Anything).Return(io.NopCloser(bytes.NewReader(wasmdata.TestModule)), nil)
 
-	eval, err := FromExtismLoader(mockLoader, WithEntryPoint(wasmdata.EntrypointGreet))
+	eval, err := FromExtismLoader(t.Context(), mockLoader, WithEntryPoint(wasmdata.EntrypointGreet))
 	require.NoError(t, err)
 	require.NotNil(t, eval)
 	mockLoader.AssertExpectations(t)
@@ -166,7 +173,7 @@ func TestFromExtismLoader_DiskLoader(t *testing.T) {
 	require.NoError(t, err)
 	require.NotNil(t, diskLoader)
 
-	eval, err := FromExtismLoader(diskLoader, WithEntryPoint(wasmdata.EntrypointGreet))
+	eval, err := FromExtismLoader(t.Context(), diskLoader, WithEntryPoint(wasmdata.EntrypointGreet))
 	require.NoError(t, err)
 	require.NotNil(t, eval)
 	assert.Equal(t, "extism.Evaluator", eval.String())
@@ -177,6 +184,7 @@ func TestFromExtismLoader_RunsEndToEnd(t *testing.T) {
 	require.NoError(t, err)
 
 	eval, err := FromExtismLoader(
+		t.Context(),
 		scriptLoader,
 		WithEntryPoint(wasmdata.EntrypointGreet),
 		WithStaticData(map[string]any{"input": "World"}),
@@ -203,7 +211,7 @@ func TestFromExtismLoader_DefaultsToSlogDefault(t *testing.T) {
 	scriptLoader, err := loader.NewFromBytes(wasmdata.TestModule)
 	require.NoError(t, err)
 
-	eval, err := FromExtismLoader(scriptLoader, WithEntryPoint(wasmdata.EntrypointGreet))
+	eval, err := FromExtismLoader(t.Context(), scriptLoader, WithEntryPoint(wasmdata.EntrypointGreet))
 	require.NoError(t, err)
 	require.NotNil(t, eval)
 }
@@ -224,3 +232,24 @@ func TestNewCompiler(t *testing.T) {
 		require.NotNil(t, comp)
 	})
 }
+
+// TestFromExtismLoader_LoaderCancelled verifies that ctx cancellation
+// during the loader IO phase aborts the constructor. This is the
+// headline behavior of #145 for engines whose WASM compile is too fast
+// to reliably observe a pre-cancelled ctx (the wazero compile of the
+// small embedded test module completes in microseconds).
+func TestFromExtismLoader_LoaderCancelled(t *testing.T) {
+	t.Parallel()
+
+	ctx, cancel := context.WithCancel(t.Context())
+	cancel() // pre-cancel; the loader's GetReader call observes it.
+
+	mockLoader := new(loaderMock)
+	mockLoader.On("GetSourceURL").Return((*url.URL)(nil))
+	mockLoader.On("GetReader", mock.Anything).Return(nil, ctx.Err())
+
+	eval, err := FromExtismLoader(ctx, mockLoader, WithEntryPoint(wasmdata.EntrypointGreet))
+	require.Error(t, err)
+	require.Nil(t, eval)
+	require.ErrorIs(t, err, context.Canceled)
+}