Separate show cancellation from rendering errors

integrations/ckconfig/report_cancellation_test.go

@@ -1,6 +1,7 @@
 package ckconfig
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"io"
@@ -67,3 +68,39 @@ func TestBufferedReportDoesNotRejectCancellationAfterDeliveryStarts(t *testing.T
 		t.Fatalf("post-delivery cancellation changed the operation outcome: %#v", got)
 	}
 }
+
+type effectiveWriterFunc func(io.Writer) error
+
+func (write effectiveWriterFunc) WriteEffective(w io.Writer) error { return write(w) }
+
+func TestShowCancellationDuringBufferedPreparation(t *testing.T) {
+	renderErr := errors.New("native rendering failed")
+	for _, tc := range []struct {
+		name      string
+		renderErr error
+	}{{name: "cancellation"}, {name: "cancellation and rendering failure", renderErr: renderErr}} {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+			acquired, secondWrites := 0, 0
+			scope := func(name string, writer EffectiveWriter) Scope[struct{}, struct{}] {
+				return Scope[struct{}, struct{}]{Name: name, Operations: []Operation{Show}, Acquire: func(context.Context, Request, struct{}, struct{}) (commandkit.Acquired[View], error) {
+					acquired++
+					return commandkit.Acquired[View]{Value: View{Effective: writer}}, nil
+				}}
+			}
+			app := newConfigTestApp(t, Command(Suite[struct{}, struct{}]{Scopes: []Scope[struct{}, struct{}]{
+				scope("app", effectiveWriterFunc(func(w io.Writer) error { _, _ = io.WriteString(w, "name: app\n"); cancel(); return tc.renderErr })),
+				scope("promptkit", effectiveWriterFunc(func(w io.Writer) error { secondWrites++; _, err := io.WriteString(w, "name: promptkit\n"); return err })),
+			}}))
+			var output bytes.Buffer
+			got := app.Execute(ctx, []string{"config", "show", "--scope=all"}, commandkit.Streams{Out: &output, Err: io.Discard})
+			if acquired != 2 || secondWrites != 0 || output.Len() != 0 || !errors.Is(got.Cause, context.Canceled) || got.Presentation.Output.WriteError != nil {
+				t.Fatalf("acquired=%d second=%d output=%q outcome=%#v", acquired, secondWrites, output.String(), got)
+			}
+			if tc.renderErr == nil && got.Presentation.Output.RenderError != nil || tc.renderErr != nil && !errors.Is(got.Presentation.Output.RenderError, tc.renderErr) {
+				t.Fatalf("render evidence = %#v", got.Presentation.Output)
+			}
+		})
+	}
+}

integrations/ckconfig/show.go

@@ -66,11 +66,13 @@ func runConfigShow[I, S any](invocation commandkit.Invocation, plan *configOpera
 		return configFailure("Configuration show was canceled.", commandkit.Explanation{}, err)
 	}
 	var value any
+	var canceled error
 	err := reporter.RenderOutput(func(io.Writer) error {
 		values := make(map[string]any, len(documents))
 		for _, document := range documents {
 			if err := invocation.Context.Err(); err != nil {
-				return err
+				canceled = err
+				return nil
 			}
 			var native bytes.Buffer
 			if err := document.view.Effective.WriteEffective(&native); err != nil {
@@ -89,6 +91,9 @@ func runConfigShow[I, S any](invocation commandkit.Invocation, plan *configOpera
 		}
 		return nil
 	})
+	if canceled != nil {
+		return configFailure("Configuration show was canceled.", commandkit.Explanation{}, canceled)
+	}
 	if err != nil {
 		if canceled := invocation.Context.Err(); canceled != nil {
 			return configFailure("Configuration show was canceled.", commandkit.Explanation{}, canceled)