Update error message for canceled root context

cmd/buf/buf.go

@@ -478,18 +478,24 @@ func newRootCommand(name string) *appcmd.Command {
 func newErrorInterceptor() appext.Interceptor {
 	return func(next func(context.Context, appext.Container) error) func(context.Context, appext.Container) error {
 		return func(ctx context.Context, container appext.Container) error {
-			return wrapError(next(ctx, container))
+			return wrapError(ctx, next(ctx, container))
 		}
 	}
 }
 
 // wrapError is used when a CLI command fails, regardless of its error code.
 // Note that this function will wrap the error so that the underlying error
 // can be recovered via 'errors.Is'.
-func wrapError(err error) error {
+func wrapError(ctx context.Context, err error) error {
 	if err == nil {
 		return nil
 	}
+	// ctx is the root context that [app.Run] wrapped with interrupt.Handle. Nothing else cancels it,
+	// so a canceled ctx suggests SIGINT/SIGTERM.
+	if errors.Is(ctx.Err(), context.Canceled) &&
+		(errors.Is(err, context.Canceled) || connect.CodeOf(err) == connect.CodeCanceled) {
+		return appFailureError(errors.New("interrupted"))
+	}
 
 	var connectErr *connect.Error
 	isConnectError := errors.As(err, &connectErr)

cmd/buf/buf_test.go

@@ -16,6 +16,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -31,6 +32,7 @@ import (
 	"buf.build/go/app/appcmd/appcmdtesting"
 	"buf.build/go/bufplugin/check"
 	"buf.build/go/standard/xslices"
+	"connectrpc.com/connect"
 	"github.com/bufbuild/buf/cmd/buf/internal/internaltesting"
 	"github.com/bufbuild/buf/private/buf/bufcli"
 	"github.com/bufbuild/buf/private/buf/bufctl"
@@ -4798,3 +4800,18 @@ func testLsRuleOutputJSON(
 		)
 	require.Equal(t, expectedRules, outputRules)
 }
+
+func TestWrapErrorInterrupt(t *testing.T) {
+	t.Parallel()
+	canceledCtx, cancel := context.WithCancel(t.Context())
+	cancel()
+	connectCanceledErr := connect.NewError(connect.CodeCanceled, context.Canceled)
+
+	// Root context is canceled.
+	require.EqualError(t, wrapError(canceledCtx, connectCanceledErr), "Failure: interrupted")
+	require.EqualError(t, wrapError(canceledCtx, context.Canceled), "Failure: interrupted")
+
+	// Root context is canceled but the command failed for an unrelated reason.
+	require.EqualError(t, wrapError(canceledCtx, errors.New("parse failed")), "Failure: parse failed")
+	require.NoError(t, wrapError(canceledCtx, nil))
+}