Fix self-upgrade interrupt handling

docs/docs/changelog.md

@@ -8,6 +8,7 @@ title: Changelog
 * `[Added]` Add `checksum.files`, `checksum.sh`, and `checksum.persist` command checksum syntax while keeping the old checksum format compatible.
 * `[Added]` Add `lets self upgrade --pre` to opt into upgrading to the latest prerelease.
 * `[Added]` Add `lets self fix` config migration command with `--dry-run` preview output for deprecated checksum syntax.
+* `[Fixed]` Allow `lets self upgrade` downloads to respond to Ctrl-C.
 * `[Fixed]` Make checksum calculation respect command-level `work_dir` overrides.
 * `[Fixed]` Restore the release checkout after the GoReleaser dry run so prerelease publishing does not fail on a dirty `go.mod`.
 

internal/cli/cli.go

@@ -159,12 +159,24 @@ func getContext() context.Context {
 	ch := make(chan os.Signal, 1)
 	signal.Notify(ch, os.Interrupt, syscall.SIGTERM)
 
-	ctx, cancel := context.WithCancel(context.Background())
+	return signalContext(context.Background(), ch, func() {
+		signal.Stop(ch)
+	})
+}
+
+func signalContext(parent context.Context, ch <-chan os.Signal, stop func()) context.Context {
+	ctx, cancel := context.WithCancel(parent)
 
 	go func() {
-		sig := <-ch
-		log.Printf("signal received: %s", sig)
-		cancel()
+		defer stop()
+
+		select {
+		case sig := <-ch:
+			log.Printf("signal received: %s", sig)
+			cancel()
+		case <-parent.Done():
+			cancel()
+		}
 	}()
 
 	return ctx

internal/cli/cli_test.go

@@ -1,7 +1,10 @@
 package cli
 
 import (
+	"context"
+	"os"
 	"testing"
+	"time"
 
 	cmdpkg "github.com/lets-cli/lets/internal/cmd"
 	"github.com/lets-cli/lets/internal/settings"
@@ -68,6 +71,57 @@ func TestFailOnConfigError(t *testing.T) {
 	}
 }
 
+func TestSignalContext(t *testing.T) {
+	assertClosed := func(t *testing.T, ch <-chan struct{}, message string) {
+		t.Helper()
+
+		select {
+		case <-ch:
+		case <-time.After(time.Second):
+			t.Fatal(message)
+		}
+	}
+
+	t.Run("cancels and stops signal notification after first signal", func(t *testing.T) {
+		signals := make(chan os.Signal, 1)
+		stopped := make(chan struct{})
+		ctx := signalContext(context.Background(), signals, func() {
+			close(stopped)
+		})
+
+		signals <- os.Interrupt
+
+		assertClosed(t, ctx.Done(), "expected signal context to be canceled")
+		assertClosed(t, stopped, "expected signal notification to stop")
+	})
+
+	t.Run("cancels when parent context is canceled", func(t *testing.T) {
+		parent, cancel := context.WithCancel(context.Background())
+		stopped := make(chan struct{})
+		ctx := signalContext(parent, make(chan os.Signal), func() {
+			close(stopped)
+		})
+
+		cancel()
+
+		assertClosed(t, ctx.Done(), "expected signal context to be canceled by parent")
+		assertClosed(t, stopped, "expected signal notification to stop")
+	})
+
+	t.Run("cancels when parent context is already canceled", func(t *testing.T) {
+		parent, cancel := context.WithCancel(context.Background())
+		cancel()
+
+		stopped := make(chan struct{})
+		ctx := signalContext(parent, make(chan os.Signal), func() {
+			close(stopped)
+		})
+
+		assertClosed(t, ctx.Done(), "expected signal context to be canceled by parent")
+		assertClosed(t, stopped, "expected signal notification to stop")
+	})
+}
+
 func TestShouldCheckForUpdate(t *testing.T) {
 	defaultSettings := settings.Default()