fix(codegen): keep watch mode alive on missing input files

Co-Authored-By: Virgil <virgil@lethean.io>

cmd/codegen/main.go

@@ -88,6 +88,17 @@ func runDaemon(ctx context.Context, inputPath, outputPath string, emitTypes bool
 	for {
 		input, err := coreio.Local.Read(inputPath)
 		if err != nil {
+			if os.IsNotExist(err) {
+				select {
+				case <-ctx.Done():
+					if errors.Is(ctx.Err(), context.Canceled) {
+						return nil
+					}
+					return ctx.Err()
+				case <-ticker.C:
+				}
+				continue
+			}
 			return log.E("codegen", "reading input file", err)
 		}
 

cmd/codegen/main_test.go

@@ -149,6 +149,34 @@ func TestRunDaemon_RecoversFromInvalidJSON(t *testing.T) {
 	require.NoError(t, <-done)
 }
 
+func TestRunDaemon_RecoversFromMissingInputFile(t *testing.T) {
+	dir := t.TempDir()
+	inputPath := dir + "/slots.json"
+	outputPath := dir + "/bundle.js"
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	done := make(chan error, 1)
+	go func() {
+		done <- runDaemon(ctx, inputPath, outputPath, false, 5*time.Millisecond)
+	}()
+
+	time.Sleep(20 * time.Millisecond)
+	require.NoError(t, writeTestFile(inputPath, `{"H":"nav-bar","C":"main-content"}`))
+
+	require.Eventually(t, func() bool {
+		got, err := readTestFile(outputPath)
+		if err != nil {
+			return false
+		}
+		return strings.Contains(got, "NavBar") && strings.Contains(got, "MainContent")
+	}, time.Second, 10*time.Millisecond)
+
+	cancel()
+	require.NoError(t, <-done)
+}
+
 func TestRunDaemon_MissingPaths(t *testing.T) {
 	err := runDaemon(context.Background(), "", "", false, time.Millisecond)
 	require.Error(t, err)

docs/development.md

@@ -151,6 +151,8 @@ To run the daemon mode, point it at an input JSON file and an output bundle path
 go run ./cmd/codegen/ -watch -input slots.json -output components.js
 ```
 
+Watch mode keeps polling through transient missing files and invalid JSON edits, then rewrites the output bundle once the input becomes valid again.
+
 Add `-dts` to emit TypeScript declarations instead of JavaScript in either mode.
 
 To test the CLI: