fix(watch): exclude Dockerfile and compose files from the sync loop

pkg/compose/watch.go

@@ -336,6 +336,11 @@ func getWatchRules(config *types.DevelopConfig, service types.ServiceConfig) ([]
 		return nil, err
 	}
 
+	dockerFileIgnore, err := dockerFileIgnoreMatcher(service)
+	if err != nil {
+		return nil, err
+	}
+
 	for _, trigger := range config.Watch {
 		ignore, err := watch.NewDockerPatternMatcher(trigger.Path, trigger.Ignore)
 		if err != nil {
@@ -352,15 +357,22 @@ func getWatchRules(config *types.DevelopConfig, service types.ServiceConfig) ([]
 			}
 		}
 
+		ignores := []watch.PathMatcher{
+			dockerIgnores,
+			watch.EphemeralPathMatcher(),
+			dotGitIgnore,
+			ignore,
+		}
+		// Copy actions only: rebuild on the same tree must still fire.
+		switch trigger.Action {
+		case types.WatchActionSync, types.WatchActionSyncRestart, types.WatchActionSyncExec:
+			ignores = append(ignores, dockerFileIgnore)
+		}
+
 		rules = append(rules, watchRule{
 			Trigger: trigger,
 			include: include,
-			ignore: watch.NewCompositeMatcher(
-				dockerIgnores,
-				watch.EphemeralPathMatcher(),
-				dotGitIgnore,
-				ignore,
-			),
+			ignore:  watch.NewCompositeMatcher(ignores...),
 			service: service.Name,
 		})
 	}
@@ -760,6 +772,19 @@ func (s *composeService) pruneDanglingImagesOnRebuild(ctx context.Context, proje
 	}
 }
 
+// **/anchored so the matcher hits both initialSync's basenames and the
+// watch loop's absolute host paths.
+func dockerFileIgnoreMatcher(service types.ServiceConfig) (watch.PathMatcher, error) {
+	if service.Build == nil {
+		return watch.EmptyMatcher{}, nil
+	}
+	name := service.Build.Dockerfile
+	if name == "" {
+		name = "Dockerfile"
+	}
+	return watch.NewDockerPatternMatcher("/", []string{"**/" + filepath.Base(name)})
+}
+
 // Walks develop.watch.path and checks which files should be copied inside the container
 // ignores develop.watch.ignore, Dockerfile, compose files, bind mounted paths and .git
 func (s *composeService) initialSync(ctx context.Context, service types.ServiceConfig, trigger types.Trigger, syncer sync.Syncer) error {
@@ -778,14 +803,14 @@ func (s *composeService) initialSync(ctx context.Context, service types.ServiceC
 		return err
 	}
 
-	// also exclude override compose files and any custom-named Dockerfile
-	dockerFilePatterns := append([]string{"Dockerfile"}, cli.DefaultFileNames...)
-	dockerFilePatterns = append(dockerFilePatterns, cli.DefaultOverrideFileNames...)
-	if service.Build != nil && service.Build.Dockerfile != "" {
-		dockerFilePatterns = append(dockerFilePatterns, filepath.Base(service.Build.Dockerfile))
+	dockerFileIgnore, err := dockerFileIgnoreMatcher(service)
+	if err != nil {
+		return err
 	}
 
-	dockerFileIgnore, err := watch.NewDockerPatternMatcher("/", dockerFilePatterns)
+	composeFiles := append([]string{}, cli.DefaultFileNames...)
+	composeFiles = append(composeFiles, cli.DefaultOverrideFileNames...)
+	composeFileIgnore, err := watch.NewDockerPatternMatcher("/", composeFiles)
 	if err != nil {
 		return err
 	}
@@ -795,6 +820,7 @@ func (s *composeService) initialSync(ctx context.Context, service types.ServiceC
 		watch.EphemeralPathMatcher(),
 		dotGitIgnore,
 		dockerFileIgnore,
+		composeFileIgnore,
 		triggerIgnore)
 
 	pathsToCopy, err := s.initialSyncFiles(service, trigger, ignoreInitialSync)

pkg/compose/watch_test.go

@@ -316,6 +316,70 @@ func TestInitialSync_ExcludesNestedCustomNamedDockerfile(t *testing.T) {
 	}})
 }
 
+// getWatchRules historically never excluded the service Dockerfile (see
+// #14117). The continuous loop matches absolute host paths, so a
+// basename-only matcher would miss them.
+func TestGetWatchRules_ExcludesDockerfileFromSync(t *testing.T) {
+	rules, err := getWatchRules(&types.DevelopConfig{
+		Watch: []types.Trigger{{
+			Path:   "/proj",
+			Action: types.WatchActionSync,
+			Target: "/app",
+		}},
+	}, types.ServiceConfig{
+		Name:  "svc",
+		Build: &types.BuildConfig{Context: t.TempDir()},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, 1, len(rules))
+
+	assert.Assert(t, rules[0].Matches(watch.NewFileEvent("/proj/Dockerfile")) == nil)
+	assert.Assert(t, rules[0].Matches(watch.NewFileEvent("/proj/compose.yaml")) != nil)
+
+	got := rules[0].Matches(watch.NewFileEvent("/proj/app.go"))
+	assert.DeepEqual(t, got, &sync.PathMapping{
+		HostPath:      "/proj/app.go",
+		ContainerPath: "/app/app.go",
+	})
+}
+
+func TestGetWatchRules_ExcludesCustomNamedDockerfileFromSync(t *testing.T) {
+	rules, err := getWatchRules(&types.DevelopConfig{
+		Watch: []types.Trigger{{
+			Path:   "/proj",
+			Action: types.WatchActionSync,
+			Target: "/app",
+		}},
+	}, types.ServiceConfig{
+		Name:  "svc",
+		Build: &types.BuildConfig{Context: t.TempDir(), Dockerfile: "docker/Dockerfile.prod"},
+	})
+	assert.NilError(t, err)
+	assert.Assert(t, rules[0].Matches(watch.NewFileEvent("/proj/docker/Dockerfile.prod")) == nil)
+	assert.Assert(t, rules[0].Matches(watch.NewFileEvent("/proj/Dockerfile")) != nil)
+	assert.Assert(t, rules[0].Matches(watch.NewFileEvent("/proj/app.go")) != nil)
+}
+
+func TestGetWatchRules_CopyActionsExcludeDockerfile(t *testing.T) {
+	rules, err := getWatchRules(&types.DevelopConfig{
+		Watch: []types.Trigger{
+			{Path: "/proj", Action: types.WatchActionSync, Target: "/app"},
+			{Path: "/proj", Action: types.WatchActionRebuild},
+			{Path: "/proj", Action: types.WatchActionSyncExec, Target: "/app"},
+		},
+	}, types.ServiceConfig{
+		Name:  "svc",
+		Build: &types.BuildConfig{Context: t.TempDir()},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, 3, len(rules))
+
+	event := watch.NewFileEvent("/proj/Dockerfile")
+	assert.Assert(t, rules[0].Matches(event) == nil)
+	assert.Assert(t, rules[1].Matches(event) != nil)
+	assert.Assert(t, rules[2].Matches(event) == nil)
+}
+
 // TestPruneDanglingImagesOnRebuild verifies the post-rebuild prune only
 // removes superseded dangling images: a dangling image whose ID matches one
 // of the freshly built images must be spared. The lookup used to probe the