diff --git a/internal/lsp/cache/session.go b/internal/lsp/cache/session.go
index a7b57a1931..1b8cd3522f 100644
--- a/internal/lsp/cache/session.go
+++ b/internal/lsp/cache/session.go
@@ -279,7 +279,7 @@ func (s *session) dropView(ctx context.Context, view *view) (int, error) {
 }
 
 // TODO: Propagate the language ID through to the view.
-func (s *session) DidOpen(ctx context.Context, uri span.URI, kind source.FileKind, text []byte) error {
+func (s *session) DidOpen(ctx context.Context, uri span.URI, kind source.FileKind, version float64, text []byte) error {
 	ctx = telemetry.File.With(ctx, uri)
 
 	// Files with _ prefixes are ignored.
@@ -303,16 +303,17 @@ func (s *session) DidOpen(ctx context.Context, uri span.URI, kind source.FileKin
 
 	// Read the file on disk and compare it to the text provided.
 	// If it is the same as on disk, we can avoid sending it as an overlay to go/packages.
-	s.openOverlay(ctx, uri, kind, text)
+	s.openOverlay(ctx, uri, kind, version, text)
 	return nil
 }
 
-func (s *session) DidSave(uri span.URI) {
+func (s *session) DidSave(uri span.URI, version float64) {
 	s.overlayMu.Lock()
 	defer s.overlayMu.Unlock()
 
 	if overlay, ok := s.overlays[uri]; ok {
 		overlay.sameContentOnDisk = true
+		overlay.version = version
 	}
 }
 
@@ -333,7 +334,7 @@ func (s *session) GetFile(uri span.URI, kind source.FileKind) source.FileHandle
 	return s.cache.GetFile(uri, kind)
 }
 
-func (s *session) SetOverlay(uri span.URI, kind source.FileKind, data []byte) bool {
+func (s *session) SetOverlay(uri span.URI, kind source.FileKind, version float64, data []byte) bool {
 	s.overlayMu.Lock()
 	defer func() {
 		s.overlayMu.Unlock()
@@ -354,6 +355,7 @@ func (s *session) SetOverlay(uri span.URI, kind source.FileKind, data []byte) bo
 		kind:      kind,
 		data:      data,
 		hash:      hashContents(data),
+		version:   version,
 		unchanged: o == nil,
 	}
 	return firstChange
@@ -368,7 +370,7 @@ func (s *session) clearOverlay(uri span.URI) {
 
 // openOverlay adds the file content to the overlay.
 // It also checks if the provided content is equivalent to the file's content on disk.
-func (s *session) openOverlay(ctx context.Context, uri span.URI, kind source.FileKind, data []byte) {
+func (s *session) openOverlay(ctx context.Context, uri span.URI, kind source.FileKind, version float64, data []byte) {
 	s.overlayMu.Lock()
 	defer func() {
 		s.overlayMu.Unlock()
@@ -381,6 +383,7 @@ func (s *session) openOverlay(ctx context.Context, uri span.URI, kind source.Fil
 		data:      data,
 		hash:      hashContents(data),
 		unchanged: true,
+		version:   version,
 	}
 	// If the file is on disk, check if its content is the same as the overlay.
 	if _, hash, err := s.cache.GetFile(uri, kind).Read(ctx); err == nil {
diff --git a/internal/lsp/cache/snapshot.go b/internal/lsp/cache/snapshot.go
index bece4f1d09..db332dc207 100644
--- a/internal/lsp/cache/snapshot.go
+++ b/internal/lsp/cache/snapshot.go
@@ -352,7 +352,7 @@ func (s *snapshot) clone(ctx context.Context, withoutURI *span.URI, withoutTypes
 
 // invalidateContent invalidates the content of a Go file,
 // including any position and type information that depends on it.
-func (v *view) invalidateContent(ctx context.Context, f source.File, kind source.FileKind, changeType protocol.FileChangeType) bool {
+func (v *view) invalidateContent(ctx context.Context, f source.File, changeType protocol.FileChangeType) bool {
 	var (
 		withoutTypes    = make(map[span.URI]struct{})
 		withoutMetadata = make(map[span.URI]struct{})
@@ -407,7 +407,7 @@ func (v *view) invalidateContent(ctx context.Context, f source.File, kind source
 	}
 
 	// Get the current FileHandle for the URI.
-	currentFH := v.session.GetFile(f.URI(), kind)
+	currentFH := v.session.GetFile(f.URI(), f.Kind())
 
 	// Check if the file's package name or imports have changed,
 	// and if so, invalidate metadata.
diff --git a/internal/lsp/cache/view.go b/internal/lsp/cache/view.go
index d872ddddb5..155a3743ee 100644
--- a/internal/lsp/cache/view.go
+++ b/internal/lsp/cache/view.go
@@ -273,8 +273,8 @@ func (v *view) storeModFileVersions() {
 
 func (v *view) fileVersion(filename string, kind source.FileKind) string {
 	uri := span.FileURI(filename)
-	f := v.session.GetFile(uri, kind)
-	return f.Identity().Identifier
+	fh := v.session.GetFile(uri, kind)
+	return fh.Identity().String()
 }
 
 func (v *view) Shutdown(ctx context.Context) {
@@ -324,7 +324,7 @@ func (v *view) getSnapshot() *snapshot {
 }
 
 // SetContent sets the overlay contents for a file.
-func (v *view) SetContent(ctx context.Context, uri span.URI, content []byte) (bool, error) {
+func (v *view) SetContent(ctx context.Context, uri span.URI, version float64, content []byte) (bool, error) {
 	v.mu.Lock()
 	defer v.mu.Unlock()
 
@@ -338,7 +338,7 @@ func (v *view) SetContent(ctx context.Context, uri span.URI, content []byte) (bo
 	}
 
 	kind := source.DetectLanguage("", uri.Filename())
-	return v.session.SetOverlay(uri, kind, content), nil
+	return v.session.SetOverlay(uri, kind, version, content), nil
 }
 
 // FindFile returns the file if the given URI is already a part of the view.
@@ -374,11 +374,11 @@ func (v *view) getFile(ctx context.Context, uri span.URI, kind source.FileKind)
 	f = &fileBase{
 		view:  v,
 		fname: uri.Filename(),
-		kind:  source.Go,
+		kind:  kind,
 	}
 	v.session.filesWatchMap.Watch(uri, func(changeType protocol.FileChangeType) bool {
 		ctx := xcontext.Detach(ctx)
-		return v.invalidateContent(ctx, f, kind, changeType)
+		return v.invalidateContent(ctx, f, changeType)
 	})
 	v.mapFile(uri, f)
 	return f, nil
diff --git a/internal/lsp/lsp_test.go b/internal/lsp/lsp_test.go
index f20b967de8..c4daa4bf21 100644
--- a/internal/lsp/lsp_test.go
+++ b/internal/lsp/lsp_test.go
@@ -58,7 +58,7 @@ func testLSP(t *testing.T, exporter packagestest.Exporter) {
 		t.Fatal(err)
 	}
 	for filename, content := range data.Config.Overlay {
-		session.SetOverlay(span.FileURI(filename), source.DetectLanguage("", filename), content)
+		session.SetOverlay(span.FileURI(filename), source.DetectLanguage("", filename), -1, content)
 	}
 	r := &runner{
 		server: &Server{
diff --git a/internal/lsp/source/source_test.go b/internal/lsp/source/source_test.go
index 4403d06dea..3ed53a50d0 100644
--- a/internal/lsp/source/source_test.go
+++ b/internal/lsp/source/source_test.go
@@ -61,7 +61,7 @@ func testSource(t *testing.T, exporter packagestest.Exporter) {
 		ctx:  ctx,
 	}
 	for filename, content := range data.Config.Overlay {
-		session.SetOverlay(span.FileURI(filename), source.DetectLanguage("", filename), content)
+		session.SetOverlay(span.FileURI(filename), source.DetectLanguage("", filename), -1, content)
 	}
 	tests.Run(t, r, data)
 }
diff --git a/internal/lsp/source/view.go b/internal/lsp/source/view.go
index 934743a328..aa1e2a8181 100644
--- a/internal/lsp/source/view.go
+++ b/internal/lsp/source/view.go
@@ -57,6 +57,12 @@ type FileSystem interface {
 	GetFile(uri span.URI, kind FileKind) FileHandle
 }
 
+// File represents a source file of any type.
+type File interface {
+	URI() span.URI
+	Kind() FileKind
+}
+
 // FileKind describes the kind of the file in question.
 // It can be one of Go, mod, or sum.
 type FileKind int
@@ -172,10 +178,10 @@ type Session interface {
 	FileSystem
 
 	// DidOpen is invoked each time a file is opened in the editor.
-	DidOpen(ctx context.Context, uri span.URI, kind FileKind, text []byte) error
+	DidOpen(ctx context.Context, uri span.URI, kind FileKind, version float64, text []byte) error
 
 	// DidSave is invoked each time an open file is saved in the editor.
-	DidSave(uri span.URI)
+	DidSave(uri span.URI, version float64)
 
 	// DidClose is invoked each time an open file is closed in the editor.
 	DidClose(uri span.URI)
@@ -184,7 +190,7 @@ type Session interface {
 	IsOpen(uri span.URI) bool
 
 	// Called to set the effective contents of a file from this session.
-	SetOverlay(uri span.URI, kind FileKind, data []byte) (wasFirstChange bool)
+	SetOverlay(uri span.URI, kind FileKind, version float64, data []byte) (wasFirstChange bool)
 
 	// DidChangeOutOfBand is called when a file under the root folder changes.
 	// If the file was open in the editor, it returns true.
@@ -222,7 +228,7 @@ type View interface {
 	FindFile(ctx context.Context, uri span.URI) File
 
 	// Called to set the effective contents of a file from this view.
-	SetContent(ctx context.Context, uri span.URI, content []byte) (wasFirstChange bool, err error)
+	SetContent(ctx context.Context, uri span.URI, version float64, content []byte) (wasFirstChange bool, err error)
 
 	// BackgroundContext returns a context used for all background processing
 	// on behalf of this view.
@@ -293,12 +299,6 @@ type Snapshot interface {
 	KnownPackages(ctx context.Context) []Package
 }
 
-// File represents a source file of any type.
-type File interface {
-	URI() span.URI
-	Kind() FileKind
-}
-
 type FileURI span.URI
 
 func (f FileURI) URI() span.URI {
diff --git a/internal/lsp/text_synchronization.go b/internal/lsp/text_synchronization.go
index 4019daca12..fbb67bfb25 100644
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@@ -21,12 +21,13 @@ import (
 func (s *Server) didOpen(ctx context.Context, params *protocol.DidOpenTextDocumentParams) error {
 	uri := span.NewURI(params.TextDocument.URI)
 	text := []byte(params.TextDocument.Text)
+	version := params.TextDocument.Version
 
 	// Confirm that the file's language ID is related to Go.
 	fileKind := source.DetectLanguage(params.TextDocument.LanguageID, uri.Filename())
 
 	// Open the file.
-	s.session.DidOpen(ctx, uri, fileKind, text)
+	s.session.DidOpen(ctx, uri, fileKind, version, text)
 
 	view := s.session.ViewOf(uri)
 
@@ -64,7 +65,7 @@ func (s *Server) didChange(ctx context.Context, params *protocol.DidChangeTextDo
 	}
 	// Cache the new file content and send fresh diagnostics.
 	view := s.session.ViewOf(uri)
-	wasFirstChange, err := view.SetContent(ctx, uri, []byte(text))
+	wasFirstChange, err := view.SetContent(ctx, uri, params.TextDocument.Version, []byte(text))
 	if err != nil {
 		return err
 	}
@@ -130,7 +131,7 @@ func (s *Server) applyChanges(ctx context.Context, uri span.URI, changes []proto
 }
 
 func (s *Server) didSave(ctx context.Context, params *protocol.DidSaveTextDocumentParams) error {
-	s.session.DidSave(span.NewURI(params.TextDocument.URI))
+	s.session.DidSave(span.NewURI(params.TextDocument.URI), params.TextDocument.Version)
 	return nil
 }
 
@@ -139,7 +140,7 @@ func (s *Server) didClose(ctx context.Context, params *protocol.DidCloseTextDocu
 	ctx = telemetry.URI.With(ctx, uri)
 	s.session.DidClose(uri)
 	view := s.session.ViewOf(uri)
-	if _, err := view.SetContent(ctx, uri, nil); err != nil {
+	if _, err := view.SetContent(ctx, uri, -1, nil); err != nil {
 		return err
 	}
 	clear := []span.URI{uri} // by default, clear the closed URI