fix(lsp): avoid null identifier in diagnostics

Author: bennypowers

go.mod

@@ -3,7 +3,7 @@ module bennypowers.dev/asimonim
 go 1.25.5
 
 require (
-	github.com/bennypowers/glsp v0.0.0-20260501152441-74e714d631a0
+	github.com/bennypowers/glsp v0.0.0-20260511074857-83c7f674baea
 	github.com/bmatcuk/doublestar/v4 v4.9.2
 	github.com/lucasb-eyer/go-colorful v1.4.0
 	github.com/mazznoer/csscolorparser v0.1.8

go.sum

@@ -12,6 +12,8 @@ github.com/bennypowers/glsp v0.0.0-20260501124255-83ab200c0f90 h1:IaAv5U5B8XKW5Z
 github.com/bennypowers/glsp v0.0.0-20260501124255-83ab200c0f90/go.mod h1:xY+tzLsKqII5jJc7lUADTw5a+ONpyuC1h2HG1WqQckw=
 github.com/bennypowers/glsp v0.0.0-20260501152441-74e714d631a0 h1:0lIJk99h9Q1ZvZQOf/euxXq2bVpppOzGSMNerKh3mWw=
 github.com/bennypowers/glsp v0.0.0-20260501152441-74e714d631a0/go.mod h1:xY+tzLsKqII5jJc7lUADTw5a+ONpyuC1h2HG1WqQckw=
+github.com/bennypowers/glsp v0.0.0-20260511074857-83c7f674baea h1:8JBUvL96De3eagEHxVID5cRCQdHseohaFof+l6GOo+Q=
+github.com/bennypowers/glsp v0.0.0-20260511074857-83c7f674baea/go.mod h1:xY+tzLsKqII5jJc7lUADTw5a+ONpyuC1h2HG1WqQckw=
 github.com/bmatcuk/doublestar/v4 v4.9.2 h1:b0mc6WyRSYLjzofB2v/0cuDUZ+MqoGyH3r0dVij35GI=
 github.com/bmatcuk/doublestar/v4 v4.9.2/go.mod h1:xBQ8jztBU6kakFMg+8WGxn0c6z1fTSPVIjEY1Wr7jzc=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=

lsp/methods/lifecycle/initialize.go

@@ -79,6 +79,7 @@ func Initialize(req *types.RequestContext, params *protocol.InitializeParams) (a
 
 	if supportsPullDiagnostics {
 		capabilities.DiagnosticProvider = protocol.DiagnosticOptions{
+			Identifier:            strPtr("asimonim"),
 			InterFileDependencies: false,
 			WorkspaceDiagnostics:  true,
 		}

lsp/methods/lifecycle/initialize_test.go

@@ -1,6 +1,7 @@
 package lifecycle
 
 import (
+	"encoding/json"
 	"testing"
 
 	"bennypowers.dev/asimonim/lsp/internal/uriutil"
@@ -110,6 +111,8 @@ func TestInitialize(t *testing.T) {
 		diagOpts, ok := caps.DiagnosticProvider.(protocol.DiagnosticOptions)
 		require.True(t, ok)
 		assert.True(t, diagOpts.WorkspaceDiagnostics)
+		require.NotNil(t, diagOpts.Identifier, "Identifier must be set to avoid Neovim null userdata crash")
+		assert.Equal(t, "asimonim", *diagOpts.Identifier)
 
 		// Verify completion provider options
 		assert.NotNil(t, caps.CompletionProvider.ResolveProvider)
@@ -122,6 +125,30 @@ func TestInitialize(t *testing.T) {
 		assert.True(t, *codeActionProvider.ResolveProvider)
 	})
 
+	t.Run("diagnostic identifier serializes as string not null", func(t *testing.T) {
+		ctx := testutil.NewMockServerContext()
+		glspCtx := &glsp.Context{}
+		req := types.NewRequestContext(ctx, glspCtx)
+		ctx.SetClientDiagnosticCapability(true)
+
+		params := &protocol.InitializeParams{
+			Capabilities: protocol.ClientCapabilities{
+				TextDocument: &protocol.TextDocumentClientCapabilities{},
+			},
+		}
+
+		result, err := Initialize(req, params)
+		require.NoError(t, err)
+
+		initResult := result.(protocol.InitializeResult)
+		data, err := json.Marshal(initResult.Capabilities)
+		require.NoError(t, err)
+
+		// Neovim crashes when identifier is null (Lua userdata vs string)
+		assert.NotContains(t, string(data), `"identifier":null`)
+		assert.Contains(t, string(data), `"identifier":"asimonim"`)
+	})
+
 	t.Run("handles client info", func(t *testing.T) {
 		ctx := testutil.NewMockServerContext()
 		glspCtx := &glsp.Context{}