Decouple snapshot ownership from project.Session so api.Session only uses one in LSP mode

tsc/internal/api/server.go

@@ -83,7 +83,7 @@ func (s *StdioServer) Run(ctx context.Context) error {
 		fs = callbackFS
 	}
 
-	projectSession := project.NewSession(&project.SessionInit{
+	sessionInit := &project.SessionInit{
 		BackgroundCtx: ctx,
 		Logger:        nil, // TODO: Add logging support
 		FS:            fs,
@@ -95,9 +95,9 @@ func (s *StdioServer) Run(ctx context.Context) error {
 			RunExternalCode:    s.options.RunExternalCode,
 		},
 		Spawner: s.options.ContentMapperSpawner,
-	})
+	}
 
-	session := NewSession(projectSession, &SessionOptions{
+	session := NewStandaloneSession(sessionInit, &SessionOptions{
 		UseBinaryResponses: !s.options.Async, // Only msgpack uses binary responses
 	})
 	defer session.Close()

tsc/internal/api/session_apistate_test.go

@@ -5,12 +5,51 @@ import (
 	"testing"
 
 	"github.com/microsoft/TypeScript/tsc/internal/bundled"
+	"github.com/microsoft/TypeScript/tsc/internal/core"
 	"github.com/microsoft/TypeScript/tsc/internal/lsp/lsproto"
 	"github.com/microsoft/TypeScript/tsc/internal/testutil/projecttestutil"
 	"github.com/microsoft/TypeScript/tsc/internal/tspath"
 	"gotest.tools/v3/assert"
 )
 
+func TestStandaloneSessionUsesSnapshotHostWithoutProjectSession(t *testing.T) {
+	t.Parallel()
+	if !bundled.Embedded {
+		t.Skip("bundled files are not embedded")
+	}
+
+	const configFileName = "/home/projects/p/tsconfig.json"
+	init, _ := projecttestutil.GetSessionInitOptions(map[string]any{
+		configFileName:                  `{ "compilerOptions": { "strict": true } }`,
+		"/home/projects/p/src/index.ts": `export const x = 1;`,
+	}, nil, &projecttestutil.TypingsInstallerOptions{})
+	session := NewStandaloneSession(init, nil)
+	defer session.Close()
+
+	firstResponse, err := session.handleUpdateSnapshot(context.Background(), &UpdateSnapshotParams{
+		OpenFiles: []DocumentIdentifier{{FileName: "/home/projects/p/src/index.ts"}},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, firstResponse.Snapshot, SnapshotID(1))
+	assert.Equal(t, len(firstResponse.Projects), 1)
+
+	response, err := session.handleUpdateSnapshot(context.Background(), &UpdateSnapshotParams{
+		OpenProjects: []DocumentIdentifier{{FileName: configFileName}},
+	})
+	assert.NilError(t, err)
+	assert.Equal(t, response.Snapshot, SnapshotID(2))
+
+	programResponse, err := session.handleCreateProgram(context.Background(), &CreateProgramParams{
+		RootFiles: []DocumentIdentifier{{FileName: "/home/projects/p/src/index.ts"}},
+		CreateProgramOptions: CreateProgramOptions{
+			CompilerOptions: core.CompilerOptions{NoLib: core.TSTrue},
+		},
+	})
+	assert.NilError(t, err)
+	assert.Assert(t, programResponse.Project != nil)
+	assert.Equal(t, programResponse.Snapshot, SnapshotID(4))
+}
+
 // TestSessionTracksAndReleasesAPIRefs verifies that an API session holds at most
 // one ref per opened project/file (opens are idempotent) and releases exactly
 // those refs when the session is closed, so it never leaks or over-releases refs
@@ -30,7 +69,8 @@ func TestSessionTracksAndReleasesAPIRefs(t *testing.T) {
 		}
 		projectSession, _ := projecttestutil.Setup(files)
 		defer projectSession.Close()
-		session := NewSession(projectSession, nil)
+		session := NewLSPSession(projectSession, nil)
+		assert.Assert(t, session.compatibilitySnapshot == nil)
 
 		_, err := session.handleUpdateSnapshot(context.Background(), &UpdateSnapshotParams{
 			OpenProjects: []DocumentIdentifier{{FileName: configFileName}},
@@ -63,7 +103,7 @@ func TestSessionTracksAndReleasesAPIRefs(t *testing.T) {
 		}
 		projectSession, _ := projecttestutil.Setup(files)
 		defer projectSession.Close()
-		session := NewSession(projectSession, nil)
+		session := NewLSPSession(projectSession, nil)
 		defer session.Close()
 
 		_, err := session.handleUpdateSnapshot(context.Background(), &UpdateSnapshotParams{
@@ -98,7 +138,7 @@ func TestSessionTracksAndReleasesAPIRefs(t *testing.T) {
 		}
 		projectSession, _ := projecttestutil.Setup(files)
 		defer projectSession.Close()
-		session := NewSession(projectSession, nil)
+		session := NewLSPSession(projectSession, nil)
 
 		_, err := session.handleUpdateSnapshot(context.Background(), &UpdateSnapshotParams{
 			OpenFiles: []DocumentIdentifier{{FileName: fileName}},
@@ -151,7 +191,7 @@ func TestSessionTracksAndReleasesAPIRefs(t *testing.T) {
 		}
 		projectSession, _ := projecttestutil.Setup(files)
 		defer projectSession.Close()
-		session := NewSession(projectSession, nil)
+		session := NewLSPSession(projectSession, nil)
 		defer session.Close()
 
 		// Open via a relative path; it should be tracked under the absolute path
@@ -230,7 +270,7 @@ func TestUpdateSnapshotResponseSkipsUnloadedAncestorProject(t *testing.T) {
 	assert.Assert(t, ancestorProject != nil)
 	assert.Assert(t, ancestorProject.CommandLine == nil)
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	response, err := session.handleUpdateSnapshot(context.Background(), &UpdateSnapshotParams{

tsc/internal/api/session_completion_test.go

@@ -38,7 +38,7 @@ func TestCompletionSymbolTypeIsResolvable(t *testing.T) {
 	}
 	projectSession, _ := projecttestutil.Setup(files)
 	defer projectSession.Close()
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	snapshotResp, err := session.handleUpdateSnapshot(t.Context(), &UpdateSnapshotParams{
@@ -110,7 +110,7 @@ func TestCompletionOnInferredProject(t *testing.T) {
 	}
 	projectSession, _ := projecttestutil.Setup(files)
 	defer projectSession.Close()
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	snapshotResp, err := session.handleUpdateSnapshot(t.Context(), &UpdateSnapshotParams{
@@ -156,7 +156,7 @@ func TestCompletionRetriesWithAutoImports(t *testing.T) {
 		IncludeCompletionsForImportStatements: core.TSTrue,
 	})
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	snapshotResp, err := session.handleUpdateSnapshot(t.Context(), &UpdateSnapshotParams{

tsc/internal/api/session_createprogram_test.go

@@ -21,7 +21,7 @@ func TestCreateProgram(t *testing.T) {
 	})
 	defer projectSession.Close()
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 	ctx := context.Background()
 
@@ -46,6 +46,7 @@ func TestCreateProgram(t *testing.T) {
 	})
 	assert.NilError(t, err)
 	assert.Assert(t, response.Snapshot != baseResponse.Snapshot)
+	assert.Equal(t, response.Snapshot, SnapshotID(4))
 	assert.Equal(t, session.latestSnapshot, baseResponse.Snapshot)
 	assert.Assert(t, response.Project != nil)
 	assert.DeepEqual(t, response.Project.RootFiles, []string{fileName})
@@ -118,7 +119,7 @@ func TestCreateProgramWithNoRootFiles(t *testing.T) {
 	projectSession, _ := projecttestutil.Setup(map[string]any{})
 	defer projectSession.Close()
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	response, err := session.handleCreateProgram(context.Background(), &CreateProgramParams{
@@ -138,6 +139,24 @@ func TestCreateProgramWithNoRootFiles(t *testing.T) {
 	assert.Equal(t, len(project.Program.GetSourceFiles()), 0)
 }
 
+func TestCreateProgramFileChangesRequireOldProgram(t *testing.T) {
+	t.Parallel()
+
+	projectSession, _ := projecttestutil.Setup(map[string]any{})
+	defer projectSession.Close()
+
+	session := NewLSPSession(projectSession, nil)
+	defer session.Close()
+
+	_, err := session.handleCreateProgram(context.Background(), &CreateProgramParams{
+		CreateProgramOptions: CreateProgramOptions{
+			CompilerOptions: core.CompilerOptions{NoLib: core.TSTrue},
+		},
+		FileChanges: &APIFileChanges{InvalidateAll: true},
+	})
+	assert.ErrorContains(t, err, "fileChanges requires an oldProgram")
+}
+
 func TestCreateProgramRemovesAllRootFiles(t *testing.T) {
 	t.Parallel()
 
@@ -147,7 +166,7 @@ func TestCreateProgramRemovesAllRootFiles(t *testing.T) {
 	})
 	defer projectSession.Close()
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 	ctx := context.Background()
 
@@ -196,7 +215,7 @@ func TestCreateProgramPreservesRootFileOrder(t *testing.T) {
 	})
 	defer projectSession.Close()
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 	ctx := context.Background()
 
@@ -236,7 +255,7 @@ func TestCreateProgramReusesProgram(t *testing.T) {
 	})
 	defer projectSession.Close()
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 	ctx := context.Background()
 
@@ -315,7 +334,7 @@ func TestCreateProgramProjectReferencesAndReuse(t *testing.T) {
 	})
 	defer projectSession.Close()
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 	ctx := context.Background()
 	libReference := &core.ProjectReference{Path: libConfigName, OriginalPath: libConfigName}
@@ -391,7 +410,7 @@ func TestCreateProgramFromConfiguredProgramDoesNotRetainOtherProjects(t *testing
 	})
 	defer projectSession.Close()
 
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 	ctx := context.Background()
 

tsc/internal/api/session_temporary_test.go

@@ -30,7 +30,7 @@ func TestUpdateTemporarySnapshot(t *testing.T) {
 	}
 	projectSession, _ := projecttestutil.Setup(files)
 	defer projectSession.Close()
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	ctx := context.Background()
@@ -114,7 +114,7 @@ func TestUpdateTemporarySnapshotAddsUnopenedFile(t *testing.T) {
 	}
 	projectSession, _ := projecttestutil.Setup(files)
 	defer projectSession.Close()
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	ctx := context.Background()
@@ -147,7 +147,7 @@ func TestUpdateTemporarySnapshotRejectsUnsupportedExtension(t *testing.T) {
 
 	projectSession, _ := projecttestutil.Setup(map[string]any{})
 	defer projectSession.Close()
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	ctx := context.Background()
@@ -176,7 +176,7 @@ func TestUpdateTemporarySnapshotUsesClientSnapshotAsBase(t *testing.T) {
 	}
 	projectSession, _ := projecttestutil.Setup(files)
 	defer projectSession.Close()
-	session := NewSession(projectSession, nil)
+	session := NewLSPSession(projectSession, nil)
 	defer session.Close()
 
 	ctx := context.Background()

tsc/internal/ipc/conn_async.go

@@ -32,6 +32,7 @@ type AsyncConn struct {
 	pendingMu sync.Mutex
 	terminal  error
 	writeMu   sync.Mutex
+	handlers  sync.WaitGroup
 }
 
 // NewAsyncConn creates a new async connection with the given transport and handler.
@@ -64,7 +65,12 @@ func (c *AsyncConn) SetCollectTiming(enabled bool) {
 // Run starts processing messages on the connection.
 // It blocks until the context is cancelled or an error occurs.
 func (c *AsyncConn) Run(ctx context.Context) (err error) {
-	defer func() { c.closePendingCalls(err) }()
+	handlerCtx, cancelHandlers := context.WithCancel(ctx)
+	defer func() {
+		c.closePendingCalls(err)
+		cancelHandlers()
+		c.handlers.Wait()
+	}()
 	for {
 		if ctx.Err() != nil {
 			return ctx.Err()
@@ -81,9 +87,13 @@ func (c *AsyncConn) Run(ctx context.Context) (err error) {
 		if msg.IsResponse() {
 			c.handleResponse(msg)
 		} else if msg.IsRequest() {
-			go c.handleRequest(ctx, msg)
+			c.handlers.Go(func() {
+				c.handleRequest(handlerCtx, msg)
+			})
 		} else if msg.IsNotification() {
-			go c.handleNotification(ctx, msg)
+			c.handlers.Go(func() {
+				c.handleNotification(handlerCtx, msg)
+			})
 		}
 	}
 }