fix(lsp): make transport recovery ownership-safe

packages/lsp/lsp-local/tests/connection.spec.ts

@@ -65,6 +65,12 @@ describe('LspConnection', () => {
     await expect(conn.request('textDocument/hover', {})).rejects.toThrow(/server refused the request/)
   })
 
+  it('treats signaling an already-closed child as a teardown race', async () => {
+    const conn = connectScript('')
+    await conn.closed
+    expect(() => { conn.kill() }).not.toThrow()
+  })
+
   it('answers a server workspace/configuration request from static config', async () => {
     const seen: SeenRequest[] = []
     const conn = connect(
@@ -272,23 +278,27 @@ describe('process-tree signaling', () => {
     expect(operations.signal).toHaveBeenCalledWith(-42, 'SIGKILL')
   })
 
-  it('falls back to the direct child and tolerates an already-dead child', () => {
+  it('surfaces a Windows taskkill failure without downgrading to the direct child', () => {
     const fallback = fakeProcessTreeOperations()
     vi.mocked(fallback.taskkill).mockImplementation(() => { throw new Error('taskkill unavailable') })
-    signalProcessTree('win32', 42, 'SIGTERM', fallback)
-    expect(fallback.killChild).toHaveBeenCalledWith('SIGTERM')
-
-    const gone = fakeProcessTreeOperations()
-    vi.mocked(gone.signal).mockImplementation(() => { throw new Error('group gone') })
-    vi.mocked(gone.killChild).mockImplementation(() => { throw new Error('child gone') })
-    expect(() => { signalProcessTree('linux', 42, 'SIGKILL', gone) }).not.toThrow()
+    expect(() => { signalProcessTree('win32', 42, 'SIGTERM', fallback) }).toThrow(/taskkill unavailable/)
+    expect(fallback.killChild).not.toHaveBeenCalled()
   })
 
-  it('runs taskkill for the full tree and rejects command failures', () => {
+  it('tolerates a POSIX tree-signaling race after the direct child is already gone', () => {
+    const posixGone = fakeProcessTreeOperations()
+    vi.mocked(posixGone.signal).mockImplementation(() => { throw new Error('group gone') })
+    vi.mocked(posixGone.killChild).mockImplementation(() => { throw new Error('child gone') })
+    expect(() => { signalProcessTree('linux', 42, 'SIGKILL', posixGone) }).not.toThrow()
+  })
+
+  it('runs taskkill for the full tree, accepts an absent tree, and rejects command failures', () => {
     const success: TaskkillRunner = vi.fn(() => ({ status: 0 }))
     taskkillProcessTree(42, success)
     expect(success).toHaveBeenCalledWith('taskkill', ['/PID', '42', '/T', '/F'], { stdio: 'ignore' })
 
+    expect(() => { taskkillProcessTree(42, () => ({ status: 128 })) }).not.toThrow()
+
     const spawnFailure = new Error('cannot spawn taskkill')
     expect(() => { taskkillProcessTree(42, () => ({ status: null, error: spawnFailure })) }).toThrow(spawnFailure)
     expect(() => { taskkillProcessTree(42, () => ({ status: 1 })) }).toThrow(/status 1/)

packages/lsp/lsp-local/tests/instance.spec.ts

@@ -216,6 +216,17 @@ describe('LspInstance query and abort', () => {
     expect(instance.dead).toBe(true)
   })
 
+  it('awaits process exit before rejecting a request write failure', async () => {
+    const instance = makeInstance({}, {
+      shutdownTimeoutMs: 100,
+      killGraceMs: 100,
+    }, failingWriter('textDocument/definition'))
+    // The pid is observed only to prove the owned subprocess reached quiescence before rejection.
+    const pid = (instance as unknown as { connection: { pid: number } }).connection.pid
+    await expect(run(instance, 'goToDefinition')).rejects.toThrow(/fixture textDocument\/definition failure/)
+    expect(processAlive(pid)).toBe(false)
+  })
+
   it('rejects when the server lacks the operation capability', async () => {
     const instance = makeInstance({ LSP_FAKE_CAPS: JSON.stringify({ definitionProvider: false }), LSP_FAKE_DEF: 'null' })
     await expect(run(instance, 'goToDefinition')).rejects.toThrow(/does not support goToDefinition/)

packages/lsp/lsp-local/tests/lifecycle.spec.ts

@@ -122,9 +122,15 @@ describe('lsp-local end to end over a fake server', () => {
     await ctx.fiber.dispose()
   })
 
-  it('rejects a non-utf-16 position encoding at initialize', async () => {
-    const ctx = await mount({ LSP_FAKE_ENCODING: 'utf-8', LSP_FAKE_DEF: 'null' })
+  it('rejects a non-utf-16 position encoding at initialize without retrying', async () => {
+    const marker = join(root, 'initialize-rejection-exit.log')
+    const ctx = await mount({
+      LSP_FAKE_ENCODING: 'utf-8',
+      LSP_FAKE_DEF: 'null',
+      LSP_FAKE_EXIT_MARKER: marker,
+    })
     await expect(ctx.lsp.query(query('goToDefinition'))).rejects.toThrow(/unsupported position encoding/)
+    expect(await readFile(marker, 'utf8')).toBe('EXIT\nCLEAN\n')
     await ctx.fiber.dispose()
   })