fix(windows): restore LSP and TUI coverage

packages/lsp/lsp-local/README.md

@@ -7,9 +7,10 @@ Namespace plugin (`name` / `inject` / `Config` / `apply`, no default export).
 ## What it does
 
 - Resolves every server-local setting before registration; an invalid mapping or registration conflict rolls back earlier entries, so a failed load leaves no provider routes.
-- Lazily single-flights one server process per `(server id, canonical workspace realpath)`. A crash fails the active query without replay; a later query may replace the process.
+- Lazily single-flights one server process per `(server id, canonical workspace realpath)`. A live server error is not replayed; if the transport becomes dead between the pool's liveness check and a read-only query, the provider evicts it and retries that query once on a fresh process.
 - Uses a compatibility-first **transient-open** sequence per query: canonicalize and read the source with Node APIs, `textDocument/didOpen` (version 1, full text), the requested request, then `textDocument/didClose` in `finally`. A failed or canceled `didOpen` write terminates the instance before the pool can reuse it. Documents close after each call, so the first version needs no `didChange`, content cache, or document LRU.
 - Serializes each source-read/open/query/close lifecycle through one abortable per-workspace queue so queued calls read current source only when their turn starts; distinct workspaces run in parallel.
+- After protocol shutdown fails, terminates the server's descendant tree through POSIX process-group signaling or synchronous Windows `taskkill /T /F`, with a direct-child fallback for teardown races.
 - Reads sources through Node filesystem APIs in the subprocess's host namespace — NOT `ctx.fs`, and emits no `fs/observed`: only the LSP result is model-visible, so a query does not satisfy read-before-write policy.
 
 ## Configuration

packages/lsp/lsp-local/src/connection.ts

@@ -8,7 +8,7 @@
  */
 
 import type { ChildProcessByStdio } from 'node:child_process'
-import { spawn } from 'node:child_process'
+import { spawn, spawnSync } from 'node:child_process'
 import type { Readable, Writable } from 'node:stream'
 import { setImmediate as yieldToEventLoop } from 'node:timers/promises'
 import { encodeMessage, MessageDecoder } from './framing.ts'
@@ -36,6 +36,105 @@ interface Pending {
   reject: (error: Error) => void
 }
 
+/**
+ * Write one JSON-RPC message to the child stdin.
+ * @param stdin - the spawned server stdin.
+ * @param message - the unencoded JSON-RPC message.
+ * @param done - callback that reports asynchronous stream settlement.
+ */
+export type ConnectionWriter = (
+  stdin: Writable,
+  message: unknown,
+  done: (error?: Error | null) => void,
+) => void
+
+/** Host operations used to signal a detached process tree. */
+export interface ProcessTreeOperations {
+  /** Signal a POSIX process group. */
+  readonly signal: (target: number, signal: NodeJS.Signals) => void
+  /** Signal the direct child when group/tree signalling is unavailable. */
+  readonly killChild: (signal: NodeJS.Signals) => void
+  /** Terminate a Windows process tree by root pid. */
+  readonly taskkill: (pid: number) => void
+}
+
+/** Narrow taskkill runner result used by the Windows process-tree adapter. */
+export interface TaskkillResult {
+  /** Process exit status, or null when spawning failed. */
+  readonly status: number | null
+  /** Spawn failure, when the executable could not run. */
+  readonly error?: Error
+}
+
+/** Invoke a command synchronously for the Windows taskkill adapter. */
+export type TaskkillRunner = (
+  command: string,
+  args: string[],
+  options: { stdio: 'ignore' },
+) => TaskkillResult
+
+/** Invoke the host process-signal primitive for a POSIX process group. */
+export type ProcessSignalRunner = (target: number, signal: NodeJS.Signals) => boolean
+
+const processSignalRunner: ProcessSignalRunner = process.kill.bind(process)
+
+const writeConnectionMessage: ConnectionWriter = (stdin, message, done) => {
+  stdin.write(encodeMessage(message), done)
+}
+
+/**
+ * Terminate one Windows process tree and wait for taskkill to finish.
+ * @param pid - root process id.
+ * @param run - command runner; tests inject results without requiring Windows.
+ */
+export function taskkillProcessTree(
+  pid: number,
+  run: TaskkillRunner = spawnSync,
+): void {
+  const result = run('taskkill', ['/PID', String(pid), '/T', '/F'], { stdio: 'ignore' })
+  if (result.error !== undefined) throw result.error
+  if (result.status !== 0) throw new Error(`taskkill exited with status ${String(result.status)}`)
+}
+
+/**
+ * Signal one POSIX process group through an injectable host primitive.
+ * @param target - negative process-group id.
+ * @param signal - requested signal.
+ * @param run - host signal runner; tests inject it without touching real processes.
+ */
+export function signalProcessGroup(
+  target: number,
+  signal: NodeJS.Signals,
+  run: ProcessSignalRunner = processSignalRunner,
+): void {
+  run(target, signal)
+}
+
+/**
+ * Signal a detached process tree with platform-correct semantics and a direct-child fallback.
+ * @param platform - host platform.
+ * @param pid - detached root process id.
+ * @param signal - requested termination signal.
+ * @param operations - host operations.
+ */
+export function signalProcessTree(
+  platform: NodeJS.Platform,
+  pid: number,
+  signal: NodeJS.Signals,
+  operations: ProcessTreeOperations,
+): void {
+  try {
+    if (platform === 'win32') operations.taskkill(pid)
+    else operations.signal(-pid, signal)
+  } catch {
+    try {
+      operations.killChild(signal)
+    } catch {
+      // The direct child already exited; teardown remains idempotent.
+    }
+  }
+}
+
 /** A live JSON-RPC endpoint bound to one child process. */
 export class LspConnection {
   private readonly child: ChildProcessByStdio<Writable, Readable, Readable>
@@ -50,14 +149,16 @@ export class LspConnection {
   /**
    * @param spec - how to launch the server and answer its config requests.
    * @param onServerRequest - answers a server→client request; rejects to send an error response.
+   * @param writer - message writer; tests inject callback failures without relying on OS pipe races.
    */
   constructor(
     private readonly spec: ConnectionSpec,
     private readonly onServerRequest: (method: string, params: unknown) => Promise<unknown>,
+    private readonly writer: ConnectionWriter = writeConnectionMessage,
   ) {
     this.decoder = new MessageDecoder(spec.maxMessageBytes)
-    // `detached` puts the server in its own process group so teardown can signal the WHOLE group
-    // (via `process.kill(-pid)`), reaching helper processes a language server spawns (e.g. tsserver).
+    // `detached` gives teardown a process-tree root: POSIX signals its negative process-group id,
+    // while Windows passes the root pid to taskkill /T so helpers such as tsserver cannot outlive it.
     this.child = spawn(spec.command, [...spec.args], {
       cwd: spec.cwd,
       env: spec.env,
@@ -94,6 +195,11 @@ export class LspConnection {
     return this.stderr.toString('utf8')
   }
 
+  /** Whether the transport has failed even if the child close event has not arrived yet. */
+  get failed(): boolean {
+    return this.closeReason !== undefined
+  }
+
   /**
    * Send a request and await its result.
    * @param method - the JSON-RPC method.
@@ -147,23 +253,23 @@ export class LspConnection {
     return this.nextId
   }
 
-  /** Send SIGTERM to the server's process group (idempotent-safe; a dead group ignores it). */
+  /** Request termination of the server's process tree. */
   terminate(): void {
-    this.signalGroup('SIGTERM')
+    this.signalTree('SIGTERM')
   }
 
-  /** Send SIGKILL to the server's process group. */
+  /** Force termination of the server's process tree. */
   kill(): void {
-    this.signalGroup('SIGKILL')
+    this.signalTree('SIGKILL')
   }
 
   /**
-   * Wait until the owned process group has no members.
+   * Wait until the owned process tree has exited.
    * @param signal - optional bound for the wait.
-   * @returns `true` when the group exited, or `false` when the signal aborted first.
+   * @returns `true` when the tree exited, or `false` when the signal aborted first.
    */
-  async waitForProcessGroupExit(signal?: AbortSignal): Promise<boolean> {
-    while (this.processGroupAlive()) {
+  async waitForProcessTreeExit(signal?: AbortSignal): Promise<boolean> {
+    while (this.processTreeAlive()) {
       if (signal?.aborted) return false
       await yieldToEventLoop()
     }
@@ -171,26 +277,21 @@ export class LspConnection {
   }
 
   /**
-   * Signal the whole process group (negative pid) so helper processes are reached; fall back to the
-   * direct child if the group send fails. Never throws — teardown races process exit.
+   * Signal the whole process tree so helper processes are reached; fall back to the direct child if
+   * tree signaling fails. Never throws because teardown races process exit.
    */
-  private signalGroup(sig: NodeJS.Signals): void {
+  private signalTree(sig: NodeJS.Signals): void {
     const pid = this.child.pid
     if (pid === undefined) return
-    try {
-      process.kill(-pid, sig)
-    } catch {
-      // The group is gone (already exited) or could not be signalled; try the direct child.
-      try {
-        this.child.kill(sig)
-      } catch {
-        // Already dead; nothing to signal.
-      }
-    }
+    signalProcessTree(process.platform, pid, sig, {
+      signal: signalProcessGroup,
+      killChild: this.child.kill.bind(this.child),
+      taskkill: taskkillProcessTree,
+    })
   }
 
-  /** Whether the detached process group still has at least one member. */
-  private processGroupAlive(): boolean {
+  /** Whether the detached tree's root or POSIX process group is still alive. */
+  private processTreeAlive(): boolean {
     const pid = this.child.pid
     /* v8 ignore next -- only an asynchronous spawn failure omits pid; its close path owns cleanup. */
     if (pid === undefined) return false
@@ -218,7 +319,7 @@ export class LspConnection {
       // A framing/JSON failure corrupts the stream position irrecoverably: fail the instance and
       // SIGKILL the whole group so helper processes don't outlive the leader.
       this.fail(asError(error))
-      this.signalGroup('SIGKILL')
+      this.signalTree('SIGKILL')
       return
     }
     for (const message of messages) this.dispatch(message)
@@ -293,7 +394,7 @@ export class LspConnection {
         reject(error)
       }
       try {
-        this.child.stdin.write(encodeMessage(message), done)
+        this.writer(this.child.stdin, message, done)
       /* v8 ignore start -- Node stream write failures are callback-delivered; this guards a
          nonconforming Writable implementation throwing synchronously. */
       } catch (error) {

packages/lsp/lsp-local/src/index.ts

@@ -2,9 +2,9 @@
  * Generic stdio language-server backend for `ctx.lsp`. One plugin instance configures a named table
  * of server commands and registers one isolated provider for each entry. Every provider lazily
  * single-flights one server process per canonical workspace realpath, serves transient-open queries
- * through it, and evicts a crashed process so a later query can replace it. Providers read sources
- * through Node APIs in the host namespace (not `ctx.fs`) and trust their configured servers — no
- * sandbox confinement.
+ * through it, and replaces a transport that dies between a pool liveness check and the next
+ * read-only query. Providers read sources through Node APIs in the host namespace (not `ctx.fs`)
+ * and trust their configured servers — no sandbox confinement.
  *
  * Namespace plugin (named exports, no default export). Lifecycle is effect-scoped: disposal
  * unregisters from `ctx.lsp` and tears down every live server.
@@ -227,6 +227,14 @@ class LocalLspProvider implements LspProvider {
       }
       try {
         return await instance.query(request, source, signal)
+      } catch (error) {
+        // A child can die after the pre-query liveness check but before or during the next write.
+        // Queries are read-only, so replace a newly failed transport once and retry transparently.
+        if (!instance.dead) throw error
+        this.evictIfCurrent(workspace, instance)
+        this.assertActive(signal)
+        instance = this.instanceFor(workspace)
+        return await instance.query(request, source, signal)
       } finally {
         // Drop a crashed slot only when it still owns this instance; a replacement must survive.
         if (instance.dead) this.evictIfCurrent(workspace, instance)

packages/lsp/lsp-local/src/instance.ts

@@ -17,7 +17,7 @@ import type {
 import { deadline } from '@deepseek-ai/dsh-timeout'
 import { abortable, abortError } from './abort.ts'
 import { LspConnection } from './connection.ts'
-import type { ConnectionSpec } from './connection.ts'
+import type { ConnectionSpec, ConnectionWriter } from './connection.ts'
 import type { HostSource } from './host.ts'
 import type { WireInitializeResult, WireServerCapabilities } from './protocol.ts'
 import {
@@ -58,9 +58,10 @@ export class LspInstance {
 
   /**
    * @param spec - the launch, initialize, and teardown parameters.
+   * @param writer - optional connection writer used by transport conformance tests.
    */
-  constructor(private readonly spec: InstanceSpec) {
-    this.connection = new LspConnection(spec, (method, params) => this.answerServerRequest(method, params))
+  constructor(private readonly spec: InstanceSpec, writer?: ConnectionWriter) {
+    this.connection = new LspConnection(spec, (method, params) => this.answerServerRequest(method, params), writer)
     this.ready = this.initialize()
     // A handshake rejection must not surface as an unhandled rejection before the first query awaits
     // it; queries attach the real handler.
@@ -70,7 +71,7 @@ export class LspInstance {
 
   /** Synchronous liveness check: true once the process has closed or the instance was disposed. */
   get dead(): boolean {
-    return this.processClosed || this.disposed
+    return this.processClosed || this.disposed || this.connection.failed
   }
 
   /**
@@ -272,7 +273,7 @@ export class LspInstance {
     try {
       await this.gracefulShutdown(shutdownDeadline.signal)
     } catch {
-      // Graceful shutdown failed or timed out; process-group cleanup below remains authoritative.
+      // Graceful shutdown failed or timed out; process-tree cleanup below remains authoritative.
     } finally {
       shutdownDeadline[Symbol.dispose]()
     }
@@ -286,20 +287,20 @@ export class LspInstance {
     await abortable(this.connection.closed, signal)
   }
 
-  /** SIGTERM the group, escalate after `killGraceMs`, then await leader and helper exit. */
+  /** Terminate the tree, escalate after `killGraceMs`, then await leader and helper exit. */
   private async forceTerminate(): Promise<void> {
     this.connection.terminate()
     const graceDeadline = deadline(undefined, this.spec.killGraceMs, 'LSP_KILL_GRACE')
-    let groupExited: boolean
+    let treeExited: boolean
     try {
-      groupExited = await this.connection.waitForProcessGroupExit(graceDeadline.signal)
+      treeExited = await this.connection.waitForProcessTreeExit(graceDeadline.signal)
     } finally {
       graceDeadline[Symbol.dispose]()
     }
-    if (!groupExited) this.connection.kill()
+    if (!treeExited) this.connection.kill()
     await Promise.all([
       this.connection.closed,
-      this.connection.waitForProcessGroupExit(),
+      this.connection.waitForProcessTreeExit(),
     ])
   }
 }

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

@@ -1,6 +1,17 @@
-import { afterEach, describe, expect, it } from 'vitest'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 import { fileURLToPath } from 'node:url'
 import { LspConnection } from '@deepseek-ai/dsh-lsp-local'
+import {
+  signalProcessGroup,
+  signalProcessTree,
+  taskkillProcessTree,
+} from '@deepseek-ai/dsh-lsp-local/src/connection.ts'
+import type {
+  ConnectionWriter,
+  ProcessSignalRunner,
+  ProcessTreeOperations,
+  TaskkillRunner,
+} from '@deepseek-ai/dsh-lsp-local/src/connection.ts'
 
 const fixtureServer = fileURLToPath(new URL('./fixture-server.ts', import.meta.url))
 
@@ -125,7 +136,7 @@ describe('LspConnection', () => {
 })
 
 /** Spawn a raw connection running an inline node script as the "server". */
-function connectScript(script: string, maxStderrBytes = 100_000): LspConnection {
+function connectScript(script: string, maxStderrBytes = 100_000, writer?: ConnectionWriter): LspConnection {
   const conn = new LspConnection({
     command: process.execPath,
     args: ['-e', script],
@@ -134,7 +145,7 @@ function connectScript(script: string, maxStderrBytes = 100_000): LspConnection
     maxMessageBytes: 16_000_000,
     maxStderrBytes,
     configuration: null,
-  }, () => Promise.resolve(null))
+  }, () => Promise.resolve(null), writer)
   open.push(conn)
   return conn
 }
@@ -209,13 +220,13 @@ describe('LspConnection edge behavior', () => {
     await expect(conn.request('initialize', {})).rejects.toThrow(/exited|closed/)
   })
 
-  it.skipIf(process.platform === 'win32')('rejects a pending request when child stdin closes but the process stays alive', async () => {
-    const conn = connectScript('const stdin=process.stdin; require("node:fs").closeSync(0); stdin._handle?.close(); setInterval(()=>{}, 1000)')
-    await new Promise<void>(resolve => setTimeout(resolve, 100))
-    const timeout = new Promise<never>((_resolve, reject) => {
-      setTimeout(() => { reject(new Error('request timed out')) }, 1000)
-    })
-    await expect(Promise.race([conn.request('initialize', {}), timeout])).rejects.not.toThrow(/timed out/)
+  it('rejects a pending request when child stdin fails but the process stays alive', async () => {
+    const failure = new Error('fixture stdin failure')
+    const writer: ConnectionWriter = (_stdin, _message, done) => {
+      queueMicrotask(() => { done(failure) })
+    }
+    const conn = connectScript('setInterval(()=>{}, 1000)', 100_000, writer)
+    await expect(conn.request('initialize', {})).rejects.toThrow(/fixture stdin failure/)
   })
 
   it('ignores a frame that is neither a valid request nor a numeric-id response', async () => {
@@ -230,6 +241,55 @@ describe('LspConnection edge behavior', () => {
   })
 })
 
+describe('process-tree signaling', () => {
+  it('forwards POSIX process-group signals through the host runner', () => {
+    const run: ProcessSignalRunner = vi.fn(() => true)
+    signalProcessGroup(-42, 'SIGKILL', run)
+    expect(run).toHaveBeenCalledWith(-42, 'SIGKILL')
+  })
+
+  it('uses taskkill for a Windows tree and a negative pid for a POSIX group', () => {
+    const operations = fakeProcessTreeOperations()
+    signalProcessTree('win32', 42, 'SIGTERM', operations)
+    expect(operations.taskkill).toHaveBeenCalledWith(42)
+    expect(operations.signal).not.toHaveBeenCalled()
+
+    signalProcessTree('linux', 42, 'SIGKILL', operations)
+    expect(operations.signal).toHaveBeenCalledWith(-42, 'SIGKILL')
+  })
+
+  it('falls back to the direct child and tolerates an already-dead 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()
+  })
+
+  it('runs taskkill for the full 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' })
+
+    const spawnFailure = new Error('cannot spawn taskkill')
+    expect(() => { taskkillProcessTree(42, () => ({ status: null, error: spawnFailure })) }).toThrow(spawnFailure)
+    expect(() => { taskkillProcessTree(42, () => ({ status: 1 })) }).toThrow(/status 1/)
+  })
+})
+
+/** Create observable process-tree operations without touching host processes. */
+function fakeProcessTreeOperations(): ProcessTreeOperations {
+  return {
+    signal: vi.fn(),
+    killChild: vi.fn(),
+    taskkill: vi.fn(),
+  }
+}
+
 /** Poll a predicate until it holds or a deadline elapses. */
 async function waitFor(predicate: () => boolean, timeoutMs = 3000): Promise<void> {
   const start = Date.now()

packages/lsp/lsp-local/tests/fixture-server.ts

@@ -16,8 +16,6 @@
  * - LSP_FAKE_OPEN_MARKER: appends each didOpen document text as one JSON line to this path.
  * - LSP_FAKE_INITIALIZED_MARKER: records when the initialized notification is received.
  * - LSP_FAKE_PAUSE_STDIN_AFTER_INITIALIZED: "1" stops consuming stdin after initialized.
- * - LSP_FAKE_CLOSE_STDIN_AFTER_INITIALIZED: "1" closes the stdin pipe after initialization.
- * - LSP_FAKE_CLOSE_STDIN_AFTER_REPLY: "1" closes the stdin pipe before the first query response.
  * - LSP_FAKE_EXIT_DELAY_MS / LSP_FAKE_EXIT_MARKER: delay protocol exit and record exit/termination.
  * - LSP_FAKE_NO_SHUTDOWN: "1" ignores the shutdown request (forces kill escalation).
  * - LSP_FAKE_ON_OPEN: server→client request to emit when a didOpen arrives, one of
@@ -28,7 +26,7 @@
  * Run: node fixture-server.ts (Node's erasable TypeScript syntax support).
  */
 
-import { appendFileSync, closeSync } from 'node:fs'
+import { appendFileSync } from 'node:fs'
 
 const enc = process.env.LSP_FAKE_ENCODING ?? 'utf-16'
 const sync: unknown = process.env.LSP_FAKE_SYNC !== undefined ? JSON.parse(process.env.LSP_FAKE_SYNC) : 1
@@ -40,8 +38,6 @@ const replyDelayMs = Number(process.env.LSP_FAKE_REPLY_DELAY_MS ?? 0)
 const openMarker = process.env.LSP_FAKE_OPEN_MARKER
 const initializedMarker = process.env.LSP_FAKE_INITIALIZED_MARKER
 const pauseStdinAfterInitialized = process.env.LSP_FAKE_PAUSE_STDIN_AFTER_INITIALIZED === '1'
-const closeStdinAfterInitialized = process.env.LSP_FAKE_CLOSE_STDIN_AFTER_INITIALIZED === '1'
-const closeStdinAfterReply = process.env.LSP_FAKE_CLOSE_STDIN_AFTER_REPLY === '1'
 const exitDelayMs = Number(process.env.LSP_FAKE_EXIT_DELAY_MS ?? 0)
 const exitMarker = process.env.LSP_FAKE_EXIT_MARKER
 const noShutdown = process.env.LSP_FAKE_NO_SHUTDOWN === '1'
@@ -146,14 +142,12 @@ function handle(message: { id?: number; method?: string; params?: unknown; resul
   if (method === 'initialized') {
     if (initializedMarker !== undefined) appendFileSync(initializedMarker, 'INITIALIZED\n')
     if (pauseStdinAfterInitialized) process.stdin.pause()
-    if (closeStdinAfterInitialized) closeStdinPipe()
     return
   }
   if (method === 'textDocument/didClose') return
   if (method?.startsWith('textDocument/')) {
     if (hang) return
     const reply = (): void => {
-      if (closeStdinAfterReply) closeStdinPipe()
       if (errorReply) {
         send({ id, error: { code: -32000, message: 'server refused the request' } })
       } else {
@@ -171,13 +165,6 @@ function handle(message: { id?: number; method?: string; params?: unknown; resul
   if (id !== undefined) send({ id, result: null })
 }
 
-/** Close both the CRT descriptor and libuv handle that can own a platform's child-stdin pipe. */
-function closeStdinPipe(): void {
-  const stdin = process.stdin as NodeJS.ReadStream & { _handle?: { close(): void } }
-  closeSync(0)
-  stdin._handle?.close()
-}
-
 /** Append one teardown event when the fixture is configured to expose process ordering. */
 function markExit(event: string): void {
   if (exitMarker !== undefined) appendFileSync(exitMarker, `${event}\n`)
@@ -209,6 +196,6 @@ function send(message: Record<string, unknown>): void {
 
 // Keep the event loop alive.
 process.stdin.resume()
-if (pauseStdinAfterInitialized || closeStdinAfterInitialized || closeStdinAfterReply) {
+if (pauseStdinAfterInitialized) {
   setInterval(() => {}, 1000)
 }

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

@@ -4,6 +4,8 @@ import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { pathToFileURL, fileURLToPath } from 'node:url'
 import { LspInstance, readHostSource } from '@deepseek-ai/dsh-lsp-local'
+import { encodeMessage } from '@deepseek-ai/dsh-lsp-local'
+import type { ConnectionWriter } from '@deepseek-ai/dsh-lsp-local/src/connection.ts'
 import type { InstanceSpec } from '@deepseek-ai/dsh-lsp-local/src/instance.ts'
 import type { LspProviderQuery, LspQueryResult } from '@deepseek-ai/dsh-lsp'
 
@@ -26,7 +28,11 @@ afterEach(async () => {
   await rm(root, { recursive: true, force: true })
 })
 
-function makeInstance(env: Record<string, string> = {}, overrides: Partial<InstanceSpec> = {}): LspInstance {
+function makeInstance(
+  env: Record<string, string> = {},
+  overrides: Partial<InstanceSpec> = {},
+  writer?: ConnectionWriter,
+): LspInstance {
   const instance = new LspInstance({
     command: process.execPath,
     args: [fixtureServer],
@@ -39,7 +45,7 @@ function makeInstance(env: Record<string, string> = {}, overrides: Partial<Insta
     shutdownTimeoutMs: 200,
     killGraceMs: 200,
     ...overrides,
-  })
+  }, writer)
   live.push(instance)
   return instance
 }
@@ -200,14 +206,11 @@ describe('LspInstance query and abort', () => {
     expect(instance.dead).toBe(true)
   })
 
-  it.skipIf(process.platform === 'win32')('terminates when stdin fails during the didOpen write', async () => {
-    // Closing stdin after initialized makes a large didOpen fail before `opened` can arm didClose;
-    // the instance must still become dead so its provider can replace it.
-    await writeFile(join(ws, 'a.ts'), 'x'.repeat(2_000_000))
-    const instance = makeInstance({ LSP_FAKE_CLOSE_STDIN_AFTER_INITIALIZED: '1' }, {
+  it('terminates when stdin fails during the didOpen write', async () => {
+    const instance = makeInstance({}, {
       shutdownTimeoutMs: 100,
       killGraceMs: 100,
-    })
+    }, failingWriter('textDocument/didOpen'))
     await expect(run(instance, 'goToDefinition')).rejects.toThrow()
     expect(instance.dead).toBe(true)
   })
@@ -225,11 +228,10 @@ describe('LspInstance query and abort', () => {
     await expect(run(instance, 'goToDefinition', controller.signal)).rejects.toThrow(/server refused/)
   })
 
-  it.skipIf(process.platform === 'win32')('keeps a settled result but awaits teardown when didClose cannot be written', async () => {
+  it('keeps a settled result but awaits teardown when didClose cannot be written', async () => {
     const instance = makeInstance({
       LSP_FAKE_DEF: 'null',
-      LSP_FAKE_CLOSE_STDIN_AFTER_REPLY: '1',
-    }, { shutdownTimeoutMs: 100, killGraceMs: 100 })
+    }, { shutdownTimeoutMs: 100, killGraceMs: 100 }, failingWriter('textDocument/didClose'))
     await expect(run(instance, 'goToDefinition')).resolves.toEqual({
       kind: 'locations',
       locations: [],
@@ -281,7 +283,7 @@ describe('LspInstance disposal', () => {
     await expect(instance.dispose()).resolves.toBeUndefined()
   })
 
-  it.skipIf(process.platform === 'win32')('awaits a surviving process-group helper on every concurrent dispose', async () => {
+  it('awaits a surviving process-tree helper on every concurrent dispose', async () => {
     const marker = join(root, 'helper.pid')
     const helper = 'process.on("SIGTERM",()=>{});setInterval(()=>{},1000);'
     const script = 'const{spawn}=require("node:child_process");const{writeFileSync}=require("node:fs");'
@@ -298,6 +300,7 @@ describe('LspInstance disposal', () => {
       await first
     } finally {
       if (processAlive(helperPid)) process.kill(helperPid, 'SIGKILL')
+      await waitForProcessExit(helperPid)
     }
   })
 
@@ -322,6 +325,26 @@ function processAlive(pid: number): boolean {
   }
 }
 
+/** Wait until a process id disappears so temporary-workspace cleanup cannot race handle release. */
+async function waitForProcessExit(pid: number, timeoutMs = 3_000): Promise<void> {
+  const started = Date.now()
+  while (processAlive(pid)) {
+    if (Date.now() - started > timeoutMs) throw new Error(`process ${pid} did not exit`)
+    await new Promise<void>(resolve => setTimeout(resolve, 10))
+  }
+}
+
+/** Write normally except for one method whose callback receives a deterministic transport error. */
+function failingWriter(method: string): ConnectionWriter {
+  return (stdin, message, done) => {
+    if ((message as { method?: unknown }).method === method) {
+      queueMicrotask(() => { done(new Error(`fixture ${method} failure`)) })
+      return
+    }
+    stdin.write(encodeMessage(message), done)
+  }
+}
+
 /** Wait until a fixture marker exists, bounded so a broken handshake cannot hang the test. */
 async function waitForFile(path: string, timeoutMs = 3000): Promise<void> {
   const started = Date.now()

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

@@ -237,7 +237,7 @@ describe('lsp-local end to end over a fake server', () => {
     await ctx.fiber.dispose()
   })
 
-  it.skipIf(process.platform === 'win32')('evicts a pooled server that died while idle and serves the next query from a fresh one', async () => {
+  it('evicts a pooled server that died while idle and serves the next query from a fresh one', async () => {
     // The first query succeeds, then the server exits before the second arrives, leaving a dead
     // instance in the pool. The next query must evict-and-replace it and still succeed, rather than
     // failing once on the closed connection first.

packages/ui/tui/tests/tui.spec.ts

@@ -198,7 +198,7 @@ describe('pi-tui chat lifecycle and transcript', () => {
     await dispose(result)
   })
 
-  it.skipIf(process.platform === 'win32')('renders its header, footer, replay, streaming answer, todos, and status', async () => {
+  it('renders its header, footer, replay, streaming answer, todos, and status', async () => {
     let now = 0
     const result = await setup({
       contextWindow: 100,
@@ -320,7 +320,9 @@ describe('pi-tui chat lifecycle and transcript', () => {
       { inputTokens: 500, outputTokens: 8 },
       { turn: 3, step: 1 },
     )
-    await tick()
+    await vi.waitFor(() => {
+      expect(result.terminal.output).toContain('final live answer')
+    })
 
     expect(result.terminal.output).toContain('◒ Working · 8s')
     expect(result.terminal.output).toContain('esc interrupt')
@@ -328,7 +330,6 @@ describe('pi-tui chat lifecycle and transcript', () => {
     expect(result.terminal.output).toContain('user context')
     expect(result.terminal.output).toContain('Prompt blocked')
     expect(result.terminal.output).toContain('Turn cancelled')
-    expect(result.terminal.output).toContain('final live answer')
     expect(result.terminal.progress).toContain(true)
 
     result.session.append('assistant/chunk', {