diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index c69de1d93b..edfff29ac9 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -6,6 +6,12 @@ on:
       - dev
   pull_request:
   workflow_dispatch:
+    inputs:
+      windows_opentui_repro:
+        description: "Run targeted Windows OpenTUI standalone crash repro"
+        required: false
+        type: boolean
+        default: false
 
 concurrency:
   # Keep every run on dev so cancelled checks do not pollute the default branch
@@ -22,6 +28,7 @@ env:
 
 jobs:
   unit:
+    if: ${{ github.event_name != 'workflow_dispatch' || inputs.windows_opentui_repro != true }}
     name: unit (${{ matrix.settings.name }})
     strategy:
       fail-fast: false
@@ -80,6 +87,7 @@ jobs:
         run: bun run test:httpapi
 
   e2e:
+    if: ${{ github.event_name != 'workflow_dispatch' || inputs.windows_opentui_repro != true }}
     name: e2e (${{ matrix.settings.name }})
     strategy:
       fail-fast: false
@@ -149,3 +157,85 @@ jobs:
           path: |
             packages/app/e2e/test-results
             packages/app/e2e/playwright-report
+
+  windows-opentui-repro:
+    if: ${{ github.event_name == 'workflow_dispatch' && inputs.windows_opentui_repro == true }}
+    name: windows opentui repro (${{ matrix.name }}, ${{ matrix.version }}, ${{ matrix.host }})
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - version: "1.17.9"
+            host: windows-latest
+            name: baseline
+            markdownLoops: 1
+            onlyMarkdown: false
+          - version: "1.17.9"
+            host: windows-latest
+            name: markdown-stress
+            markdownLoops: 10
+            onlyMarkdown: true
+          - version: "1.17.10"
+            host: windows-latest
+            name: baseline
+            markdownLoops: 1
+            onlyMarkdown: false
+          - version: "1.17.10"
+            host: windows-latest
+            name: markdown-stress
+            markdownLoops: 10
+            onlyMarkdown: true
+          - version: "1.17.11"
+            host: windows-latest
+            name: baseline
+            markdownLoops: 1
+            onlyMarkdown: false
+          - version: "1.17.11"
+            host: windows-latest
+            name: markdown-stress
+            markdownLoops: 10
+            onlyMarkdown: true
+          - version: "1.17.10"
+            host: windows-2022
+            name: baseline
+            markdownLoops: 1
+            onlyMarkdown: false
+    runs-on: ${{ matrix.host }}
+    defaults:
+      run:
+        shell: pwsh
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Setup Node
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
+        with:
+          node-version: "24.11.1"
+
+      - name: Run Windows standalone repro
+        timeout-minutes: 30
+        run: |
+          $reproArgs = @{
+            Version = "${{ matrix.version }}"
+            MarkdownLoops = ${{ matrix.markdownLoops }}
+          }
+          if ("${{ matrix.onlyMarkdown }}" -eq "true") {
+            $reproArgs.OnlyMarkdown = $true
+          }
+          ./script/repro-windows-opentui-crash.ps1 @reproArgs
+
+      - name: Upload Windows repro artifacts
+        if: always()
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: windows-opentui-repro-${{ matrix.name }}-${{ matrix.version }}-${{ matrix.host }}-${{ github.run_attempt }}
+          if-no-files-found: ignore
+          retention-days: 7
+          path: |
+            ${{ runner.temp }}/opencode-windows-opentui-${{ matrix.version }}/**/*.log
+            ${{ runner.temp }}/opencode-windows-opentui-${{ matrix.version }}/**/*.jsonl
+            ${{ runner.temp }}/*.out.log
+            ${{ runner.temp }}/*.err.log
diff --git a/packages/tui/src/routes/session/index.tsx b/packages/tui/src/routes/session/index.tsx
index f832174aa4..47dc19dbdd 100644
--- a/packages/tui/src/routes/session/index.tsx
+++ b/packages/tui/src/routes/session/index.tsx
@@ -1528,7 +1528,7 @@ function AssistantMessage(props: { message: AssistantMessage; parts: Part[]; las
           customBorderChars={SplitBorder.customBorderChars}
           borderColor={theme.error}
         >
-          <text fg={theme.textMuted}>{props.message.error?.data.message}</text>
+          <text fg={theme.textMuted}>{String(props.message.error?.data.message ?? "")}</text>
         </box>
       </Show>
       <Switch>
diff --git a/packages/tui/src/ui/dialog-prompt.tsx b/packages/tui/src/ui/dialog-prompt.tsx
index d627ea2970..63dc2ca6dd 100644
--- a/packages/tui/src/ui/dialog-prompt.tsx
+++ b/packages/tui/src/ui/dialog-prompt.tsx
@@ -8,7 +8,7 @@ import { useBindings, useCommandShortcut } from "../keymap"
 
 export type DialogPromptProps = {
   title: string
-  description?: () => JSX.Element
+  description?: JSX.Element | (() => JSX.Element)
   placeholder?: string
   value?: string
   busy?: boolean
@@ -25,6 +25,11 @@ export function DialogPrompt(props: DialogPromptProps) {
   const [textareaTarget, setTextareaTarget] = createSignal<TextareaRenderable>()
   let textarea: TextareaRenderable
 
+  const description = () => {
+    if (typeof props.description === "function") return props.description()
+    return props.description
+  }
+
   function confirm() {
     if (props.busy) return
     props.onConfirm?.(textarea.plainText)
@@ -83,7 +88,7 @@ export function DialogPrompt(props: DialogPromptProps) {
         </text>
       </box>
       <box gap={1}>
-        {props.description}
+        {description()}
         <textarea
           height={3}
           ref={(val: TextareaRenderable) => {
diff --git a/script/repro-windows-opentui-crash.ps1 b/script/repro-windows-opentui-crash.ps1
new file mode 100644
index 0000000000..71437ea5c1
--- /dev/null
+++ b/script/repro-windows-opentui-crash.ps1
@@ -0,0 +1,256 @@
+param(
+  [Parameter(Mandatory = $true)]
+  [string]$Version,
+  [int]$McpLoops = 0,
+  [int]$McpServers = 20,
+  [int]$MarkdownLoops = 1,
+  [int]$StartupSeconds = 20,
+  [int]$PtySeconds = 120,
+  [switch]$OnlyMarkdown
+)
+
+$ErrorActionPreference = "Stop"
+
+function Write-Section([string]$Name) {
+  Write-Host ""
+  Write-Host "==== $Name ===="
+}
+
+function Read-TextFile([string]$Path) {
+  if (!(Test-Path $Path)) {
+    return ""
+  }
+  return [System.IO.File]::ReadAllText($Path)
+}
+
+function Test-CrashText([string]$Text) {
+  if ($Text -match "Segmentation fault") { return $true }
+  if ($Text -match "Bun has crashed") { return $true }
+  if ($Text -match "ACCESS_VIOLATION") { return $true }
+  if ($Text -match "0xC0000005") { return $true }
+  if ($Text -match "322122") { return $true }
+  if ($Text -match "panic\(main thread\)") { return $true }
+  return $false
+}
+
+function Invoke-Opencode {
+  param(
+    [Parameter(Mandatory = $true)]
+    [string]$Label,
+    [Parameter(Mandatory = $true)]
+    [string]$Exe,
+    [string[]]$Args = @(),
+    [Parameter(Mandatory = $true)]
+    [string]$WorkingDirectory,
+    [int]$TimeoutSeconds = 60,
+    [switch]$AllowNonZero,
+    [switch]$AllowTimeout
+  )
+
+  Write-Section $Label
+  Write-Host "cwd=$WorkingDirectory"
+  Write-Host "cmd=$Exe $($Args -join ' ')"
+
+  $safe = ($Label -replace "[^A-Za-z0-9_.-]", "_")
+  $stdout = Join-Path $env:RUNNER_TEMP "$safe.out.log"
+  $stderr = Join-Path $env:RUNNER_TEMP "$safe.err.log"
+  Remove-Item -ErrorAction SilentlyContinue $stdout, $stderr
+
+  $process = Start-Process -FilePath $Exe -ArgumentList $Args -WorkingDirectory $WorkingDirectory -NoNewWindow -PassThru -RedirectStandardOutput $stdout -RedirectStandardError $stderr
+  $exited = $process.WaitForExit($TimeoutSeconds * 1000)
+  if (!$exited) {
+    Write-Host "timeout after ${TimeoutSeconds}s; terminating process id $($process.Id)"
+    Stop-Process -Id $process.Id -Force -ErrorAction SilentlyContinue
+    Start-Sleep -Seconds 1
+  }
+
+  $outText = Read-TextFile $stdout
+  $errText = Read-TextFile $stderr
+  if ($outText.Length -gt 0) {
+    Write-Host "--- stdout ---"
+    Write-Host $outText
+  }
+  if ($errText.Length -gt 0) {
+    Write-Host "--- stderr ---"
+    Write-Host $errText
+  }
+
+  $combined = $outText + "`n" + $errText
+  if (Test-CrashText $combined) {
+    throw "native crash signature detected in $Label"
+  }
+
+  if (!$exited) {
+    if ($AllowTimeout) {
+      Write-Host "timeout accepted for long-running TUI startup check"
+      return
+    }
+    throw "timeout in $Label"
+  }
+
+  $exitCode = [int64]$process.ExitCode
+  Write-Host "exitCode=$exitCode"
+  if (@(3, -1073741819, -1073740791, -1073741571) -contains $exitCode) {
+    throw "native crash exit code $exitCode in $Label"
+  }
+  if (!$AllowNonZero -and $process.ExitCode -ne 0) {
+    throw "unexpected exit code $($process.ExitCode) in $Label"
+  }
+}
+
+function Invoke-PtyScenario {
+  param(
+    [Parameter(Mandatory = $true)]
+    [string]$Scenario,
+    [Parameter(Mandatory = $true)]
+    [string]$Exe,
+    [Parameter(Mandatory = $true)]
+    [string]$Project,
+    [Parameter(Mandatory = $true)]
+    [string]$Version,
+    [Parameter(Mandatory = $true)]
+    [int]$Seconds
+  )
+
+  node (Join-Path $PSScriptRoot "repro-windows-opentui-pty-session.mjs") -- --exe $Exe --project $Project --version $Version --seconds $Seconds --scenario $Scenario
+  if ($LASTEXITCODE -ne 0) {
+    $script:PtyFailures += "PTY scenario '$Scenario' failed with exit code $LASTEXITCODE"
+    Write-Host "::error::$($script:PtyFailures[-1])"
+  }
+}
+
+function Invoke-MarkdownScenarios {
+  param(
+    [Parameter(Mandatory = $true)]
+    [string]$Exe,
+    [Parameter(Mandatory = $true)]
+    [string]$Project,
+    [Parameter(Mandatory = $true)]
+    [string]$Version,
+    [Parameter(Mandatory = $true)]
+    [int]$Seconds,
+    [Parameter(Mandatory = $true)]
+    [int]$Loops
+  )
+
+  for ($i = 1; $i -le $Loops; $i++) {
+    $suffix = if ($Loops -gt 1) { "-$($i.ToString('00'))" } else { "" }
+    if ($Version -eq "1.17.10") {
+      Invoke-PtyScenario -Scenario "markdown-no-native-render$suffix" -Exe $Exe -Project $Project -Version $Version -Seconds $Seconds
+    }
+    Invoke-PtyScenario -Scenario "markdown$suffix" -Exe $Exe -Project $Project -Version $Version -Seconds $Seconds
+  }
+}
+
+Write-Section "Environment"
+node --version
+npm --version
+Write-Host "RUNNER_OS=$env:RUNNER_OS RUNNER_ARCH=$env:RUNNER_ARCH"
+Write-Host "PROCESSOR_ARCHITECTURE=$env:PROCESSOR_ARCHITECTURE"
+Write-Host "MarkdownLoops=$MarkdownLoops OnlyMarkdown=$OnlyMarkdown"
+if ($MarkdownLoops -lt 1) {
+  throw "MarkdownLoops must be >= 1"
+}
+
+Write-Section "Install opencode-ai@$Version"
+npm uninstall -g opencode-ai opencode-windows-x64 2>$null | Out-Host
+npm install -g "opencode-ai@$Version"
+if ($LASTEXITCODE -ne 0) {
+  throw "npm install opencode-ai@$Version failed with exit code $LASTEXITCODE"
+}
+
+$npmRoot = (npm root -g).Trim()
+$exe = Join-Path $npmRoot "opencode-ai\bin\opencode.exe"
+if (!(Test-Path $exe)) {
+  $cmd = Get-Command opencode -ErrorAction Stop
+  $exe = $cmd.Source
+}
+Write-Host "opencode executable=$exe"
+if (Test-Path $exe) {
+  $info = (Get-Item $exe).VersionInfo
+  Write-Host "FileDescription=$($info.FileDescription) FileVersion=$($info.FileVersion) ProductVersion=$($info.ProductVersion) CompanyName=$($info.CompanyName)"
+}
+
+$root = Join-Path $env:RUNNER_TEMP "opencode-windows-opentui-$Version"
+Remove-Item -Recurse -Force -ErrorAction SilentlyContinue $root
+New-Item -ItemType Directory -Force $root | Out-Null
+$env:XDG_CONFIG_HOME = Join-Path $root "xdg-config"
+$env:XDG_DATA_HOME = Join-Path $root "xdg-data"
+$env:XDG_CACHE_HOME = Join-Path $root "xdg-cache"
+$env:XDG_STATE_HOME = Join-Path $root "xdg-state"
+$env:APPDATA = Join-Path $root "appdata"
+$env:LOCALAPPDATA = Join-Path $root "localappdata"
+$env:OPENCODE_DISABLE_AUTOUPDATE = "1"
+$env:OPENCODE_DISABLE_EXTERNAL_SKILLS = "1"
+$env:OPENCODE_DISABLE_LSP_DOWNLOAD = "1"
+$env:OPENCODE_PURE = "1"
+New-Item -ItemType Directory -Force $env:XDG_CONFIG_HOME, $env:XDG_DATA_HOME, $env:XDG_CACHE_HOME, $env:XDG_STATE_HOME, $env:APPDATA, $env:LOCALAPPDATA | Out-Null
+
+$emptyProject = Join-Path $root "empty-project"
+$mcpProject = Join-Path $root "mcp-project"
+$sessionProject = Join-Path $root "session-project"
+New-Item -ItemType Directory -Force $emptyProject, $mcpProject, $sessionProject | Out-Null
+
+Invoke-Opencode -Label "version" -Exe $exe -Args @("--version") -WorkingDirectory $emptyProject -TimeoutSeconds 30
+Invoke-Opencode -Label "help" -Exe $exe -Args @("--help") -WorkingDirectory $emptyProject -TimeoutSeconds 30
+
+Write-Section "Write MCP spawn-storm config"
+$servers = [ordered]@{}
+for ($i = 1; $i -le $McpServers; $i++) {
+  $name = "server$($i.ToString('00'))"
+  $servers[$name] = [ordered]@{
+    type = "local"
+    command = @("node", "-e", "setTimeout(() => {}, 30000)")
+    timeout = 350
+  }
+}
+$config = [ordered]@{
+  autoupdate = $false
+  mcp = $servers
+}
+($config | ConvertTo-Json -Depth 10) | Set-Content -Encoding UTF8 (Join-Path $mcpProject "opencode.json")
+Get-Content (Join-Path $mcpProject "opencode.json") | Write-Host
+
+for ($i = 1; $i -le $McpLoops; $i++) {
+  Invoke-Opencode -Label "mcp-list-$i" -Exe $exe -Args @("mcp", "list") -WorkingDirectory $mcpProject -TimeoutSeconds 90 -AllowNonZero
+}
+
+Invoke-Opencode -Label "empty-startup-tui" -Exe $exe -Args @() -WorkingDirectory $emptyProject -TimeoutSeconds $StartupSeconds -AllowTimeout -AllowNonZero
+
+Write-Section "Install PTY dependency"
+$ptyRoot = Join-Path $root "pty-harness"
+New-Item -ItemType Directory -Force $ptyRoot | Out-Null
+Push-Location $ptyRoot
+try {
+  npm init -y | Out-Host
+  if ($LASTEXITCODE -ne 0) {
+    throw "npm init for PTY harness failed with exit code $LASTEXITCODE"
+  }
+  npm install "@lydell/node-pty@1.2.0-beta.12" | Out-Host
+  if ($LASTEXITCODE -ne 0) {
+    throw "npm install @lydell/node-pty failed with exit code $LASTEXITCODE"
+  }
+  $script:PtyFailures = @()
+  if ($OnlyMarkdown) {
+    Invoke-MarkdownScenarios -Exe $exe -Project $sessionProject -Version $Version -Seconds $PtySeconds -Loops $MarkdownLoops
+  } else {
+    Invoke-PtyScenario -Scenario "text" -Exe $exe -Project $sessionProject -Version $Version -Seconds $PtySeconds
+    Invoke-MarkdownScenarios -Exe $exe -Project $sessionProject -Version $Version -Seconds $PtySeconds -Loops $MarkdownLoops
+    Invoke-PtyScenario -Scenario "bash-permission" -Exe $exe -Project $sessionProject -Version $Version -Seconds $PtySeconds
+    Invoke-PtyScenario -Scenario "task-permission" -Exe $exe -Project $sessionProject -Version $Version -Seconds $PtySeconds
+    Invoke-PtyScenario -Scenario "mcp-npx" -Exe $exe -Project $sessionProject -Version $Version -Seconds $PtySeconds
+    if ($Version -eq "1.17.10") {
+      Invoke-PtyScenario -Scenario "mcp-npx-no-native-render" -Exe $exe -Project $sessionProject -Version $Version -Seconds $PtySeconds
+    }
+  }
+  if ($script:PtyFailures.Count -gt 0) {
+    Write-Section "PTY Failures"
+    $script:PtyFailures | ForEach-Object { Write-Host $_ }
+    throw "$($script:PtyFailures.Count) PTY scenario(s) failed"
+  }
+} finally {
+  Pop-Location
+}
+
+Write-Section "Result"
+Write-Host "No native crash signature detected for opencode-ai@$Version"
diff --git a/script/repro-windows-opentui-pty-session.mjs b/script/repro-windows-opentui-pty-session.mjs
new file mode 100644
index 0000000000..78d1319e5b
--- /dev/null
+++ b/script/repro-windows-opentui-pty-session.mjs
@@ -0,0 +1,447 @@
+import { createRequire } from "node:module"
+import { createServer } from "node:http"
+import { mkdirSync, writeFileSync } from "node:fs"
+import { join, resolve } from "node:path"
+import { pathToFileURL } from "node:url"
+import { setTimeout as delay } from "node:timers/promises"
+
+const require = createRequire(join(process.cwd(), "pty-harness.cjs"))
+const pty = require("@lydell/node-pty")
+
+const args = process.argv.slice(2)
+const value = (name, fallback) => {
+  const index = args.indexOf(name)
+  if (index === -1) return fallback
+  return args[index + 1]
+}
+
+const exe = value("--exe")
+const project = value("--project")
+const version = value("--version")
+const seconds = Number(value("--seconds", "120"))
+const scenario = value("--scenario", "text")
+
+if (!exe || !project || !version) {
+  throw new Error("Usage: repro-windows-opentui-pty-session.mjs -- --exe <path> --project <path> --version <version>")
+}
+
+const crashPattern = /Segmentation fault|Bun has crashed|ACCESS_VIOLATION|0xC0000005|322122|panic\(main thread\)/i
+const outputFile = join(project, `pty-output-${version}-${scenario}.log`)
+const requestsFile = join(project, `provider-requests-${version}-${scenario}.jsonl`)
+let output = ""
+let providerRequests = 0
+let exited = false
+let exitCode = undefined
+let exitSignal = undefined
+let permissionSubmitted = false
+let toolCallSent = false
+
+function writeMcpStubPackage() {
+  const stubDir = join(project, "mcp-stub-package")
+  const binDir = join(stubDir, "bin")
+  mkdirSync(binDir, { recursive: true })
+  writeFileSync(
+    join(stubDir, "package.json"),
+    JSON.stringify(
+      {
+        name: "opencode-mcp-stub",
+        version: "1.0.0",
+        type: "module",
+        bin: { "opencode-mcp-stub": "./bin/opencode-mcp-stub.mjs" },
+      },
+      null,
+      2,
+    ) + "\n",
+  )
+  writeFileSync(
+    join(binDir, "opencode-mcp-stub.mjs"),
+    `#!/usr/bin/env node
+const idArg = process.argv.indexOf("--id")
+const id = idArg === -1 ? "server" : process.argv[idArg + 1]
+let buffer = ""
+function send(message) {
+  process.stdout.write(JSON.stringify(message) + "\\n")
+}
+function result(request, result) {
+  send({ jsonrpc: "2.0", id: request.id, result })
+}
+process.stdin.setEncoding("utf8")
+process.stdin.on("data", (chunk) => {
+  buffer += chunk
+  while (true) {
+    const index = buffer.indexOf("\\n")
+    if (index === -1) return
+    const line = buffer.slice(0, index).trim()
+    buffer = buffer.slice(index + 1)
+    if (!line) continue
+    const request = JSON.parse(line)
+    if (request.method === "initialize") {
+      result(request, { protocolVersion: request.params?.protocolVersion ?? "2025-06-18", capabilities: { tools: {} }, serverInfo: { name: id, version: "1.0.0" } })
+      continue
+    }
+    if (request.method === "tools/list") {
+      result(request, { tools: [{ name: "ping", description: "Return a deterministic response", inputSchema: { type: "object", properties: {}, additionalProperties: false } }] })
+      continue
+    }
+    if (request.method === "tools/call") {
+      result(request, { content: [{ type: "text", text: id + " pong" }] })
+      continue
+    }
+    if (request.id !== undefined) result(request, {})
+  }
+})
+setInterval(() => {}, 1000)
+`,
+  )
+  return pathToFileURL(stubDir).href
+}
+
+mkdirSync(project, { recursive: true })
+
+function appendOutput(text) {
+  output += text
+  writeFileSync(outputFile, output)
+}
+
+async function readBody(req) {
+  const chunks = []
+  for await (const chunk of req) chunks.push(chunk)
+  return Buffer.concat(chunks).toString("utf8")
+}
+
+function writeSse(res, event) {
+  res.write(`data: ${JSON.stringify(event)}\n\n`)
+}
+
+function responseText() {
+  if (scenario.startsWith("bash-")) {
+    return "The bash tool completed and the session continued after tool execution."
+  }
+
+  if (scenario.startsWith("task-")) {
+    return "The subagent task completed and returned control to the parent session."
+  }
+
+  if (scenario.startsWith("mcp-npx")) {
+    return "The MCP npx spawn storm initialized and the session completed."
+  }
+
+  if (scenario.startsWith("markdown")) {
+    const sections = []
+    for (let i = 0; i < 40; i++) {
+      sections.push(`## Section ${i + 1}`)
+      sections.push("")
+      sections.push("- This line intentionally exercises markdown wrapping in the OpenTUI renderer.")
+      sections.push("- It includes `inline code`, **bold text**, [a link](https://example.com), and CJK text 漢字かなカナ.")
+      sections.push("")
+      sections.push("```ts")
+      sections.push(`const value${i} = { index: ${i}, text: "OpenTUI Windows repro" }`)
+      sections.push("console.log(value" + i + ")")
+      sections.push("```")
+      sections.push("")
+    }
+    return sections.join("\n")
+  }
+
+  return "This is a deterministic CI response from the fake provider."
+}
+
+function hasToolResult(parsedBody) {
+  return parsedBody?.messages?.some?.((message) => message.role === "tool" || message.role === "function") ?? false
+}
+
+function shouldCallBash(parsedBody) {
+  if (!scenario.startsWith("bash-")) return false
+  if (!parsedBody?.tools?.some?.((tool) => (tool.function?.name ?? tool.name) === "bash")) return false
+  if (hasToolResult(parsedBody) || toolCallSent) return false
+  toolCallSent = true
+  return true
+}
+
+function shouldCallTask(parsedBody) {
+  if (!scenario.startsWith("task-")) return false
+  if (!parsedBody?.tools?.some?.((tool) => (tool.function?.name ?? tool.name) === "task")) return false
+  if (hasToolResult(parsedBody) || toolCallSent) return false
+  toolCallSent = true
+  return true
+}
+
+const server = createServer(async (req, res) => {
+  const body = await readBody(req)
+  providerRequests++
+  const parsedBody = body ? JSON.parse(body) : undefined
+  console.log(
+    `provider request ${providerRequests}: ${req.method} ${req.url} stream=${parsedBody?.stream ?? false} messages=${parsedBody?.messages?.length ?? "n/a"} tools=${parsedBody?.tools?.map?.((tool) => tool.function?.name ?? tool.name).join(",") ?? "none"}`,
+  )
+  writeFileSync(
+    requestsFile,
+    JSON.stringify({ method: req.method, url: req.url, body: parsedBody }) + "\n",
+    { flag: "a" },
+  )
+
+  if (req.url?.endsWith("/models")) {
+    res.writeHead(200, { "content-type": "application/json" })
+    res.end(JSON.stringify({ object: "list", data: [{ id: "test-model", object: "model" }] }))
+    return
+  }
+
+  if (req.url?.endsWith("/chat/completions")) {
+    const parsed = parsedBody ?? {}
+    const callBash = shouldCallBash(parsed)
+    const callTask = shouldCallTask(parsed)
+    const text = responseText()
+    if (parsed.stream) {
+      res.writeHead(200, {
+        "content-type": "text/event-stream",
+        "cache-control": "no-cache",
+        connection: "keep-alive",
+      })
+      writeSse(res, {
+        id: "chatcmpl-opentui-repro",
+        object: "chat.completion.chunk",
+        created: Math.floor(Date.now() / 1000),
+        model: "test-model",
+        choices: [{ index: 0, delta: { role: "assistant" }, finish_reason: null }],
+      })
+      await delay(50)
+      if (callBash || callTask) {
+        const toolName = callBash ? "bash" : "task"
+        const toolArguments = callBash
+          ? { command: "echo opentui-tool-repro > opentui-tool-repro.txt" }
+          : {
+              description: "subagent repro",
+              prompt: "Respond with one sentence for the Windows OpenTUI crash repro.",
+              subagent_type: "general",
+            }
+        writeSse(res, {
+          id: "chatcmpl-opentui-repro",
+          object: "chat.completion.chunk",
+          created: Math.floor(Date.now() / 1000),
+          model: "test-model",
+          choices: [
+            {
+              index: 0,
+              delta: {
+                tool_calls: [
+                  {
+                    index: 0,
+                    id: `call_opentui_repro_${toolName}`,
+                    type: "function",
+                    function: {
+                      name: toolName,
+                      arguments: JSON.stringify(toolArguments),
+                    },
+                  },
+                ],
+              },
+              finish_reason: null,
+            },
+          ],
+        })
+        await delay(50)
+        writeSse(res, {
+          id: "chatcmpl-opentui-repro",
+          object: "chat.completion.chunk",
+          created: Math.floor(Date.now() / 1000),
+          model: "test-model",
+          choices: [{ index: 0, delta: {}, finish_reason: "tool_calls" }],
+        })
+        res.write("data: [DONE]\n\n")
+        res.end()
+        return
+      }
+
+      writeSse(res, {
+        id: "chatcmpl-opentui-repro",
+        object: "chat.completion.chunk",
+        created: Math.floor(Date.now() / 1000),
+        model: "test-model",
+        choices: [{ index: 0, delta: { content: text }, finish_reason: null }],
+      })
+      await delay(50)
+      writeSse(res, {
+        id: "chatcmpl-opentui-repro",
+        object: "chat.completion.chunk",
+        created: Math.floor(Date.now() / 1000),
+        model: "test-model",
+        choices: [{ index: 0, delta: {}, finish_reason: "stop" }],
+      })
+      res.write("data: [DONE]\n\n")
+      res.end()
+      return
+    }
+
+    res.writeHead(200, { "content-type": "application/json" })
+    res.end(
+      JSON.stringify({
+        id: "chatcmpl-opentui-repro",
+        object: "chat.completion",
+        created: Math.floor(Date.now() / 1000),
+        model: "test-model",
+        choices: [
+          {
+            index: 0,
+            message: { role: "assistant", content: text },
+            finish_reason: "stop",
+          },
+        ],
+        usage: { prompt_tokens: 1, completion_tokens: 1, total_tokens: 2 },
+      }),
+    )
+    return
+  }
+
+  res.writeHead(404, { "content-type": "application/json" })
+  res.end(JSON.stringify({ error: { message: `Unhandled fake provider route: ${req.url}` } }))
+})
+
+await new Promise((resolveListen) => server.listen(0, "127.0.0.1", resolveListen))
+const { port } = server.address()
+const baseURL = `http://127.0.0.1:${port}/v1`
+const mcpPackageUrl = scenario.startsWith("mcp-npx") ? writeMcpStubPackage() : undefined
+const mcpServers = {}
+if (mcpPackageUrl) {
+  for (let index = 1; index <= 12; index++) {
+    const id = `server${String(index).padStart(2, "0")}`
+    mcpServers[id] = {
+      type: "local",
+      command: ["npx", "-y", mcpPackageUrl, "--id", id],
+      timeout: 15000,
+    }
+  }
+}
+
+writeFileSync(
+  join(project, "opencode.json"),
+  `${JSON.stringify(
+    {
+      $schema: "https://opencode.ai/config.json",
+      autoupdate: false,
+      ...(mcpPackageUrl ? { mcp: mcpServers } : {}),
+      enabled_providers: ["test"],
+      provider: {
+        test: {
+          name: "Test",
+          id: "test",
+          env: [],
+          npm: "@ai-sdk/openai-compatible",
+          models: {
+            "test-model": {
+              id: "test-model",
+              name: "Test Model",
+              attachment: false,
+              reasoning: false,
+              temperature: false,
+              tool_call: true,
+              release_date: "2025-01-01",
+              limit: { context: 100000, output: 10000 },
+              cost: { input: 0, output: 0 },
+              options: {},
+            },
+          },
+          options: { apiKey: "test-key", baseURL },
+        },
+      },
+    },
+    null,
+    2,
+  )}\n`,
+)
+
+console.log(`scenario=${scenario}`)
+if (mcpPackageUrl) console.log(`mcp package=${mcpPackageUrl}`)
+console.log(`fake provider baseURL=${baseURL}`)
+console.log(`pty output log=${outputFile}`)
+console.log(`provider requests log=${requestsFile}`)
+
+const env = {
+  ...process.env,
+  OPENCODE_DISABLE_AUTOUPDATE: "1",
+  OPENCODE_DISABLE_EXTERNAL_SKILLS: "1",
+  OPENCODE_DISABLE_LSP_DOWNLOAD: "1",
+  OPENCODE_LOG_LEVEL: "DEBUG",
+  OPENCODE_PRINT_LOGS: "1",
+  OPENCODE_PURE: "1",
+  OTUI_DEBUG: "1",
+  OTUI_DUMP_CAPTURES: "1",
+  ...(scenario.includes("no-native-render") ? { OTUI_NO_NATIVE_RENDER: "1" } : {}),
+  OTUI_USE_CONSOLE: "1",
+  OTUI_SHOW_STATS: "1",
+}
+
+const proc = pty.spawn(
+  exe,
+  [
+    "--model",
+    "test/test-model",
+    "--prompt",
+    scenario.startsWith("bash-")
+      ? "run a shell command through the bash tool, then summarize"
+      : scenario.startsWith("task-")
+        ? "delegate a small task to a subagent, then summarize"
+      : "start a CI repro session and answer briefly",
+  ],
+  {
+    name: "xterm-256color",
+    cols: 120,
+    rows: 40,
+    cwd: resolve(project),
+    env,
+  },
+)
+
+proc.onData((data) => {
+  appendOutput(data)
+  process.stdout.write(data)
+  if (
+    (scenario === "bash-permission" || scenario === "task-permission") &&
+    !permissionSubmitted &&
+    /Permission required|Allow once|Call tool bash|Call tool task|subagent repro/.test(output)
+  ) {
+    permissionSubmitted = true
+    setTimeout(() => proc.write("\r"), 250)
+  }
+})
+
+proc.onExit((event) => {
+  exited = true
+  exitCode = event.exitCode
+  exitSignal = event.signal
+})
+
+const deadline = Date.now() + seconds * 1000
+let completedAt
+while (Date.now() < deadline) {
+  if (crashPattern.test(output)) break
+  if (exited) break
+  if (!completedAt && output.includes("message=\"exiting loop\"")) completedAt = Date.now()
+  if (completedAt && Date.now() - completedAt > 8000) break
+  await delay(500)
+}
+
+if (!exited) {
+  proc.write("\x03")
+  await delay(1500)
+}
+if (!exited) {
+  proc.kill()
+  await delay(500)
+}
+
+await new Promise((resolveClose) => server.close(resolveClose))
+
+console.log(`\npty exitCode=${exitCode} signal=${exitSignal} providerRequests=${providerRequests}`)
+
+if (crashPattern.test(output)) {
+  throw new Error("native crash signature detected in PTY session")
+}
+
+if (exitCode === 3 || exitCode === -1073741819 || exitCode === -1073740791 || exitCode === -1073741571) {
+  throw new Error(`native crash exit code detected in PTY session: ${exitCode}`)
+}
+
+if (providerRequests === 0) {
+  throw new Error("PTY session did not send a request to the fake provider")
+}
+
+process.exit(0)