Use direct remote command for smoke SSH probes

Author: mjenkinsaktion

docs/exec-plans/active/EP-001-portable-coder-foundation-and-multi-provider-mvp.md

@@ -46,6 +46,7 @@ Initial user target providers/tools:
 - [x] (2026-02-20) Make Windows smoke SSH probe tolerate transient native-command connection errors during VM boot
 - [x] (2026-02-20) Increase VM SSH readiness timeouts and diagnostics for slow first-boot cloud images
 - [x] (2026-02-20) Fix Windows smoke SSH probe command invocation so readiness check validates `echo vm-ready` output correctly
+- [x] (2026-02-20) Update Windows smoke SSH probe to pass remote commands directly (avoids PowerShell stdin encoding edge cases)
 - [ ] (2026-02-18) Document setup/runbook and close out EP-001
 
 ## Context and Orientation
@@ -127,6 +128,7 @@ Acceptance criteria for EP-001:
 - 2026-02-20: On some PowerShell environments, transient `ssh` connection failures surfaced as exceptions; smoke probing must retry instead of aborting early.
 - 2026-02-20: First boot SSH readiness on some hosts can exceed 120 seconds, so timeout windows need to be configurable and longer by default.
 - 2026-02-20: Passing `ssh ... bash -lc <script>` as split args can drop expected output semantics; piping script content to `bash -s` is safer for deterministic probing.
+- 2026-02-20: Piping probe scripts into native `ssh` from Windows PowerShell can hit stdin encoding edge cases; direct remote command args are more reliable.
 
 ## Decision Log
 - 2026-02-18: Adopt harness-first planning model before implementation.

scripts/runtime/windows/smoke-check.ps1

@@ -66,11 +66,11 @@ function Invoke-Ssh {
     '-o', 'UserKnownHostsFile=NUL',
     '-o', 'ConnectTimeout=5',
     "$SshUser@127.0.0.1",
-    'bash', '-s'
+    $Script
   )
 
   try {
-    $output = $Script | & $SshExe @args 2>&1
+    $output = & $SshExe @args 2>&1
     return @{
       status = $LASTEXITCODE
       output = [string]::Join("`n", $output)