Tests-only handoff for PR #18172
Repository/head: Quicksaver/t3code fix/ssh-device-host-commands
Original head: 177c39e5cfabb45d3ce3d6b74ed2ce6bb0dc47fa
Pinned main: ab6be13d43
Commit: 614fbe1355364350f7862540864d9205962a3e1a
Title: test(server): focus SSH device command regressions
Unpushed. Existing merge/history preserved. No production changes.

Case counts:
- SshDeviceHost.test.ts: 1 -> 1 (existing public service case extended).
- sshDeviceScript.test.ts: 8 -> 4.
- Total: 9 -> 5. PR-added cases: 5 -> 1; all four pre-existing cases retained.
- Removed duplicate bootstrap/argument transport tests and two Node PATH matrix cases.
- Replaced the large npm candidate/runtime/error matrix with one public probe/install scenario.
- Net change: 71 added lines, 303 removed lines across the two tests.

Retained proof:
- Public host bootstrap/probe/lifecycle commands use only sh -s as remote command arguments.
- Public host run preserves quoted/multiline arguments, CR/NUL/backslash input, and omitted stdin through a real local POSIX shell.
- Generated bootstrap probe/install runs npm CLI through selected Node in paths with spaces.
- npm lifecycle child resolves that same Node through PATH; install exit 23/diagnostic is retained.
- Windows platform dispatch is modeled by the fixture; this run was Linux.

Red verification against pinned main production:
- Host check fails: received sh -c plus embedded shell script, expected sh -s.
- npm check fails: npm is missing from non-interactive SSH PATH despite a usable fixture CLI beside Node.
- Exit 1: 2 failed, 3 intentionally filtered out.
- Both production files restored exactly in finally; SHA256 and byte comparisons recorded.

Green/checks:
- Focused vitest after restoration: 2 files, 5 passed, exit 0.
- Scoped lint on both test files: exit 0.
- Server typecheck (pnpm exec vp run --filter t3 typecheck): exit 0, suggestions only.
- git diff --check: passed.
- Commit hook formatting: passed.

Limitations/blockers:
- Actual Windows PowerShell SSH transport, successful registry installation, helper start/stop,
  and interruption/cancellation remain unverified. Native verification is BLOCKED.
- No native Windows claims, browser/dev-server/native-app launches, agents, GitHub edits, or pushes.
- The existing POSIX helper lifecycle test still runs its scoped test-fixture subprocesses.
- PR link registered in T3 thread; this does not modify GitHub.

Artifacts:
- 18172-tests-counts.json
- 18172-tests-red.log
- 18172-tests-red-restoration.json
- 18172-tests-green.log
- 18172-tests-green-restored.log
- 18172-tests-lint.log
- 18172-tests-typecheck.log
- 18172-tests-format.log
- 18172-tests-commands.txt
- 18172-tests-original-*.test.ts and 18172-tests-production-*.ts exact snapshots
- 18172-tests-green-initial.log records a discarded nonzero-exit assertion that did not match
  the existing public-host error mapping; final transport checks retain successful byte delivery.
