fix(e2e): remove unenforced PTY signing (#9421)

<!-- markdownlint-disable MD041 -->
## Summary

Merged PR #9389 moved terminal-mode observation from reopening the
root-owned PTY to the inherited descriptor, but its response-signing
design staged a private key at a known path owned by the same sandbox
UID. This follow-up removes the key writer, key file, and signing
protocol while retaining inherited-descriptor observation, identity
checks, and mode restrictions that limit unprivileged access to the
sandbox UID. The E2E harness trusts that UID; authenticating a hostile
same-UID process would require an upstream OpenShell boundary that
attests the inherited process or provides direct execution.

## Related Issue

Follow-up to #9384 and merged PR #9389.

Original E2E root-cause key:
`security-posture-openclaw::recorded-pty-termios-query`.

Follow-up correction: remove the unenforced same-UID key-file boundary
added while repairing that root cause.

The post-merge runs below do not establish a complete pass for the
affected OpenClaw live E2E targets:

- [Run `32101568976`, job
`95603202167`](https://github.com/NVIDIA/NemoClaw/actions/runs/32101568976/job/95603202167)
failed the launch-readiness producer before the TUI verifier.
- [Run `32101603265`, security-posture job
`95604178951`](https://github.com/NVIDIA/NemoClaw/actions/runs/32101603265/job/95604178951)
repeated the earlier launch-readiness publication failure.
- [Run `32101603265`, gateway-guard job
`95604178855`](https://github.com/NVIDIA/NemoClaw/actions/runs/32101603265/job/95604178855)
failed the same publication gate after gateway recovery.
- [Run `32101603265`, `full-e2e` job
`95604179404`](https://github.com/NVIDIA/NemoClaw/actions/runs/32101603265/job/95604179404)
reached the TUI but failed structured-turn evidence without the original
`pty_termios_unavailable` signature.
- [Run `32102697569`, job
`95606379760`](https://github.com/NVIDIA/NemoClaw/actions/runs/32102697569/job/95606379760)
passed the launch-readiness check and PTY qualification, then repeated
the structured-turn failure after the first input.
- [Run `32110926109`, job
`95630372285`](https://github.com/NVIDIA/NemoClaw/actions/runs/32110926109/job/95630372285)
tested candidate `6fd4d4574` before PR #9422 merged. Phases 1–3 passed.
Phase 4 child lifecycle 16 passed the PTY input-mode gate, then failed
with `launch did not record the required structured session turns`;
cleanup passed. The log contains no `pty_termios_*` failure. This run
does not evaluate `c7fdfe331`.
- [Run `32112329966`, job
`95634597620`](https://github.com/NVIDIA/NemoClaw/actions/runs/32112329966/job/95634597620)
and [run `32112353122`, job
`95636753522`](https://github.com/NVIDIA/NemoClaw/actions/runs/32112353122/job/95636753522)
tested main commit `9ca0d6c98` after PR #9422 merged. Both passed the
direct hosted-inference probe, in-sandbox inference request, gateway
recovery, and launch-readiness probe. The first startup-aware launch
then exited nonzero after about 13 seconds. The E2E test reported only
`Error: launch session failed:` with no command diagnostic.

The readiness failures have the distinct root key
`security-posture-openclaw / launch-readiness producer publication /
complete probe succeeds but final evidence cannot be verified or
published`. Commit `b09eecef8` did not show this readiness failure;
merged commit `7b43d6705` did. This evidence does not identify the
introducing commit.

The historical structured-turn root is `full-e2e / first structured PTY
launch / no complete post-baseline user-assistant pair before the
session deadline`. PR #9422, merged as `e11abd27a` and included in base
commit `9ca0d6c98`, owns that correction. PR #9421 does not claim or
duplicate it. The launch-readiness publication root remains outside PR
#9421.

The post-#9422 main failures have the separate root key
`security-posture-openclaw / first startup-aware launch / nonzero exit
with no captured command diagnostic`. PR #9421 does not claim to correct
this failure. PR #9421's cleanup-diagnostic change preserves stderr from
later cleanup actions, but it does not establish that cleanup caused
these failures. Source inspection, a regression test, and live E2E
evidence are required to establish any relationship.

Exact-commit CI and two sequential `security-posture-openclaw` live E2E
passes remain pending for `c7fdfe331`. Earlier runs do not satisfy those
acceptance results.

## Changes

- Remove Ed25519 generation, the extra OpenShell key-writer command, the
sandbox key file, response signatures, and their cleanup lifecycle.
- Return one fresh bounded termios observation per connection through
the existing Unix socket. Keep the inherited PTY descriptor, exact
run-directory, socket, and PTY identity checks, the absolute response
deadline, bounded printable diagnostics, and fail-closed cleanup.
- Retain readiness gating, bounded monitor shutdown, the
unreadable-device-path regression, canonical-state rejection,
malformed-response and PTY-identity rejection, two ordered turns, and
monitor process-lifecycle coverage.
- Report a residual monitor socket distinctly and verify that cleanup
refuses to remove it.
- Run every cleanup action before returning the original launch status,
and remove host-side session state before the bounded PTY monitor wait.
- Scale the deadlines for Linux PTY source tests through the repository
`testTimeout` helper.
- Preserve launch cleanup diagnostics and assert the structured-session
baseline cleanup message.

## Type of Change

- [x] Code change (feature, bug fix, or refactor)
- [ ] Code change with doc updates
- [ ] Doc only (prose changes, no code sample modifications)
- [ ] Doc only (includes code sample changes)

## Quality Gates

- [x] Tests added or updated for changed behavior
- [ ] Existing tests cover changed behavior — justification:
- [ ] Tests not applicable — justification:
- [x] Sensitive paths changed (security, policy, credentials, preflight,
onboarding, inference, runner, sandbox, or messaging)
- [x] Sensitive-path review completed or maintainer-approved waiver
recorded — reviewer/approval link/justification: independent security
review of the commit under review, `c7fdfe331`, passed all nine security
categories under the explicit same-UID E2E harness trust boundary
([security-review
comment](#9421 (comment))).
- [ ] Non-success, skipped, or missing CI check accepted by maintainer —
check name, approval link, and follow-up issue:

## DGX Station Hardware Evidence

Not applicable; this PR does not change
`scripts/prepare-dgx-station-host.sh`.

- [ ] Tested on DGX Station
- Tested commit: Not applicable.
- Station profile/scenario: Not applicable.
- Result: Not applicable.
- Supporting evidence: Not applicable.

## Verification

- [x] PR description includes a `Signed-off-by:` line and every commit
appears as `Verified` in GitHub
- [x] Normal `pre-commit`, `commit-msg`, and `pre-push` hooks passed, or
`npm run validate:pr` passed after refreshing `origin/main` when hooks
were skipped or unavailable — `npm run validate:pr` passed on
`c7fdfe331` after refreshing `origin/main`.
- [x] Targeted behavior tests pass for the current change set, or tests
are marked not applicable above
- Fail-first at `9d6dd421c`: `npm exec -- vitest run --project
e2e-support test/e2e/support/launch-agent-turn.test.ts -t 'intercepts
one OpenClaw launch'` failed 2/2 because the merged harness made four
OpenShell calls instead of three.
  - Correction at `9726c786c`: the same focused command passed 2/2.
- At commit under review `c7fdfe331`, `npm exec -- vitest run --project
e2e-support test/e2e/support/launch-agent-turn.test.ts`: 20 passed, 25
intentional Linux-only skips on macOS.
- `npm exec -- vitest run --project integration
test/growth-guardrails.test.ts`: 25 passed.
- `git diff --check
9ca0d6c...c7fdfe3`:
passed.
- [ ] Applicable broad gate passed — `npm test` for broad
runtime/test-harness changes; `npm run check` for repo-wide
validation/coverage changes — exact-commit CI pending.
- [x] Quality Gates section completed with required justifications or
waivers
- [x] No secrets, API keys, or credentials committed
- [ ] `npm run docs` builds without warnings (doc changes only)
- [ ] Doc pages follow the [style
guide](https://github.com/NVIDIA/NemoClaw/blob/main/docs/CONTRIBUTING.md)
(doc changes only)
- [ ] New doc pages include SPDX header and frontmatter (new pages only)

Documentation impact: none. This changes only the internal live E2E
harness and does not change a supported command, configuration, workflow
input, or operator action.

---
Signed-off-by: Julie Yaunches <jyaunches@nvidia.com>

---------

Signed-off-by: Julie Yaunches <jyaunches@nvidia.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: 2 people