fix(server): t3 service install works on Linux hosts without a login session - #29923

Eligibility
This repairs explicitly requested Linux background-service installation on hosts without a login session while retaining prerequisite checks and sudo-root safeguards. The remaining comments concern error guidance and bounded installation delays, rather than material changes to service policy or exposure.

Additional Thinking

Your Custom Policy

Default criteria apply. This restores the existing explicitly requested service-install behavior rather than changing product defaults; enabling lingering was already part of installation. The assessed diff adds no static-analysis suppression directives. The omitted file remains outside the assessment under the supplied ignore rules.

Code

The visible change repairs explicit Linux service installation without a login session: supplies a missing user runtime directory, enables existing lingering setup when the manager is initially unreachable, retries startup probes, and rediscovers the manager's unit directory. Root-under-sudo is excluded from the new environment fallback and lingering recovery. The customer-ignored file was not reconstructed.

Review Context

The author is a repository admin and ping-devs member; no code-ownership requirement was supplied. Two unresolved external comments concern misleading administrative guidance and polling that can last roughly a minute. Both are limited installer usability concerns, not material operational risks requiring human judgment. No Macroscope correctness findings or check results were supplied; the configured medium-severity gate applies independently.

Verdict

The operational effect is limited to a user explicitly installing a persistent background service, whose existing installation already enables lingering. The change repairs sessionless access to that user's manager, retains prerequisite checks, and avoids the new recovery under sudo-root. The supplied concerns involve bounded failure delays and error guidance, with no obvious material risk requiring human approval.

Notes:
No code owners found in target merge base 61c3794

Agent Credits: 30 credits
Approvability runs at a flat rate of 30 credits whenever the agent is asked for a verdict.