fix(dgw): ignore bad agent_tunnel.db when tunnel is off

[irvingouj@Devolutions (irvingoujAtDevolution)]

With the agent tunnel off, a 2026.3 agent_tunnel.db that can't be imported no longer stops the Gateway from starting; the failure is logged as a warning. The import still runs when the tunnel is off, so turning the tunnel back on later keeps the enrolled Agents. With the tunnel on, a failed import still stops the start.

Follow-up to this review on #2039.

[irvingouj@Devolutions (irvingoujAtDevolution)]

Why not just skip the import when the tunnel is off: GatewayDb::open creates gateway.db on every start, and once it exists the import ignores agent_tunnel.db for good (upgrade.rs). So someone who used the tunnel on 2026.3, turned it off and then upgraded would lose their Agents when turning it back on. Keeping the import and only tolerating its failure avoids that.

Ran the debug build locally with a broken and a valid agent_tunnel.db:

Tunnel	agent_tunnel.db	Result
off	garbage	starts, warning logged, /jet/health 200
on	garbage	refuses to start, same as before
off	valid 2026.3	imported into gateway.db
on	valid 2026.3	imported

Note

LLM-assisted content (no human feedback).

[github-actions]

Let maintainers know that an action is required on their side

• Add the label release-required Please cut a new release (Devolutions Gateway, Devolutions Agent, Jetsocat, PowerShell module) when you request a maintainer to cut a new release (Devolutions Gateway, Devolutions Agent, Jetsocat, PowerShell module)

• Add the label release-blocker Follow-up is required before cutting a new release if a follow-up is required before cutting a new release

• Add the label publish-required Please publish libraries (`Devolutions.Gateway.Utils`, OpenAPI clients, etc) when you request a maintainer to publish libraries (Devolutions.Gateway.Utils, OpenAPI clients, etc.)

• Add the label publish-blocker Follow-up is required before publishing libraries if a follow-up is required before publishing libraries

[Copilot]

🟡 Changes recommended

Creating gateway.db after an ignored failure prevents future import retries when the tunnel is re-enabled.

1 open finding

• Preserve import retry when tunnel is re-enabled · New

What changed in this PR

Allows Gateway startup to continue when a legacy Agent Tunnel database import fails while tunneling is disabled.

Changes:

• Makes import failures conditional on Agent Tunnel state.
• Logs ignored failures as warnings.

File	Description
devolutions-gateway/​src/​service.rs	Handles legacy database import failures during startup.

🧠 Review effort: Balanced

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