fix(server): advertise the tailnet editor target when Tailscale SSH serves without a local sshd

[Mnigos]

"Open in editor" advertises the SSH hosts the environment can be reached on, but the server bails out with an empty list when nothing listens on localhost port 22. A host that runs Tailscale SSH has no local sshd at all, so the menu shows "No SSH route" even though ssh <tailnet-name> works from the viewer's machine.

This follows the split-gate direction from the triage on #11052. tailscale status --json does not report the local node's own SSH host keys (the Self entry never carries sshHostKeys), so enablement comes from the local prefs: tailscale debug prefs reports RunSSH, the switch tailscale up --ssh flips. @t3tools/tailscale gains readTailscaleSshEnabled on the same command runner as readTailscaleStatus, and RemoteOpenTargets consults it only when no loopback sshd answers. The tailnet name is advertised when either a local sshd or Tailscale SSH is serving; a running tailscaled alone (--tailscale-serve) still advertises nothing. The mDNS name still requires a local sshd, since Tailscale SSH only answers on the tailnet address. readTailscaleStatus also reports running from BackendState, and the tailnet name is only advertised while the daemon is Running: after tailscale down the status still carries the node name but nothing answers on it. The existing test that expects [] with Tailscale up but no SSH anywhere is unchanged.

Verification

• RemoteOpenTargets.test.ts: the spawner now answers status --json and debug prefs separately. No loopback sshd plus RunSSH: true yields the tailnet target alone; RunSSH: true with tailscale down or with BackendState: "Stopped" yields nothing (a stopped daemon plus a local sshd still yields the mDNS name only); the existing no-sshd and ordering cases are unchanged. The prefs fixtures are the real tailscale debug prefs shape (trimmed) from tailscale 1.94.
• tailscale.test.ts: readTailscaleSshEnabled runs tailscale debug prefs and decodes RunSSH; missing or false reads as disabled, malformed JSON is a parse error.
• vp test run on both files (23 tests), plus typecheck and lint for packages/tailscale, apps/server and apps/desktop (the other readTailscaleStatus consumers).

Fixes #11052. ## Checked against a real Tailscale install, and what could not be

On my Mac (macOS 15.7.5, Tailscale 1.102.3, the GUI build) the two commands this change reads behave as the fixtures assume: tailscale status --json reports BackendState: "Running" with a Self.DNSName, and tailscale debug prefs prints a JSON object with RunSSH (currently false) and WantRunning. With RunSSH false and no sshd on port 22, no tailnet target is advertised, before and after this change.

The case this PR fixes, Tailscale SSH serving without a local sshd, could not be produced on this machine: tailscale set --ssh=true answers The Tailscale SSH server does not run in sandboxed Tailscale GUI builds. and RunSSH stays false. That configuration exists on Linux hosts and on the open-source tailscaled, as in #11052, and is covered here only by RemoteOpenTargets.test.ts and tailscale.test.ts.

Implemented with Claude Code (Claude Fable 5.1).

[macroscopeapp]

Approvability

Verdict: Approved at 6aa6c8f

Macroscope's review found this PR approvable — This is a contained server-side fix that adds a tailnet editor target only when Tailscale is running and Tailscale SSH has been explicitly enabled, while preserving local-sshd and mDNS behavior. The shared CLI handling and conditional cases are covered by focused tests, with no schema, deployment, default-configuration, or static-analysis changes.

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📝 Walkthrough

Walkthrough

Tailscale status now reports daemon state, and tailscale debug prefs provides SSH preference state. Remote target resolution uses these values with local sshd availability to determine Tailscale and mDNS targets.

Changes

Tailscale SSH discovery

Layer / File(s)	Summary
Read Tailscale status and SSH preferences packages/tailscale/src/tailscale.ts, packages/tailscale/src/tailscale.test.ts	The command layer supports debug output, parses BackendState, exposes running, and reads the RunSSH, ShieldsUp, and WantRunning preferences. Tests cover running and stopped status values and preference parsing.
Resolve targets from daemon and SSH state apps/server/src/environment/RemoteOpenTargets.ts	The resolver advertises a Tailscale target only when Tailscale is running and either local sshd or Tailscale SSH is available. It advertises mDNS only when local sshd listens.
Validate command routing and target gating apps/server/src/environment/RemoteOpenTargets.test.ts	Fixtures distinguish status and debug preference commands. Tests cover Tailscale SSH without local sshd, Tailscale down, and a stopped daemon.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Sequence Diagram(s)

sequenceDiagram
  participant RemoteOpenTargets
  participant LoopbackSSHD
  participant TailscaleCommands
  participant MDNS
  LoopbackSSHD->>RemoteOpenTargets: report listening state
  RemoteOpenTargets->>TailscaleCommands: read status and SSH preference when needed
  TailscaleCommands-->>RemoteOpenTargets: return daemon and SSH state
  RemoteOpenTargets->>MDNS: resolve hostname when sshd listens
  RemoteOpenTargets-->>RemoteOpenTargets: advertise eligible targets

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Suggested reviewers: t3dotgg, juliusmarminge

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Merge Risk | ⚪ Minimal · up to d39fe

Merge Risk: ⚪ Minimal · up to d39fe

Stopped Tailscale daemons no longer produce unusable editor targets, and mDNS remains conditional on local sshd. The change is mergeable subject to normal checks.

Security Architecture Review

Security architecture risk: ⚪ Minimal · up to d39fe

The change makes an independently enabled Tailscale SSH route discoverable without enabling SSH, granting privileges, or changing authentication. Stopped daemons and failed checks do not produce tailnet targets, and LAN targets still require a local SSH server. No material security risk introduced or worsened by this change was identified.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The newly discoverable information is the serving environment's tailnet hostname, distributed through existing configuration and remote-editor selection. The inspected path does not distribute credentials or grant access to additional hosts or data stores.

Trust Boundaries and Controls

• observed — The exported reads invoke fixed local command arguments, not viewer-supplied commands. Preference failures are consumed as false, and nonzero command exits retain output lengths and a classified stderr label rather than raw CLI text. The browser receives target metadata, not access to the command runner.

Resilience and Maintainability Implications

• inferred — Each resolution builds a fresh local array and performs no durable state transition. Partial failure or changes between availability reads can affect advertised metadata, but this path cannot strand an enabled listener, reservation, credential, or modified authorization policy.

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the primary change: advertising the tailnet editor target when Tailscale SSH is available without a local sshd.
Description check	✅ Passed	The description explains the problem, implementation, scope, verification results, environment limitations, linked issue, and agent usage. It provides specific test coverage and observed behavior rath…
Linked Issues check	✅ Passed	The changes satisfy issue #11052. RemoteOpenTargets.resolveTargets no longer requires a localhost SSH listener before Tailscale discovery. It advertises the Tailscale hostname only when Tailscale is…
Out of Scope Changes check	✅ Passed	The changes remain within issue #11052. The added Tailscale running-state parsing, preference reader, target gating, and focused tests directly support reliable remote editor target discovery. No unre…

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[shivamhwp]

Note: GPT-6 on behalf of shivam (@shivamhwp).

The new enablement check reads a field that tailscale status --json does not provide as written. PeerStatus.SSH_HostKeys has the JSON tag sshHostKeys, not SSH_HostKeys: https://github.com/tailscale/tailscale/blob/v1.94.2/ipn/ipnstate/ipnstate.go#L301 . The fixtures currently use the Go field name, so they hide this mismatch.

Changing the spelling alone is insufficient for the local node. updateStatusLocked fills SSH host keys for peer entries, but its MutateSelfStatus block does not populate them: https://github.com/tailscale/tailscale/blob/v1.94.2/ipn/ipnlocal/local.go#L1311 . The same split remains in current upstream. Please use a supported local SSH-enablement signal, such as the local RunSSH preference, and cover output from an actual enabled node with no loopback sshd. Keep the independent mDNS gate.

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Inline comments:
In `@apps/server/src/environment/RemoteOpenTargets.ts`:
- Around line 52-58: Update readTailscaleStatus and the tailscaleSshServing
condition in RemoteOpenTargets to parse BackendState and require it to equal
"Running" before advertising the SSH target. In RemoteOpenTargets.test.ts,
update the stopped fixture to use exit code 0 with BackendState "Stopped", a DNS
name, and RunSSH true, then assert that no target is returned.

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[Mnigos]

@shivamhwp you're right on both counts, switched to RunSSH from tailscale debug prefs in 495593b, mDNS gate unchanged.

Dismissing prior approval to re-evaluate 495593b

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Actionable comments posted: 1

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Inline comments:
Review comments at @packages/tailscale/src/tailscale.ts:
- Around line 299-303: Update the Tailscale preferences schema and predicate in
`readTailscaleSshEnabled` to include `WantRunning` and return false when it is
explicitly false. Preserve the existing `RunSSH` and `ShieldsUp` checks for all
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[Mnigos]

Note

🤖 Claude Fable 5.1 on behalf of Mnigos

Closing to keep my open queue focused; happy to reopen if this is still wanted.