fix(tvOS): use writable local paths for prefs, auth config, and Go state

[CicerBro]

What this fixes

Several tvOS failures share one root cause: App Group containers and related default paths are not usable the way they are on iOS.

1. Preferences / device name — App-group UserDefaults do not work on tvOS (cfprefsd detaches), so shared prefs and the cached device name silently read as nil. DEBUG fallbacks under Application Support also fail because that directory is read-only in the sandbox.
2. Management server / auth — NetBirdSDKNewAuth creates/updates netbird.cfg at the given path before SSO. That path came from the App Group container, so changing the management server failed with EPERM before UserDefaults/IPC fallbacks ran.
3. Extension state persistence — The Go client was created with an empty state path, so the state manager wrote temp files into the extension CWD (read-only) and logged repeating EPERM errors about every 10 seconds.

Change

• Use UserDefaults.standard on tvOS and writable Caches for DEBUG file-path fallbacks.
• Point configFile() at caches as scratch space for NewAuth (persistence stays UserDefaults + IPC).
• Point stateFile() at caches and pass it into NetBirdSDKNewClient so the Go state manager has a writable location.

Summary by CodeRabbit

• Bug Fixes
  • Improved tvOS device-name persistence and synchronization.
  • Updated tvOS configuration and state storage to use writable cache locations.
  • Added safer fallback handling when cache directories are unavailable.
  • Prevented network services from starting without a valid writable state location.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: a27124eb-6272-4df5-a288-9df58c3a872e

📥 Commits

Reviewing files that changed from the base of the PR and between 5e68621 and ac6352d.

📒 Files selected for processing (3)

• NetbirdKit/Device.swift
• NetbirdKit/Preferences.swift
• NetbirdNetworkExtension/NetBirdAdapter.swift

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📝 Walkthrough

Walkthrough

tvOS storage now uses writable Caches or temporary directories, with standard process-local defaults. Device-name persistence uses the shared defaults. Network extension initialization validates and passes the resolved state path to the SDK.

Changes

tvOS storage and device persistence

Layer / File(s)	Summary
tvOS storage and device persistence NetbirdKit/Preferences.swift, NetbirdKit/Device.swift	tvOS config and state paths now use writable Caches with temporary-directory fallback. tvOS defaults use UserDefaults.standard. Device-name persistence uses shared defaults.
Validated tvOS client initialization NetbirdNetworkExtension/NetBirdAdapter.swift	Initialization stops when Preferences.stateFile() returns an empty path. The validated path is passed to NetBirdSDKNewClient.

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

Sequence Diagram(s)

sequenceDiagram
  participant NetBirdAdapter
  participant Preferences
  participant UserDefaults
  participant NetBirdSDKNewClient

  NetBirdAdapter->>Preferences: request stateFile()
  Preferences-->>NetBirdAdapter: return writable state path
  NetBirdAdapter->>NetBirdSDKNewClient: initialize with state path
  Preferences->>UserDefaults: use standard defaults for tvOS

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Possibly related PRs

• netbirdio/ios-client#134: Related platform-specific storage paths and SDK client initialization.
• netbirdio/ios-client#160: Related Preferences.sharedUserDefaults() changes.

Suggested reviewers: evgeniychepelev

Poem

A rabbit checks the cache with care,
Finds writable paths waiting there.
Device names hop into defaults,
The SDK starts with state it trusts.
tvOS paths now guide the way.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the tvOS path changes for preferences, authentication configuration, and Go state.
Description check	✅ Passed	The description clearly explains the tvOS failures, root causes, and changes that address them.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[Copilot]

Pull request overview

Fixes tvOS-specific sandbox/path issues by switching preference storage and SDK file paths away from App Group locations that are not usable on tvOS, ensuring config/auth setup and Go state persistence have writable locations.

Changes:

• Pass a writable state path into NetBirdSDKNewClient on tvOS to prevent Go state persistence failures.
• Adjust Preferences to use tvOS-appropriate UserDefaults and to place config/state files in writable locations.
• Update tvOS device-name caching to use the shared defaults abstraction.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
NetbirdNetworkExtension/NetBirdAdapter.swift	Passes a state path into the tvOS SDK client initialization to avoid EPERM persistence errors.
NetbirdKit/Preferences.swift	Updates tvOS defaults handling and redirects config/state paths to writable directories.
NetbirdKit/Device.swift	Uses Preferences.sharedUserDefaults() for tvOS device-name persistence.

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