feat(): Epic Offline Mode for offline launches

[phobos665]

Description

Added a new option in the Container settings for launching games offline when using Epic.

Now correctly launches games offline if the device or the setting has been enabled.

Also added translations.

Fixes games such as Tomb Raider 1-3 Remastered where the game can only launch in offline mode.

Recording

Recording of Offline mode for Epic games:
https://github.com/user-attachments/assets/639704e0-f41f-4d53-9b6f-0833edda3729

Type of Change

• Bug fix
• Performance / stability improvement
• Compatibility improvements
• Other (requires prior approval)

Checklist

• If I have access to #code-changes, I have discussed this change there and it has been green-lighted. If I do not have access, I have still provided clear context in this PR. If I skip both, I accept that this change may face delays in review, may not be reviewed at all, or may be closed.
• This change aligns with the current project scope (core functionality, stability, or performance). If not, it has been explicitly approved beforehand.
• I have attached a recording of the change.
• I have read and agree to the contribution guidelines in CONTRIBUTING.md.

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Summary by cubic

Add Epic Offline Mode for Epic game launches. Games can now launch without authentication when the device is offline or the setting is enabled, with per‑container persistence and localized UI.

• New Features
  • Added “Epic Offline Mode” switch in Container settings (General tab), persisted via PrefManager.epicOfflineMode, ContainerData.epicOfflineMode, and Container getters/setters.
  • Wired offline state through XServerScreen to Epic launches; EpicGameLauncher now skips token fetch when offline.
  • Added translations for the new labels across supported locales.

^{Written for commit 1062f4b. Summary will update on new commits. Review in cubic}

Summary by CodeRabbit

• New Features
  • Added Epic offline mode option to application settings. Users can now enable offline launching for Epic Games titles when internet connectivity is unavailable. Localized support for 15+ languages.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds Epic Games offline mode support by introducing a new user-configurable preference that flows through the container configuration system to the launch path. The feature persists offline mode state across app sessions and passes it to the Epic game launcher.

Changes

Epic Offline Mode Implementation

Layer / File(s)	Summary
Container persistence layer for offline mode com/winlator/container/Container.java	epicOfflineMode field added with JSON serialization in saveData() and loadData(), plus public accessors isEpicOfflineMode() and setEpicOfflineMode(boolean).
Configuration data model extension com/winlator/container/ContainerData.kt	New epicOfflineMode property (default false) added to data class with serialization support in Saver companion for both save and restore paths.
Preference and configuration lifecycle app/gamenative/PrefManager.kt, app/gamenative/utils/ContainerUtils.kt	PrefManager.epicOfflineMode preference added; ContainerUtils now threads the value through getDefaultContainerData(), setDefaultContainerData(), toContainerData(), applyBestConfigMapToContainerData(), applyToContainer(), and createNewContainer() to persist and synchronize across config operations.
Settings UI configuration switch app/gamenative/ui/component/dialog/GeneralTab.kt	New SettingsSwitch added for config.epicOfflineMode with wiring to update state; unused local_saves_only switch block removed.
Launch path offline flag threading app/gamenative/ui/screen/xserver/XServerScreen.kt, app/gamenative/service/epic/EpicGameLauncher.kt	isOffline flag passed to setupXEnvironment(...) and threaded to getWineStartCommand(...); Epic launch parameters computed as offlineLaunch = offline || container.isEpicOfflineMode; EpicGameLauncher.buildLaunchParameters() simplified to always return successful offline parameters when offline is true.
Localized UI strings app/src/main/res/values*/strings.xml (14 locales)	epic_offline_mode and epic_offline_mode_description string resources added in Danish, German, Spanish, French, Italian, Korean, Polish, Portuguese-BR, Romanian, Russian, Ukrainian, Simplified Chinese, Traditional Chinese, and English default.

Sequence Diagram

sequenceDiagram
  participant User as User
  participant Settings as GeneralTab
  participant Prefs as PrefManager
  participant Utils as ContainerUtils
  participant Container as Container
  participant XServer as XServerScreen
  participant Epic as EpicGameLauncher
  User->>Settings: Toggle epicOfflineMode
  Settings->>Prefs: epicOfflineMode = true
  Prefs->>Utils: setDefaultContainerData()
  Utils->>Container: setEpicOfflineMode(true)
  User->>XServer: Launch game with offline flag
  XServer->>Container: isEpicOfflineMode() check
  XServer->>Epic: buildLaunchParameters(offline=true)
  Epic->>Epic: Return offline launch success

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• utkarshdalal/GameNative#1139: Overlaps on modifications to GeneralTabContent in GeneralTab.kt with removal of the local_saves_only settings switch.

Poem

🐰 A rabbit's ode to offline play:
An Epic mode for offline days,
Through Container streams and Pref displays,
From UI switch to launch's deep ways,
Now games run free, no internet delays!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 11.76% which is insufficient. The required threshold is 80.00%.	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 main feature added: Epic Offline Mode support for offline launches. It is specific, relevant, and directly summarizes the primary change.
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.
Description check	✅ Passed	The pull request description covers all required sections from the template: a clear description of changes, an attached recording, type of change selected, and all checklist items completed.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[phobos665]

removed some old params, and removed navigateBack as it wasn't used.

Added in "offline" from the XServerScreen constructor to do a similar check as Steam.

[cubic-dev-ai]

No issues found across 21 files

_{Re-trigger cubic}