FR-8: Settings Persistence

Persist user preferences locally without cloud sync.

Requirement

1. Store settings in a JSON file located in the platform-appropriate app data directory
2. ($HOME/Library/Application Support/Speakr/settings.json).
3. Write changes atomically to avoid corruption.
4. Migration framework supports future schema evolution with versioning.
5. No data leaves the device.

Rationale

Local persistence offers instant access, privacy, and offline capability.

Acceptance Criteria

• Settings file created on first launch with defaults.
• Modifying settings updates file within 100 ms.
• Corrupt settings file triggers automatic recovery to defaults.
• Unit tests cover load/save error paths.

Test-Driven Design

Write failing unit tests for load/save, corruption recovery, and migration before implementation; pass them in CI.

References

PRD §6 Functional Requirements – FR-8