Fix Clear All Announces to preserve My Contacts (#365)

[torlando-tech]

Summary

• Fix "Clear All Announces" deleting contact announces, which caused "Node not found" errors when opening conversations with saved contacts
• Adds deleteAllAnnouncesExceptContacts(identityHash) to DAO using a SQL subquery that exempts contacts scoped to the active identity
• Routes ViewModel through identity-aware delete with fallback to original deleteAllAnnounces() when no active identity exists
• Updates dialog text to inform users that contacts are preserved
• Adds 6 DAO tests (Robolectric + in-memory Room) and 3 ViewModel tests (MockK) covering deletion, preservation, identity scoping, edge cases, and regression

Test plan

• Full project builds: assembleDebug ✓
• All unit tests pass: testDebugUnitTest ✓
• Code quality: detektCheck ✓
• Manual: Tap "Clear All Announces" → non-contact announces removed, contact announces preserved
• Manual: Open conversation with saved contact after clearing → no "Node not found" error
• Manual: Switch identities → only active identity's contacts are preserved

Closes #365

🤖 Generated with Claude Code

[sentry]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[greptile-apps]

Greptile Overview

Greptile Summary

This PR fixes a bug where "Clear All Announces" was deleting contact announces, causing "Node not found" errors when opening conversations with saved contacts.

Implementation:

• Added deleteAllAnnouncesExceptContacts(identityHash) to AnnounceDao using a SQL subquery that filters contacts by the active identity
• Routed AnnounceStreamViewModel.deleteAllAnnounces() through identity-aware deletion with fallback to original deleteAllAnnounces() when no active identity exists
• Updated UI dialog text to inform users that contacts are preserved
• Added comprehensive test coverage: 6 DAO tests (Robolectric + in-memory Room) and 3 ViewModel tests (MockK)

Key changes:

• The SQL query correctly uses a NOT IN subquery to exempt announces whose destinationHash matches contacts scoped to the active identity
• Identity scoping ensures proper data isolation in multi-identity scenarios
• Tests cover preservation, deletion, identity scoping, edge cases, and regression scenarios
• All builds and tests pass according to the PR description

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The implementation is clean, well-tested, and uses proper SQL patterns. The SQL subquery correctly preserves identity-scoped contacts while deleting other announces. The fallback mechanism ensures backward compatibility when no active identity exists. Test coverage is comprehensive with 9 tests covering all scenarios including edge cases. Code style improvements are minor formatting changes. No security vulnerabilities or logical errors identified.
• No files require special attention

Important Files Changed

Filename	Overview
data/src/main/java/com/lxmf/messenger/data/db/dao/AnnounceDao.kt	Added deleteAllAnnouncesExceptContacts(identityHash) SQL query using subquery to preserve contact announces, formatting improvements
data/src/main/java/com/lxmf/messenger/data/repository/AnnounceRepository.kt	Added repository method deleteAllAnnouncesExceptContacts(identityHash) delegating to DAO, code style improvements
app/src/main/java/com/lxmf/messenger/viewmodel/AnnounceStreamViewModel.kt	Updated deleteAllAnnounces() to use identity-aware deletion with fallback to original method when no active identity, formatting improvements
app/src/main/java/com/lxmf/messenger/ui/screens/AnnounceStreamScreen.kt	Updated dialog text to inform users that contacts are preserved when clearing announces, formatting improvements
data/src/test/java/com/lxmf/messenger/data/db/dao/AnnounceDaoTest.kt	Added 6 comprehensive tests for deleteAllAnnouncesExceptContacts covering preservation, identity scoping, edge cases, and regression
app/src/test/java/com/lxmf/messenger/viewmodel/AnnounceStreamViewModelTest.kt	Added 3 ViewModel tests verifying identity-aware delete routing, error handling, and fallback behavior when no active identity

Sequence Diagram

sequenceDiagram
    participant User
    participant UI as AnnounceStreamScreen
    participant VM as AnnounceStreamViewModel
    participant Repo as AnnounceRepository
    participant DAO as AnnounceDao
    participant DB as Room Database
    
    User->>UI: Tap "Clear All Announces"
    UI->>UI: Show ClearAllAnnouncesDialog
    User->>UI: Confirm deletion
    UI->>VM: deleteAllAnnounces()
    
    VM->>VM: Get active identity
    alt Active identity exists
        VM->>Repo: deleteAllAnnouncesExceptContacts(identityHash)
        Repo->>DAO: deleteAllAnnouncesExceptContacts(identityHash)
        DAO->>DB: DELETE FROM announces<br/>WHERE destinationHash NOT IN<br/>(SELECT destinationHash FROM contacts<br/>WHERE identityHash = :identityHash)
        DB-->>DAO: Contact announces preserved
        DAO-->>Repo: Success
        Repo-->>VM: Success
        VM->>VM: Log: "Deleted non-contact announces"
    else No active identity
        VM->>Repo: deleteAllAnnounces()
        Repo->>DAO: deleteAllAnnounces()
        DAO->>DB: DELETE FROM announces
        DB-->>DAO: All announces deleted
        DAO-->>Repo: Success
        Repo-->>VM: Success
        VM->>VM: Log: "Deleted all announces (no active identity)"
    end
    
    VM-->>UI: Operation complete
    UI->>User: Dialog dismissed, list updated

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