feat(#689): persistent meal-planner session state to prevent RAG leakage

[lokhor]

Summary

Add conversation-scoped, Room-backed meal-planner session state and wire it into the chat prompt pipeline. During active meal-planner turns, the model receives structured session context (preferences, plan, current day) instead of relying on chat history — and episodic/RAG context is suppressed to prevent stale memory leakage.

Changes

New files

• MealPlanSessionEntity.kt — Room entity with conversationId PK, status, peopleCount, days, dietary/protein preferences (JSON), high-level plan, current day index, updatedAt
• MealPlanSessionDao.kt — DAO with getByConversationId, upsert, deleteByConversationId, deleteAll
• MealPlanSessionRepository.kt — Convenience layer: createOrReset, updateStatus, updatePreferences, saveHighLevelPlan, advanceDay, markCompleted

Modified files

• KernelDatabase.kt — Added MealPlanSessionEntity, mealPlanSessionDao() abstract method, MIGRATION_23_24, bumped version to 24
• MemoryModule.kt — Added DAO/repository providers, included MIGRATION_23_24 in migration list
• ChatViewModel.kt — Added MealPlanSessionRepository injection, session detection block that:
  • Checks for active (non-completed) meal-planner session
  • Builds structured context block via buildMealPlanContext()
  • Suppresses RAG context (effectiveRagContextForPrompt)
  • Forces needsHistoryReplay = true to clear stale episodic KV cache
  • Injects meal-plan context into prompt before anaphora/system blocks
• VerboseLoggingPreferenceUseCase.kt — Merge conflict resolution from bringing main up to date (added missing @ApplicationContext import)

Architecture

User query → ChatViewModel.sendMessage()
    │
    ▼
Check mealPlanSessionRepository.getSession(conversationId)
    │
    ├─ Active session? → Suppress RAG, inject session context, force replay
    │
    └─ No active session → Normal RAG + episodic flow

Session context block (injected into prompt)

[Meal Planner Session]
Status: collecting_preferences
People: 4
Days: 3
Dietary: ["vegetarian","gluten-free"]
Proteins: ["chicken","fish"]
Plan: [{"day1":"..."},{"day2":"..."}]
Current day: 1
[End Meal Planner Session]

Testing

• ./gradlew assembleDebug — builds clean
• Unit tests pass (pre-existing failures in MemoryRepositoryImplTest and LatexConversionTest are unrelated)
• Lint failures in core:inference are pre-existing (unrelated)

Next steps (out of scope for this PR)

• Session transition updates in MealPlannerSkill (stage 4 of the plan)
• MealPlannerSkill instruction updates (stage 5)
• Regression tests for repository and prompt injection (stage 6)

Closes #689

[github-actions]

Debug APK ready

Download app-debug.apk

Commit: fece906 - Build #1061

Updated on each push. Removed when PR is merged or closed.

[lokhor]

Rebased and addressed code review: #698