# v0.3 Research: Architecture

**Milestone:** v0.3 Reimagining Cloud Storage integration
**Date:** 2026-06-17

## Target Model

Cloud files become virtual documents: provider-owned bytes remain in the connected storage, while DocuVault stores metadata, extracted text, topics, embeddings/search data, status, and a bounded cache of temporary bytes.

## Proposed Components

### Provider Capability Layer

Add a cloud file operation interface separate from the current object-storage `StorageBackend` contract:

- `list_folder`
- `get_metadata`
- `download_bytes` / streaming equivalent
- `upload_file`
- `rename_item`
- `move_item`
- `delete_item`
- `create_folder`
- `get_change_cursor` / `list_changes` where available
- `capabilities()` returning action support and limitations

This avoids forcing local/MinIO object semantics onto provider file-manager behavior.

### Cloud Item Index

Add durable tables for cloud-visible items and analysis/index state:

- `cloud_items`: user, connection, provider, provider item id/path, parent id/path, name, kind, MIME/content type, size, etag/version, mtime, path snapshot, last_seen_at, deleted_at.
- `cloud_item_analysis`: item, status, extracted_text, topic links, semantic index status, last_analyzed_etag, error, job id, timestamps.
- Optional `cloud_file_cache`: item, etag/version, byte location, size, last_accessed_at, expires_at, pin reason, eviction state.

Keep `documents` for DocuVault-owned local/imported files unless a later design intentionally merges local and cloud into one polymorphic table.

### API Shape

Split `backend/api/cloud.py` when implementation starts:

- `api/cloud/connections.py`
- `api/cloud/browse.py`
- `api/cloud/actions.py`
- `api/cloud/analysis.py`
- `api/cloud/search.py` or reuse a shared search API
- shared schemas in `api/schemas.py` or `api/cloud/schemas.py`

Every endpoint must assert `connection.user_id == current_user.id` and `cloud_item.user_id == current_user.id`.

### Frontend Shape

`FileManagerView` and `CloudFolderView` remain thin data providers. `StorageBrowser.vue` becomes capability-aware:

- accepts `capabilities` prop
- shows action buttons based on capabilities
- emits generic events for open/upload/rename/move/delete/analyze
- displays status badges for cached/indexed/analyzing/stale/error

Cloud-specific stores own provider state and API calls; `StorageBrowser` stays store-agnostic.

### Byte Cache and Offload

Cache flow:

1. User opens/previews/analyzes cloud item.
2. Backend verifies ownership and provider metadata.
3. Backend downloads bytes into a bounded cache or streams through memory if small.
4. Extraction/preview reads from cache.
5. Cache entry records item id, etag/version, byte size, last access, expiry.
6. Eviction removes bytes once unpinned and stale or over budget.

The cache is not the source of truth. Provider metadata and extracted/indexed data are.

### Analysis Flow

1. User selects file/folder/provider and clicks Analyze.
2. Backend resolves selection into cloud items, stores/updates metadata rows, and enqueues Celery jobs.
3. Jobs hydrate bytes as needed, extract text, classify topics, optionally create embeddings, and persist analysis state.
4. Search reads only persisted text/vector/topic metadata; it should not download cloud bytes during query.
5. Opening a result hydrates bytes on demand if preview/download needs them.

## Build Order

1. Capability model + provider action interface + tests.
2. Cloud item metadata/index schema + browse persistence.
3. Unified browser actions for cloud files/folders.
4. Cloud analysis jobs and cache/offload service.
5. Unified smart search over local and analyzed cloud documents.
6. Provider change detection, stale markers, and polish.
