This is very clear now. Let me summarize what I've found: ## Summary: Where OpenCode Stores Session/Message Data **Yes, OpenCode stores all session and message data in the file system** using JSON files. ### Location The storage root is at: ``` ~/.local/share/opencode/storage/ ``` This is derived from the XDG Base Directory Specification (`xdgData`) in [`packages/opencode/src/global/index.ts`](packages/opencode/src/global/index.ts:8). ### Directory Structure From the `Storage` module ([`packages/opencode/src/storage/storage.ts`](packages/opencode/src/storage/storage.ts)), data is organized as: ``` ~/.local/share/opencode/storage/ ├── session//.json # Session metadata ├── message//.json # Messages ├── part//.json # Message parts (tool calls, etc.) ├── session_diff/.json # File diffs per session ├── share/.json # Share info (if session is shared) ├── project/.json # Project metadata └── migration # Migration version tracker ``` ### Storage API The `Storage` namespace provides simple CRUD operations: - `Storage.write(key[], content)` - Write JSON to `key.json` - `Storage.read(key[])` - Read JSON from `key.json` - `Storage.update(key[], fn)` - Read-modify-write pattern - `Storage.remove(key[])` - Delete a file - `Storage.list(prefix[])` - List all files under a prefix ### Examples from Session code: - **Create session**: `Storage.write(["session", projectID, sessionID], result)` - **Get session**: `Storage.read(["session", projectID, sessionID])` - **Save message**: `Storage.write(["message", sessionID, messageID], msg)` - **Save part**: `Storage.write(["part", messageID, partID], part)` So it's all plain JSON files on the local filesystem - no database involved!