[FEATURE] Memory system should be opt-in (like plan mode), not automatic

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The file-based memory system in Claude Code writes to and reads from ~/.claude/projects/.../memory/ automatically, without the user's knowledge or explicit consent. This means:

1. Uninvited writes: Information gets saved to disk during a conversation even when the user never asked for it to be remembered.
2. No control: There is no way for users to opt out of memory being written without digging into settings or deleting files manually.
3. Unexpected behavior: Users may be surprised to find that Claude has been silently persisting information about them, their preferences, and their work across sessions.

This is analogous to the subagent spawning issue — behavior that has real side effects happening without user awareness or control.

Proposed Solution

Add a memory mode toggle, similar to plan mode, that controls whether the memory system is active:

• Off (default): No memory is read from or written to disk automatically. Claude operates statelessly per session.
• On (opt-in): Current behavior — memory is read at session start and written during the session when relevant information is encountered.

Users can enable it explicitly when they want persistent memory across sessions.

Alternative Solutions

• Prompt the user for confirmation before writing any memory entry
• Provide a clear /memory command to view, edit, and delete memory entries, giving users full visibility and control

Priority

Medium-High — this touches user privacy and trust

Feature Category

Core CLI behavior / memory system

Use Case Example

A user asks to create a file locally and document something. Without memory mode being opt-in, notes about that action get silently written to the memory index. The user only discovers this when they notice unexpected files in ~/.claude/. With an opt-in memory mode, nothing is persisted unless the user has explicitly enabled it.