Built-in cloud sync of session history ("recents") across machines

What I'm requesting

A built-in way to sync Claude Code session history (the "recents" shown in claude --resume) across multiple machines, without manual file copying.

Problem

Today, conversation history is stored only locally in ~/.claude/projects/<encoded-project-path>/ as JSONL transcripts. There's no built-in sync, so a conversation started on one Mac isn't available on another. The only workarounds are manually syncing ~/.claude/projects/ via Dropbox/iCloud/rsync or third-party tools — which are fragile:

• Sessions are keyed by the project's absolute path, so they only resume if the project lives at the identical path on every machine.
• Concurrent use risks conflicts/corruption of session files.
• Users must carefully avoid syncing machine-specific/credential files like .claude.json.

Proposed solution

First-class, opt-in cloud sync of session history across devices signed into the same account, ideally:

• Syncs recents so claude --resume shows conversations from any device.
• Handles the absolute-path-keying problem (e.g. sync by project identity/repo rather than raw local path, or remap paths per machine).
• Safe concurrent-use handling (conflict resolution / per-device session ownership).
• Excludes credentials and machine-local state by design.
• Configurable scope (which projects sync) and an off switch for privacy.

Why it matters

Many developers work across a laptop and a desktop (or multiple Macs) and expect continuity of their in-progress work — similar to how editors and shells sync history. This removes a real source of friction and the risk of manual-sync corruption.