Cross Agent Session Resumer

casr

Cross Agent Session Resumer for coding agents: resume a session created in one provider (Claude Code, Codex, Gemini, and more) using a different provider by converting through a canonical session model.

Quick Install (Recommended)

That installer is the primary distribution path. It handles platform detection, secure artifact verification, fallback source builds, shell completions, and agent-oriented local setup in one step.

TL;DR

The Problem: AI coding sessions are siloed by provider. A useful Codex session cannot be resumed directly in Claude Code, and vice versa.

The Solution: casr discovers a session across installed providers, reads it into a canonical IR, writes a native session file for your target provider, verifies read-back fidelity, and prints the exact resume command.

Why Use casr?

Quick Example

Design Philosophy

1. Provider fungibility over lock-in: sessions are portable assets.
2. Native fidelity over lossy export: writers target real provider session formats.
3. Safety over convenience: atomic writes, conflict checks, read-back verification.
4. Permissive conversion over brittle strictness: warnings for imperfect input when conversion is still useful.
5. Observability by default: rich logs and actionable errors for every pipeline stage.

How casr Compares

Supported Providers

Notes:
- Initial core focus is Claude Code, Codex, and Gemini CLI.
- Additional providers are implemented through the same Provider trait model.
- Grok Build (xAI's official grok CLI) is read and write: casr synthesizes the native session tree (updates.jsonl + summary.json), which was round-trip verified against a live grok --resume (the CLI lists, exports, and resumes casr-written sessions with full conversation context).
- OpenCode's opencode.db comes in three…