Claude Code's cross-session messaging is just a JSON directory and one Unix socket per session
LeonKohli · reddit · 2026-09-22
- Claude Code quietly shipped cross-session messaging in v2.1.224, buried as a single changelog line with no announcement.
- Discovery is simply a directory: each session writes /.claude/sessions/<pid>. with its PID, cwd, name, socket path and status, and ListAgents reads that folder — no daemon, no service.
- Transport is one Unix socket per session (mode 0600) carrying newline-delimited JSON messages, with control frames for delivery receipts and idle notifications.
- The author built claude-uds-bridge (MIT, macOS/Linux), a plugin that registers a running Codex task in the registry so it appears in /list-agents and answers like any other session. Original transport work by PeterSR.
More from coding & agent
- MechFaber: Claude Code designs a 99-part quadruped with firmware co-simulated in Renode and MuJoCo — SpeedyBrowser45 · 2026-09-22
- Exa MCP hits 5,000 GitHub stars as AI agents flock to its search integration — TheIshanGoswami · 2026-09-22
- 670,000 agent skills, no trust layer: bot scan finds 69% never reliably fire — markjeffrey · 2026-09-22
- Eight disruptive use cases for Jev: from millisecond evals to AI guardrails — nkmrao · 2026-09-22
- Training on production traces: single-trajectory RL may unlock continual learning — rhythmrg · 2026-09-22
- Anthropic's Swiss cheese model explains why passing evals isn't enough for agents — hugobowne · 2026-09-22