Three tools route agent context around vendor compaction

Three separate projects landed on the same fix independently, per coverage dated August 10, 2026. That matters for anyone running agents through long sessions. Memory handling stops being a prompt technique and becomes a separate process you deploy and trust.

LeanCTX is a Rust binary that proxies the wire and decides what an agent is allowed to read. MemPalace runs local-first with zero API calls and hooks in before compaction fires. claude-mem captures what a session does, compresses it, and re-injects it on the next run, per its GitHub repo.

The shared target is vendor auto-compaction. All three treat it as the lossy step, not the solution. That's a claim about where the failure lives: the vendor's own summarization, not the model's context window size.

A Rust binary proxying the wire is a process boundary. It runs outside the vendor's control, which means it can preserve what the vendor's compaction would drop. That also makes you responsible for running and trusting a separate piece of software to keep your agent's memory intact.

Watch whether one of these gets folded into a vendor's own tool instead of staying independent. That would show whether vendors see local context control as a threat worth absorbing or a feature request.

None of the three report how their latency or context retention compares to vendor compaction, per their repos. That's the gap to check before picking one for production.