Remote Control: WebSocket connection breaks on message sync mismatch, stuck stale message blocks recovery

Description

The Remote Control (RC) WebSocket connection — both the web UI (claude.ai/code/session_*) and the desktop client — frequently drops into an unrecoverable error state due to message synchronization issues between the client and the remote CLI host.

Symptoms

1. A single message gets "stuck" at the bottom of the conversation, rendered in a faded/dimmed style
2. The message queue continues scrolling (new messages appear), but the stuck message cannot be cleared or processed
3. Eventually a "Retry connection" button appears, indicating the connection has entered an error state
4. Clicking "Retry connection" sometimes works, but often the same stuck message reappears

Reproduction triggers

This is most reliably triggered by:

• Context compaction: When the conversation hits the context limit and the system compresses/summarizes prior messages, the RC client often loses sync with the host's message stream
• Mid-execution user input: Sending a message from the RC client while the CLI agent is actively processing (running tools, streaming output) — if the timing doesn't align with the host's expected message flow, the connection desynchronizes
• Long-running tool calls: Extended Bash executions or Agent subprocesses seem to increase the likelihood

Expected behavior

The RC client should gracefully handle message ordering mismatches and recover without manual intervention. If a message cannot be reconciled with the host stream, it should be discarded or re-requested rather than getting permanently stuck in the render queue.

Environment

• Claude Code CLI (latest)
• macOS (Darwin 25.3.0, Mac mini)
• Tested on both claude.ai/code/session_* web UI and the desktop app RC view
• Model: claude-opus-4-6

Additional context

The self-healing capability of the WebSocket connection seems limited — once the client and host message streams diverge, recovery rarely succeeds without a full /rc restart on the CLI side. This makes RC unreliable for extended sessions, especially ones that hit context compaction (which is inevitable for long conversations).