Tell Directives

A tell directive is a message pushed into a running session from another channel — for example, sending an instruction from Telegram that lands in an active VS Code session.

The flow

1. A directive is posted to the gateway addressed to an active session.
2. Each shell runs a persistent subscription (a tell-listener) that watches for directives addressed to it.
3. When one arrives, it is injected into the session so LISA acts on it within the current thread of work — no new session required.

Why it exists

Tell directives make the operator's reach channel-independent. The operator can redirect, add, or halt work from whichever channel is at hand, and the instruction reaches the session that is actually doing the work. This is the write-side counterpart to the read-side awareness provided by the session registry.