Under the hoodTier: how much it should matter to you
3Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
Session StateArea: what it touches
ImprovementsKind: in v2.1.229,
ImprovementsSection of the release
What
Caches that were previously process-wide now live in a per-session store: the WebFetch URL and domain-check caches, the send-file duplicate set, Bash working-directory tracking, the alias-probe fired set, plus per-host containers holding plugin sync state, the keybinding writer, the diagnostics manager and the binary-check cache. In a process running more than one session at once (SDK, runner, cowork) these no longer bleed across sessions.
Details
The store is created with the session context and carried through context construction, forking and agent spawn.
Disposing a session installs a fresh store rather than clearing shared maps.
Evidence
toolState: this.toolState, toolState
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
