The per-session ProjectionValueStore was deleted on host/session-removed
even though the Session instance survives removal (open() is idempotent and
drop() only removes the map entry). A re-added or re-listed session resumed
on the same instance with an empty projection face, so projection-backed UI
(such as the OpenRouter cost readout) reverted to blank until a fresh host
baseline landed.
Retain the store on removal and lift the removed tombstone from the
surviving instance on revival (host/session-added and list-refresh
re-listing), so chat switching keeps cost readouts populated.
A test file under packages/client now says which face it covers:
`*.client.spec.{ts,tsx}` and its `*.client.{ts,tsx}` helpers belong to the
Client aggregate, `*.host.spec.ts` to the host aggregate. The carrier's four
node-half specs take the Host suffix.
The two suffixes are mutually exclusive, so each aggregate excludes the
other's and both keep one broad test glob: `exclude` wins over `include`, and
`packages/client/**` no longer has to be excluded wholesale from the host
program with per-file `files` entries carved back out of it. A Host-face spec
that reaches only Host source therefore needs no cross-face project
reference, which the split-project rule rejects.
vitest still discovers every file through `**/*.spec.{ts,tsx}`.
