fix: harden workspace activation and snapshot retention

docs/install/local-workspace-registry.md

@@ -111,7 +111,7 @@ THT_WS_PSD_CLINICAL_VECTOR_API_KEY_FILE=/run/secrets/psd-vector-api-key
 ```
 
 ```dotenv
-# SSH tunnel; host-key verification and TLS target name remain mandatory.
+# SSH tunnel diagnostic only; runtime sessions are fail-closed in this release.
 THT_WS_PSD_CLINICAL_DWH_TRANSPORT=ssh_tunnel
 THT_WS_PSD_CLINICAL_DWH_USER=thoth_reader
 THT_WS_PSD_CLINICAL_DWH_PASSWORD_FILE=/run/secrets/psd-dwh-reader
@@ -128,6 +128,10 @@ Repeat the SSH names for `VECTOR` where needed. REST diagnostics reject a privat
 rather than weakening TLS; use runtime-trusted HTTPS or verified direct/SSH native TLS. See the
 [diagnostic protocol](../workspace-diagnostic-protocol.md).
 
+An SSH connector can prove installation reachability, host-key verification, authentication, and
+target identity, but it intentionally returns `workspace_not_activatable`; select direct or REST
+before creating sessions. Git pull/push over SSH remains fully supported and is independent.
+
 ## Bootstrap, first pull, and diagnostics
 
 Copy [the local Compose example](examples/local-compose.workspace-registry.yaml) and exactly one