fix(sandbox): scope data volume per workspace to prevent SQLite contention

Sessions, snapshots, logs, and the SQLite database in ~/.local/share/opencode
are all project-specific. Sharing a single opencode-data volume across
workspaces risks WAL-mode write contention when multiple containers run
concurrently, and causes session bleed between unrelated projects. Scoping
the volume name to the sanitized workspace directory name isolates each
project's data cleanly.

Author: crallen

bin/opencode-sandbox

@@ -272,8 +272,9 @@ done
 # Persistent state volume (theme, model selection, prompt history)
 VOLUME_FLAGS+=(-v "opencode-state:/home/opencode/.local/state/opencode")
 
-# Persistent data volume (sessions, auth, snapshots)
-VOLUME_FLAGS+=(-v "opencode-data:/home/opencode/.local/share/opencode")
+# Persistent data volume (sessions, snapshots, logs — scoped per workspace to
+# avoid SQLite WAL contention and session bleed between unrelated projects)
+VOLUME_FLAGS+=(-v "opencode-data-${WORKSPACE_NAME}:/home/opencode/.local/share/opencode")
 
 # ---------------------------------------------------------------------------
 # Run