Why: the squad core has to compile without agent-native or agent-intent. Ports stay in the core; adapters and the CLI own the concrete clients.
Evidence: GOWORK=off go test -count=1 ./squad/ ./store/ ./textextract/ ./schema/ passed, and the intent, sqlite, native, and cmd modules passed their own go test.
Impact: core go.mod keeps error-code-system only. Nested gitlinks stay. Callers register the native backend through agent-squad/adapters/native.
Refs: D1
Co-authored-by: Cursor <cursoragent@cursor.com>