feat: 迁移 Database Instance 领域基线

internal/database/domain/instance/observation_target.go

@@ -0,0 +1,81 @@
+/*
+Copyright 2026.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package instance
+
+// Definition is the immutable effective configuration of an Instance.
+// Available extensions are observations, not part of the declared configuration.
+type Definition struct {
+	endpoint        Endpoint
+	adminCredential CredentialReference
+}
+
+func NewDefinition(endpoint Endpoint, adminCredential CredentialReference) (Definition, error) {
+	definition := Definition{endpoint: endpoint, adminCredential: adminCredential}
+	if err := definition.Validate(); err != nil {
+		return Definition{}, err
+	}
+	return definition, nil
+}
+
+func (d Definition) Endpoint() Endpoint                   { return d.endpoint }
+func (d Definition) AdminCredential() CredentialReference { return d.adminCredential }
+
+// Validate rejects invalid zero-value components even when constructors were bypassed.
+func (d Definition) Validate() error {
+	if err := d.endpoint.Validate(); err != nil {
+		return err
+	}
+	return d.adminCredential.Validate()
+}
+
+// ObservationTarget binds facts to a registration and its declared configuration.
+// It does not identify a physical PostgreSQL server or prove observation freshness.
+// Secret content refresh and same-target observation freshness remain application
+// responsibilities; no credentials or Secret contents are carried by this value.
+type ObservationTarget struct {
+	identity   Identity
+	revision   Revision
+	definition Definition
+}
+
+func NewObservationTarget(identity Identity, revision Revision, definition Definition) (ObservationTarget, error) {
+	target := ObservationTarget{identity: identity, revision: revision, definition: definition}
+	if err := target.Validate(); err != nil {
+		return ObservationTarget{}, err
+	}
+	return target, nil
+}
+
+func (t ObservationTarget) Identity() Identity     { return t.identity }
+func (t ObservationTarget) Revision() Revision     { return t.revision }
+func (t ObservationTarget) Definition() Definition { return t.definition }
+
+func (t ObservationTarget) Validate() error {
+	if err := t.identity.Validate(); err != nil {
+		return err
+	}
+	if err := t.revision.Validate(); err != nil {
+		return err
+	}
+	return t.definition.Validate()
+}
+
+// Matches rejects invalid targets before comparing values. Matching is necessary,
+// but not sufficient, for the aggregate to accept a fresh capability observation.
+func (t ObservationTarget) Matches(other ObservationTarget) bool {
+	return t.Validate() == nil && other.Validate() == nil && t == other
+}