feat: 接入 Instance 版本与扩展可用性观测

docs/database/README.md

@@ -46,8 +46,9 @@ Secret metadata 和无关字段变化不重建连接。观测后再次读取 Sec
 不把旧连接的成功作为新凭据有效的证据；这不构成跨 Kubernetes/PostgreSQL 的原子事务。
 Instance UID、endpoint 或凭据引用变化也会释放旧连接；Forget/Close 只释放本地资源。
 
-当前只有 `ObserveVersion` 版本查询用例，不能产生完整 CapabilityObservation 或 Ready。
+当前通过 `ObserveMetadata` 读取服务器版本和可用扩展，`ObserveVersion` 只是其版本读取便捷入口，
-controller 接入、Secret watch、finalizer、registry 与真实权限检查仍待后续切片；并发 CR 更新
+不能产生完整 CapabilityObservation 或 Ready。
+controller 接入、Secret watch、finalizer、registry 观测装配与真实权限检查仍待后续切片；并发 CR 更新
 必须由调用者通过 resourceVersion 校验。应用层沿用源实现的串行处理，本阶段未引入新的调度框架。
 
 运行 `make test-database-integration` 验证真实 API server + 一次性 PostgreSQL；fixture 不接受外部
@@ -58,6 +59,49 @@ namespace 边界、有效值轮换、metadata 无关变化、中途轮换、重
 integration 标签代码。领域单测、真实 API 行为与真实 PostgreSQL 行为分别验收，不以本切片
 替代整个 Instance controller 的集成验收。
 
+## 服务器 metadata 与扩展观测
+
+SQL adapter 通过一条只读语句读取 `pg_catalog.current_setting('server_version')` 和
+`pg_catalog.pg_available_extensions`，避免从已安装列表推断可用列表，且不依赖可修改的
+`search_path`。查询失败丢弃整份结果；成功返回空列表与尚未观察严格区分。
+参考 PostgreSQL 的 [pg_available_extensions](https://www.postgresql.org/docs/18/view-pg-available-extensions.html)
+与 [CREATE EXTENSION](https://www.postgresql.org/docs/18/sql-createextension.html) 合同：可用列表
+表示服务器提供的扩展，不证明管理账号有安装权限，也不保证依赖和其他安装前提满足。
+
+`InstanceService` 保留原有 CredentialReader → Connector → Database 边界，复用同一个
+凭据读取、连接刷新和串行释放流程，不新增连接池封装或任意查询回调。每次重新查询 metadata，
+并在 Secret 有效值回读一致后生成不可变的 `MetadataObservation`，绑定本次 target（含当前
+generation），不绑定建池时的旧 target。结果不包含凭据，扩展集合不与 driver 的可变 slice 共享。
+凭据中途变化、读取失败或查询失败时，返回零值观察并释放连接，不复用旧的扩展列表。
+
+调用方可将 `Target()` 与 `Extensions()` 交给 Instance 的 `ObserveExtensions`；应用调用链
+仍负责同轮次使用，不能持久化或跨轮缓存这份证据。metadata 读取不安装扩展、不初始化 registry、
+不设置 Ready，也不授予 Tenant 写权限。管理权限矩阵、registry 完整回读及 controller 的
+checkpoint/status/finalizer 链路仍是后续切片。
+
+真实 API server + PostgreSQL 测试验证未安装扩展可被观察、名称保持大小写、search_path 遮蔽
+不改变查询来源、低权限账号读取、权限撤回失败与恢复、Secret 中途变化丢弃扩展结果。
+单元测试补充成功空列表、查询附带部分数据时丢弃、结果与可变 slice 隔离、每轮重新读取和
+generation 变化时的目标绑定；原凭据/TLS/超时/并发测试沿同一 metadata 路径继续运行。
+
+## Registry 所有权存储切片
+
+`adapter/postgresql/registry` 直接迁入上述固定基线的 `internal/postgresql/registry`，
+保留原 schema、版本表和唯一约束，不接回旧 controller。Store 使用调用方提供的 pgx 连接或
+连接池，不创建连接池、不读取凭据、不管理重连。迁移复用 tern v2.4.3 的事务和 advisory lock，
+所有权变更复用 PostgreSQL 唯一约束与行锁，没有新增迁移或锁框架。
+
+Claim 支持相同归属的幂等重试；Retain 保留不可重新占用的墓碑；Delete 仅删除匹配归属的
+managed 记录，且只应在调用方确认外部资源已删除后调用。Store 本身不删除 database、role
+或凭据，也不授予 Tenant provisioning 权限。驱动错误仅供内部调用方分类，接入 controller 时
+仍须按安全合同转换为脱敏的 Condition/Event，不能直接发布原始错误。
+
+真实 PostgreSQL 测试覆盖重复/并发初始化、唯一约束冲突、并发 Claim、归属不匹配、Retain
+与 Delete 重试、连接重建、取消恢复、未知 schema/超前版本拒绝，以及真实事务提交后注入
+客户端失败的恢复分支。后者确定性模拟“提交成功但调用方不知道”，不声称覆盖真实网络分区。
+registry 尚未装配到 InstanceService；初始化成功不能当作完整 registry 回读或 Instance Ready。
+controller 重启、Secret watch、finalizer 与跨后端删除仍由后续 envtest/端到端切片验收。
+
 ## 设计入口
 
 - [系统规格](specification.md)：规范性行为与验收标准；

docs/database/development.md

@@ -3,7 +3,7 @@
 > 本页迁入作为 Database 模块的测试分层与 fixture 合同。旧项目的 Make target、devcontainer
 > 和脚手架版本尚未适配 Ayatori；实现时应复用 Ayatori 现有工具链，并保持这里定义的测试边界。
 
-## Ayatori 已接入的凭据切片测试
+## Ayatori 已接入的凭据、metadata 与 registry 切片测试
 
 本节命令已在 Ayatori 接入；以下历史 Compose/Kind 操作仍属于迁入的目标合同。
 
@@ -28,7 +28,17 @@ runner 后端修复上线，不能从本地测试通过推断远端已经可用
 fixture 启动失败会保留退出错误与 stderr，并遮蔽测试密码，
 以区分缺少命令、daemon 不可达、权限和镜像拉取失败。
 
-这些测试尚不包含 Instance CRD/controller、Secret watch、status/finalizer 事件链、registry、
+metadata 测试验证版本与可用扩展的只读查询，包括未安装扩展、大小写保持、search_path 遮蔽、
+低权限账号读取、catalog 访问被撤回后的失败与恢复，以及凭据中途变化时同时丢弃版本和扩展。
+权限撤回只修改每个场景自建 PostgreSQL 容器的 ACL；不连接现有服务。
+可用列表不等于安装权限，这些检查不替代后续的完整管理权限矩阵或 Instance Ready 验收。
+
+registry 测试独立使用一次性 PostgreSQL，不启动 Kubernetes API server。覆盖重复和并发迁移、
+所有权唯一约束、并发占用、Retain 墓碑与 Delete 幂等、连接重建、取消恢复、未知 schema 与
+超前版本拒绝。通过在真实 COMMIT 成功后注入客户端错误，验证结果不确定时的重试；这不替代
+真实网络故障测试，也不覆盖跨后端的删除步骤。
+
+这些测试尚不包含 Instance CRD/controller、Secret watch、status/finalizer 事件链、registry 观测装配、
 权限探测矩阵、ESO 或 Tenant 供应。版本查询成功不意味着 Instance Ready。
 
 本项目同时依赖 Kubernetes API、PostgreSQL、OpenBao 和 ESO。日常开发不连接 homelab

go.mod

@@ -4,6 +4,7 @@ go 1.27.1
 
 require (
 	github.com/jackc/pgx/v5 v5.11.0
+	github.com/jackc/tern/v2 v2.4.3
 	k8s.io/api v0.37.0
 	k8s.io/apimachinery v0.37.0
 	k8s.io/client-go v0.37.0
@@ -12,6 +13,10 @@ require (
 
 require (
 	cel.dev/expr v0.25.1 // indirect
+	dario.cat/mergo v1.0.2 // indirect
+	github.com/Masterminds/goutils v1.1.1 // indirect
+	github.com/Masterminds/semver/v3 v3.5.0 // indirect
+	github.com/Masterminds/sprig/v3 v3.3.0 // indirect
 	github.com/antlr4-go/antlr/v4 v4.13.1 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/blang/semver/v4 v4.0.0 // indirect
@@ -44,11 +49,14 @@ require (
 	github.com/google/gnostic-models v0.7.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.29.0 // indirect
+	github.com/huandu/xstrings v1.5.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
@@ -57,6 +65,8 @@ require (
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.70.0 // indirect
 	github.com/prometheus/procfs v0.21.1 // indirect
+	github.com/shopspring/decimal v1.4.0 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
 	github.com/spf13/cobra v1.10.2 // indirect
 	github.com/spf13/pflag v1.0.10 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
@@ -72,14 +82,15 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.27.1 // indirect
 	go.yaml.in/yaml/v2 v2.4.4 // indirect
-	go.yaml.in/yaml/v3 v3.0.4 // indirect
+	go.yaml.in/yaml/v3 v3.0.5 // indirect
+	golang.org/x/crypto v0.55.0 // indirect
 	golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f // indirect
 	golang.org/x/net v0.57.0 // indirect
 	golang.org/x/oauth2 v0.36.0 // indirect
 	golang.org/x/sync v0.22.0 // indirect
 	golang.org/x/sys v0.47.0 // indirect
 	golang.org/x/term v0.45.0 // indirect
-	golang.org/x/text v0.40.0 // indirect
+	golang.org/x/text v0.41.0 // indirect
 	golang.org/x/time v0.15.0 // indirect
 	gomodules.xyz/jsonpatch/v2 v2.4.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20260526163538-3dc84a4a5aaa // indirect

go.sum

@@ -1,7 +1,13 @@
 cel.dev/expr v0.25.1 h1:1KrZg61W6TWSxuNZ37Xy49ps13NUovb66QLprthtwi4=
 cel.dev/expr v0.25.1/go.mod h1:hrXvqGP6G6gyx8UAHSHJ5RGk//1Oj5nXQ2NI02Nrsg4=
-github.com/Masterminds/semver/v3 v3.4.0 h1:Zog+i5UMtVoCU8oKka5P7i9q9HgrJeGzI9SA1Xbatp0=
+dario.cat/mergo v1.0.2 h1:85+piFYR1tMbRrLcDwR18y4UKJ3aH1Tbzi24VRW1TK8=
-github.com/Masterminds/semver/v3 v3.4.0/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
+dario.cat/mergo v1.0.2/go.mod h1:E/hbnu0NxMFBjpMIE34DRGLWqDy0g5FuKDhCb31ngxA=
+github.com/Masterminds/goutils v1.1.1 h1:5nUrii3FMTL5diU80unEVvNevw1nH4+ZV4DSLVJLSYI=
+github.com/Masterminds/goutils v1.1.1/go.mod h1:8cTjp+g8YejhMuvIA5y2vz3BpJxksy863GQaJW2MFNU=
+github.com/Masterminds/semver/v3 v3.5.0 h1:kQceYJfbupGfZOKZQg0kou0DgAKhzDg2NZPAwZ/2OOE=
+github.com/Masterminds/semver/v3 v3.5.0/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
+github.com/Masterminds/sprig/v3 v3.3.0 h1:mQh0Yrg1XPo6vjYXgtf5OtijNAKJRNcTdOOGZe3tPhs=
+github.com/Masterminds/sprig/v3 v3.3.0/go.mod h1:Zy1iXRYNqNLUolqCpL4uhk6SHUMAOSCzdgBfDb35Lz0=
 github.com/antlr4-go/antlr/v4 v4.13.1 h1:SqQKkuVZ+zWkMMNkjy5FZe5mr5WURWnlpmOuzYWrPrQ=
 github.com/antlr4-go/antlr/v4 v4.13.1/go.mod h1:GKmUxMtwp6ZgGwZSva4eWPC5mS6vUAmOABFgjdkM7Nw=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
@@ -25,6 +31,8 @@ github.com/evanphx/json-patch/v5 v5.9.11 h1:/8HVnzMq13/3x9TPvjG08wUGqBTmZBsCWzjT
 github.com/evanphx/json-patch/v5 v5.9.11/go.mod h1:3j+LviiESTElxA4p3EMKAB9HXj3/XEtnUf6OZxqIQTM=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
+github.com/frankban/quicktest v1.14.6 h1:7Xjx+VpznH+oBnejlPUj8oUpdxnVs4f8XU8WnHkI4W8=
+github.com/frankban/quicktest v1.14.6/go.mod h1:4ptaffx2x8+WTWXmUCuVU6aPUX1/Mz7zb5vbUoiM6w0=
 github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
 github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
 github.com/fxamacker/cbor/v2 v2.9.1 h1:2rWm8B193Ll4VdjsJY28jxs70IdDsHRWgQYAI80+rMQ=
@@ -89,6 +97,8 @@ github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.29.0 h1:5VipnvEpbqr2gA2VbM+nYVbkIF28c5ZQfqCBQ5g2xfk=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.29.0/go.mod h1:Hyl3n6Twe1hvtd9XUXDec4pTvgMSEixRuQKPTMH2bNs=
+github.com/huandu/xstrings v1.5.0 h1:2ag3IFq9ZDANvthTwTiqSSZLjDc+BedvHPAp5tJy2TI=
+github.com/huandu/xstrings v1.5.0/go.mod h1:y5/lhBue+AyNmUVz9RLU9xbLR0o4KIIExikq4ovT0aE=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
@@ -99,6 +109,8 @@ github.com/jackc/pgx/v5 v5.11.0 h1:IzBBtyK9AHqf98cctWFifYSci2hgQR/cd56wB4p+ogg=
 github.com/jackc/pgx/v5 v5.11.0/go.mod h1:mal1tBGAFfLHvZzaYh77YS/eC6IX9OWbRV1QIIM0Jn4=
 github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo=
 github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
+github.com/jackc/tern/v2 v2.4.3 h1:g293d3OZgW7OFEhsYXgEv0C21jea2boNr0VR4K5I7OY=
+github.com/jackc/tern/v2 v2.4.3/go.mod h1:rMpMuRYcff5wWLptoTSO1qcDxJ4OodysvK17i2SVBys=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
 github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
 github.com/klauspost/compress v1.19.0 h1:sXLILfc9jV2QYWkzFOPWStmcUVH2RHEB1JCdY2oVvCQ=
@@ -109,6 +121,10 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
+github.com/mitchellh/copystructure v1.2.0 h1:vpKXTN4ewci03Vljg/q9QvCGUDttBOGBIa15WveJJGw=
+github.com/mitchellh/copystructure v1.2.0/go.mod h1:qLl+cE2AmVv+CoeAwDPye/v+N2HKCj9FbZEVFJRxO9s=
+github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zxSIeXaQ=
+github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -137,6 +153,10 @@ github.com/prometheus/procfs v0.21.1/go.mod h1:aB55Cww9pdSJVHk0hUf0inxWyyjPogFIj
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/shopspring/decimal v1.4.0 h1:bxl37RwXBklmTi0C79JfXCEBD1cqqHt0bbgBAGFp81k=
+github.com/shopspring/decimal v1.4.0/go.mod h1:gawqmDU56v4yIKSwfBSFip1HdCCXN8/+DMd9qYNcwME=
+github.com/spf13/cast v1.10.0 h1:h2x0u2shc1QuLHfxi+cTJvs30+ZAHOGRic8uyGTDWxY=
+github.com/spf13/cast v1.10.0/go.mod h1:jNfB8QC9IA6ZuY2ZjDp0KtFO2LZZlg4S/7bzP6qqeHo=
 github.com/spf13/cobra v1.10.2 h1:DMTTonx5m65Ic0GOoRY2c16WCbHxOOw6xxezuLaBpcU=
 github.com/spf13/cobra v1.10.2/go.mod h1:7C1pvHqHw5A4vrJfjNwvOdzYu0Gml16OCs2GRiTUUS4=
 github.com/spf13/pflag v1.0.9/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
@@ -147,8 +167,8 @@ github.com/stretchr/objx v0.5.3 h1:jmXUvGomnU1o3W/V5h2VEradbpJDwGrzugQQvL0POH4=
 github.com/stretchr/objx v0.5.3/go.mod h1:rDQraq+vQZU7Fde9LOZLr8Tax6zZvy4kuNKF+QYS+U0=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
-github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
 github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
 github.com/x448/float16 v0.8.4/go.mod h1:14CWIYCyZA/cWjXOioeEpHeN/83MdbZDRQHoFcYsOfg=
 go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
@@ -179,12 +199,15 @@ go.uber.org/zap v1.27.1 h1:08RqriUEv8+ArZRYSTXy1LeBScaMpVSTBhCeaZYfMYc=
 go.uber.org/zap v1.27.1/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
 go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
 go.yaml.in/yaml/v2 v2.4.4/go.mod h1:gMZqIpDtDqOfM0uNfy0SkpRhvUryYH0Z6wdMYcacYXQ=
-go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
+go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=
+go.yaml.in/yaml/v3 v3.0.5/go.mod h1:HVTZu1O7/Vkt2N+BFy8Zza+lnLsABggaTM2ZpNIGuKg=
+golang.org/x/crypto v0.55.0 h1:+KWHjbgOaAQ66dh/YlkZKHlz9ZUlq61AFirAR9ntP8M=
+golang.org/x/crypto v0.55.0/go.mod h1:uq0V9dE/fzQuJtbnL+2EhWOE63vo164FY8xqEnV9xis=
 golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f h1:W3F4c+6OLc6H2lb//N1q4WpJkhzJCK5J6kUi1NTVXfM=
 golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f/go.mod h1:J1xhfL/vlindoeF/aINzNzt2Bket5bjo9sdOYzOsU80=
-golang.org/x/mod v0.37.0 h1:vF1DjpVEshcIqoEaauuHebaLk1O1forxjxBaVn884JQ=
+golang.org/x/mod v0.38.0 h1:MECBjubtXD7yj4HrhIUcywNaGeNVUdfVnxmPajOk4yk=
-golang.org/x/mod v0.37.0/go.mod h1:m8S8VeM9r4dzDwjrKO0a1sZP3YjeMamRRlD+fmR2Q/0=
+golang.org/x/mod v0.38.0/go.mod h1:V6Xz0pq8TQ3dGqVQ1FVHuelZpAL0uNhSkk9ogYP3c40=
 golang.org/x/net v0.57.0 h1:K5+3DljvIuDG9/Jv9rvyMywYNFCQ9RSUY6OOTTkT+tE=
 golang.org/x/net v0.57.0/go.mod h1:KpXc8iv+r3XplLAG/f7Jsf9RPszJzdR0f58q9vGOuEU=
 golang.org/x/oauth2 v0.36.0 h1:peZ/1z27fi9hUOFCAZaHyrpWG5lwe0RJEEEeH0ThlIs=
@@ -195,12 +218,12 @@ golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
 golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.45.0 h1:NwWyBmoJCbfTHpxrWoZ9C6/VxOf7ic219I8xZZFdrf0=
 golang.org/x/term v0.45.0/go.mod h1:9aqxs0blBcrm/n0L9QW0aRVD+ktan8ssZromtqJC43w=
-golang.org/x/text v0.40.0 h1:Ub2Z6/xjgF1WrYQz2nuITOEegKFtiIy+rieRJ5lHZKs=
+golang.org/x/text v0.41.0 h1:vz/seA0lnX87Othu2f/0L24RcgrXD9/YFTSuGjj3rH8=
-golang.org/x/text v0.40.0/go.mod h1:hpnzDAfGV753zIKo+wk3u1bVKCGPbrnF7+7LBF/UHVY=
+golang.org/x/text v0.41.0/go.mod h1:jvf1O8ajNzZqhSrQBPbutR/EB83Cc0CFrezNQIwbb5M=
 golang.org/x/time v0.15.0 h1:bbrp8t3bGUeFOx08pvsMYRTCVSMk89u4tKbNOZbp88U=
 golang.org/x/time v0.15.0/go.mod h1:Y4YMaQmXwGQZoFaVFk4YpCt4FLQMYKZe9oeV/f4MSno=
-golang.org/x/tools v0.47.0 h1:7Kn5x/d1svx/PzryTsqeoZN4TZwqeH5pGWjefhLi/1Q=
+golang.org/x/tools v0.48.0 h1:3+hClM1aLL5mjMKm5ovokw9epgRXPuu2tILgismM6RE=
-golang.org/x/tools v0.47.0/go.mod h1:dFHnyTvFWY212G+h7ZY4Vsp/K3U4/7W9TyVaAul8uCA=
+golang.org/x/tools v0.48.0/go.mod h1:08xX0orndb/F7jJxGDicx061tyd5pcMto75YMAXr6lk=
 gomodules.xyz/jsonpatch/v2 v2.4.0 h1:Ci3iUJyx9UeRx7CeFN8ARgGbkESwJK+KB9lLcWxY/Zw=
 gomodules.xyz/jsonpatch/v2 v2.4.0/go.mod h1:AH3dM2RI6uoBZxn3LVrfvJ3E0/9dG4cSrbuBJT4moAY=
 gonum.org/v1/gonum v0.17.0 h1:VbpOemQlsSMrYmn7T2OUvQ4dqxQXU+ouZFQsZOx50z4=
@@ -214,8 +237,6 @@ google.golang.org/grpc v1.82.1/go.mod h1:yzTZ1TB1Z3SG+LIYaI+WiE8D5+PZ3ArnrSp8zF3
 google.golang.org/protobuf v1.36.12-0.20260120151049-f2248ac996af h1:+5/Sw3GsDNlEmu7TfklWKPdQ0Ykja5VEmq2i817+jbI=
 google.golang.org/protobuf v1.36.12-0.20260120151049-f2248ac996af/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
-gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/evanphx/json-patch.v4 v4.13.0 h1:czT3CmqEaQ1aanPc5SdlgQrrEIb8w/wwCvWWnfEbYzo=
 gopkg.in/evanphx/json-patch.v4 v4.13.0/go.mod h1:p8EYWUEYMpynmqDbY58zCKCFZw8pRWMG4EsWvDvM72M=
 gopkg.in/inf.v0 v0.9.1 h1:73M5CoZyi3ZLMOyDlQh031Cx6N9NDJ2Vvfl76EDAgDc=

internal/database/adapter/postgresql/connector.go

@@ -47,14 +47,6 @@ func (d *database) Close() {
 	d.pool.Close()
 }
 
-func (d *database) Version(ctx context.Context) (string, error) {
-	var version string
-	if err := d.pool.QueryRow(ctx, "SHOW server_version").Scan(&version); err != nil {
-		return "", safeError(err, application.ErrObservation)
-	}
-	return version, nil
-}
-
 func (c Connector) Connect(ctx context.Context, endpoint instance.Endpoint, credentials application.Credentials) (application.Database, error) {
 	if err := endpoint.Validate(); err != nil {
 		return nil, err

internal/database/adapter/postgresql/credentials_integration_test.go

@@ -131,13 +131,17 @@ func TestObservationDiscardsResultWhenCredentialsChange(t *testing.T) {
 		}
 	}
 
-	version, err := fixture.service.ObserveVersion(fixture.ctx, fixture.target)
+	observation, err := fixture.service.ObserveMetadata(fixture.ctx, fixture.target)
 	if !errors.Is(err, application.ErrCredentialsChanged) {
 		t.Fatal("in-flight rotation was not detected")
 	}
-	if version != "" {
+	if observation.Version() != "" {
 		t.Fatal("observation returned data obtained with stale credentials")
 	}
+	requested := instance.NewExtensionSet([]string{fixtureExtension})
+	if observation.Extensions().Check(requested).Decision != instance.ExtensionSupportUnobserved {
+		t.Fatal("observation returned extension support obtained with stale credentials")
+	}
 	if fixture.backendIDs(t) != "" {
 		t.Fatal("stale connection was retained after rotation")
 	}

internal/database/adapter/postgresql/fixture_integration_test.go

@@ -42,6 +42,7 @@ import (
 const (
 	fixtureHost         = "fixture.invalid"
 	fixtureUser         = "postgres"
+	fixtureExtension    = "plpgsql"
 	dockerExec          = "exec"
 	fixtureImage        = "postgres@sha256:18cfe3ef5e6815560c98237d6216d1e5119702fb0f3894c8785dd58b8bbe5d73"
 	fixturePassword     = "AYATORI-TEST-ONLY-initial-password"

internal/database/adapter/postgresql/metadata.go

@@ -0,0 +1,48 @@
+/*
+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 postgresql
+
+import (
+	"context"
+
+	"git.ddupan.top/panxiao81/ayatori/internal/database/application"
+)
+
+// 使用 pg_catalog 限定名称，避免管理账号的 search_path 改变查询来源。
+// 一个语句读取版本和可用列表；ARRAY 子查询在无行时返回空数组，而非 NULL。
+// 不查询 pg_extension：已安装集合不能代表服务器提供的全部扩展。
+const inspectMetadataStatement = `
+SELECT
+    pg_catalog.current_setting('server_version'),
+    ARRAY(
+        SELECT name::text
+        FROM pg_catalog.pg_available_extensions
+        ORDER BY name
+    )`
+
+func (d *database) InspectMetadata(ctx context.Context) (application.DatabaseMetadata, error) {
+	var metadata application.DatabaseMetadata
+	err := d.pool.QueryRow(ctx, inspectMetadataStatement).Scan(
+		&metadata.Version,
+		&metadata.AvailableExtensions,
+	)
+	if err != nil {
+		// 不返回部分结果，也不把查询失败转换为“成功观察到空列表”。
+		return application.DatabaseMetadata{}, safeError(err, application.ErrObservation)
+	}
+	return metadata, nil
+}

internal/database/adapter/postgresql/metadata_integration_test.go

@@ -0,0 +1,115 @@
+//go:build integration
+
+/*
+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 postgresql_test
+
+import (
+	"errors"
+	"testing"
+
+	corev1 "k8s.io/api/core/v1"
+
+	"git.ddupan.top/panxiao81/ayatori/internal/database/application"
+	"git.ddupan.top/panxiao81/ayatori/internal/database/domain/instance"
+)
+
+func TestMetadataObservesAvailableExtensionsWithoutInstalling(t *testing.T) {
+	f := newCredentialFixture(t)
+	f.createSecret(t, controllerNamespace)
+	if installed := f.queryPostgres(t, "SELECT count(*) FROM pg_catalog.pg_extension WHERE extname = 'hstore'"); installed != "0" {
+		t.Fatal("fixture unexpectedly has hstore installed")
+	}
+	// 提供同名遮蔽对象，验证 adapter 不依赖管理账号可修改的 search_path。
+	f.queryPostgres(t, "CREATE VIEW public.pg_available_extensions AS SELECT 'fake_extension'::name AS name")
+	f.queryPostgres(t, "ALTER ROLE postgres SET search_path = public, pg_catalog")
+	observed, err := f.service.ObserveMetadata(f.ctx, f.target)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !observed.Target().Matches(f.target) || observed.Version() == "" {
+		t.Fatal("metadata was not bound to the current target")
+	}
+	requested := instance.NewExtensionSet([]string{"hstore", fixtureExtension})
+	if observed.Extensions().Check(requested).Decision != instance.ExtensionsAccepted {
+		t.Fatal("available but uninstalled extension was omitted")
+	}
+	unsupported := instance.NewExtensionSet([]string{"fake_extension", "HSTORE"})
+	check := observed.Extensions().Check(unsupported)
+	if check.Decision != instance.ExtensionsUnsupported || len(check.Unsupported) != 2 {
+		t.Fatal("metadata accepted shadowed or case-normalized extension names")
+	}
+	if installed := f.queryPostgres(t, "SELECT count(*) FROM pg_catalog.pg_extension WHERE extname = 'hstore'"); installed != "0" {
+		t.Fatal("metadata observation installed an extension")
+	}
+	if schemas := f.queryPostgres(t, "SELECT count(*) FROM pg_catalog.pg_namespace WHERE nspname = 'postgresql_tenant_operator'"); schemas != "0" {
+		t.Fatal("metadata observation initialized the registry")
+	}
+
+	aggregate, err := instance.Reconstitute(f.target, instance.Snapshot{}, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := aggregate.ObserveExtensions(observed.Target(), observed.Extensions()); err != nil {
+		t.Fatal(err)
+	}
+	if aggregate.CheckExtensions(requested).Decision != instance.ExtensionsAccepted {
+		t.Fatal("domain rejected observed extension availability")
+	}
+	if err := aggregate.RequireProvisioningReady(); err == nil {
+		t.Fatal("extension availability incorrectly authorized provisioning")
+	}
+}
+
+func TestMetadataPermissionFailureAndRecovery(t *testing.T) {
+	f := newCredentialFixture(t)
+	f.createSecret(t, controllerNamespace)
+	// 低权限账号也能读取可用列表；这不能证明具备 role/database/extension 管理权限。
+	f.queryPostgres(t, "CREATE ROLE metadata_reader LOGIN PASSWORD '"+fixturePassword+"'")
+	f.updateSecret(t, func(secret *corev1.Secret) {
+		secret.Data["login"] = []byte("metadata_reader")
+	})
+	if flags := f.queryPostgres(t, "SELECT rolsuper, rolcreaterole, rolcreatedb FROM pg_catalog.pg_roles WHERE rolname = 'metadata_reader'"); flags != "f|f|f" {
+		t.Fatal("metadata reader unexpectedly has management privileges")
+	}
+	requested := instance.NewExtensionSet([]string{fixtureExtension})
+	observed, err := f.service.ObserveMetadata(f.ctx, f.target)
+	if err != nil || observed.Extensions().Check(requested).Decision != instance.ExtensionsAccepted {
+		t.Fatalf("read-only account could not observe metadata: %v", err)
+	}
+
+	// 仅操作本测试独占容器的 catalog ACL；失败不能转换成“不支持任何扩展”。
+	f.queryPostgres(t, "REVOKE SELECT ON pg_catalog.pg_available_extensions FROM PUBLIC")
+	failed, err := f.service.ObserveMetadata(f.ctx, f.target)
+	if !errors.Is(err, application.ErrObservation) {
+		t.Fatalf("metadata permission failure was not reported safely: %v", err)
+	}
+	if failed.Version() != "" || failed.Target().Validate() == nil {
+		t.Fatal("permission failure returned partial metadata")
+	}
+	if failed.Extensions().Check(requested).Decision != instance.ExtensionSupportUnobserved {
+		t.Fatal("permission failure returned an observed empty set")
+	}
+	if f.backendIDs(t) != "" {
+		t.Fatal("failed metadata connection was retained")
+	}
+	f.queryPostgres(t, "GRANT SELECT ON pg_catalog.pg_available_extensions TO PUBLIC")
+	recovered, err := f.service.ObserveMetadata(f.ctx, f.target)
+	if err != nil || recovered.Extensions().Check(requested).Decision != instance.ExtensionsAccepted {
+		t.Fatalf("metadata observation did not recover: %v", err)
+	}
+}

internal/database/adapter/postgresql/registry/migrations/001_create_registry.sql

@@ -0,0 +1,25 @@
+CREATE SCHEMA postgresql_tenant_operator;
+
+CREATE TABLE postgresql_tenant_operator.tenant_ownership (
+    instance_uid text NOT NULL,
+    tenant_uid text NOT NULL,
+    tenant_namespace text NOT NULL,
+    tenant_name text NOT NULL,
+    database_name text NOT NULL,
+    role_name text NOT NULL,
+    credential_path text NOT NULL,
+    managed boolean NOT NULL DEFAULT true,
+    created_at timestamptz NOT NULL DEFAULT clock_timestamp(),
+    updated_at timestamptz NOT NULL DEFAULT clock_timestamp(),
+    retained_at timestamptz,
+    PRIMARY KEY (instance_uid, tenant_uid),
+    UNIQUE (instance_uid, tenant_namespace, tenant_name),
+    UNIQUE (instance_uid, database_name),
+    UNIQUE (instance_uid, role_name),
+    UNIQUE (credential_path),
+    CHECK (managed OR retained_at IS NOT NULL)
+);
+
+---- create above / drop below ----
+
+DROP SCHEMA postgresql_tenant_operator CASCADE;

internal/database/adapter/postgresql/registry/registry.go

@@ -0,0 +1,326 @@
+/*
+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 registry persists controller ownership evidence in the PostgreSQL
+// management database. It deliberately does not persist reconciliation phases;
+// those belong to the Kubernetes resource status.
+package registry
+
+import (
+	"context"
+	"embed"
+	"errors"
+	"fmt"
+	"io/fs"
+	"time"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+	"github.com/jackc/tern/v2/migrate"
+)
+
+const migrationVersionTable = "public.postgresql_tenant_operator_schema_version"
+
+//go:embed migrations/*.sql
+var migrationFiles embed.FS
+
+var (
+	// ErrNotFound indicates that the registry has no matching ownership record.
+	ErrNotFound = errors.New("registry ownership record not found")
+	// ErrConflict indicates that a requested name or path belongs to another Tenant UID.
+	ErrConflict = errors.New("registry ownership conflict")
+)
+
+// Beginner is implemented by pgx.Conn and pgxpool.Pool.
+type Beginner interface {
+	Begin(context.Context) (pgx.Tx, error)
+}
+
+// Store manages ownership records in one PostgreSQLInstance management database.
+type Store struct {
+	db Beginner
+}
+
+// NewStore creates a registry store backed by a PostgreSQL connection or pool.
+func NewStore(db Beginner) *Store {
+	return &Store{db: db}
+}
+
+// Ownership identifies every external resource reserved for one Tenant UID.
+type Ownership struct {
+	InstanceUID     string
+	TenantUID       string
+	TenantNamespace string
+	TenantName      string
+	DatabaseName    string
+	RoleName        string
+	CredentialPath  string
+}
+
+// Record is the persisted ownership state.
+type Record struct {
+	Ownership
+	Managed    bool
+	CreatedAt  time.Time
+	UpdatedAt  time.Time
+	RetainedAt *time.Time
+}
+
+// ClaimResult reports whether Claim inserted a new record or found the same claim.
+type ClaimResult string
+
+const (
+	ClaimCreated ClaimResult = "Created"
+	ClaimOwned   ClaimResult = "Owned"
+)
+
+// Bootstrap applies all pending versioned registry migrations idempotently.
+func (s *Store) Bootstrap(ctx context.Context) error {
+	if s == nil || s.db == nil {
+		return errors.New("bootstrap registry: nil database")
+	}
+
+	return s.withMigrationConnection(ctx, func(conn *pgx.Conn) error {
+		migrations, err := fs.Sub(migrationFiles, "migrations")
+		if err != nil {
+			return fmt.Errorf("open embedded registry migrations: %w", err)
+		}
+		migrator, err := migrate.NewMigrator(ctx, conn, migrationVersionTable)
+		if err != nil {
+			return fmt.Errorf("initialize registry migrator: %w", err)
+		}
+		if err := migrator.LoadMigrations(migrations); err != nil {
+			return fmt.Errorf("load registry migrations: %w", err)
+		}
+		if err := migrator.Migrate(ctx); err != nil {
+			return fmt.Errorf("apply registry migrations: %w", err)
+		}
+		return nil
+	})
+}
+
+// Claim reserves all names for an owner. Repeating an identical claim is idempotent.
+func (s *Store) Claim(ctx context.Context, owner Ownership) (ClaimResult, error) {
+	if s == nil || s.db == nil {
+		return "", errors.New("claim registry ownership: nil database")
+	}
+	if err := owner.validate(); err != nil {
+		return "", err
+	}
+
+	tx, err := s.db.Begin(ctx)
+	if err != nil {
+		return "", fmt.Errorf("begin registry claim: %w", err)
+	}
+	defer func() { _ = tx.Rollback(ctx) }()
+
+	_, err = scanRecord(tx.QueryRow(ctx, claimStatement,
+		owner.InstanceUID,
+		owner.TenantUID,
+		owner.TenantNamespace,
+		owner.TenantName,
+		owner.DatabaseName,
+		owner.RoleName,
+		owner.CredentialPath,
+	))
+	if err != nil && !errors.Is(err, ErrNotFound) {
+		return "", fmt.Errorf("insert registry claim: %w", err)
+	}
+	if errors.Is(err, ErrNotFound) {
+		record, err := getByTenantUID(ctx, tx, owner.InstanceUID, owner.TenantUID)
+		if err != nil {
+			if errors.Is(err, ErrNotFound) {
+				return "", fmt.Errorf("%w: database, role, tenant identity, or credential path is already reserved", ErrConflict)
+			}
+			return "", err
+		}
+		if !record.equal(owner) || !record.Managed {
+			return "", fmt.Errorf("%w: database, role, tenant identity, or credential path is already reserved", ErrConflict)
+		}
+		if err := tx.Commit(ctx); err != nil {
+			return "", fmt.Errorf("commit registry claim: %w", err)
+		}
+		return ClaimOwned, nil
+	}
+
+	if err := tx.Commit(ctx); err != nil {
+		return "", fmt.Errorf("commit registry claim: %w", err)
+	}
+	return ClaimCreated, nil
+}
+
+func (s *Store) withMigrationConnection(ctx context.Context, run func(*pgx.Conn) error) error {
+	switch db := s.db.(type) {
+	case *pgx.Conn:
+		return run(db)
+	case *pgxpool.Pool:
+		conn, err := db.Acquire(ctx)
+		if err != nil {
+			return fmt.Errorf("acquire registry migration connection: %w", err)
+		}
+		defer conn.Release()
+		return run(conn.Conn())
+	default:
+		return fmt.Errorf("bootstrap registry: database type %T cannot provide a migration connection", s.db)
+	}
+}
+
+// Get returns the ownership record for an Instance UID and Tenant UID.
+func (s *Store) Get(ctx context.Context, instanceUID, tenantUID string) (Record, error) {
+	if s == nil || s.db == nil {
+		return Record{}, errors.New("get registry record: nil database")
+	}
+	if instanceUID == "" || tenantUID == "" {
+		return Record{}, errors.New("get registry record: instance UID and tenant UID are required")
+	}
+
+	tx, err := s.db.Begin(ctx)
+	if err != nil {
+		return Record{}, fmt.Errorf("begin registry read: %w", err)
+	}
+	defer func() { _ = tx.Rollback(ctx) }()
+
+	record, err := getByTenantUID(ctx, tx, instanceUID, tenantUID)
+	if err != nil {
+		return Record{}, err
+	}
+	if err := tx.Commit(ctx); err != nil {
+		return Record{}, fmt.Errorf("commit registry read: %w", err)
+	}
+	return record, nil
+}
+
+// MarkRetained changes a matching managed ownership record into an unmanaged tombstone.
+// Repeating the operation for the same tombstone is safe.
+func (s *Store) MarkRetained(ctx context.Context, owner Ownership) error {
+	return s.changeOwnership(ctx, owner, "mark registry record retained", func(ctx context.Context, tx pgx.Tx, record Record) error {
+		if !record.Managed {
+			return nil
+		}
+		tag, err := tx.Exec(ctx, markRetainedStatement, owner.InstanceUID, owner.TenantUID)
+		if err != nil {
+			return err
+		}
+		if tag.RowsAffected() != 1 {
+			return ErrConflict
+		}
+		return nil
+	})
+}
+
+// Delete removes a matching managed record after its external resources have been deleted.
+// An already absent record is treated as a successful retry; a retained record is never deleted.
+func (s *Store) Delete(ctx context.Context, owner Ownership) error {
+	return s.changeOwnership(ctx, owner, "delete registry record", func(ctx context.Context, tx pgx.Tx, record Record) error {
+		if !record.Managed {
+			return ErrConflict
+		}
+		tag, err := tx.Exec(ctx, deleteStatement, owner.InstanceUID, owner.TenantUID)
+		if err != nil {
+			return err
+		}
+		if tag.RowsAffected() != 1 {
+			return ErrConflict
+		}
+		return nil
+	})
+}
+
+func (s *Store) changeOwnership(
+	ctx context.Context,
+	owner Ownership,
+	operation string,
+	change func(context.Context, pgx.Tx, Record) error,
+) error {
+	if s == nil || s.db == nil {
+		return fmt.Errorf("%s: nil database", operation)
+	}
+	if err := owner.validate(); err != nil {
+		return fmt.Errorf("%s: %w", operation, err)
+	}
+
+	tx, err := s.db.Begin(ctx)
+	if err != nil {
+		return fmt.Errorf("begin %s: %w", operation, err)
+	}
+	defer func() { _ = tx.Rollback(ctx) }()
+
+	record, err := getByTenantUIDForUpdate(ctx, tx, owner.InstanceUID, owner.TenantUID)
+	if errors.Is(err, ErrNotFound) && operation == "delete registry record" {
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("%s: %w", operation, err)
+	}
+	if !record.equal(owner) {
+		return fmt.Errorf("%s: %w", operation, ErrConflict)
+	}
+	if err := change(ctx, tx, record); err != nil {
+		return fmt.Errorf("%s: %w", operation, err)
+	}
+	if err := tx.Commit(ctx); err != nil {
+		return fmt.Errorf("commit %s: %w", operation, err)
+	}
+	return nil
+}
+
+func getByTenantUIDForUpdate(ctx context.Context, tx pgx.Tx, instanceUID, tenantUID string) (Record, error) {
+	return scanRecord(tx.QueryRow(ctx, getByTenantUIDForUpdateStatement, instanceUID, tenantUID))
+}
+
+func getByTenantUID(ctx context.Context, tx pgx.Tx, instanceUID, tenantUID string) (Record, error) {
+	return scanRecord(tx.QueryRow(ctx, getByTenantUIDStatement, instanceUID, tenantUID))
+}
+
+type rowScanner interface {
+	Scan(...any) error
+}
+
+func scanRecord(row rowScanner) (Record, error) {
+	var record Record
+	err := row.Scan(
+		&record.InstanceUID,
+		&record.TenantUID,
+		&record.TenantNamespace,
+		&record.TenantName,
+		&record.DatabaseName,
+		&record.RoleName,
+		&record.CredentialPath,
+		&record.Managed,
+		&record.CreatedAt,
+		&record.UpdatedAt,
+		&record.RetainedAt,
+	)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return Record{}, ErrNotFound
+	}
+	if err != nil {
+		return Record{}, fmt.Errorf("read registry record: %w", err)
+	}
+	return record, nil
+}
+
+func (o Ownership) validate() error {
+	if o.InstanceUID == "" || o.TenantUID == "" || o.TenantNamespace == "" || o.TenantName == "" ||
+		o.DatabaseName == "" || o.RoleName == "" || o.CredentialPath == "" {
+		return errors.New("claim registry ownership: all ownership fields are required")
+	}
+	return nil
+}
+
+func (o Ownership) equal(other Ownership) bool {
+	return o == other
+}

internal/database/adapter/postgresql/registry/sql.go

@@ -0,0 +1,68 @@
+/*
+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 registry
+
+const claimStatement = `
+INSERT INTO postgresql_tenant_operator.tenant_ownership (
+    instance_uid,
+    tenant_uid,
+    tenant_namespace,
+    tenant_name,
+    database_name,
+    role_name,
+    credential_path
+) VALUES ($1, $2, $3, $4, $5, $6, $7)
+ON CONFLICT DO NOTHING
+RETURNING
+    instance_uid,
+    tenant_uid,
+    tenant_namespace,
+    tenant_name,
+    database_name,
+    role_name,
+    credential_path,
+    managed,
+    created_at,
+    updated_at,
+    retained_at`
+
+const getByTenantUIDStatement = `
+SELECT
+    instance_uid,
+    tenant_uid,
+    tenant_namespace,
+    tenant_name,
+    database_name,
+    role_name,
+    credential_path,
+    managed,
+    created_at,
+    updated_at,
+    retained_at
+FROM postgresql_tenant_operator.tenant_ownership
+WHERE instance_uid = $1 AND tenant_uid = $2`
+
+const getByTenantUIDForUpdateStatement = getByTenantUIDStatement + ` FOR UPDATE`
+
+const markRetainedStatement = `
+UPDATE postgresql_tenant_operator.tenant_ownership
+SET managed = false, retained_at = clock_timestamp(), updated_at = clock_timestamp()
+WHERE instance_uid = $1 AND tenant_uid = $2 AND managed = true`
+
+const deleteStatement = `
+DELETE FROM postgresql_tenant_operator.tenant_ownership
+WHERE instance_uid = $1 AND tenant_uid = $2 AND managed = true`

internal/database/adapter/postgresql/registry_integration_test.go

@@ -0,0 +1,427 @@
+//go:build integration
+
+/*
+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 postgresql_test
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/url"
+	"strconv"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"git.ddupan.top/panxiao81/ayatori/internal/database/adapter/postgresql/registry"
+)
+
+// registryFixture 只连接本测试创建的容器，不接受外部数据库地址。
+type registryFixture struct {
+	ctx   context.Context
+	pool  *pgxpool.Pool
+	store *registry.Store
+}
+
+func newRegistryFixture(t *testing.T) *registryFixture {
+	t.Helper()
+	ctx, cancel := context.WithTimeout(context.Background(), 90*time.Second)
+	t.Cleanup(cancel)
+	_, port := postgresFixture(t, ctx)
+	endpoint := url.URL{
+		Scheme:   "postgres",
+		User:     url.UserPassword(fixtureUser, fixturePassword),
+		Host:     net.JoinHostPort("127.0.0.1", strconv.Itoa(port)),
+		Path:     "/postgres",
+		RawQuery: "sslmode=disable",
+	}
+	pool, err := pgxpool.New(ctx, endpoint.String())
+	if err != nil {
+		t.Fatal("cannot configure registry fixture connection")
+	}
+	t.Cleanup(pool.Close)
+	if err := pool.Ping(ctx); err != nil {
+		t.Fatal("cannot connect to registry fixture")
+	}
+	return &registryFixture{ctx: ctx, pool: pool, store: registry.NewStore(pool)}
+}
+
+func registryOwner(suffix string) registry.Ownership {
+	return registry.Ownership{
+		InstanceUID:     "instance-uid",
+		TenantUID:       "tenant-uid-" + suffix,
+		TenantNamespace: "applications",
+		TenantName:      "tenant-" + suffix,
+		DatabaseName:    "database_" + suffix,
+		RoleName:        "role_" + suffix,
+		CredentialPath:  "credentials/" + suffix,
+	}
+}
+
+func (f *registryFixture) bootstrap(t *testing.T) {
+	t.Helper()
+	if err := f.store.Bootstrap(f.ctx); err != nil {
+		t.Fatalf("bootstrap registry: %v", err)
+	}
+}
+
+func (f *registryFixture) claim(t *testing.T, owner registry.Ownership, expected registry.ClaimResult) {
+	t.Helper()
+	result, err := f.store.Claim(f.ctx, owner)
+	if err != nil || result != expected {
+		t.Fatalf("claim: result=%q, error=%v; want %q", result, err, expected)
+	}
+}
+
+func TestRegistryOwnershipLifecycle(t *testing.T) {
+	f := newRegistryFixture(t)
+	f.bootstrap(t)
+	f.bootstrap(t)
+	owner := registryOwner("lifecycle")
+	f.claim(t, owner, registry.ClaimCreated)
+	f.claim(t, owner, registry.ClaimOwned)
+	record, err := f.store.Get(f.ctx, owner.InstanceUID, owner.TenantUID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if record.Ownership != owner || !record.Managed || record.CreatedAt.IsZero() || record.RetainedAt != nil {
+		t.Fatalf("unexpected ownership record: %+v", record)
+	}
+
+	// 错误的资源归属不能删除或 Retain 原记录。
+	wrongOwner := owner
+	wrongOwner.RoleName = "another_role"
+	if err := f.store.Delete(f.ctx, wrongOwner); !errors.Is(err, registry.ErrConflict) {
+		t.Fatalf("delete mismatched owner: %v", err)
+	}
+	if err := f.store.MarkRetained(f.ctx, wrongOwner); !errors.Is(err, registry.ErrConflict) {
+		t.Fatalf("retain mismatched owner: %v", err)
+	}
+	for range 2 {
+		if err := f.store.Delete(f.ctx, owner); err != nil {
+			t.Fatalf("delete retry: %v", err)
+		}
+	}
+	if _, err := f.store.Get(f.ctx, owner.InstanceUID, owner.TenantUID); !errors.Is(err, registry.ErrNotFound) {
+		t.Fatalf("read deleted record: %v", err)
+	}
+}
+
+func TestRegistryRetainedRecordCannotBeReclaimed(t *testing.T) {
+	f := newRegistryFixture(t)
+	f.bootstrap(t)
+	owner := registryOwner("retained")
+	f.claim(t, owner, registry.ClaimCreated)
+	if err := f.store.MarkRetained(f.ctx, owner); err != nil {
+		t.Fatal(err)
+	}
+	retained, err := f.store.Get(f.ctx, owner.InstanceUID, owner.TenantUID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if retained.Managed || retained.RetainedAt == nil {
+		t.Fatalf("missing retained tombstone: %+v", retained)
+	}
+	if err := f.store.MarkRetained(f.ctx, owner); err != nil {
+		t.Fatalf("retain retry: %v", err)
+	}
+	retried, err := f.store.Get(f.ctx, owner.InstanceUID, owner.TenantUID)
+	if err != nil || !retried.UpdatedAt.Equal(retained.UpdatedAt) {
+		t.Fatalf("retain retry changed tombstone: %+v, %v", retried, err)
+	}
+	if err := f.store.Delete(f.ctx, owner); !errors.Is(err, registry.ErrConflict) {
+		t.Fatalf("delete retained record: %v", err)
+	}
+	if _, err := f.store.Claim(f.ctx, owner); !errors.Is(err, registry.ErrConflict) {
+		t.Fatalf("reclaim retained record: %v", err)
+	}
+	owner.TenantUID = "replacement-uid"
+	if _, err := f.store.Claim(f.ctx, owner); !errors.Is(err, registry.ErrConflict) {
+		t.Fatalf("replacement tenant reclaimed tombstone: %v", err)
+	}
+}
+
+func TestRegistryUniqueReservations(t *testing.T) {
+	f := newRegistryFixture(t)
+	f.bootstrap(t)
+	owner := registryOwner("original")
+	f.claim(t, owner, registry.ClaimCreated)
+	tests := []struct {
+		name   string
+		change func(*registry.Ownership)
+	}{
+		{name: "tenant UID", change: func(other *registry.Ownership) { other.TenantUID = owner.TenantUID }},
+		{name: "tenant name", change: func(other *registry.Ownership) { other.TenantName = owner.TenantName }},
+		{name: "database", change: func(other *registry.Ownership) { other.DatabaseName = owner.DatabaseName }},
+		{name: "role", change: func(other *registry.Ownership) { other.RoleName = owner.RoleName }},
+		{name: "credential path", change: func(other *registry.Ownership) { other.CredentialPath = owner.CredentialPath }},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			other := registryOwner("other")
+			tt.change(&other)
+			if _, err := f.store.Claim(f.ctx, other); !errors.Is(err, registry.ErrConflict) {
+				t.Fatalf("conflicting reservation: %v", err)
+			}
+		})
+	}
+}
+
+func TestRegistryConcurrentBootstrapAndClaims(t *testing.T) {
+	f := newRegistryFixture(t)
+	const workers = 8
+	start := make(chan struct{})
+	results := make(chan error, workers)
+	var group sync.WaitGroup
+	for range workers {
+		group.Go(func() {
+			<-start
+			results <- f.store.Bootstrap(f.ctx)
+		})
+	}
+	close(start)
+	group.Wait()
+	close(results)
+	for err := range results {
+		if err != nil {
+			t.Fatalf("concurrent bootstrap: %v", err)
+		}
+	}
+
+	owner := registryOwner("concurrent")
+	type claimOutcome struct {
+		result registry.ClaimResult
+		err    error
+	}
+	claims := make(chan claimOutcome, workers)
+	start = make(chan struct{})
+	for range workers {
+		group.Go(func() {
+			<-start
+			result, err := f.store.Claim(f.ctx, owner)
+			claims <- claimOutcome{result: result, err: err}
+		})
+	}
+	close(start)
+	group.Wait()
+	close(claims)
+	created := 0
+	for outcome := range claims {
+		if outcome.err != nil {
+			t.Fatal(outcome.err)
+		}
+		switch outcome.result {
+		case registry.ClaimCreated:
+			created++
+		case registry.ClaimOwned:
+		default:
+			t.Fatalf("unexpected claim result: %q", outcome.result)
+		}
+	}
+	if created != 1 {
+		t.Fatalf("created %d records for the same owner; want 1", created)
+	}
+}
+
+func TestRegistryRestartAndCanceledRequestRecovery(t *testing.T) {
+	f := newRegistryFixture(t)
+	f.bootstrap(t)
+	owner := registryOwner("restart")
+	f.claim(t, owner, registry.ClaimCreated)
+	config := f.pool.Config()
+	f.pool.Close()
+	pool, err := pgxpool.NewWithConfig(f.ctx, config)
+	if err != nil {
+		t.Fatal("cannot reopen fixture connection")
+	}
+	t.Cleanup(pool.Close)
+	f.store = registry.NewStore(pool)
+	f.bootstrap(t)
+	// 模拟客户端丢失上次成功结果后，以新连接重试；归属证据必须来自数据库。
+	f.claim(t, owner, registry.ClaimOwned)
+	canceled, cancel := context.WithCancel(f.ctx)
+	cancel()
+	if _, err := f.store.Claim(canceled, registryOwner("canceled")); !errors.Is(err, context.Canceled) {
+		t.Fatalf("canceled claim: %v", err)
+	}
+	f.claim(t, registryOwner("canceled"), registry.ClaimCreated)
+}
+
+func TestRegistryBootstrapRejectsUnknownSchema(t *testing.T) {
+	f := newRegistryFixture(t)
+	// 人工创建的同名 schema 不能被初始化过程接管或覆盖。
+	if _, err := f.pool.Exec(f.ctx, "CREATE SCHEMA postgresql_tenant_operator"); err != nil {
+		t.Fatal(err)
+	}
+	if err := f.store.Bootstrap(f.ctx); err == nil {
+		t.Fatal("bootstrap accepted an unmanaged schema")
+	}
+	var version int
+	if err := f.pool.QueryRow(f.ctx, "SELECT version FROM public.postgresql_tenant_operator_schema_version").Scan(&version); err != nil {
+		t.Fatal(err)
+	}
+	if version != 0 {
+		t.Fatalf("failed migration advanced version to %d", version)
+	}
+	// 仅在本测试拥有的临时数据库中清除空冲突 schema，然后重试失败的迁移。
+	if _, err := f.pool.Exec(f.ctx, "DROP SCHEMA postgresql_tenant_operator"); err != nil {
+		t.Fatal(err)
+	}
+	f.bootstrap(t)
+	if _, err := f.pool.Exec(f.ctx, "UPDATE public.postgresql_tenant_operator_schema_version SET version = 100"); err != nil {
+		t.Fatal(err)
+	}
+	if err := f.store.Bootstrap(f.ctx); err == nil {
+		t.Fatal("bootstrap accepted a future migration version")
+	}
+	if err := f.pool.QueryRow(f.ctx, "SELECT version FROM public.postgresql_tenant_operator_schema_version").Scan(&version); err != nil {
+		t.Fatal(err)
+	}
+	if version != 100 {
+		t.Fatalf("bootstrap rewrote future version to %d", version)
+	}
+}
+
+// 数据库执行真实 COMMIT 后才注入客户端错误，模拟客户端无法确认提交结果。
+// 这不是网络故障测试，但能确定性覆盖已提交、调用者却收到失败的恢复分支。
+type lostCommitReply struct {
+	registry.Beginner
+	err error
+}
+
+func (db lostCommitReply) Begin(ctx context.Context) (pgx.Tx, error) {
+	tx, err := db.Beginner.Begin(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return uncertainCommit{Tx: tx, err: db.err}, nil
+}
+
+type uncertainCommit struct {
+	pgx.Tx
+	err error
+}
+
+func (tx uncertainCommit) Commit(ctx context.Context) error {
+	if err := tx.Tx.Commit(ctx); err != nil {
+		return err
+	}
+	return tx.err
+}
+
+func TestRegistryRetriesAfterLostCommitReply(t *testing.T) {
+	f := newRegistryFixture(t)
+	f.bootstrap(t)
+	replyLost := errors.New("test-only lost commit reply")
+	uncertain := registry.NewStore(lostCommitReply{Beginner: f.pool, err: replyLost})
+	owner := registryOwner("uncertain")
+	if _, err := uncertain.Claim(f.ctx, owner); !errors.Is(err, replyLost) {
+		t.Fatalf("claim did not report lost reply: %v", err)
+	}
+	f.claim(t, owner, registry.ClaimOwned)
+	if err := uncertain.MarkRetained(f.ctx, owner); !errors.Is(err, replyLost) {
+		t.Fatalf("retain did not report lost reply: %v", err)
+	}
+	if err := f.store.MarkRetained(f.ctx, owner); err != nil {
+		t.Fatalf("retry uncertain retain: %v", err)
+	}
+	if err := f.store.Delete(f.ctx, owner); !errors.Is(err, registry.ErrConflict) {
+		t.Fatalf("uncertain retain lost tombstone protection: %v", err)
+	}
+	deletable := registryOwner("uncertain_delete")
+	f.claim(t, deletable, registry.ClaimCreated)
+	if err := uncertain.Delete(f.ctx, deletable); !errors.Is(err, replyLost) {
+		t.Fatalf("delete did not report lost reply: %v", err)
+	}
+	if err := f.store.Delete(f.ctx, deletable); err != nil {
+		t.Fatalf("retry uncertain delete: %v", err)
+	}
+}
+
+func TestRegistryConcurrentConflictingClaims(t *testing.T) {
+	f := newRegistryFixture(t)
+	f.bootstrap(t)
+	first := registryOwner("first")
+	second := registryOwner("second")
+	second.DatabaseName = first.DatabaseName
+	start := make(chan struct{})
+	results := make(chan error, 2)
+	var group sync.WaitGroup
+	for _, owner := range []registry.Ownership{first, second} {
+		group.Go(func() {
+			<-start
+			_, err := f.store.Claim(f.ctx, owner)
+			results <- err
+		})
+	}
+	close(start)
+	group.Wait()
+	close(results)
+	created, conflicts := 0, 0
+	for err := range results {
+		switch {
+		case err == nil:
+			created++
+		case errors.Is(err, registry.ErrConflict):
+			conflicts++
+		default:
+			t.Fatalf("unexpected concurrent claim error: %v", err)
+		}
+	}
+	if created != 1 || conflicts != 1 {
+		t.Fatalf("concurrent reservation: created=%d conflicts=%d; want one of each", created, conflicts)
+	}
+}
+
+func TestRegistryConcurrentRetainAndDelete(t *testing.T) {
+	f := newRegistryFixture(t)
+	f.bootstrap(t)
+	owner := registryOwner("delete_race")
+	f.claim(t, owner, registry.ClaimCreated)
+	start := make(chan struct{})
+	retainResult := make(chan error, 1)
+	deleteResult := make(chan error, 1)
+	go func() {
+		<-start
+		retainResult <- f.store.MarkRetained(f.ctx, owner)
+	}()
+	go func() {
+		<-start
+		deleteResult <- f.store.Delete(f.ctx, owner)
+	}()
+	close(start)
+	retainErr, deleteErr := <-retainResult, <-deleteResult
+	record, readErr := f.store.Get(f.ctx, owner.InstanceUID, owner.TenantUID)
+	switch {
+	case retainErr == nil:
+		// Retain 先取得行锁时，Delete 必须拒绝删除墓碑。
+		if !errors.Is(deleteErr, registry.ErrConflict) || readErr != nil || record.Managed || record.RetainedAt == nil {
+			t.Fatalf("retain won but tombstone was not protected: delete=%v read=%v record=%+v", deleteErr, readErr, record)
+		}
+	case errors.Is(retainErr, registry.ErrNotFound):
+		// Delete 先提交时，Retain 必须报告记录已不存在，不能重建墓碑。
+		if deleteErr != nil || !errors.Is(readErr, registry.ErrNotFound) {
+			t.Fatalf("delete won but record remains: delete=%v read=%v", deleteErr, readErr)
+		}
+	default:
+		t.Fatalf("unexpected retain/delete race: retain=%v delete=%v", retainErr, deleteErr)
+	}
+}

internal/database/adapter/postgresql/tls_integration_test.go

@@ -107,7 +107,7 @@ func TestPostgreSQLTLSHostIdentity(t *testing.T) {
 	if err != nil {
 		t.Fatal("trusted DNS SAN connection failed", err)
 	}
-	if version, err := db.Version(ctx); err != nil || version == "" {
+	if metadata, err := db.InspectMetadata(ctx); err != nil || metadata.Version == "" {
 		db.Close()
 		t.Fatal("TLS metadata read failed", err)
 	}

internal/database/application/instance_service.go

@@ -33,9 +33,9 @@ var (
 )
 
 // Database 与 Connector 复用原项目 internal/instance/service.go 的能力边界。
-// 版本查询只是本切片的连通性观察，不能产生领域 Ready。
+// Metadata 只查询版本与可用扩展，不能产生领域 Ready。
 type Database interface {
-	Version(context.Context) (string, error)
+	InspectMetadata(context.Context) (DatabaseMetadata, error)
 	Close()
 }
 
@@ -74,19 +74,25 @@ func NewInstanceService(source CredentialReader, connector Connector) (*Instance
 func (s *InstanceService) String() string   { return "[redacted instance service]" }
 func (s *InstanceService) GoString() string { return s.String() }
 
-// ObserveVersion 返回当前目标和凭据下的版本；任何失败均返回空结果。
+// ObserveVersion 是完整 metadata 读取的便捷入口，不再维护另一条连接或查询路径。
-// 调用者仍需使用 CR resourceVersion 保存前提防止 spec 并发修改；本方法不建立跨系统事务。
 func (s *InstanceService) ObserveVersion(ctx context.Context, target instance.ObservationTarget) (string, error) {
+	observation, err := s.ObserveMetadata(ctx, target)
+	return observation.Version(), err
+}
+
+// ObserveMetadata 返回当前目标和凭据下的版本与扩展；任何失败均丢弃全部结果。
+// 调用者仍需使用 CR resourceVersion 保存前提防止 spec 并发修改；本方法不建立跨系统事务。
+func (s *InstanceService) ObserveMetadata(ctx context.Context, target instance.ObservationTarget) (MetadataObservation, error) {
 	if err := target.Validate(); err != nil {
-		return "", err
+		return MetadataObservation{}, err
 	}
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	if s.closed {
-		return "", ErrClosed
+		return MetadataObservation{}, ErrClosed
 	}
 	if err := ctx.Err(); err != nil {
-		return "", err
+		return MetadataObservation{}, err
 	}
 
 	// 先读取有效凭据。读取失败时不得继续使用缓存中的旧连接。
@@ -94,11 +100,11 @@ func (s *InstanceService) ObserveVersion(ctx context.Context, target instance.Ob
 	credentials, err := s.source.Read(ctx, target.Definition().AdminCredential())
 	if err != nil {
 		s.release(name)
-		return "", credentialError(err)
+		return MetadataObservation{}, credentialError(err)
 	}
 	if credentials.username == "" || credentials.password == "" {
 		s.release(name)
-		return "", ErrCredentialsInvalid
+		return MetadataObservation{}, ErrCredentialsInvalid
 	}
 
 	// 连接身份与有效值均未变化时复用 pgxpool；generation 本身不要求换池。
@@ -111,7 +117,7 @@ func (s *InstanceService) ObserveVersion(ctx context.Context, target instance.Ob
 	if current == nil {
 		database, err := s.connector.Connect(ctx, target.Definition().Endpoint(), credentials)
 		if err != nil {
-			return "", err
+			return MetadataObservation{}, err
 		}
 		current = &entry{
 			target:      target,
@@ -121,23 +127,31 @@ func (s *InstanceService) ObserveVersion(ctx context.Context, target instance.Ob
 		s.entries[name] = current
 	}
 
-	version, err := current.database.Version(ctx)
+	metadata, err := current.database.InspectMetadata(ctx)
 	if err != nil {
 		s.release(name)
-		return "", err
+		return MetadataObservation{}, err
+	}
+	if metadata.Version == "" {
+		s.release(name)
+		return MetadataObservation{}, ErrObservation
 	}
 
 	// 回读后再检查凭据，避免把轮换前取得的结果交给新凭据的调用链。
 	latest, err := s.source.Read(ctx, target.Definition().AdminCredential())
 	if err != nil {
 		s.release(name)
-		return "", credentialError(err)
+		return MetadataObservation{}, credentialError(err)
 	}
 	if latest != credentials {
 		s.release(name)
-		return "", ErrCredentialsChanged
+		return MetadataObservation{}, ErrCredentialsChanged
 	}
-	return version, nil
+	return MetadataObservation{
+		target:     target,
+		version:    metadata.Version,
+		extensions: instance.ObserveExtensionSupport(metadata.AvailableExtensions),
+	}, nil
 }
 
 func credentialError(err error) error {

internal/database/application/instance_service_test.go

@@ -24,6 +24,8 @@ import (
 	"git.ddupan.top/panxiao81/ayatori/internal/database/domain/instance"
 )
 
+const serviceTestPassword = "test-only"
+
 // 延续源项目 Service 测试，用于穷举身份与装配失败；真实行为由 adapter 集成测试验证。
 type sourceStub struct {
 	credentials Credentials
@@ -37,9 +39,12 @@ func (s *sourceStub) Read(context.Context, instance.CredentialReference) (Creden
 type databaseStub struct {
 	closes   int
 	err      error
+	metadata DatabaseMetadata
 }
 
-func (d *databaseStub) Version(context.Context) (string, error) { return "17", d.err }
+func (d *databaseStub) InspectMetadata(context.Context) (DatabaseMetadata, error) {
+	return d.metadata, d.err
+}
 func (d *databaseStub) Close() {
 	d.closes++
 }
@@ -53,7 +58,12 @@ func (c *connectorStub) Connect(context.Context, instance.Endpoint, Credentials)
 	if c.err != nil {
 		return nil, c.err
 	}
-	db := &databaseStub{}
+	db := &databaseStub{
+		metadata: DatabaseMetadata{
+			Version:             "17",
+			AvailableExtensions: []string{"plpgsql"},
+		},
+	}
 	c.databases = append(c.databases, db)
 	return db, nil
 }
@@ -98,7 +108,7 @@ func serviceTarget(t *testing.T, uid, host, secret string, generation int64) ins
 }
 
 func TestInstanceConnectionIdentity(t *testing.T) {
-	source := &sourceStub{credentials: Credentials{username: testUsername, password: "test-only"}}
+	source := &sourceStub{credentials: Credentials{username: testUsername, password: serviceTestPassword}}
 	connector := &connectorStub{}
 	service, err := NewInstanceService(source, connector)
 	if err != nil {
@@ -118,9 +128,13 @@ func TestInstanceConnectionIdentity(t *testing.T) {
 		{"same name with new UID", serviceTarget(t, "uid-2", "second", "replacement", 1), 4},
 	}
 	for _, testCase := range cases {
-		if _, err := service.ObserveVersion(ctx, testCase.target); err != nil {
+		observation, err := service.ObserveMetadata(ctx, testCase.target)
+		if err != nil {
 			t.Fatal(err)
 		}
+		if !observation.Target().Matches(testCase.target) {
+			t.Fatalf("%s: observation was bound to a previous target", testCase.name)
+		}
 		if len(connector.databases) != testCase.wantConnections {
 			t.Fatalf("%s: got %d connections, want %d", testCase.name, len(connector.databases), testCase.wantConnections)
 		}
@@ -137,11 +151,64 @@ func TestInstanceConnectionIdentity(t *testing.T) {
 	}
 }
 
+func TestMetadataObservationFreshnessAndFailure(t *testing.T) {
+	source := &sourceStub{credentials: Credentials{username: testUsername, password: serviceTestPassword}}
+	connector := &connectorStub{}
+	service, err := NewInstanceService(source, connector)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer service.Close()
+	ctx := context.Background()
+	target := serviceTarget(t, "metadata-uid", "first", "admin", 1)
+	observed, err := service.ObserveMetadata(ctx, target)
+	if err != nil || observed.Version() != "17" || !observed.Target().Matches(target) {
+		t.Fatalf("metadata observation: %v", err)
+	}
+	requested := instance.NewExtensionSet([]string{"plpgsql"})
+	if observed.Extensions().Check(requested).Decision != instance.ExtensionsAccepted {
+		t.Fatal("extension list was not observed")
+	}
+
+	// 连接可以复用，但每轮必须重新查询；旧观察还必须与 adapter 的可变 slice 脱离。
+	database := connector.databases[0]
+	database.metadata.AvailableExtensions[0] = "replacement"
+	if observed.Extensions().Check(requested).Decision != instance.ExtensionsAccepted {
+		t.Fatal("adapter mutation changed a completed observation")
+	}
+	refreshed, err := service.ObserveMetadata(ctx, target)
+	if err != nil || refreshed.Extensions().Check(requested).Decision != instance.ExtensionsUnsupported {
+		t.Fatalf("extension list was cached across observations: %v", err)
+	}
+	database.metadata.AvailableExtensions = nil
+	empty, err := service.ObserveMetadata(ctx, target)
+	if err != nil || empty.Extensions().Check(requested).Decision != instance.ExtensionsUnsupported {
+		t.Fatalf("successful empty list was treated as unobserved: %v", err)
+	}
+
+	// 即使 adapter 附带部分数据，错误仍使整个观察失效。
+	database.err = ErrObservation
+	failed, err := service.ObserveMetadata(ctx, target)
+	if !errors.Is(err, ErrObservation) || failed.Version() != "" || failed.Target().Validate() == nil {
+		t.Fatal("failed query returned a bound observation")
+	}
+	if failed.Extensions().Check(requested).Decision != instance.ExtensionSupportUnobserved {
+		t.Fatal("failed query was interpreted as an empty extension list")
+	}
+	if _, err := service.ObserveMetadata(ctx, target); err != nil {
+		t.Fatalf("retry after query failure: %v", err)
+	}
+	connector.databases[1].metadata.Version = ""
+	if _, err := service.ObserveMetadata(ctx, target); !errors.Is(err, ErrObservation) {
+		t.Fatal("missing server version was accepted as complete metadata")
+	}
+}
+
 func TestInstanceAssemblyFailureRecovery(t *testing.T) {
 	ctx := context.Background()
 	target := serviceTarget(t, "uid-1", "first", "admin", 1)
 	source := &sourceStub{
-		credentials: Credentials{username: testUsername, password: "test-only"},
+		credentials: Credentials{username: testUsername, password: serviceTestPassword},
 		err:         errors.New("unsafe source error"),
 	}
 	connector := &connectorStub{err: ErrConnection}

internal/database/application/metadata.go

@@ -0,0 +1,40 @@
+/*
+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 application
+
+import "git.ddupan.top/panxiao81/ayatori/internal/database/domain/instance"
+
+// DatabaseMetadata 是一次只读查询的事实，不包含管理权限或 registry 就绪结论。
+// AvailableExtensions 是服务器提供的可用列表，不是已安装列表或安装授权。
+type DatabaseMetadata struct {
+	Version             string
+	AvailableExtensions []string
+}
+
+// MetadataObservation 只在查询成功且有效凭据再次核对一致后产生。
+// target 绑定本次调用，而非连接最初创建时的 generation；零值表示没有观察。
+type MetadataObservation struct {
+	target     instance.ObservationTarget
+	version    string
+	extensions instance.ExtensionSupport
+}
+
+func (o MetadataObservation) Target() instance.ObservationTarget { return o.target }
+func (o MetadataObservation) Version() string                    { return o.version }
+func (o MetadataObservation) Extensions() instance.ExtensionSupport {
+	return o.extensions
+}