diff --git a/catalog/capability-types.yaml b/catalog/capability-types.yaml
index 280f233..905ad98 100644
--- a/catalog/capability-types.yaml
+++ b/catalog/capability-types.yaml
@@ -119,3 +119,14 @@ spec:
         - http-api
         - event-stream
       tags: [coordination, state-hub, planning]
+
+    - id: ecosystem-registry
+      name: Ecosystem registry
+      lifecycle: active
+      description: Registers repositories and exposes graph, inventory, and visualization projections over the ecosystem model.
+      default_criticality: high
+      default_data_classification: internal
+      expected_interface_types:
+        - http-api
+        - web-ui
+      tags: [registry, discovery, graph, visualization]
diff --git a/catalog/interface-types.yaml b/catalog/interface-types.yaml
index a446d50..bcf916a 100644
--- a/catalog/interface-types.yaml
+++ b/catalog/interface-types.yaml
@@ -17,6 +17,14 @@ spec:
       typical_auth_methods: [none, oidc, jwt, mtls, api_key]
       versioning: path, header, media-type, or documented semantic version.
 
+    - id: web-ui
+      name: Web UI
+      lifecycle: active
+      description: Browser-based user interface for humans and agents operating through a visual surface.
+      category: ui
+      typical_auth_methods: [none, oidc, jwt, mtls, api_key]
+      versioning: URL path, static asset version, and documented user-facing workflow compatibility.
+
     - id: oidc-discovery
       name: OIDC discovery
       lifecycle: active
diff --git a/docs/type-catalog.md b/docs/type-catalog.md
index 4f3c788..859f985 100644
--- a/docs/type-catalog.md
+++ b/docs/type-catalog.md
@@ -28,12 +28,14 @@ Machine-readable catalog files:
 | `audit-event-sink` | planned | high | confidential | `event-stream`, `http-api` |
 | `scope-generation` | active | medium | internal | `cli`, `http-api` |
 | `coordination-read-model` | active | high | internal | `http-api`, `event-stream` |
+| `ecosystem-registry` | active | high | internal | `http-api`, `web-ui` |
 
 ## Interface Types
 
 | Type | Lifecycle | Category | Typical Auth |
 |------|-----------|----------|--------------|
 | `http-api` | active | api | `none`, `oidc`, `jwt`, `mtls`, `api_key` |
+| `web-ui` | active | ui | `none`, `oidc`, `jwt`, `mtls`, `api_key` |
 | `oidc-discovery` | active | identity | `none` |
 | `kubernetes-secret` | active | kubernetes | `kubernetes_service_account` |
 | `kubernetes-crd` | active | kubernetes | `kubernetes_service_account` |
diff --git a/fabric/capabilities/railiance-fabric-ecosystem-registry.yaml b/fabric/capabilities/railiance-fabric-ecosystem-registry.yaml
new file mode 100644
index 0000000..7cb1dce
--- /dev/null
+++ b/fabric/capabilities/railiance-fabric-ecosystem-registry.yaml
@@ -0,0 +1,24 @@
+apiVersion: railiance.fabric/v1alpha1
+kind: CapabilityDeclaration
+metadata:
+  id: railiance-fabric.registry.ecosystem-registry
+  name: Railiance ecosystem registry
+  owner: railiance-fabric
+  repo: railiance-fabric
+  domain: railiance
+  source_links:
+    - label: Registry store
+      path: railiance_fabric/registry.py
+    - label: Registry API docs
+      path: docs/registry-api.md
+spec:
+  lifecycle: active
+  environments: [dev]
+  description: Registers repositories, ingests Fabric graph snapshots and library inventory, and exposes registry projections for discovery, State Hub export, xRegistry, and the interactive Fabric map.
+  capability_type: ecosystem-registry
+  service_id: railiance-fabric.registry
+  interface_ids:
+    - railiance-fabric.registry.http-api
+    - railiance-fabric.registry.graph-explorer-ui
+  criticality: high
+  data_classification: internal
diff --git a/fabric/interfaces/railiance-fabric-registry-graph-explorer-ui.yaml b/fabric/interfaces/railiance-fabric-registry-graph-explorer-ui.yaml
new file mode 100644
index 0000000..76130e5
--- /dev/null
+++ b/fabric/interfaces/railiance-fabric-registry-graph-explorer-ui.yaml
@@ -0,0 +1,28 @@
+apiVersion: railiance.fabric/v1alpha1
+kind: InterfaceDeclaration
+metadata:
+  id: railiance-fabric.registry.graph-explorer-ui
+  name: Railiance Fabric Graph Explorer UI
+  owner: railiance-fabric
+  repo: railiance-fabric
+  domain: railiance
+  source_links:
+    - label: UI shell
+      path: railiance_fabric/graph_explorer_ui.py
+    - label: Graph explorer operations
+      path: docs/graph-explorer-operations.md
+spec:
+  lifecycle: active
+  environments: [dev]
+  description: Browser UI for exploring the local Fabric registry graph, onboarding gaps, dependencies, interfaces, saved local views, and shareable graph state.
+  interface_type: web-ui
+  version: v1alpha1
+  service_id: railiance-fabric.registry
+  capability_ids:
+    - railiance-fabric.registry.ecosystem-registry
+  endpoint:
+    url: http://127.0.0.1:8765/ui/graph-explorer
+    notes: Local workstation UI when the registry service is running.
+  auth:
+    method: none
+  data_classification: internal
diff --git a/fabric/interfaces/railiance-fabric-registry-http-api.yaml b/fabric/interfaces/railiance-fabric-registry-http-api.yaml
new file mode 100644
index 0000000..6e38b20
--- /dev/null
+++ b/fabric/interfaces/railiance-fabric-registry-http-api.yaml
@@ -0,0 +1,28 @@
+apiVersion: railiance.fabric/v1alpha1
+kind: InterfaceDeclaration
+metadata:
+  id: railiance-fabric.registry.http-api
+  name: Railiance Fabric Registry HTTP API
+  owner: railiance-fabric
+  repo: railiance-fabric
+  domain: railiance
+  source_links:
+    - label: HTTP routes
+      path: railiance_fabric/server.py
+    - label: API docs
+      path: docs/registry-api.md
+spec:
+  lifecycle: active
+  environments: [dev]
+  description: Local HTTP API for repository registration, graph snapshot ingestion, graph queries, inventory views, State Hub export, Backstage projection, xRegistry projection, and graph explorer payloads.
+  interface_type: http-api
+  version: v1alpha1
+  service_id: railiance-fabric.registry
+  capability_ids:
+    - railiance-fabric.registry.ecosystem-registry
+  endpoint:
+    url: http://127.0.0.1:8765
+    notes: Local workstation endpoint when the registry service is running.
+  auth:
+    method: none
+  data_classification: internal
diff --git a/fabric/services/railiance-fabric-registry.yaml b/fabric/services/railiance-fabric-registry.yaml
new file mode 100644
index 0000000..209fbef
--- /dev/null
+++ b/fabric/services/railiance-fabric-registry.yaml
@@ -0,0 +1,23 @@
+apiVersion: railiance.fabric/v1alpha1
+kind: ServiceDeclaration
+metadata:
+  id: railiance-fabric.registry
+  name: Railiance Fabric Registry
+  owner: railiance-fabric
+  repo: railiance-fabric
+  domain: railiance
+  source_links:
+    - label: Registry server implementation
+      path: railiance_fabric/server.py
+    - label: Operations guide
+      path: docs/graph-explorer-operations.md
+spec:
+  lifecycle: active
+  environments: [dev]
+  description: Local ecosystem registry and graph explorer service for registered Railiance repositories, Fabric graph snapshots, inventory, and map-oriented exports.
+  service_type: registry-service
+  provides_capabilities:
+    - railiance-fabric.registry.ecosystem-registry
+  exposes_interfaces:
+    - railiance-fabric.registry.http-api
+    - railiance-fabric.registry.graph-explorer-ui