diff --git a/bazel/rules/rules_score/docs/index.rst b/bazel/rules/rules_score/docs/index.rst
index aa4246cc..4135f7fa 100644
--- a/bazel/rules/rules_score/docs/index.rst
+++ b/bazel/rules/rules_score/docs/index.rst
@@ -40,6 +40,7 @@ safety analysis to the top-level SEooC assembly.
    tool_reference/specs/bazel_component
    tool_reference/specs/class_design_implementation
    tool_reference/specs/component_internal_api
+   tool_reference/specs/component_public_api
    tool_reference/specs/component_sequence
    tool_reference/specs/sequence_internal_api
 
diff --git a/validation/core/BUILD b/validation/core/BUILD
index 8ff02994..b02efb8b 100644
--- a/validation/core/BUILD
+++ b/validation/core/BUILD
@@ -25,6 +25,7 @@ filegroup(
         "docs/specifications/bazel_component.md",
         "docs/specifications/class_design_implementation.md",
         "docs/specifications/component_internal_api.md",
+        "docs/specifications/component_public_api.md",
         "docs/specifications/component_sequence.md",
         "docs/specifications/sequence_internal_api.md",
     ],
diff --git a/validation/core/docs/requirements/tool_requirements.trlc b/validation/core/docs/requirements/tool_requirements.trlc
index bbe08621..87a1daa3 100644
--- a/validation/core/docs/requirements/tool_requirements.trlc
+++ b/validation/core/docs/requirements/tool_requirements.trlc
@@ -148,6 +148,27 @@ section "Tool Requirements" {
 
         }
 
+        section "Component Public API Validator" {
+
+            ToolQualification.ToolRequirement ComponentPublicApiInterfaceDeclarationConsistency {
+                description = '''The validator shall report an error when a
+                public API interface declared in the component diagram is not
+                declared as an interface in the public API class diagram.'''
+                derived_from = [UseCases.Validate_Architecture_Specification_Documents]
+                satisfied_by = Verifier
+            }
+
+            ToolQualification.ToolRequirement ComponentPublicApiSeoocRelationshipConsistency {
+                description = '''The validator shall report an error when a
+                public API interface declared in the component diagram is not
+                connected by an interface-binding relationship from the SEooC
+                in the component diagram.'''
+                derived_from = [UseCases.Validate_Architecture_Specification_Documents]
+                satisfied_by = Verifier
+            }
+
+        }
+
         section "Class Design Implementation Validator" {
 
             ToolQualification.ToolRequirement ClassDesignImplementationEntityConsistency {
diff --git a/validation/core/docs/specifications/component_public_api.md b/validation/core/docs/specifications/component_public_api.md
new file mode 100644
index 00000000..36c4e2bb
--- /dev/null
+++ b/validation/core/docs/specifications/component_public_api.md
@@ -0,0 +1,101 @@
+<!-- ----------------------------------------------------------------------------
+  Copyright (c) 2026 Contributors to the Eclipse Foundation
+
+  See the NOTICE file(s) distributed with this work for additional
+  information regarding copyright ownership.
+
+  This program and the accompanying materials are made available under the
+  terms of the Apache License Version 2.0 which is available at
+  https://www.apache.org/licenses/LICENSE-2.0
+
+  SPDX-License-Identifier: Apache-2.0
+----------------------------------------------------------------------------- -->
+
+# Component Public API Specification
+
+## Purpose
+
+This validator enforces consistency between public API interfaces in the
+static design (component diagram) and interfaces declared by the public API
+design (class diagram).
+
+It shall make sure that every public API interface declared by the static design
+is also declared by the public API and is connected to the SEooC boundary.
+
+## What is Validated
+
+The validator compares static design diagrams with public API design diagrams.
+It receives two indexed diagram inputs:
+
+| Input | Source | Meaning |
+|---|---|---|
+| `component_diagrams` | static design component diagram FlatBuffers | Public API interface references from the static design |
+| `public_api_diagrams` | public API class diagram FlatBuffers | Public API interfaces declared by the class design |
+
+For this validator, a public API interface is a top-level interface declared in
+the static design. Interfaces declared inside the SEooC, components, or units
+are treated as internal API interfaces.
+
+### Interface Declaration Consistency
+
+Every public API interface declared in the static design diagram must resolve
+to an interface declared in the public API class diagram.
+*(Requirement: {requirement:downstream-ref}`Tools.ComponentPublicApiInterfaceDeclarationConsistency`)*
+
+The component public API interface is matched against public API interface
+entries derived from the public API diagram. Matching is exact and
+case-sensitive.
+
+```text
+' static design diagram
+package "Sample SEooC" as sample_seooc <<SEooC>> {
+}
+
+interface "Sample Library API" as SampleLibraryAPI
+sample_seooc )- SampleLibraryAPI
+
+' public API diagram
+interface "Sample Library API" as SampleLibraryAPI <<interface>> {
+  +GetNumber(): int
+}
+```
+
+### SEooC Relationship Consistency
+
+Every public API interface declared in the static design diagram must be
+connected from the SEooC in the static design diagram.
+*(Requirement: {requirement:downstream-ref}`Tools.ComponentPublicApiSeoocRelationshipConsistency`)*
+
+This item covers the SEooC boundary relation only. The interface declaration in
+the public API diagram is covered by Interface Declaration Consistency.
+
+```text
+' static design diagram
+package "Sample SEooC" as sample_seooc <<SEooC>> {
+}
+
+interface "Sample Library API" as SampleLibraryAPI
+sample_seooc )- SampleLibraryAPI
+```
+
+The validator collects relationships from SEooC entities and checks whether the
+public API interface is a relation target. Relations from components or units do
+not satisfy this rule.
+
+## Failure Cases
+
+| Failure case | Validation rule |
+|---|---|
+| Missing public API interface declaration | Interface Declaration Consistency |
+| Public API interface not connected from the SEooC | SEooC Relationship Consistency |
+
+## Debug Output
+
+The validator emits debug output containing:
+
+- public API interfaces declared in the static design
+- public API interfaces referenced by SEooC relations
+- public API identifiers available from the public API diagram
+
+Failure messages list the public API interface IDs that are missing or not
+connected from the SEooC.