[rules_score] add archver

- provide tool for validation of sw arch design
- initial check for consistency between plantuml and bazel

Author: hoe-jo

.github/CODEOWNERS

@@ -16,5 +16,6 @@
 # were modified. All directories should have a proper codeowner
 # Syntax: https://help.github.com/articles/about-codeowners/
 
-/plantuml/ @castler @hoe-jo @LittleHuba @limdor @ramceb
 /bazel/rules/rules_score/ @castler @hoe-jo @LittleHuba @limdor @ramceb
+/plantuml/ @castler @hoe-jo @LittleHuba @limdor @ramceb
+/validation/ @castler @hoe-jo @LittleHuba @limdor @ramceb

plantuml/parser/puml_serializer/src/fbs/BUILD

@@ -40,6 +40,7 @@ rust_library(
     ],
     visibility = [
         "//plantuml/parser:__subpackages__",
+        "//validation/archver:__pkg__",
     ],
     deps = [
         "@crates//:flatbuffers",

validation/BUILD

@@ -0,0 +1,12 @@
+# *******************************************************************************
+# 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
+# *******************************************************************************

validation/archver/BUILD

@@ -0,0 +1,38 @@
+# *******************************************************************************
+# 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
+# *******************************************************************************
+load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_test")
+
+rust_binary(
+    name = "archver",
+    srcs = [
+        "src/bazel_reader.rs",
+        "src/diagram_reader.rs",
+        "src/main.rs",
+        "src/models.rs",
+        "src/validation.rs",
+    ],
+    crate_root = "src/main.rs",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//plantuml/parser/puml_serializer/src/fbs:component_fbs",
+        "@crates//:clap",
+        "@crates//:flatbuffers",
+        "@crates//:serde",
+        "@crates//:serde_json",
+    ],
+)
+
+rust_test(
+    name = "archver_test",
+    crate = ":archver",
+)

validation/archver/README.md

@@ -0,0 +1,82 @@
+<!--
+  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
+-->
+
+# Architecture Verifier (archver)
+
+Validates that PlantUML component diagrams match the Bazel build graph structure.
+
+## Overview
+
+The archver tool ensures architectural consistency by comparing:
+- **Bazel build graph**: Dependable element, component and unit hierarchy from the build system
+- **PlantUML diagrams**: Static architecture documentation with stereotypes
+
+## Usage
+
+### Standalone CLI
+
+```bash
+archver \
+  --architecture-json path/to/architecture.json \
+  --static-fbs path/to/diagram1.fbs.bin path/to/diagram2.fbs.bin
+
+# Write a debug log in addition to stderr output
+archver \
+  --architecture-json path/to/architecture.json \
+  --static-fbs path/to/diagram.fbs.bin \
+  --output path/to/archver.log
+```
+
+Exits with code `0` on success, `1` on any validation error or I/O failure.
+
+## What is Validated
+
+### Dependable Element
+The dependable element is represented in the Bazel JSON as a top-level component
+entry. In PlantUML, it corresponds to a `package` with stereotype `<<SEooC>>`.
+The alias of the PlantUML package must match the Bazel dependable element name.
+
+### Component Validation (Check 1)
+For each unique `(component_alias, parent_alias)` combination that Bazel expects:
+- PlantUML must have the exact same number of components with that combination
+- Uses target name only (package path is stripped)
+- Components nested under the dependable element have the dependable element as parent
+- Entities must have stereotype `<<component>>`
+
+### Unit Validation (Check 2)
+For each unique `(unit_alias, parent_component_alias)` combination that Bazel expects:
+- PlantUML must have the exact same number of units with that combination
+- Uses target name only (e.g., `unit_1`, `unit_2`)
+- Entities must have stereotype `<<unit>>`
+
+### Duplicate Detection
+If two Bazel targets resolve to the same `(alias, parent)` key (e.g., same target
+name in different packages), or two PlantUML entities have the same key, an error
+is emitted.
+
+### Example
+If Bazel build graph has:
+- Dependable element: `safety_software_seooc_example` → key: `safety_software_seooc_example`
+- Component: `@//examples/seooc:component_example` → key: `component_example` (parent: `safety_software_seooc_example`)
+- Unit: `@//examples/seooc/unit_1:unit_1` → key: `unit_1` (parent: `component_example`)
+- Unit: `@//examples/seooc/unit_2:unit_2` → key: `unit_2` (parent: `component_example`)
+
+PlantUML must have:
+```plantuml
+package "Safety Software SEooC Example" as safety_software_seooc_example <<SEooC>> {
+    component "ComponentExample" as component_example <<component>> {
+        component "Unit 1" as unit_1 <<unit>>
+        component "Unit 2" as unit_2 <<unit>>
+    }
+}
+```

validation/archver/design/static_design.puml

@@ -0,0 +1,64 @@
+' *******************************************************************************
+' 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
+' *******************************************************************************
+
+@startuml
+
+package "archver" as archver {
+
+    component "main" as main <<component>> {
+        component "Args" as args <<unit>>
+    }
+
+    component "models" as models <<component>> {
+        component "BazelInput" as bazel_input <<unit>>
+        component "BazelArchitecture" as bazel_architecture <<unit>>
+        component "DiagramInputs" as diagram_inputs_model <<unit>>
+        component "DiagramInput" as diagram_input_model <<unit>>
+        component "DiagramArchitecture" as diagram_architecture <<unit>>
+    }
+
+    component "bazel_reader" as bazel_reader <<component>> {
+        component "BazelReader" as bazel_reader_cls <<unit>>
+    }
+
+    component "diagram_reader" as reader <<component>> {
+        component "DiagramReader" as diagram_reader_cls <<unit>>
+    }
+
+    component "validation" as validation <<component>> {
+        component "Validator" as validator <<unit>>
+    }
+
+}
+
+file "architecture.json\n(from dependable_element rule)" as arch_json_file
+file "*.fbs.bin\n(from architectural_design rule)" as fbs_files
+
+main --> bazel_reader_cls   : reads JSON
+main --> diagram_reader_cls : reads FBS files
+main --> validator          : runs validation
+
+bazel_reader_cls   --> bazel_input         : produces
+diagram_reader_cls --> diagram_inputs_model : produces
+
+bazel_input --> bazel_architecture         : to_bazel_architecture()
+diagram_inputs_model --> diagram_architecture : to_diagram_architecture()
+validator --> bazel_architecture : compares
+validator --> diagram_architecture  : compares
+
+arch_json_file ..> bazel_reader_cls   : --architecture-json
+fbs_files      ..> diagram_reader_cls : --static-fbs
+
+bazel_architecture -[hidden]r-> diagram_architecture
+
+@enduml

validation/archver/src/bazel_reader.rs

@@ -0,0 +1,30 @@
+// *******************************************************************************
+// 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
+// *******************************************************************************
+
+use std::fs;
+
+use crate::models::BazelInput;
+
+/// Reads the `architecture.json` file produced by the `dependable_element`
+/// Bazel rule and deserializes it into a [`BazelInput`] model.
+pub struct BazelReader;
+
+impl BazelReader {
+    /// Read and parse the architecture JSON at `path`.
+    pub fn read(path: &str) -> Result<BazelInput, String> {
+        let json_content =
+            fs::read_to_string(path).map_err(|e| format!("Failed to read {path}: {e}"))?;
+        serde_json::from_str(&json_content)
+            .map_err(|e| format!("Failed to parse architecture JSON: {e}"))
+    }
+}

validation/archver/src/diagram_reader.rs

@@ -0,0 +1,61 @@
+// *******************************************************************************
+// 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
+// *******************************************************************************
+
+use crate::models::{DiagramInput, DiagramInputs};
+use component_fbs::component as fb_component;
+use std::fs;
+
+pub struct DiagramReader;
+
+impl DiagramReader {
+    /// Read all `Component` and `Package` entities from the given FlatBuffers
+    /// binary files.
+    pub fn read(paths: &[String]) -> Result<DiagramInputs, String> {
+        let mut out = Vec::new();
+
+        for path in paths {
+            let data = fs::read(path).map_err(|e| format!("Failed to read {path}: {e}"))?;
+
+            let graph = flatbuffers::root::<fb_component::ComponentGraph>(&data)
+                .map_err(|e| format!("Failed to parse FlatBuffer {path}: {e}"))?;
+
+            if let Some(entries) = graph.components() {
+                for entry in entries.iter() {
+                    if let Some(comp) = entry.value() {
+                        match comp.comp_type() {
+                            fb_component::ComponentType::Component
+                            | fb_component::ComponentType::Package => {
+                                out.push(DiagramInput {
+                                    id: comp.id().unwrap_or_default().to_string(),
+                                    alias: comp.alias().map(|s| s.to_string()),
+                                    parent_id: comp.parent_id().map(|s| s.to_string()),
+                                    stereotype: comp.stereotype().map(|s| s.to_string()),
+                                });
+                            }
+                            // Other diagram entity types (Artifact, Database, etc.)
+                            // are not relevant for architecture verification.
+                            _ => {}
+                        }
+                    } else {
+                        return Err(format!(
+                            "FlatBuffer entry with key {:?} has null value in {path} (corrupted or truncated file)",
+                            entry.key()
+                        ));
+                    }
+                }
+            }
+        }
+
+        Ok(DiagramInputs { entities: out })
+    }
+}