diff --git a/bazel/rules/rules_score/BUILD b/bazel/rules/rules_score/BUILD
index d00047b..d089de9 100644
--- a/bazel/rules/rules_score/BUILD
+++ b/bazel/rules/rules_score/BUILD
@@ -147,6 +147,7 @@ py_binary(
         requirement("rst2pdf"),
         requirement("sphinxcontrib-umlet"),
         requirement("svglib"),
+        requirement("sphinxcontrib-mermaid"),
         requirement("sphinxcontrib-plantuml"),
     ],
 )
@@ -199,3 +200,4 @@ string_flag(
     ],
     visibility = ["//visibility:public"],
 )
+
diff --git a/bazel/rules/rules_score/README.md b/bazel/rules/rules_score/README.md
index 5546d0c..10b8668 100644
--- a/bazel/rules/rules_score/README.md
+++ b/bazel/rules/rules_score/README.md
@@ -94,6 +94,10 @@ architectural_design(
 Diagrams in `public_api` are classified separately so their lobster items flow
 through `public_api_lobster_files` for failure-mode traceability.
 
+Mermaid diagrams are also available in Sphinx-authored `.rst` and `.md`
+sources via the bundled `sphinxcontrib-mermaid` extension, but unlike `.puml`
+inputs they are not parsed into FlatBuffers or LOBSTER artifacts.
+
 ---
 
 ## `unit`
diff --git a/bazel/rules/rules_score/private/dependable_element.bzl b/bazel/rules/rules_score/private/dependable_element.bzl
index 6a6368f..d65d794 100644
--- a/bazel/rules/rules_score/private/dependable_element.bzl
+++ b/bazel/rules/rules_score/private/dependable_element.bzl
@@ -1255,6 +1255,7 @@ def dependable_element(
         maturity = "release",
         sphinx = Label("//bazel/rules/rules_score:score_build"),
         testonly = True,
+        extra_opts = [],
         **kwargs):
     """Define a dependable element (Safety Element out of Context - SEooC) following S-CORE process guidelines.
 
@@ -1333,6 +1334,7 @@ def dependable_element(
         deps = [d + "_doc" for d in deps],
         sphinx = sphinx,
         testonly = testonly,
+        extra_opts = extra_opts,
         **kwargs
     )
 
diff --git a/bazel/rules/rules_score/private/sphinx_module.bzl b/bazel/rules/rules_score/private/sphinx_module.bzl
index 219e161..d3170e6 100644
--- a/bazel/rules/rules_score/private/sphinx_module.bzl
+++ b/bazel/rules/rules_score/private/sphinx_module.bzl
@@ -98,6 +98,8 @@ def _score_needs_impl(ctx):
         "--log-level",
         get_log_level(ctx),
     ]
+    for opt in ctx.attr.extra_opts:
+        needs_args.append(ctx.expand_location(opt, targets = ctx.attr.srcs))
     ctx.actions.run(
         inputs = needs_inputs,
         outputs = [needs_output],
@@ -277,7 +279,10 @@ def _score_html_impl(ctx):
 # ======================================================================================
 _score_needs = rule(
     implementation = _score_needs_impl,
-    attrs = sphinx_rule_attrs,
+    attrs = dict(
+        sphinx_rule_attrs,
+        extra_opts = attr.string_list(doc = "Regular additional string options to pass onto Sphinx."),
+    ),
     toolchains = ["//bazel/rules/rules_score:toolchain_type"],
 )
 _score_html = rule(
@@ -349,6 +354,7 @@ def sphinx_module(
         index = index,
         deps = [d + "_needs" for d in deps],
         testonly = testonly,
+        extra_opts = extra_opts,
         **kwargs
     )
     _score_html(
diff --git a/bazel/rules/rules_score/requirements.in b/bazel/rules/rules_score/requirements.in
index c09147d..ce877b7 100644
--- a/bazel/rules/rules_score/requirements.in
+++ b/bazel/rules/rules_score/requirements.in
@@ -4,6 +4,7 @@ rst2pdf
 sphinx
 sphinx-needs
 sphinx-design
+sphinxcontrib-mermaid
 sphinxcontrib-plantuml
 sphinxcontrib-umlet
 sphinx-rtd-theme
diff --git a/bazel/rules/rules_score/requirements.txt b/bazel/rules/rules_score/requirements.txt
index d477567..87185f5 100644
--- a/bazel/rules/rules_score/requirements.txt
+++ b/bazel/rules/rules_score/requirements.txt
@@ -751,6 +751,10 @@ sphinxcontrib-jsmath==1.0.1 \
     --hash=sha256:2ec2eaebfb78f3f2078e73666b1415417a116cc848b72e5172e596c871103178 \
     --hash=sha256:a9925e4a4587247ed2191a22df5f6970656cb8ca2bd6284309578f2153e0c4b8
     # via sphinx
+sphinxcontrib-mermaid==2.0.0 \
+    --hash=sha256:59a73249bbee2c74b1a4db036f8e8899ade65982bdda6712cf22b4f4e9874bb5 \
+    --hash=sha256:cf4f7d453d001132eaba5d1fdf53d42049f02e913213cf8337427483bfca26f4
+    # via -r bazel/rules/rules_score/requirements.in
 sphinxcontrib-plantuml==0.31 \
     --hash=sha256:fd74752f8ea070e641c3f8a402fccfa1d4a4056e0967b56033d2a76282d9f956
     # via -r bazel/rules/rules_score/requirements.in
diff --git a/bazel/rules/rules_score/test/requirements.in b/bazel/rules/rules_score/test/requirements.in
index 05d941e..eb6b3db 100644
--- a/bazel/rules/rules_score/test/requirements.in
+++ b/bazel/rules/rules_score/test/requirements.in
@@ -4,5 +4,6 @@ sphinx
 sphinx-needs
 sphinx-design
 myst-parser
+sphinxcontrib-mermaid
 sphinxcontrib-plantuml
 sphinx-rtd-theme
diff --git a/bazel/rules/rules_score/test/requirements.txt b/bazel/rules/rules_score/test/requirements.txt
index 8666593..b00590e 100644
--- a/bazel/rules/rules_score/test/requirements.txt
+++ b/bazel/rules/rules_score/test/requirements.txt
@@ -488,6 +488,10 @@ sphinxcontrib-jsmath==1.0.1 \
     --hash=sha256:2ec2eaebfb78f3f2078e73666b1415417a116cc848b72e5172e596c871103178 \
     --hash=sha256:a9925e4a4587247ed2191a22df5f6970656cb8ca2bd6284309578f2153e0c4b8
     # via sphinx
+sphinxcontrib-mermaid==2.0.0 \
+    --hash=sha256:59a73249bbee2c74b1a4db036f8e8899ade65982bdda6712cf22b4f4e9874bb5 \
+    --hash=sha256:cf4f7d453d001132eaba5d1fdf53d42049f02e913213cf8337427483bfca26f4
+    # via -r requirements.in
 sphinxcontrib-plantuml==0.31 \
     --hash=sha256:fd74752f8ea070e641c3f8a402fccfa1d4a4056e0967b56033d2a76282d9f956
     # via -r requirements.in