diff --git a/_assets/img/sublime-theme/flower_of_life.svg b/_assets/img/sublime-theme/flower-of-life.svg
similarity index 100%
rename from _assets/img/sublime-theme/flower_of_life.svg
rename to _assets/img/sublime-theme/flower-of-life.svg
diff --git a/_assets/img/sublime-theme/prism_outro.svg b/_assets/img/sublime-theme/prism-outro.svg
similarity index 100%
rename from _assets/img/sublime-theme/prism_outro.svg
rename to _assets/img/sublime-theme/prism-outro.svg
diff --git a/build/tasks/verify/verify-filenames.mts b/build/tasks/verify/verify-filenames.mts
new file mode 100644
index 000000000..6c1677f0f
--- /dev/null
+++ b/build/tasks/verify/verify-filenames.mts
@@ -0,0 +1,73 @@
+/**
+ * @file Verify filenames adhere to the project naming convention.
+ * @author The OpenINF Authors & Friends
+ * @license MIT OR Apache-2.0 OR BlueOak-1.0.0
+ * @module {type ES6Module} build/tasks/verify/verify-filenames
+ */
+
+import { glob } from '@openinf/portal/build/utils';
+
+/**
+ * Lowercase words joined by hyphens. A leading underscore is Eleventy's and
+ * Sass's marking for something that is not itself output -- `_layouts/`,
+ * `_custom.scss` -- and is left alone.
+ */
+const KEBAB_CASE = /^_?[a-z0-9]+(?:-[a-z0-9]+)*$/;
+
+/**
+ * The shouted names convention reserves for metadata that sits beside the
+ * work rather than being part of it: `README.md`, `AUTHORS`, `LICENSE/`, and
+ * the licence identifiers inside it, such as `CC-BY-SA-4.0.txt`.
+ */
+const METADATA_CASE = /^[A-Z][A-Z0-9_-]*$/;
+
+/**
+ * Names a tool dictates and we do not get to choose. Anything under a
+ * dot-directory is exempt wholesale, on the same reasoning.
+ */
+const EXEMPT = new Set([
+  // Eleventy takes the global data key from the filename, so kebab-casing
+  // this one would quietly unhook the front matter validator.
+  '_data/eleventyDataSchema.mjs',
+]);
+
+const files = await glob(['**/*', '!_site/', '!node_modules/']);
+
+// A directory is only ever seen here as part of some file's path, and the
+// same directory is part of many, so each is judged once.
+const checked = new Set<string>();
+const offenders: string[] = [];
+
+for (const file of files) {
+  const segments = file.split('/');
+
+  // `.github/ISSUE_TEMPLATE/`, `.vscode/settings.json`: whatever reads these
+  // decides what they are called.
+  if (segments.some((segment) => segment.startsWith('.'))) continue;
+
+  for (const [index, segment] of segments.entries()) {
+    const path = segments.slice(0, index + 1).join('/');
+
+    if (checked.has(path) || EXEMPT.has(path)) continue;
+
+    checked.add(path);
+
+    // Extensions are not part of the name, and there may be several of them
+    // (`vnu-jar.d.ts`, `main.min.css`). Directories have none to shed.
+    const isFile = index === segments.length - 1;
+    const name = isFile ? (segment.split('.')[0] ?? segment) : segment;
+
+    if (!(KEBAB_CASE.test(name) || METADATA_CASE.test(name))) {
+      offenders.push(path);
+    }
+  }
+}
+
+if (offenders.length > 0) {
+  console.error(
+    `Not in kebab-case:\n${offenders.map((path) => `  ${path}`).join('\n')}\n\n` +
+      'Renaming a file changes what links to it, and under `collections/` it ' +
+      'changes a published URL, so this task reports rather than fixes.'
+  );
+  process.exitCode = 1;
+}
diff --git a/package-scripts.yml b/package-scripts.yml
index b7003c256..73d79d1ff 100644
--- a/package-scripts.yml
+++ b/package-scripts.yml
@@ -12,6 +12,7 @@ scripts:
     scss: node build/tasks/verify/verify-scss.mts
     dockerfile: node build/tasks/verify/verify-dockerfile.mts
     fileModes: node build/tasks/verify/verify-file-modes.mts
+    filenames: node build/tasks/verify/verify-filenames.mts
     htmlValidForVNU: node build/tasks/verify/verify-html-valid-for-vnu.mts
     js: node build/tasks/verify/verify-js.mts
     json: node build/tasks/verify/verify-json.mts