feat(md-deck): support structured data-config with template layers

Allow md-deck layers to render markdown templates via {{var}}
substitution instead of only CSV props. Add config.ts to normalize
a JSON data-config attribute (size, grid, shape, layers) emitted by
the yaml code-block tag, taking precedence over legacy string props.

src/markdown/code-block-yaml-tag.test.ts

@@ -0,0 +1,60 @@
+import markedCodeBlockYamlTag from "./code-block-yaml-tag";
+
+const ext = markedCodeBlockYamlTag().extensions?.[0] as unknown as {
+  tokenizer: (src: string) => any;
+  renderer: (token: any) => string;
+};
+
+function render(src: string): string {
+  const token = ext.tokenizer(src);
+  return ext.renderer(token);
+}
+
+describe("code-block-yaml-tag", () => {
+  test("renders body and scalar props as attributes", () => {
+    const html = render(
+      "```yaml/tag\ntag: md-deck\nbody: ./cards.csv\nsize: 54x86\n```",
+    );
+    expect(html).toContain("<md-deck size=\"54x86\">./cards.csv</md-deck>");
+  });
+
+  test("serializes data-config to a JSON attribute", () => {
+    const html = render(
+      [
+        "```yaml/tag",
+        "tag: md-deck",
+        "body: ./cards.csv",
+        "data-config:",
+        "  size: 63x88",
+        "  layers:",
+        "    - prop: title",
+        "      x1: 1",
+        "      y1: 1",
+        "      x2: 5",
+        "      y2: 1",
+        "      font: 12",
+        "```",
+      ].join("\n"),
+    );
+    expect(html).toContain("<md-deck data-config=");
+    expect(html).toContain("./cards.csv</md-deck>");
+    // data-config must be valid JSON with escaped quotes for the attribute
+    const m = html.match(/data-config="([^"]*)"/);
+    expect(m).not.toBeNull();
+    const decoded = (m![1] || "").replace(/&quot;/g, '"');
+    const config = JSON.parse(decoded);
+    expect(config.size).toBe("63x88");
+    expect(config.layers).toHaveLength(1);
+    expect(config.layers[0]).toMatchObject({
+      prop: "title",
+      x1: 1,
+      y1: 1,
+      font: 12,
+    });
+  });
+
+  test("handles missing tag and body", () => {
+    const html = render("```yaml/tag\nclass: foo\n```");
+    expect(html).toContain("<tag-unknown class=\"foo\"></tag-unknown>");
+  });
+});

src/markdown/code-block-yaml-tag.ts

@@ -33,6 +33,18 @@ export default function markedCodeBlockYamlTag(): MarkedExtension {
               delete (rest as Record<string, unknown>).body;
             }
 
+            // A structured `data-config` object is serialized to JSON and
+            // passed as a single attribute (e.g. md-deck layers/templates).
+            let configAttr = "";
+            if ("data-config" in rest) {
+              const rawConfig = rest["data-config"];
+              delete (rest as Record<string, unknown>)["data-config"];
+              if (rawConfig !== undefined && rawConfig !== null) {
+                const json = JSON.stringify(rawConfig).replace(/"/g, "&quot;");
+                configAttr = ` data-config="${json}"`;
+              }
+            }
+
             const propsStr = Object.entries(rest)
               .map(([key, value]) => {
                 const strValue = String(value);
@@ -48,13 +60,15 @@ export default function markedCodeBlockYamlTag(): MarkedExtension {
               raw: match[0],
               tagName,
               props: propsStr,
+              config: configAttr,
               content,
             };
           }
         },
         renderer(token: any) {
           const propsAttr = token.props ? ` ${token.props}` : "";
-          return `<${token.tagName}${propsAttr}>${token.content || ""}</${token.tagName}>\n`;
+          const configAttr = token.config || "";
+          return `<${token.tagName}${propsAttr}${configAttr}>${token.content || ""}</${token.tagName}>\n`;
         },
       },
     ],