add title canonicalization html postprocessor

Author: cscheid

src/command/render/pandoc.ts

@@ -173,6 +173,7 @@ import { cacheCodePage, clearCodePageCache } from "../../core/windows.ts";
 import { textHighlightThemePath } from "../../quarto-core/text-highlighting.ts";
 import { resolveAndFormatDate, resolveDate } from "../../core/date.ts";
 import { katexPostProcessor } from "../../format/html/format-html-math.ts";
+// import { canonicalizeTitlePostprocessor } from "../../format/html/format-html-title.ts";
 import {
   readAndInjectDependencies,
   writeDependencies,
@@ -201,6 +202,7 @@ import {
   MarkdownPipelineHandler,
 } from "../../core/markdown-pipeline.ts";
 import { getEnv } from "../../../package/src/util/utils.ts";
+import { canonicalizeTitlePostprocessor } from "../../format/html/format-html-title.ts";
 
 // in case we are running multiple pandoc processes
 // we need to make sure we capture all of the trace files
@@ -431,6 +433,9 @@ export async function runPandoc(
     // record postprocessors
     postprocessors.push(...(extras.postprocessors || []));
 
+    // Fix H1 title inconsistency
+    htmlPostprocessors.push(canonicalizeTitlePostprocessor);
+
     // add a keep-source post processor if we need one
     if (
       options.format?.render[kKeepSource] || formatHasCodeTools(options.format)

src/format/html/format-html-title.ts

@@ -8,11 +8,17 @@ import { existsSync } from "../../deno_ral/fs.ts";
 import { dirname, isAbsolute, join } from "../../deno_ral/path.ts";
 import { kDateFormat, kTocLocation } from "../../config/constants.ts";
 import { Format, Metadata, PandocFlags } from "../../config/types.ts";
-import { Document } from "../../core/deno-dom.ts";
+import { Document, Element } from "../../core/deno-dom.ts";
 import { formatResourcePath } from "../../core/resources.ts";
 import { sassLayer } from "../../core/sass.ts";
 import { TempContext } from "../../core/temp-types.ts";
 import { MarkdownPipeline } from "../../core/markdown-pipeline.ts";
+import {
+  HtmlPostProcessResult,
+  PandocInputTraits,
+  RenderedFormat,
+} from "../../command/render/types.ts";
+import { InternalError } from "../../core/lib/error.ts";
 
 export const kTitleBlockStyle = "title-block-style";
 const kTitleBlockBanner = "title-block-banner";
@@ -177,6 +183,45 @@ export function documentTitlePartial(
   }
 }
 
+export async function canonicalizeTitlePostprocessor(
+  doc: Document,
+  _options: {
+    inputMetadata: Metadata;
+    inputTraits: PandocInputTraits;
+    renderedFormats: RenderedFormat[];
+    quiet?: boolean;
+  },
+): Promise<HtmlPostProcessResult> {
+  // https://github.com/quarto-dev/quarto-cli/issues/10567
+  const titleBlock = doc.querySelector("header.quarto-title-block");
+  if (!titleBlock) {
+    const main = doc.querySelector("main");
+    if (!main) {
+      throw new InternalError("No main element found in document");
+    }
+    const header = doc.createElement("header");
+    header.id = "title-block-header";
+    header.classList.add("quarto-title-block");
+    main.insertBefore(header, main.firstChild);
+    const h1s = Array.from(doc.querySelectorAll("h1"));
+    for (const h1n of h1s) {
+      const h1 = h1n as Element;
+      if (!h1.classList.contains("quarto-secondary-nav-title")) {
+        const div = doc.createElement("div");
+        div.classList.add("quarto-title-banner");
+        h1.classList.add("title");
+        header.appendChild(h1);
+        break;
+      }
+    }
+  }
+
+  return {
+    resources: [],
+    supporting: [],
+  };
+}
+
 export function processDocumentTitle(
   input: string,
   format: Format,