feat(Giscus): persist discussions via commentId

- require frontmatter commentId when giscus uses mapping "specific" so each page keeps its discussion
- clear prior giscus embeds on SPA navigation before reinjecting and skip when term is missing
- keep layout.ts wrapping Comments with a commentId guard

quartz/components/Comments.tsx

@@ -35,6 +35,15 @@ export default ((opts: Options) => {
       return <></>
     }
 
+    const mapping = opts.options.mapping ?? "url"
+    const commentId = fileData.frontmatter?.commentId as string | undefined
+
+    if (mapping === "specific" && !commentId) {
+      const identifier = fileData.filePath ?? fileData.slug ?? "unknown"
+      console.warn(`[Quartz] Missing commentId for page ${identifier}, skipping giscus mounting.`)
+      return <></>
+    }
+
     return (
       <div
         class={classNames(displayClass, "giscus")}
@@ -42,7 +51,8 @@ export default ((opts: Options) => {
         data-repo-id={opts.options.repoId}
         data-category={opts.options.category}
         data-category-id={opts.options.categoryId}
-        data-mapping={opts.options.mapping ?? "url"}
+        data-mapping={mapping}
+        data-term={mapping === "specific" ? commentId : undefined}
         data-strict={boolToStringBool(opts.options.strict ?? true)}
         data-reactions-enabled={boolToStringBool(opts.options.reactionsEnabled ?? true)}
         data-input-position={opts.options.inputPosition ?? "bottom"}

quartz/components/scripts/comments.inline.ts

@@ -56,6 +56,7 @@ type GiscusElement = Omit<HTMLElement, "dataset"> & {
     reactionsEnabled: string
     inputPosition: "top" | "bottom"
     lang: string
+    term?: string
   }
 }
 
@@ -65,6 +66,15 @@ document.addEventListener("nav", () => {
     return
   }
 
+  giscusContainer
+    .querySelectorAll("iframe.giscus-frame, script[src*='giscus.app']")
+    .forEach((node) => node.remove())
+
+  if (giscusContainer.dataset.mapping === "specific" && !giscusContainer.dataset.term) {
+    console.warn("[Giscus] mapping='specific' but data-term is missing; skipping widget injection.")
+    return
+  }
+
   const giscusScript = document.createElement("script")
   giscusScript.src = "https://giscus.app/client.js"
   giscusScript.async = true
@@ -76,6 +86,9 @@ document.addEventListener("nav", () => {
   giscusScript.setAttribute("data-category", giscusContainer.dataset.category)
   giscusScript.setAttribute("data-category-id", giscusContainer.dataset.categoryId)
   giscusScript.setAttribute("data-mapping", giscusContainer.dataset.mapping)
+  if (giscusContainer.dataset.term) {
+    giscusScript.setAttribute("data-term", giscusContainer.dataset.term)
+  }
   giscusScript.setAttribute("data-strict", giscusContainer.dataset.strict)
   giscusScript.setAttribute("data-reactions-enabled", giscusContainer.dataset.reactionsEnabled)
   giscusScript.setAttribute("data-input-position", giscusContainer.dataset.inputPosition)