diff --git a/astro.config.mjs b/astro.config.mjs
index a6438b3..95d50d3 100644
--- a/astro.config.mjs
+++ b/astro.config.mjs
@@ -10,41 +10,101 @@ import rehypeAutolinkHeadings from "rehype-autolink-headings";
 import rehypeDetailsSections from "./scripts/rehype-details-sections.mjs";
 import rehypeParagraphIds from "./src/plugins/rehype-paragraph-ids.js";
 
-const must = (name, fn) => {
-  if (typeof fn !== "function") {
-    throw new Error(`[astro.config] rehype plugin "${name}" is not a function (export default vs named?)`);
-  }
-  return fn;
-};
+/**
+ * Cast minimal pour satisfaire @ts-check sans dépendre de types internes Astro/Unified.
+ * @param {unknown} x
+ * @returns {any}
+ */
+const asAny = (x) => /** @type {any} */ (x);
+
+/**
+ * @param {any} node
+ * @param {string} cls
+ * @returns {boolean}
+ */
+function hasClass(node, cls) {
+  const cn = node?.properties?.className;
+  if (Array.isArray(cn)) return cn.includes(cls);
+  if (typeof cn === "string") return cn.split(/\s+/).includes(cls);
+  return false;
+}
+
+/**
+ * Rehype plugin: retire les ids dupliqués en gardant en priorité:
+ * 1) span.details-anchor
+ * 2) h1..h6
+ * 3) sinon: premier rencontré
+ * @returns {(tree: any) => void}
+ */
+function rehypeDedupeIds() {
+  /** @param {any} tree */
+  return (tree) => {
+    /** @type {Map<string, Array<{node:any, pref:number, idx:number}>>} */
+    const occ = new Map();
+    let idx = 0;
+
+    /** @param {any} node */
+    const walk = (node) => {
+      if (!node || typeof node !== "object") return;
+
+      if (node.type === "element") {
+        const id = node.properties?.id;
+        if (typeof id === "string" && id) {
+          let pref = 2;
+          if (node.tagName === "span" && hasClass(node, "details-anchor")) pref = 0;
+          else if (/^h[1-6]$/.test(String(node.tagName || ""))) pref = 1;
+
+          const arr = occ.get(id) || [];
+          arr.push({ node, pref, idx: idx++ });
+          occ.set(id, arr);
+        }
+
+        const children = node.children;
+        if (Array.isArray(children)) for (const c of children) walk(c);
+      } else if (Array.isArray(node.children)) {
+        for (const c of node.children) walk(c);
+      }
+    };
+
+    walk(tree);
+
+    for (const [id, items] of occ.entries()) {
+      if (items.length <= 1) continue;
+
+      items.sort((a, b) => (a.pref - b.pref) || (a.idx - b.idx));
+      const keep = items[0];
+
+      for (let i = 1; i < items.length; i++) {
+        const n = items[i].node;
+        if (n?.properties?.id === id) delete n.properties.id;
+      }
+
+      // safety: on s'assure qu'un seul garde bien l'id
+      if (keep?.node?.properties) keep.node.properties.id = id;
+    }
+  };
+}
 
 export default defineConfig({
   output: "static",
   trailingSlash: "always",
-
   site: process.env.PUBLIC_SITE ?? "http://localhost:4321",
 
   integrations: [
-    mdx(),
+    // Important: MDX hérite du pipeline markdown (ids p-… + autres plugins)
+    mdx({ extendMarkdownConfig: true }),
     sitemap({
       filter: (page) => !page.includes("/api/") && !page.endsWith("/robots.txt"),
     }),
   ],
 
-  // ✅ Plugins appliqués AU MDX
-  mdx: {
-    // ✅ MDX hérite déjà de markdown.rehypePlugins
-    // donc ici on ne met QUE le spécifique MDX
-    rehypePlugins: [
-      must("rehype-details-sections", rehypeDetailsSections),
-    ],
-  },
-
-  // ✅ Plugins appliqués au Markdown non-MDX
   markdown: {
     rehypePlugins: [
-      must("rehype-slug", rehypeSlug),
-      [must("rehype-autolink-headings", rehypeAutolinkHeadings), { behavior: "append" }],
-      must("rehype-paragraph-ids", rehypeParagraphIds),
+      asAny(rehypeSlug),
+      [asAny(rehypeAutolinkHeadings), { behavior: "append" }],
+      asAny(rehypeDetailsSections),
+      asAny(rehypeParagraphIds),
+      asAny(rehypeDedupeIds),
     ],
   },
 });
diff --git a/package.json b/package.json
index 42824ee..4b01f46 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
     "build": "astro build",
     "build:clean": "npm run clean && npm run build",
 
-    "postbuild": "node scripts/inject-anchor-aliases.mjs && npx pagefind --site dist",
+    "postbuild": "node scripts/inject-anchor-aliases.mjs && node scripts/dedupe-ids-dist.mjs && npx pagefind --site dist",
 
     "import": "node scripts/import-docx.mjs",
     "apply:ticket": "node scripts/apply-ticket.mjs",
diff --git a/scripts/dedupe-ids-dist.mjs b/scripts/dedupe-ids-dist.mjs
new file mode 100644
index 0000000..1aed449
--- /dev/null
+++ b/scripts/dedupe-ids-dist.mjs
@@ -0,0 +1,134 @@
+import { promises as fs } from "node:fs";
+import path from "node:path";
+
+const DIST_DIR = path.resolve("dist");
+
+/** @param {string} dir */
+async function walkHtml(dir) {
+  /** @type {string[]} */
+  const out = [];
+  const entries = await fs.readdir(dir, { withFileTypes: true });
+  for (const e of entries) {
+    const p = path.join(dir, e.name);
+    if (e.isDirectory()) out.push(...(await walkHtml(p)));
+    else if (e.isFile() && p.endsWith(".html")) out.push(p);
+  }
+  return out;
+}
+
+/** @param {string} attrs */
+function getClass(attrs) {
+  const m = attrs.match(/\bclass="([^"]*)"/i);
+  return m ? m[1] : "";
+}
+
+/** @param {{tag:string,id:string,cls:string}} occ */
+function score(occ) {
+  // plus petit = mieux (on garde)
+  if (occ.tag === "span" && /\bdetails-anchor\b/.test(occ.cls)) return 0;
+  if (/^h[1-6]$/.test(occ.tag)) return 1;
+  if (occ.tag === "p" && occ.id.startsWith("p-")) return 2;
+  return 10; // tout le reste (toc, nav, etc.)
+}
+
+async function main() {
+  let changedFiles = 0;
+  let removed = 0;
+
+  const files = await walkHtml(DIST_DIR);
+
+  for (const file of files) {
+    let html = await fs.readFile(file, "utf8");
+
+    // capture: <tag ... id="X" ...>
+    const re = /<([A-Za-z][\w:-]*)([^>]*?)\s+id="([^"]+)"([^>]*?)>/g;
+
+    /** @type {Array<{id:string,tag:string,pre:string,post:string,start:number,end:number,cls:string,idx:number}>} */
+    const occs = [];
+    let m;
+    let idx = 0;
+
+    while ((m = re.exec(html)) !== null) {
+      const tag = m[1].toLowerCase();
+      const pre = m[2] || "";
+      const id = m[3] || "";
+      const post = m[4] || "";
+      const fullAttrs = `${pre}${post}`;
+      const cls = getClass(fullAttrs);
+
+      occs.push({
+        id,
+        tag,
+        pre,
+        post,
+        start: m.index,
+        end: m.index + m[0].length,
+        cls,
+        idx: idx++,
+      });
+    }
+
+    if (occs.length === 0) continue;
+
+    /** @type {Map<string, Array<typeof occs[number]>>} */
+    const byId = new Map();
+    for (const o of occs) {
+      if (!o.id) continue;
+      const arr = byId.get(o.id) || [];
+      arr.push(o);
+      byId.set(o.id, arr);
+    }
+
+    /** @type {Array<{start:number,end:number,repl:string}>} */
+    const edits = [];
+
+    for (const [id, arr] of byId.entries()) {
+      if (arr.length <= 1) continue;
+
+      // choisir le “meilleur” porteur d’id : details-anchor > h2/h3... > p-... > reste
+      const sorted = [...arr].sort((a, b) => {
+        const sa = score(a);
+        const sb = score(b);
+        if (sa !== sb) return sa - sb;
+        return a.idx - b.idx; // stable: premier
+      });
+
+      const keep = sorted[0];
+
+      for (const o of sorted.slice(1)) {
+        // remplacer l’ouverture de tag en supprimant l’attribut id
+        // <tag{pre} id="X"{post}>  ==>  <tag{pre}{post}>
+        const repl = `<${o.tag}${o.pre}${o.post}>`;
+        edits.push({ start: o.start, end: o.end, repl });
+        removed++;
+      }
+
+      // sécurité: on “force” l'id sur le keep (au cas où il aurait été modifié plus haut)
+      // (on ne touche pas au keep ici, juste on ne le retire pas)
+      void keep;
+      void id;
+    }
+
+    if (edits.length === 0) continue;
+
+    // appliquer de la fin vers le début
+    edits.sort((a, b) => b.start - a.start);
+    for (const e of edits) {
+      html = html.slice(0, e.start) + e.repl + html.slice(e.end);
+    }
+
+    await fs.writeFile(file, html, "utf8");
+    changedFiles++;
+  }
+
+  if (changedFiles > 0) {
+    console.log(`✅ dedupe-ids-dist: files_changed=${changedFiles} ids_removed=${removed}`);
+  } else {
+    console.log("ℹ️  dedupe-ids-dist: no duplicates found");
+  }
+}
+
+main().catch((err) => {
+  console.error("❌ dedupe-ids-dist failed:", err);
+  process.exit(1);
+});