[v6] disallow number in getStaticPaths params

src/content/docs/en/guides/upgrade-to/v6.mdx

@@ -840,6 +840,39 @@ If you want to keep the old ID generation for backward compatibility reasons, yo
 
 <ReadMore>Learn more about [Heading IDs](/en/guides/markdown-content/#heading-ids).</ReadMore>
 
+### Changed: numbers are no longer allowed in `params` returned by `getStaticPaths()`.
+
+<SourcePR number="14586" title="fix!: disallow number in getStaticPaths params"/>
+
+Previously, `getStaticPaths()` could return `params` with number values. However, at runtime `Astro.params` values are always strings or undefined because they come from URL segments. This change removes that mismatch so the types reflect runtime behavior.
+
+#### What should I do?
+
+In the returned `params` object from `getStaticPaths()`, convert any numbers to strings (for example, `String(id)`).
+
+```diff
+---
+// src/pages/post/[id]/[label].astro
+export function getStaticPaths() {
+    return [
+        {
+            params: {
+-               id: 1,
++               id: "1",
+                label: "foo",
+            }
+        },
+        {
+            params: {
+-               id: 2,
++               id: "2",
+                label: "bar",
+            }
+        },
+    ]
+}
+---
+
 ## Community Resources
 
 Know a good resource for Astro v5.0? [Edit this page](https://github.com/withastro/docs/edit/main/src/content/docs/en/guides/upgrade-to/v6.mdx) and add a link below!