revalidatePath vs revalidateTag: Location or Label

A strong answer covers

• Calls revalidatePath on the specific post's route to refresh that one page
• Calls revalidateTag on whatever tag the footer widget's fetch uses, since it's a completely different route
• Explains that revalidatePath only knows about the route file location it's given, with no awareness of other pages sharing the same data
• Recognizes these aren't redundant — they invalidate along different axes (location vs. label) and are often used together for one mutation

Likely follow-ups

• What would change if the post page uses a dynamic segment like [slug] and you wanted to revalidate every post at once rather than just this one?
• Suppose the footer widget's fetch was never tagged with next: { tags: [...] } in the first place — what happens when you call revalidateTag for it?
• If a next.config.js rewrite maps a friendlier URL to this post's actual route file, which path do you pass to revalidatePath?