Build a redirect map for a site migration

[yourdomain.com] is migrating from a flat URL structure (/post-name/) to a
category-based structure (/category/post-name/) as part of a WordPress replatform
scheduled for [August 2026]. There are 1,240 published URLs, and about 60 of them no
longer have a clear equivalent because the categories were merged.

CURRENT URL LIST (export or paste a sample): [paste here]
NEW SITE ARCHITECTURE: [list new top-level categories, e.g. /reviews/, /guides/,
/news/]
PAGES BEING MERGED OR RETIRED: [list any old posts being combined into one new page]

Approach this like the person who will be blamed if rankings crater the week after
launch:
1. Map each old URL to exactly one new URL using 301s, matching on topical
   equivalence, not just similar titles, since two posts can share a title but
   target different intents.
2. For the ~60 pages with no clean 1:1 match, decide case by case whether to redirect
   to the closest topical parent, redirect to a new consolidated page, or let it 404
   because the content is genuinely obsolete and redirecting it would just pass
   authority to an irrelevant page. State your reasoning for each judgment call, not
   just the destination.
3. Flag any redirect chains this map would create (old URL to interim URL to final
   URL) and resolve them to a single hop.
4. List the 20 highest-organic-traffic URLs from the current list and mark them for
   manual QA after launch, since automated redirect testing tools often miss soft
   404s.
5. Output the final map as a table: old URL, new URL, redirect type, reason.