Fix wp term migrate skipping posts after post type migration

[Copilot]

When posts are migrated to a new post type before running wp term migrate, the command silently skips reassigning terms because it checks the post type against the source taxonomy's object_type — not the destination's. This causes term relationships to be lost entirely.

Changes

• Core fix: Replace the source taxonomy object type check ($tax->object_type) with a destination taxonomy check ($dest_tax->object_type). Posts whose current type is registered with the destination taxonomy get the term assigned correctly.
• Explicit validation: Fetch and validate $dest_tax upfront with a clear error if the destination taxonomy doesn't exist.
• Warning instead of silent skip: Posts whose current type is not registered with the destination taxonomy now emit WP_CLI::warning() rather than being silently ignored.
• Accurate post count: Success message now reflects only posts that were actually assigned the new term.

Example scenario now works

# Step 1: Migrate post type
for post_id in $(wp post list --post_type="post" --format=ids); do
  wp post update $post_id --post_type="news"
done

# Step 2: Migrate terms — previously silently skipped all posts
for term_id in $(wp term list category --format=ids); do
  wp term migrate $term_id --from=category --to=topic
done

New test scenarios

• Term migrates correctly when posts have been moved to a different post type that supports the destination taxonomy.
• Warning is emitted (and posts skipped) when the post's current type is not registered with the destination taxonomy.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Terms migration assignment fails when 2 differents post types</issue_title>
<issue_description>This is an exemple to enlight a missing behaviour or documentation improvement. I have posts with categories that I want to migrate to news with topics.

1. I do a wp cli post edit to migrate the post type from posts to news: for post_id in $(wp post list --post_type="post" --format=ids); do wp post update $post_id --post_type="news"; done;
2. I do a wp term migrate to migrate the terms from categories to topics: for term_id in $(wp term list category --format=ids); do wp term migrate $term_id --from=category --to=topic; done;

It results in not having anymore the news assigned to the topics 😢 Which is kind of normal since it would also require to change the relathionships.

What do you think about this?
Do you think it's a good idea to patch it or just add a warning in the documentation? or even both?

Anyway, I would be glad to contribute to this! 😃</issue_description>

Comments on the Issue (you are @copilot in this section)

@schlessera Yes, I think this should be a supported use case, probably using an additional flag or two.

Do you have a plan of attack for this already?</comment_new>
<comment_new>@schlessera
The above does not really guarantee that the target taxonomy does even apply to the CPT you've migrated the posts to. That's also something that WP-CLI can't really change, as the CPT is registered via code.

I think we're missing a piece of the logic here, and I'm not entirely sure we can properly solve this reliably.

Should the reassignment logic check the taxonomy<=>CPT relationship and throw an error if incorrect?</comment_new>

• Fixes Terms migration assignment fails when 2 differents post types #296

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[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/Term_Command.php	87.50%	1 Missing ⚠️

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