unity-yaml-editing

Open the script's .cs.meta file to read its current GUID, then find the m_Script entry in the prefab YAML and set its guid to that value while keeping fileID 11500000 and type 3. Reimport the asset in Unity to confirm the component resolves.

Unity YAML is line-mergeable because each object is an independent --- !u!<classID> &<fileID> block. Resolve per block, taking the changed side for single-side edits and doing a true 3-way merge for blocks changed on both sides, then verify every referenced fileID still has a defining block.

Only as a last resort: when compile failures prevent deserialization, when editing .meta files or hidden ProjectSettings fields with no API, or when resolving merge conflicts. For normal object, prefab, or scene work, use the Editor or REST-based tooling instead.

Each component block has a matching entry in the owner GameObject's m_Component list. Removing the --- !u!114 block without deleting its {component: {fileID: N}} entry leaves a dangling reference that breaks the GameObject, so both must be removed together.

Yes, but only by generating a uuid4 value programmatically and updating every reference across all .asset, .prefab, .unity, and .meta files in the same change. Grep the whole project for the old GUID first, and never hand-write GUID values.