The previous handler folded every null target into one error code
("WORK_PRODUCT_NOT_FOUND: Work product not found or its workspace
is unresolved"). When a user couldn't open a file we had no way to
tell whether the row was archived, the provider/external_id was
empty, the workspace had no local_path, or the external_id escaped
the root.
Widen resolveWorkProductTarget's return from (target | null) to
(target | error) where error carries one of five reasons:
not_found row missing for id+company
archived status == "archived" tombstone
no_target provider != filesystem and no url
workspace_unresolved all three workspace_id / task_id / run_id
lookups returned no local_path
path_escape external_id is absolute or steps outside root
Each reason includes the concrete detail (ids checked, paths tried)
so the toast on the renderer side tells the user exactly which slot
is null without having to open the DB.
The IPC handler maps each reason to its own failure code and passes
the detail through, so WorkProductRow's toast now reads e.g.
"workspace_id=null task_id=null run_id=null — none led to a
workspace with a local_path" instead of a generic unresolved.
Typecheck and build:verify clean.
ZacharyZhang-NY
390f76fa76