In-fragment SQL mutations for a free-standing dynamic/1,2 call — the condition a user builds ahead of time and splices later:

d = dynamic([p], p.views > 100)
Repo.all(where(query, ^d))

The condition body is the same SQL fragment a hosted where/having contains, so the same catalog walks it (Mutare.Ecto.Fragment, scalar and aggregate swaps folded in — sum↔avg for a dynamic used in a having). At the where(q, ^d) splice site, a top-level ^d is hosted like any other condition, but the catalog stops at the pin. Its interior contains only a bare variable, which core does not mutate (Mutare.Ecto.Island). The splice therefore produces no mutations; this module mutates the dynamic where it is built.

Delivery differs from the hosted path. dynamic is registered :raw (Mutare.Ecto.Surface.macro_registrations/0), so core never descends into its DSL arguments — but core still offers the whole call to mutate/2 (which is why it is :raw, not the call-level :skip: a skipped call is never passed to a mutator), and a free-standing dynamic sits in an ordinary expression position (its value is a runtime %Ecto.Query.DynamicExpr{}, not a spliced query clause). So each mutant is the whole call rebuilt with exactly one point of the condition swapped, delivered by Mutare's ordinary in-place selector case — the same Bucket-1 delivery as the whole-from rewrites in Mutare.Ecto.Query. No host / ^-weaving is needed, each selector branch invokes the dynamic macro independently, and exactly one DynamicExpr builds per run. Each mutant is still reported at the mutated expression — the walk anchors it (Mutare.Ecto.Walk) — so a line-scoped # mutare:ignore reaches one comparison of a multi-line dynamic.

The written binding list is re-emitted byte-for-byte (Mutare.Ecto.BindingReorder handles positional reordering). A ^ pin's interior — nested (p.x > ^(min + 1)) or the whole body (dynamic([p], ^(if params.sort, do: a, else: b))) — is never mutated by this catalog: it is passed to core through the same interface the host uses (Mutare.Ecto.Island), only delivered as this module's whole-call rewrite instead of a weave.