diff --git a/compiler/ast2nif.nim b/compiler/ast2nif.nim
index 861cca6526..bb33ad5dbb 100644
--- a/compiler/ast2nif.nim
+++ b/compiler/ast2nif.nim
@@ -284,7 +284,14 @@ proc writeTypeDef(w: var Writer; dest: var TokenBuf; typ: PType) =
 proc writeType(w: var Writer; dest: var TokenBuf; typ: PType) =
   if typ == nil:
     dest.addDotToken()
-  elif typ.itemId.module == w.currentModule and typ.state == Complete:
+  elif typ.uniqueId.module == w.currentModule and typ.state == Complete:
+    # Ownership for serialization is decided by `uniqueId`, not `itemId`: the NIF
+    # name (`typeToNifSym`) and the loader (`createTypeStub`) both key off
+    # `uniqueId`, so the module that *created* the type (uniqueId.module) must be
+    # the one that emits its definition. `itemId.module` can be reassigned and
+    # diverge from `uniqueId.module`; gating on it filed the def in the wrong
+    # module (or nowhere), leaving dangling references (e.g. `symbol has no
+    # offset` for a `pointer` type whose itemId.module drifted away).
     typ.state = Sealed
     writeTypeDef(w, dest, typ)
   else:
diff --git a/compiler/modulegraphs.nim b/compiler/modulegraphs.nim
index a50d40b5e6..fe01fa6b2d 100644
--- a/compiler/modulegraphs.nim
+++ b/compiler/modulegraphs.nim
@@ -290,9 +290,22 @@ proc setAttachedOp*(g: ModuleGraph; module: int; t: PType; op: TTypeAttachedOp;
     # Use key-based deduplication for opsLog because different type objects
     # (e.g. canon vs orig) can have different itemIds but same structural key
     if key notin g.loadedOps[op]:
-      # Hooks should be written to the module where the type is defined,
-      # not the module that triggered the registration
-      let ownerModule = if t.sym != nil: t.sym.itemId.module.int else: module
+      # For a *nominal*, non-instantiated type the hook belongs to the module
+      # that defines the type (so it is emitted once there). But for a generic
+      # instance or a structural type (ref/ptr/seq/... over an instance) there is
+      # no honest definition site: the generic's home module is upstream of the
+      # type arguments and structurally blind to the instance, so it can never
+      # realize the hook. Such hooks can only be produced by the *instantiating*
+      # module — which is exactly the one running now (`module`). Stamping them
+      # with the type's def module produced a `LogEntry` that no module ever
+      # writes (the def module never instantiates it; the instantiating module's
+      # writer skips it because `op.module != thisModule`), so the hook was lost
+      # and codegen failed with "'=destroy' operator not found". Duplicate
+      # registrations across instantiating modules are reconciled deterministically
+      # at load time (see the HookEntry replay in `replayStateChanges`).
+      let nominal = t.sym != nil and t.kind in {tyObject, tyEnum, tyDistinct} and
+                    tfFromGeneric notin t.flags
+      let ownerModule = if nominal: t.sym.itemId.module.int else: module
       g.opsLog.add LogEntry(kind: HookEntry, op: op, module: ownerModule, key: key, sym: value)
       g.loadedOps[op][key] = value
   g.attachedOps[op][t.itemId] = value
@@ -691,7 +704,16 @@ when not defined(nimKochBootstrap):
     for x in result.logOps:
       case x.kind
       of HookEntry:
-        g.loadedOps[x.op][x.key] = x.sym
+        # The same structural hook may be serialized by several instantiating
+        # modules (a generic/structural instance has no single def site, so each
+        # using module owns its copy). Pick one deterministic program-wide winner
+        # by the smaller owning-module name, so every lookup resolves to the same
+        # sym regardless of module load order.
+        let existing = g.loadedOps[x.op].getOrDefault(x.key)
+        if existing == nil or
+           cachedModuleSuffix(g.config, x.sym.itemId.module.FileIndex) <
+           cachedModuleSuffix(g.config, existing.itemId.module.FileIndex):
+          g.loadedOps[x.op][x.key] = x.sym
       of ConverterEntry:
         g.ifaces[fileIdx.int].converters.add x.sym
       of MethodEntry:
diff --git a/compiler/semtypinst.nim b/compiler/semtypinst.nim
index ce026eac89..621ef14a1a 100644
--- a/compiler/semtypinst.nim
+++ b/compiler/semtypinst.nim
@@ -446,6 +446,12 @@ proc handleGenericInvocation(cl: var TReplTypeVars, t: PType): PType =
         header[i] = x
         propagateToOwner(header, x)
     else:
+      # Honor the same copy-before-mutate invariant as the branch above: never
+      # mutate the original invocation type `t` in place. Besides being cleaner,
+      # under IC `t` may be a loaded dep type (Sealed/immutable), and mutating it
+      # would assert. The flags propagated here end up on `header`, which is what
+      # is used downstream (`result.flags = header.flags`).
+      if header == t: header = instCopyType(cl, t)
       propagateToOwner(header, x)
 
   if header != t:
diff --git a/compiler/typekeys.nim b/compiler/typekeys.nim
index d1c77ec3fe..bf9108c784 100644
--- a/compiler/typekeys.nim
+++ b/compiler/typekeys.nim
@@ -147,7 +147,14 @@ proc typeKey(c: var Context; t: PType; flags: set[ConsiderFlag]; conf: ConfigRef
     else:
       symKey(c, t.symImpl, conf)
   of tyGenericInst:
-    if sfInfixCall in t.sonsImpl[0].symImpl.flagsImpl:
+    # The generic head (son[0]) may be a lazily-loaded stub under IC; ensure it
+    # is materialised before peeking at its symbol. A nil sym means this is not
+    # an imported C++ generic, so fall through to the normal `skipModifierB`.
+    var base = t.sonsImpl[0]
+    if base.state == Partial:
+      assert c.tl != nil
+      c.tl(base)
+    if base.symImpl != nil and sfInfixCall in base.symImpl.flagsImpl:
       # This is an imported C++ generic type.
       # We cannot trust the `lastSon` to hold a properly populated and unique
       # value for each instantiation, so we hash the generic parameters here: