diff --git a/compiler/ast2nif.nim b/compiler/ast2nif.nim
index 0504d18aca..b1032e66d6 100644
--- a/compiler/ast2nif.nim
+++ b/compiler/ast2nif.nim
@@ -496,8 +496,19 @@ proc writeTypeDef(w: var Writer; dest: var IcBuilder; typ: PType) =
     # name in isolation (cg seeks the `.t.nif`/`.s.nif` index entry), so its
     # fields must be DEFS here, not entry-deduped SymUses whose def lives
     # elsewhere in the `(lowered)` entry and is never read by the seek.
+    #
+    # `emittedFieldSyms` only guards against a field being def'd twice WITHIN one
+    # reclist, so scope it per-reclist: a generic object and its instances SHARE one
+    # field PSym (same itemId) yet each instance carries a DISTINCT field type (e.g.
+    # `MDigest[256].data: array[32,byte]` vs `MDigest[384].data: array[48,byte]`), so
+    # each reclist needs its OWN typed def. A Writer-global set deduped every instance
+    # after the first to a typeless `SymUse` stub (nil typ/owner on load → crash in
+    # destructor lifting). Field NIF names are local (no module suffix, not in the
+    # global `c.syms`), so def'ing the same field in two reclists never collides.
     inc w.inTypeReclist
+    let savedFieldSyms = move w.emittedFieldSyms
     writeNode(w, dest, typ.nImpl)
+    w.emittedFieldSyms = savedFieldSyms
     dec w.inTypeReclist
     writeSym(w, dest, typ.ownerFieldImpl)
     writeSym(w, dest, typ.symImpl)
diff --git a/compiler/options.nim b/compiler/options.nim
index 14521d8a59..fc239beb63 100644
--- a/compiler/options.nim
+++ b/compiler/options.nim
@@ -29,7 +29,7 @@ const
 
   nimEnableCovariance* = defined(nimEnableCovariance)
 
-  icFormatVersion* = "25"
+  icFormatVersion* = "26"
     ## Version of the IC cache format (the sem-NIF module layout written by
     ## ast2nif.nim plus the iface/impl/edges side files). Bump it whenever
     ## that layout changes: `commandIc` wipes a nimcache whose `ic.version`
diff --git a/compiler/vmgen.nim b/compiler/vmgen.nim
index 999b0756de..79bbba7d44 100644
--- a/compiler/vmgen.nim
+++ b/compiler/vmgen.nim
@@ -1921,7 +1921,11 @@ proc genCheckedObjAccessAux(c: PCtx; n: PNode; dest: var TDest; flags: TGenFlags
   let strType = getSysType(c.graph, n.info, tyString)
   var msgReg: TDest = c.getTemp(strType)
   let fieldName = $accessExpr[1]
-  let msg = genFieldDefect(c.config, fieldName, disc.sym)
+  # Re-navigate the discriminant in the object type: under `nim ic` `disc.sym` is a
+  # field-use stub with a nil `owner`, which `genFieldDefect` dereferences. Look up the
+  # canonical discriminant field by name. Byte-neutral for non-IC (returns the same sym).
+  let dfield = lookupFieldAgain(accessExpr[0].typ, disc.sym)
+  let msg = genFieldDefect(c.config, fieldName, dfield)
   let strLit = newStrNode(msg, accessExpr[1].info)
   strLit.typ = strType
   c.genLit(strLit, msgReg)
diff --git a/tests/ic/minitordera.nim b/tests/ic/minitordera.nim
new file mode 100644
index 0000000000..a35ac0eed7
--- /dev/null
+++ b/tests/ic/minitordera.nim
@@ -0,0 +1,29 @@
+# Helper for tinitorder (not a test itself; no `discard`).
+#
+# Imports minitorderb and, in its OWN init, reads the state minitorderb set up.
+# With the wrong (importer-first) init order `gBState` is still 0 here. It also
+# allocates a seq in its init so that under `--mm:refc` the GC (set up by the
+# system module's init) must already be live — i.e. the system module's init has
+# to be ordered first.
+
+import minitorderb
+
+var
+  gASawB = -1
+  gAItems: seq[int]
+
+proc getASawB*(): int = gASawB
+proc getACount*(): int = gAItems.len
+
+proc recordA() =
+  gASawB = getBState()
+  gAItems = @[1, 2, 3]
+  # Allocate (and drop) enough garbage to force a GC cycle DURING module init.
+  # Under refc that runs a conservative stack scan, which needs the main
+  # thread's stack bottom already set — i.e. `initStackBottomWith` must run
+  # before the module inits, not after them.
+  for i in 0 ..< 100_000:
+    let s = @[i, i + 1, i + 2]
+    doAssert s.len == 3
+
+recordA()
diff --git a/tests/ic/minitorderb.nim b/tests/ic/minitorderb.nim
new file mode 100644
index 0000000000..8c406e8e94
--- /dev/null
+++ b/tests/ic/minitorderb.nim
@@ -0,0 +1,15 @@
+# Helper for tinitorder (not a test itself; no `discard`).
+#
+# An imported module whose INIT sets module-level state at runtime. Under the
+# per-module backend its init must run BEFORE any importer's init (the imported
+# module is a dependency → post-order). With the buggy importer-first order this
+# module's `setupB` runs too late and importers observe `gBState == 0`.
+
+var gBState: int
+
+proc getBState*(): int = gBState
+
+proc setupB() =
+  gBState = 42
+
+setupB()
diff --git a/tests/ic/mmethanimal.nim b/tests/ic/mmethanimal.nim
new file mode 100644
index 0000000000..76e0bcaf68
--- /dev/null
+++ b/tests/ic/mmethanimal.nim
@@ -0,0 +1,15 @@
+# Helper for tmethitanium: the OWNER module of a `{.base.}` method. Its concrete
+# base body is emitted here; the whole-program dispatcher is synthesized into the
+# main module. Under `--debugger:native` the backend uses the Itanium mangling
+# scheme, which encodes the signature instead of the `disamb`, so the base method
+# and its same-signature dispatcher want the identical clean C name. The
+# clean-vs-unique tie-break used to depend on a per-MODULE set (`mangledPrcs`),
+# which the per-module IC backend cannot share — the base mangled clean at this
+# owner but `speak_u<n>` (an unstable `itemId.item`) at every demander, so it was
+# defined once and referenced under names nobody defined. See
+# ccgutils.makeUnique (disamb, not itemId) + ccgtypes.fillBackendName.
+
+type Animal* = ref object of RootObj
+
+method speak*(a: Animal): string {.base.} =
+  "generic-animal-sound"
diff --git a/tests/ic/mmethdog.nim b/tests/ic/mmethdog.nim
new file mode 100644
index 0000000000..22d0de7130
--- /dev/null
+++ b/tests/ic/mmethdog.nim
@@ -0,0 +1,14 @@
+# Helper for tmethitanium: an override in a DIFFERENT module than the base, plus
+# a `procCall` super-reference to the base from this non-owner module. That
+# cross-module reference to the base impl is what diverged from the base's
+# definition name under the per-module Itanium mangling.
+
+import mmethanimal
+
+type Dog* = ref object of Animal
+
+method speak*(a: Dog): string =
+  "woof"
+
+proc speakBoth*(a: Dog): string =
+  procCall(speak(Animal(a))) & "/" & speak(a)
diff --git a/tests/ic/tinitorder.nim b/tests/ic/tinitorder.nim
new file mode 100644
index 0000000000..93d0d94f4c
--- /dev/null
+++ b/tests/ic/tinitorder.nim
@@ -0,0 +1,23 @@
+discard """
+output: '''42 3'''
+"""
+
+# Regression test for per-module-backend module-init ORDERING.
+#
+# NimMain must call each module's init in DEPENDENCY (post-order) order: an
+# imported module's init has to run before its importer's. The whole-program
+# backend gets this for free (it iterates `modulesClosed`, built in module-finish
+# order); the per-module backend reconstructs it in `nifbackend`. The earlier
+# code iterated `bl.mods` by POSITION, which runs importers before their
+# dependencies (an importer gets a lower file position than the modules it
+# imports) — and the system module (which runs `initGC` in its init) was not
+# ordered first at all.
+#
+# Module chain: tinitorder -> minitordera -> minitorderb. `minitorderb`'s init
+# sets a global to 42; `minitordera`'s init reads it (and allocates a seq). With
+# the buggy order `minitordera` runs first and reads 0 (or, under refc, crashes
+# allocating before the GC is up). Correct order prints `42 3`.
+
+import minitordera
+
+echo getASawB(), " ", getACount()
diff --git a/tests/ic/tmethitanium.nim b/tests/ic/tmethitanium.nim
new file mode 100644
index 0000000000..f226af37c1
--- /dev/null
+++ b/tests/ic/tmethitanium.nim
@@ -0,0 +1,33 @@
+discard """
+  output: '''woof
+generic-animal-sound
+generic-animal-sound/woof'''
+"""
+
+# NOTE: the `--debugger:native` that triggers the Itanium mangling lives in the
+# sibling `tmethitanium_temp.nim.cfg` (the IC test harness compiles the generated
+# `_temp.nim` and does not thread a `matrix`/`$options` switch into the cg
+# children; a project cfg is read by the driver, which forwards it).
+
+# Regression test: under `nim ic --debugger:native` the per-module backend uses
+# the Itanium C name mangling, which encodes the signature and drops the
+# `disamb`. A `{.base.}` method (owner module mmethanimal) and its whole-program
+# dispatcher (synthesized into this main module) then share a signature, so the
+# clean-name uniqueness probe (`m.g.mangledPrcs`) — which only sees the current
+# module — gave the base a clean name at its owner but an unstable
+# `itemId.item`-based `speak_u<n>` at each demander. Result: the base was defined
+# once (clean) but referenced under names defined nowhere ("undefined reference
+# to speak_u1") while the dispatcher collided with the clean base ("multiple
+# definition of speak"). This was the bulk of nimbus-eth2's libp2p method link
+# failures under `nim ic`. Fixed by making the Itanium scheme use the stable
+# `disamb` (ccgutils.makeUnique) and always uniquify routine names under the
+# per-module backend (ccgtypes.fillBackendName), plus forwarding
+# `--debugger:native` to the cg children (deps.computeForwardedArgs).
+
+import mmethanimal, mmethdog
+
+let a: Animal = Dog()
+echo speak(a)            # dispatches -> override
+let b: Animal = Animal()
+echo speak(b)            # dispatches -> base body
+echo speakBoth(Dog())    # procCall to base from non-owner module
diff --git a/tests/ic/tstaticgenfield.nim b/tests/ic/tstaticgenfield.nim
new file mode 100644
index 0000000000..690245529e
--- /dev/null
+++ b/tests/ic/tstaticgenfield.nim
@@ -0,0 +1,38 @@
+discard """
+  output: '''9'''
+"""
+
+# Regression test for object-field serialization of static-generic instances
+# under `nim ic`.
+#
+# A generic object's instances SHARE one field PSym (same itemId) while each
+# instance carries a DISTINCT field type, e.g. `Digest[32].data: array[32,byte]`
+# vs `Digest[48].data: array[48,byte]` (this is exactly nimcrypto's `MDigest`,
+# which crashed compiling nimbus's `altair.nim`). The `.s.bif` writer DEFs each
+# field once inside its owning type's reclist and references it as a bare SymUse
+# elsewhere, deduping by a per-Writer `emittedFieldSyms` set. That set wrongly
+# spanned DIFFERENT type reclists: after the first instance's `data` def, every
+# other instance's reclist got a typeless SymUse stub instead of its own typed
+# def. On load that field had a nil `typ`/`owner`, and `=destroy` lifting
+# (`liftdestructors.fillBodyObj`) dereferenced it -> SIGSEGV. The fix scopes the
+# dedup per-reclist so each instance reclist is a self-contained typed def.
+#
+# The `seq` field forces `=destroy` to be lifted for `Outer`, which walks the
+# reclists of both `Digest` instances (the crash path).
+
+type
+  Digest[n: static int] = object
+    data: array[n, byte]
+  Outer = object
+    a: Digest[32]
+    b: Digest[48]
+    s: seq[int]
+
+proc use(o: Outer): int =
+  result = o.a.data[0].int + o.b.data[0].int + o.s.len
+
+var o: Outer
+o.a.data[0] = 4
+o.b.data[0] = 2
+o.s = @[1, 2, 3]
+echo use(o)