diff --git a/MobileGL/MG_Impl/Pipe/PipeFill.cpp b/MobileGL/MG_Impl/Pipe/PipeFill.cpp
index 6537838b..e298c8f1 100644
--- a/MobileGL/MG_Impl/Pipe/PipeFill.cpp
+++ b/MobileGL/MG_Impl/Pipe/PipeFill.cpp
@@ -338,6 +338,13 @@ namespace MobileGL::MG_Pipe {
         PipeInputs g_snapshot{};    // the second arm
         PipeInputs g_readScratch{}; // where the compare-at-read re-read lands
 
+        // The read hook arms at the first fill (ArmVerify below), so it cannot see a read
+        // made before that. That window is covered by the poison instead: MGP_INPUT_CHECK
+        // precedes MGP_INPUT_VERIFY_READ in every accessor and a stamp of 0 is never fresh,
+        // so such a read is Fatal{UnmigratedPipeInput, "<Field>@<none>"} before the hook
+        // could matter - which holds only while a verify build always carries the poison.
+        static_assert(MOBILEGL_PIPE_POISON, "the compare-at-read hook relies on the poison for reads before the first fill");
+
         struct VerifyState {
             Bool Parsed = false;
             Bool Enabled = false;
@@ -515,7 +522,9 @@ namespace MobileGL::MG_Pipe {
 #endif
 #if MOBILEGL_PIPE_POISON
         MGPipeFilledState& filled = MGPipeFillAccess::Filled(inputs);
-        // Starts at 1, so FilledGen == 0 means "never filled".
+        // Starts at 1: FilledGen == 0 is "never filled", and MGPipeInputFieldIsFresh refuses
+        // it on both branches, so a read before this first bump is
+        // Fatal{UnmigratedPipeInput, "<Field>@<none>"} rather than default storage.
         ++filled.CurrentVerbSerial;
 #endif
         MGPipeFillAccess::SetVerb(inputs, verb);
diff --git a/MobileGL/MG_Pipe/generated/PipeFilled.inc b/MobileGL/MG_Pipe/generated/PipeFilled.inc
index 91e82514..4c485cfd 100644
--- a/MobileGL/MG_Pipe/generated/PipeFilled.inc
+++ b/MobileGL/MG_Pipe/generated/PipeFilled.inc
@@ -310,8 +310,12 @@ struct MGPipeFilledState {
     std::abort();
 }
 
+// FilledGen == 0 is "never filled" on BOTH branches: before the first MGPipeFillForVerb the
+// serial is 0 as well, and a read in that window is the poison's "<Field>@<none>" case
+// (P1 brief D6), never a fresh read of default-constructed storage.
 inline Bool MGPipeInputFieldIsFresh(const MGPipeFilledState& state, MGPipeInputField field) {
     const SizeT index = static_cast<SizeT>(field);
-    return kMGPipeInputFieldSticky[index] ? state.FilledGen[index] != 0
-                                          : state.FilledGen[index] == state.CurrentVerbSerial;
+    const Uint64 gen = state.FilledGen[index];
+    if (gen == 0) return false;
+    return kMGPipeInputFieldSticky[index] || gen == state.CurrentVerbSerial;
 }
diff --git a/scripts/gen_pipe.py b/scripts/gen_pipe.py
index a26d1ad9..7ae0fe56 100644
--- a/scripts/gen_pipe.py
+++ b/scripts/gen_pipe.py
@@ -807,10 +807,14 @@ def gen_filled(accessors, calls, sticky):
     std::abort();
 }
 
+// FilledGen == 0 is "never filled" on BOTH branches: before the first MGPipeFillForVerb the
+// serial is 0 as well, and a read in that window is the poison's "<Field>@<none>" case
+// (P1 brief D6), never a fresh read of default-constructed storage.
 inline Bool MGPipeInputFieldIsFresh(const MGPipeFilledState& state, MGPipeInputField field) {
     const SizeT index = static_cast<SizeT>(field);
-    return kMGPipeInputFieldSticky[index] ? state.FilledGen[index] != 0
-                                          : state.FilledGen[index] == state.CurrentVerbSerial;
+    const Uint64 gen = state.FilledGen[index];
+    if (gen == 0) return false;
+    return kMGPipeInputFieldSticky[index] || gen == state.CurrentVerbSerial;
 }""")
     return "\n".join(out) + "\n"