diff --git a/stage0/corpus.zig b/stage0/corpus.zig
index 89022fe5e5..a3e49a378b 100644
--- a/stage0/corpus.zig
+++ b/stage0/corpus.zig
@@ -3,7 +3,7 @@
 /// `num_passing` controls how many files are tested and pre-generated.
 /// Both build.zig and stages_test.zig import this file.
 /// To enable more tests: just increment `num_passing`.
-pub const num_passing: usize = 61;
+pub const num_passing: usize = 67;
 
 pub const files = [_][]const u8{
     "stage0/sema_tests/empty.zig",
diff --git a/stage0/sema.c b/stage0/sema.c
index ffa1378266..0389cf611b 100644
--- a/stage0/sema.c
+++ b/stage0/sema.c
@@ -10551,8 +10551,13 @@ static void analyzeMemoizedStateC(Sema* sema) {
 
         // Track CC (builtin 2) range: these entries are in Zig's local
         // shard and should NOT be skipped during main analysis dedup.
+        // Start 1 entry earlier to include the CC ptr_nav that
+        // AddressSpace resolution creates as a side effect (the ptr_nav
+        // for the CallingConvention declaration is created when the
+        // std.builtin namespace is scanned during AddressSpace resolution).
         if (i == 2)
-            sema->zcu->preamble_cc_start = sema->ip->items_len;
+            sema->zcu->preamble_cc_start
+                = sema->ip->items_len > 0 ? sema->ip->items_len - 1 : 0;
 
         InternPoolIndex val = ensureNavValUpToDate(sema, nav);
         if (val == IP_INDEX_NONE)
@@ -10597,18 +10602,12 @@ static void ensureFullMemoizedStateC(Sema* sema) {
         = sema->zcu->file_namespaces[sema->zcu->builtin_file_idx];
 
     // Shard simulation: clear builtins 0-4 state so they get re-resolved
-    // as fresh entries during main analysis. Ported from upstream: Zig's
-    // sharded IP keeps preamble entries in a separate shard, so main
-    // analysis creates fresh entries for builtins 0-4 types. We simulate
-    // this by enabling skip_dedup on the preamble memoized range and
-    // clearing the cached nav resolutions.
+    // as fresh entries during main analysis. The skip_dedup range is
+    // already set at preamble end (see preamble setup). Here we just
+    // clear the cached nav resolutions so ensureNavValUpToDate re-resolves
+    // builtins 0-4 with fresh IP entries.
     if (sema->zcu->preamble_memoized_end
         > sema->zcu->preamble_memoized_start) {
-        sema->ip->skip_dedup_start = sema->zcu->preamble_memoized_start;
-        sema->ip->skip_dedup_end = sema->zcu->preamble_memoized_end;
-        sema->ip->cc_keep_start = sema->zcu->preamble_cc_start;
-        sema->ip->cc_keep_end = sema->zcu->preamble_cc_end;
-
         // Clear builtins 0-4 values so they're re-resolved.
         for (int i = 0; i < 5 && i < NUM_BUILTIN_DECL_MAIN; i++)
             sema->zcu->builtin_decl_values[i] = IP_INDEX_NONE;
@@ -10653,12 +10652,6 @@ static void ensureFullMemoizedStateC(Sema* sema) {
         sema->zcu->builtin_decl_values[i] = val;
     }
 
-    // Disable shard simulation after Phase 1.
-    sema->ip->skip_dedup_start = 0;
-    sema->ip->skip_dedup_end = 0;
-    sema->ip->cc_keep_start = 0;
-    sema->ip->cc_keep_end = 0;
-
     // Phase 2: Call resolveTypeFullyC on ALL type builtins.
     // Ported from analyzeMemoizedState line 37560:
     //   try uncoerced_val.toType().resolveFully(pt);
@@ -12788,6 +12781,20 @@ SemaFuncAirList semaAnalyze(Sema* sema) {
                 sema->zcu->in_main_analysis = false;
             }
 
+            // Enable shard simulation for the entire main analysis.
+            // Ported from upstream: Zig's sharded IP keeps preamble
+            // memoized state entries in a separate shard. Any main
+            // analysis interning that matches a preamble entry will
+            // create a fresh entry instead of deduplicating.
+            if (sema->zcu->preamble_memoized_end
+                > sema->zcu->preamble_memoized_start) {
+                sema->ip->skip_dedup_start
+                    = sema->zcu->preamble_memoized_start;
+                sema->ip->skip_dedup_end = sema->zcu->preamble_memoized_end;
+                sema->ip->cc_keep_start = sema->zcu->preamble_cc_start;
+                sema->ip->cc_keep_end = sema->zcu->preamble_cc_end;
+            }
+
         } else {
             // No module root — root module is file_idx=0.
             if (sema->zcu->num_files == 0) {