diff --git a/docs/semantic-parity.md b/docs/semantic-parity.md
index 23fd142..e1bef63 100644
--- a/docs/semantic-parity.md
+++ b/docs/semantic-parity.md
@@ -10,7 +10,10 @@ prove today; its status reflects current evidence only.
 > new contract against pin `d4dd2f0127e8934d125b2a26a90fe88239ca98a2`; rows
 > below still describe the f29815c-era audit and are being re-proved through
 > the gate (the differential oracle and archive-client e2e now run upstream's
-> d4dd2f0 client against Stream).
+> d4dd2f0 client against Stream). One deliberate non-port: upstream's
+> PDS-direct fleet bootstrap and its four backfill flags
+> (environment_contract.py `upstream_unported`) — Stream's bootstrap
+> remains relay-getRepo until that design is ported on purpose.
 
 ## Audit basis
 
diff --git a/tests/environment_contract.py b/tests/environment_contract.py
index 0f525c5..c20236e 100644
--- a/tests/environment_contract.py
+++ b/tests/environment_contract.py
@@ -64,10 +64,28 @@ def exact_pinned_map_case() -> None:
     stream_only = {
         "JETSTREAM_REBLOOM_SWEEP": "rebloom-sweep",
     }
+    # Upstream variables Stream knowingly has NOT ported: the PDS-direct
+    # fleet bootstrap (upstream specs/notes/2026-08-03-pds-direct-backfill-
+    # design.md, landed by d4dd2f0). Stream's bootstrap remains relay-getRepo;
+    # declaring these flags without the behavior would mislead operators.
+    # Each entry is asserted ABSENT from Stream's map, so porting the feature
+    # forces this list to shrink rather than rot.
+    upstream_unported = {
+        "JETSTREAM_BACKFILL_GLOBAL_DOWNLOADS",
+        "JETSTREAM_BACKFILL_HOST_WORKERS_MAX",
+        "JETSTREAM_BACKFILL_MAX_ACTIVE_HOSTS",
+        "JETSTREAM_BACKFILL_MAX_HOSTS",
+    }
     assert not (stream_only.keys() & upstream.keys()), (
         f"stream_only entries collide with upstream: {sorted(stream_only.keys() & upstream.keys())}"
     )
-    expected = upstream | stream_only
+    assert upstream_unported <= upstream.keys(), (
+        f"upstream_unported names not declared upstream anymore: {sorted(upstream_unported - upstream.keys())}"
+    )
+    assert not (upstream_unported & stream.keys()), (
+        f"unported variables now present in stream; remove them from upstream_unported: {sorted(upstream_unported & stream.keys())}"
+    )
+    expected = {k: v for k, v in upstream.items() if k not in upstream_unported} | stream_only
     assert stream == expected, (
         f"environment map drift\n"
         f"missing/wrong: {sorted(expected.items() - stream.items())}\n"