v3.12.1: bump version in GUI + lib

src/codex-launcher-gui

@@ -27,6 +27,11 @@ model_catalog_json = ""
 """
 
 CHANGELOG = [
+    ("3.12.1", "2026-05-27", [
+        "Fix Antigravity adapter (PR #15): simplified model resolution",
+        "Removed broken schema sanitization, restored headers",
+        "Re-enabled gRPC fallback by default",
+    ]),
     ("3.12.0", "2026-05-27", [
         "gRPC auto-fallback for Antigravity (PR #13)",
         "Dynamic version fetch with probe validation",

src/codex_launcher_lib.py

@@ -83,6 +83,12 @@ model_catalog_json = ""
 """
 
 CHANGELOG = [
+    ("3.12.1", "2026-05-27", [
+        "Fix Antigravity adapter (PR #15): simplify model resolution",
+        "Removed broken schema sanitization, restored correct headers",
+        "Expanded model alias map for all Antigravity variants",
+        "Re-enabled gRPC fallback by default",
+    ]),
     ("3.12.0", "2026-05-27", [
         "gRPC auto-fallback for Antigravity provider (PR #13)",
         "New antigravity_grpc module with protobuf client",

src/translate-proxy.py

@@ -6571,6 +6571,9 @@ class Handler(http.server.BaseHTTPRequestHandler):
             headers["X-Client-Name"] = "antigravity"
             headers["X-Client-Version"] = _ensure_antigravity_client_version()
             headers["x-goog-api-client"] = "gl-node/18.18.2 fire/0.8.6 grpc/1.10.x"
+            # Add X-Machine-Session-Id header as seen in badrisnarayanan/antigravity-claude-proxy
+            if "request" in wrapped and "sessionId" in wrapped["request"]:
+                headers["X-Machine-Session-Id"] = wrapped["request"]["sessionId"]
         else:
             headers["User-Agent"] = "google-api-nodejs-client/9.15.1"
             headers["X-Goog-Api-Client"] = "gl-node/22.17.0"