diff --git a/packages/modal-infra/src/images/base.py b/packages/modal-infra/src/images/base.py
index bfa2c7cc..639c6281 100644
--- a/packages/modal-infra/src/images/base.py
+++ b/packages/modal-infra/src/images/base.py
@@ -26,8 +26,8 @@
 CODE_SERVER_VERSION = "4.109.5"
 
 # Cache buster - change this to force Modal image rebuild
-# v42: code-server pin + GPT-5.4 codex allowlist
-CACHE_BUSTER = "v42-code-server-gpt54"
+# v43: copy=True on sandbox dir, version stamp, auth consolidation
+CACHE_BUSTER = "v43"
 
 # Base image with all development tools
 base_image = (
@@ -100,7 +100,7 @@
     # Install OpenCode CLI and plugin for custom tools
     # CACHE_BUSTER is embedded in a no-op echo so Modal invalidates this layer on bump.
     .run_commands(
-        f"echo 'cache: {CACHE_BUSTER}' > /dev/null",
+        f"echo 'cache: {CACHE_BUSTER}' > /tmp/.cache-buster",
         "npm install -g opencode-ai@latest",
         "opencode --version || echo 'OpenCode installed'",
         # Install @opencode-ai/plugin globally for custom tools
@@ -143,10 +143,13 @@
         }
     )
     # Add sandbox code to the image (includes plugin at /app/sandbox/inspect-plugin.js)
+    # copy=True bakes files into the image layer so run_commands can follow
     .add_local_dir(
         str(SANDBOX_DIR),
         remote_path="/app/sandbox",
+        copy=True,
     )
+    .run_commands(f"echo 'sandbox_version={CACHE_BUSTER}' > /app/sandbox/.version")
 )
 
 # Image variant optimized for Node.js/TypeScript projects
diff --git a/packages/modal-infra/src/sandbox/entrypoint.py b/packages/modal-infra/src/sandbox/entrypoint.py
index 30915383..cab18414 100644
--- a/packages/modal-infra/src/sandbox/entrypoint.py
+++ b/packages/modal-infra/src/sandbox/entrypoint.py
@@ -89,10 +89,12 @@ def __init__(self):
             session_id=session_id,
         )
 
+        self.log.info("session_config.loaded", keys=list(self.session_config.keys()))
+
     @property
     def base_branch(self) -> str:
         """The branch to clone/fetch — defaults to 'main'."""
-        return self.session_config.get("branch", "main")
+        return self.session_config.get("branch") or "main"
 
     def _build_repo_url(self, authenticated: bool = True) -> str:
         """Build the HTTPS URL for the repository, optionally with clone credentials."""
@@ -291,25 +293,42 @@ def _install_tools(self, workdir: Path) -> None:
             package_json.write_text('{"name": "opencode-tools", "type": "module"}')
 
     def _setup_openai_oauth(self) -> None:
-        """Write OpenCode auth.json for ChatGPT OAuth if refresh token is configured."""
-        refresh_token = os.environ.get("OPENAI_OAUTH_REFRESH_TOKEN")
-        if not refresh_token:
-            return
+        """Write OpenCode auth.json for configured LLM providers.
 
-        try:
-            auth_dir = Path.home() / ".local" / "share" / "opencode"
-            auth_dir.mkdir(parents=True, exist_ok=True)
+        Builds a unified auth.json from environment variables:
+        - OPENAI_OAUTH_REFRESH_TOKEN → OpenAI OAuth entry
+        - OPENCODE_ZEN_API_KEY → OpenCode Zen (pay-as-you-go) entry
+        - OPENCODE_GO_API_KEY → OpenCode Go (subscription) entry
+        """
+        auth_data: dict[str, dict] = {}
 
-            openai_entry = {
+        refresh_token = os.environ.get("OPENAI_OAUTH_REFRESH_TOKEN")
+        if refresh_token:
+            entry: dict = {
                 "type": "oauth",
                 "refresh": "managed-by-control-plane",
                 "access": "",
                 "expires": 0,
             }
-
             account_id = os.environ.get("OPENAI_OAUTH_ACCOUNT_ID")
             if account_id:
-                openai_entry["accountId"] = account_id
+                entry["accountId"] = account_id
+            auth_data["openai"] = entry
+
+        zen_key = os.environ.get("OPENCODE_ZEN_API_KEY")
+        if zen_key:
+            auth_data["opencode"] = {"type": "api", "key": zen_key}
+
+        go_key = os.environ.get("OPENCODE_GO_API_KEY")
+        if go_key:
+            auth_data["opencode-go"] = {"type": "api", "key": go_key}
+
+        if not auth_data:
+            return
+
+        try:
+            auth_dir = Path.home() / ".local" / "share" / "opencode"
+            auth_dir.mkdir(parents=True, exist_ok=True)
 
             auth_file = auth_dir / "auth.json"
             tmp_file = auth_dir / ".auth.json.tmp"
@@ -318,12 +337,12 @@ def _setup_openai_oauth(self) -> None:
             # atomically rename so the target is never world-readable.
             fd = os.open(str(tmp_file), os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o600)
             try:
-                os.write(fd, json.dumps({"openai": openai_entry}).encode())
+                os.write(fd, json.dumps(auth_data).encode())
             finally:
                 os.close(fd)
             tmp_file.replace(auth_file)
 
-            self.log.info("openai_oauth.setup")
+            self.log.info("openai_oauth.setup", providers=list(auth_data.keys()))
         except Exception as e:
             self.log.warn("openai_oauth.setup_error", exc=e)
 
@@ -647,7 +666,7 @@ async def monitor_processes(self) -> None:
 
     async def _report_fatal_error(self, message: str) -> None:
         """Report a fatal error to the control plane."""
-        self.log.error("supervisor.fatal", message=message)
+        self.log.error("supervisor.fatal", error_message=message)
 
         if not self.control_plane_url:
             return
diff --git a/packages/modal-infra/tests/test_openai_oauth_setup.py b/packages/modal-infra/tests/test_openai_oauth_setup.py
index 6d39c211..60e0fbe9 100644
--- a/packages/modal-infra/tests/test_openai_oauth_setup.py
+++ b/packages/modal-infra/tests/test_openai_oauth_setup.py
@@ -68,17 +68,71 @@ def test_includes_account_id_when_present(self, tmp_path):
         data = json.loads(_auth_file(tmp_path).read_text())
         assert data["openai"]["accountId"] == "acct_xyz"
 
-    def test_skips_when_no_refresh_token(self, tmp_path, monkeypatch):
+    def test_skips_when_no_providers_configured(self, tmp_path, monkeypatch):
         sup = _make_supervisor()
 
-        # Explicitly remove the key so it is absent regardless of test ordering
+        # Explicitly remove all provider keys so none are present
         monkeypatch.delenv("OPENAI_OAUTH_REFRESH_TOKEN", raising=False)
+        monkeypatch.delenv("OPENCODE_ZEN_API_KEY", raising=False)
+        monkeypatch.delenv("OPENCODE_GO_API_KEY", raising=False)
 
         with patch("pathlib.Path.home", return_value=tmp_path):
             sup._setup_openai_oauth()
 
         assert not _auth_file(tmp_path).exists()
 
+    def test_writes_zen_only(self, tmp_path, monkeypatch):
+        sup = _make_supervisor()
+
+        monkeypatch.delenv("OPENAI_OAUTH_REFRESH_TOKEN", raising=False)
+        monkeypatch.delenv("OPENCODE_GO_API_KEY", raising=False)
+
+        with (
+            patch.dict("os.environ", {"OPENCODE_ZEN_API_KEY": "zen_key_123"}, clear=False),
+            patch("pathlib.Path.home", return_value=tmp_path),
+        ):
+            sup._setup_openai_oauth()
+
+        data = json.loads(_auth_file(tmp_path).read_text())
+        assert data == {"opencode": {"type": "api", "key": "zen_key_123"}}
+
+    def test_writes_go_only(self, tmp_path, monkeypatch):
+        sup = _make_supervisor()
+
+        monkeypatch.delenv("OPENAI_OAUTH_REFRESH_TOKEN", raising=False)
+        monkeypatch.delenv("OPENCODE_ZEN_API_KEY", raising=False)
+
+        with (
+            patch.dict("os.environ", {"OPENCODE_GO_API_KEY": "go_key_456"}, clear=False),
+            patch("pathlib.Path.home", return_value=tmp_path),
+        ):
+            sup._setup_openai_oauth()
+
+        data = json.loads(_auth_file(tmp_path).read_text())
+        assert data == {"opencode-go": {"type": "api", "key": "go_key_456"}}
+
+    def test_writes_all_providers_combined(self, tmp_path, monkeypatch):
+        sup = _make_supervisor()
+
+        with (
+            patch.dict(
+                "os.environ",
+                {
+                    "OPENAI_OAUTH_REFRESH_TOKEN": "rt_abc",
+                    "OPENCODE_ZEN_API_KEY": "zen_key",
+                    "OPENCODE_GO_API_KEY": "go_key",
+                },
+                clear=False,
+            ),
+            patch("pathlib.Path.home", return_value=tmp_path),
+        ):
+            sup._setup_openai_oauth()
+
+        data = json.loads(_auth_file(tmp_path).read_text())
+        assert "openai" in data
+        assert data["opencode"] == {"type": "api", "key": "zen_key"}
+        assert data["opencode-go"] == {"type": "api", "key": "go_key"}
+
     def test_sets_secure_permissions(self, tmp_path):
         sup = _make_supervisor()
 
diff --git a/packages/shared/src/models.ts b/packages/shared/src/models.ts
index 97868543..983ed5c2 100644
--- a/packages/shared/src/models.ts
+++ b/packages/shared/src/models.ts
@@ -23,6 +23,9 @@ export const VALID_MODELS = [
   "opencode/kimi-k2.5",
   "opencode/minimax-m2.5",
   "opencode/glm-5",
+  "opencode-go/kimi-k2.5",
+  "opencode-go/minimax-m2.5",
+  "opencode-go/glm-5",
 ] as const;
 
 export type ValidModel = (typeof VALID_MODELS)[number];
@@ -130,11 +133,19 @@ export const MODEL_OPTIONS: ModelCategory[] = [
       { id: "opencode/glm-5", name: "GLM 5", description: "Z.ai 744B MoE" },
     ],
   },
+  {
+    category: "OpenCode Go",
+    models: [
+      { id: "opencode-go/kimi-k2.5", name: "Kimi K2.5", description: "Moonshot AI (Go)" },
+      { id: "opencode-go/minimax-m2.5", name: "MiniMax M2.5", description: "MiniMax (Go)" },
+      { id: "opencode-go/glm-5", name: "GLM 5", description: "Z.ai 744B MoE (Go)" },
+    ],
+  },
 ];
 
 /**
  * Models enabled by default when no preferences are stored.
- * Excludes zen models which must be opted into via settings.
+ * Excludes Zen and Go models which must be opted into via settings.
  */
 export const DEFAULT_ENABLED_MODELS: ValidModel[] = [
   "anthropic/claude-haiku-4-5",