diff --git a/open-sse/config/providerRegistry.ts b/open-sse/config/providerRegistry.ts
index 08c8eef6dd..9ca49f5dd2 100644
--- a/open-sse/config/providerRegistry.ts
+++ b/open-sse/config/providerRegistry.ts
@@ -641,6 +641,25 @@ export const REGISTRY: Record<string, RegistryEntry> = {
     ],
   },
 
+  blackbox: {
+    id: "blackbox",
+    alias: "bb",
+    format: "openai",
+    executor: "default",
+    baseUrl: "https://api.blackbox.ai/v1/chat/completions",
+    modelsUrl: "https://api.blackbox.ai/v1/models",
+    authType: "apikey",
+    authHeader: "bearer",
+    models: [
+      { id: "gpt-4o", name: "GPT-4o" },
+      { id: "gemini-2.5-flash", name: "Gemini 2.5 Flash" },
+      { id: "claude-sonnet-4", name: "Claude Sonnet 4" },
+      { id: "deepseek-v3", name: "DeepSeek V3" },
+      { id: "blackboxai", name: "Blackbox AI" },
+      { id: "blackboxai-pro", name: "Blackbox AI Pro" },
+    ],
+  },
+
   xai: {
     id: "xai",
     alias: "xai",
diff --git a/open-sse/executors/antigravity.ts b/open-sse/executors/antigravity.ts
index 3f38ba184e..ad5fdaae67 100644
--- a/open-sse/executors/antigravity.ts
+++ b/open-sse/executors/antigravity.ts
@@ -36,7 +36,18 @@ export class AntigravityExecutor extends BaseExecutor {
   }
 
   transformRequest(model, body, stream, credentials) {
-    const projectId = credentials?.projectId || this.generateProjectId();
+    const bodyProjectId = body?.project;
+    const credentialsProjectId = credentials?.projectId;
+    const hasExplicitProject = !!(bodyProjectId || credentialsProjectId);
+    const projectId = bodyProjectId || credentialsProjectId || this.generateProjectId();
+
+    if (!hasExplicitProject) {
+      console.warn(
+        `[Antigravity] ⚠️ No projectId provided via body or credentials — using generated fallback "${projectId}". ` +
+          `This may cause 404 errors if the account has no active GCP project. ` +
+          `Ensure the OAuth token includes a valid project or the request includes a project field.`
+      );
+    }
 
     // Fix contents for Claude models via Antigravity
     const normalizedContents =
diff --git a/open-sse/translator/request/openai-to-gemini.ts b/open-sse/translator/request/openai-to-gemini.ts
index 6f3ca2ab65..6f5a0365c7 100644
--- a/open-sse/translator/request/openai-to-gemini.ts
+++ b/open-sse/translator/request/openai-to-gemini.ts
@@ -271,8 +271,16 @@ export function openaiToGeminiCLIRequest(model, body, stream) {
 
 // Wrap Gemini CLI format in Cloud Code wrapper
 function wrapInCloudCodeEnvelope(model, geminiCLI, credentials = null, isAntigravity = false) {
+  const hasRealProject = !!credentials?.projectId;
   const projectId = credentials?.projectId || generateProjectId();
 
+  if (!hasRealProject) {
+    console.warn(
+      `[${isAntigravity ? "Antigravity" : "GeminiCLI"}] ⚠️ No projectId in credentials — using generated fallback "${projectId}". ` +
+        `This may cause 404 errors. Ensure the OAuth token includes a valid GCP project.`
+    );
+  }
+
   const cleanModel = model.includes("/") ? model.split("/").pop()! : model;
 
   const envelope: Record<string, any> = {
@@ -315,10 +323,17 @@ function wrapInCloudCodeEnvelope(model, geminiCLI, credentials = null, isAntigra
   return envelope;
 }
 
-// Wrap Claude format in Cloud Code envelope for Antigravity
 function wrapInCloudCodeEnvelopeForClaude(model, claudeRequest, credentials = null) {
+  const hasRealProject = !!credentials?.projectId;
   const projectId = credentials?.projectId || generateProjectId();
 
+  if (!hasRealProject) {
+    console.warn(
+      `[Antigravity/Claude] ⚠️ No projectId in credentials — using generated fallback "${projectId}". ` +
+        `This may cause 404 errors. Ensure the OAuth token includes a valid GCP project.`
+    );
+  }
+
   const cleanModel = model.includes("/") ? model.split("/").pop()! : model;
 
   const envelope: Record<string, any> = {
diff --git a/public/providers/blackbox.png b/public/providers/blackbox.png
new file mode 100644
index 0000000000..5c836c9669
Binary files /dev/null and b/public/providers/blackbox.png differ