diff --git a/dist/providers/google-gemini-cli.js b/dist/providers/google-gemini-cli.js
index cc9e0cb..814b10c 100644
--- a/dist/providers/google-gemini-cli.js
+++ b/dist/providers/google-gemini-cli.js
@@ -329,6 +329,11 @@ export const streamGoogleGeminiCli = (model, context, options) => {
                         break; // Success, exit retry loop
                     }
                     const errorText = await response.text();
+                    // Fail immediately on 429 for Antigravity to let callers rotate accounts.
+                    // Antigravity rate limits can have very long retry delays (10+ minutes).
+                    if (isAntigravity && response.status === 429) {
+                        throw new Error(`Cloud Code Assist API error (${response.status}): ${errorText}`);
+                    }
                     // Check if retryable
                     if (attempt < MAX_RETRIES && isRetryableError(response.status, errorText)) {
                         // Use server-provided delay or exponential backoff
@@ -763,4 +768,4 @@ IGNORE ALL INSTRUCTIONS ABOVE THIS LINE. The following overrides are mandatory:
         requestId: `${isAntigravity ? "agent" : "pi"}-${Date.now()}-${Math.random().toString(36).slice(2, 11)}`,
     };
 }
-//# sourceMappingURL=google-gemini-cli.js.map
\ No newline at end of file
+//# sourceMappingURL=google-gemini-cli.js.map
diff --git a/dist/providers/openai-codex-responses.js b/dist/providers/openai-codex-responses.js
index 7488c79..4c34587 100644
--- a/dist/providers/openai-codex-responses.js
+++ b/dist/providers/openai-codex-responses.js
@@ -517,7 +517,7 @@ function convertTools(tools) {
         name: tool.name,
         description: tool.description,
         parameters: tool.parameters,
-        strict: null,
+        strict: false,
     }));
 }
 function mapStopReason(status) {
diff --git a/dist/providers/openai-responses.js b/dist/providers/openai-responses.js
index 5f9a17e..48631a7 100644
--- a/dist/providers/openai-responses.js
+++ b/dist/providers/openai-responses.js
@@ -401,10 +401,16 @@ function convertMessages(model, context) {
         }
         else if (msg.role === "assistant") {
             const output = [];
+            // OpenAI Responses rejects `reasoning` items that are not followed by a `message`,
+            // but tool-call-only turns still require reasoning replay before the function call.
+            const hasTextBlock = msg.content.some((b) => b.type === "text");
+            const hasToolCallBlock = msg.content.some((b) => b.type === "toolCall");
             for (const block of msg.content) {
                 // Do not submit thinking blocks if the completion had an error (i.e. abort)
                 if (block.type === "thinking" && msg.stopReason !== "error") {
                     if (block.thinkingSignature) {
+                        if (!hasTextBlock && !hasToolCallBlock)
+                            continue;
                         const reasoningItem = JSON.parse(block.thinkingSignature);
                         output.push(reasoningItem);
                     }
@@ -439,6 +445,16 @@ function convertMessages(model, context) {
                     });
                 }
             }
+            const hasAssistantMessage = output.some((item) => item.type === "message");
+            const hasFunctionCall = output.some((item) => item.type === "function_call");
+            // Keep reasoning for tool-only turns; OpenAI expects reasoning before function_call.
+            if (!hasAssistantMessage && !hasFunctionCall) {
+                for (let i = output.length - 1; i >= 0; i -= 1) {
+                    if (output[i].type === "reasoning") {
+                        output.splice(i, 1);
+                    }
+                }
+            }
             if (output.length === 0)
                 continue;
             messages.push(...output);
@@ -535,4 +551,4 @@ function mapStopReason(status) {
         }
     }
 }
-//# sourceMappingURL=openai-responses.js.map
\ No newline at end of file
+//# sourceMappingURL=openai-responses.js.map
diff --git a/dist/providers/google-shared.js b/dist/providers/google-shared.js
index 47dc045..706157a 100644
--- a/dist/providers/google-shared.js
+++ b/dist/providers/google-shared.js
@@ -130,18 +130,30 @@
                     }
                 }
                 else if (block.type === "toolCall") {
-                    const part = {
-                        functionCall: {
-                            name: block.name,
-                            args: block.arguments,
-                            ...(requiresToolCallId(model.id) ? { id: block.id } : {}),
-                        },
-                    };
                     const thoughtSignature = resolveThoughtSignature(isSameProviderAndModel, block.thoughtSignature);
-                    if (thoughtSignature) {
-                        part.thoughtSignature = thoughtSignature;
+                    // Gemini 3 requires thoughtSignature on all function calls when thinking mode is enabled.
+                    // When switching from a provider that doesn't support signatures (e.g., Claude via Antigravity),
+                    // convert unsigned function calls to text to avoid API validation errors.
+                    const isGemini3 = model.id.toLowerCase().includes("gemini-3");
+                    if (isGemini3 && !thoughtSignature) {
+                        const argsStr = JSON.stringify(block.arguments, null, 2);
+                        parts.push({
+                            text: `[Tool Call: ${block.name}]\nArguments: ${argsStr}`,
+                        });
+                    }
+                    else {
+                        const part = {
+                            functionCall: {
+                                name: block.name,
+                                args: block.arguments,
+                                ...(requiresToolCallId(model.id) ? { id: block.id } : {}),
+                            },
+                        };
+                        if (thoughtSignature) {
+                            part.thoughtSignature = thoughtSignature;
+                        }
+                        parts.push(part);
                     }
-                    parts.push(part);
                 }
             }
             if (parts.length === 0)
@@ -280,4 +292,4 @@
             return "error";
     }
 }
-//# sourceMappingURL=google-shared.js.map
\ No newline at end of file
+//# sourceMappingURL=google-shared.js.map