fix(agents): harden Cloud Code Assist compatibility

- Expand schema scrubber to strip additional constraint keywords rejected
  by Cloud Code Assist (examples, minLength, maxLength, minimum, maximum,
  multipleOf, pattern, format, minItems, maxItems, uniqueItems,
  minProperties, maxProperties)
- Extend tool call ID sanitization to cover toolUse and toolCall block
  types (previously only functionCall was sanitized)
- Update pi-tools test to include 'examples' in unsupported keywords

Fixes 400 errors when using google-antigravity/claude-opus-4-5-thinking:
- tools.N.custom.input_schema: JSON schema is invalid
- messages.N.content.N.tool_use.id: String should match pattern

src/agents/pi-embedded-helpers.ts

@@ -146,18 +146,20 @@ export async function sanitizeSessionMessagesImages(
         // Also sanitize tool call IDs in assistant messages (function call blocks)
         const sanitizedContent = await Promise.all(
           filteredContent.map(async (block) => {
-            if (
-              block &&
-              typeof block === "object" &&
-              (block as { type?: unknown }).type === "functionCall" &&
-              (block as { id?: unknown }).id
-            ) {
-              const functionBlock = block as { type: string; id: string };
+            if (!block || typeof block !== "object") return block;
+
+            const type = (block as { type?: unknown }).type;
+            const id = (block as { id?: unknown }).id;
+            if (typeof id !== "string" || !id) return block;
+
+            // Cloud Code Assist tool blocks require ids matching ^[a-zA-Z0-9_-]+$.
+            if (type === "functionCall" || type === "toolUse" || type === "toolCall") {
               return {
-                ...functionBlock,
-                id: sanitizeToolCallId(functionBlock.id),
+                ...((block as unknown) as Record<string, unknown>),
+                id: sanitizeToolCallId(id),
               };
             }
+
             return block;
           }),
         );

src/agents/pi-tools.test.ts

@@ -384,6 +384,7 @@ describe("createClawdbotCodingTools", () => {
       "$ref",
       "$defs",
       "definitions",
+      "examples",
     ]);
 
     const findUnsupportedKeywords = (

src/agents/schema/clean-for-gemini.ts

@@ -10,6 +10,23 @@ const UNSUPPORTED_SCHEMA_KEYWORDS = new Set([
   "$ref",
   "$defs",
   "definitions",
+  // Non-standard (OpenAPI) keyword; Claude validators reject it.
+  "examples",
+
+  // Cloud Code Assist appears to validate tool schemas more strictly/quirkily than
+  // draft 2020-12 in practice; these constraints frequently trigger 400s.
+  "minLength",
+  "maxLength",
+  "minimum",
+  "maximum",
+  "multipleOf",
+  "pattern",
+  "format",
+  "minItems",
+  "maxItems",
+  "uniqueItems",
+  "minProperties",
+  "maxProperties",
 ]);
 
 // Check if an anyOf/oneOf array contains only literal values that can be flattened.
@@ -134,14 +151,14 @@ function cleanSchemaForGeminiWithDefs(
       const result: Record<string, unknown> = {
         ...(cleaned as Record<string, unknown>),
       };
-      for (const key of ["description", "title", "default", "examples"]) {
+      for (const key of ["description", "title", "default"]) {
         if (key in obj && obj[key] !== undefined) result[key] = obj[key];
       }
       return result;
     }
 
     const result: Record<string, unknown> = {};
-    for (const key of ["description", "title", "default", "examples"]) {
+    for (const key of ["description", "title", "default"]) {
       if (key in obj && obj[key] !== undefined) result[key] = obj[key];
     }
     return result;
@@ -157,7 +174,7 @@ function cleanSchemaForGeminiWithDefs(
         type: flattened.type,
         enum: flattened.enum,
       };
-      for (const key of ["description", "title", "default", "examples"]) {
+      for (const key of ["description", "title", "default"]) {
         if (key in obj && obj[key] !== undefined) result[key] = obj[key];
       }
       return result;
@@ -171,7 +188,7 @@ function cleanSchemaForGeminiWithDefs(
         type: flattened.type,
         enum: flattened.enum,
       };
-      for (const key of ["description", "title", "default", "examples"]) {
+      for (const key of ["description", "title", "default"]) {
         if (key in obj && obj[key] !== undefined) result[key] = obj[key];
       }
       return result;