fix: isolate visual tool failures from agent runs

capabilities.mjs

@@ -470,6 +470,39 @@ export function developerToolsFromPolicy(sessionPolicy) {
   return (sandboxFs ?? developer)?.available_tools ?? [];
 }
 
+/**
+ * Visual inspection is optional for H5 Agent runs. When the active text model
+ * rejects image content, remove read_image for the recovery session without
+ * weakening any workspace or data capability boundary.
+ */
+export function withoutSessionImageRead(sessionPolicy) {
+  if (!sessionPolicy || !Array.isArray(sessionPolicy.extensionOverrides)) {
+    return sessionPolicy;
+  }
+  let changed = false;
+  const extensionOverrides = sessionPolicy.extensionOverrides
+    .map((extension) => {
+      if (String(extension?.name ?? '') !== 'developer') return extension;
+      const tools = Array.isArray(extension.available_tools)
+        ? extension.available_tools
+        : [];
+      const availableTools = tools.filter((tool) => tool !== 'read_image');
+      if (availableTools.length === tools.length) return extension;
+      changed = true;
+      if (availableTools.length === 0) return null;
+      return {
+        ...extension,
+        available_tools: availableTools,
+      };
+    })
+    .filter(Boolean);
+  if (!changed) return sessionPolicy;
+  return {
+    ...sessionPolicy,
+    extensionOverrides,
+  };
+}
+
 function mergeDeveloperTools(capabilities) {
   const tools = [];
   if (capabilities.shell) tools.push('shell');