## Problem/Motivation Opening the AI agent form (`AiAgentForm`) with a tool that has an empty map input crashes with a PHP `TypeError`. Since #3582972, the Tool module's serializer intentionally emits empty schema objects (e.g. a map input with no declared properties) as `\ArrayObject` instead of `[]`, so JSON encoding produces `{}` rather than `[]` — strict providers such as Anthropic reject an array where a JSON Schema object is expected. `SchemaToolsPropertyConverter::convert()` in tool_ai_connector passed that normalized schema straight into the AI module's `ToolsPropertyInput`, whose constructor routes properties through `setProperties(array ...)` — a strict `array` type — so any `\ArrayObject` in the schema caused the `TypeError`. The converter's own recursion also skipped these values, because its `is_array()` guard on `properties` is FALSE for an `\ArrayObject`. ## Steps to reproduce 1. Enable tool, tool_ai_connector, ai, ai_agents. 2. Have any tool exposing a `MapInputDefinition` with no declared properties (e.g. `comprehensive_types_tool`'s `attributes` input from tool_test). 3. Open the AI agent form and select the tool → `TypeError`. ## Proposed resolution `SchemaToolsPropertyConverter::convert()` recursively casts every `\ArrayObject` in the incoming schema back to a plain array (new `arrayObjectsToArrays()` helper) before preparing the schema and constructing `ToolsPropertyInput`. This happens at every nesting depth, so nested empty maps (an object property whose child is an empty map) are covered too. The `{}`-vs-`[]` distinction is only needed at JSON-encoding time; `ToolsPropertyInput` does its own rendering, so nothing is lost by handing it plain arrays. ## Test coverage `testConvertsArrayObjectSchemaValues` in `SchemaToolsPropertyConverterTest` covers both the top-level case (`'properties' => new \ArrayObject()`) and the nested case. Full converter kernel suite passes (5 tests, 32 assertions). ## AI usage (if applicable) - [x] **AI Assisted Issue:** This issue was generated with AI assistance, but was reviewed and refined by the creator. - [x] **AI Assisted Code:** This code was mainly generated by a human, with AI autocompleting or parts AI generated, but under full human supervision. - [ ] **AI Generated Code:** This code was mainly generated by an AI with human guidance, and reviewed, tested, and refined by a human. - [ ] **Vibe Coded:** This code was generated by an AI and has only been functionally tested.