### The Engine Schema (Draft-07)

This schema uses a `oneOf` discriminator block. This forces the LLM's output
validator to strictly adhere to the specific property requirements of each
node type, rejecting any hybrid or hallucinated nodes.

```json
{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "AgentState",
  "description": "The complete execution state and AST for the AI Agent
microkernel.",
  "type": "object",
  "properties": {
    "status": {
      "type": "string",
      "enum": ["RUNNING", "HALTED", "COMPLETED", "WAITING"]
    },
    "intent_log": { "type": "array", "items": { "type": "object" }, "default":
[] },
    "debug_buffer": { "type": "array", "items": { "type": "object" },
"default": [] },
    "cpu_state": {
      "type": "object",
      "properties": {
        "instruction_pointer": {
          "type": "string",
          "description": "Must match a key in program_ast"
        },
        "local_vars": {
          "type": "object",
          "description": "Initial key-value pairs for the execution memory."
        },
        "global_memory": { "type": "object" }
      },
      "required": ["instruction_pointer", "local_vars"]
    },
    "program_ast": {
      "type": "object",
      "description": "The flat-map Abstract Syntax Tree. Keys are node IDs.",
      "patternProperties": {
        "^[a-zA-Z0-9_]+$": {
          "$ref": "#/definitions/ast_node"
        }
      },
      "additionalProperties": false
    }
  },
  "required": ["status", "cpu_state", "program_ast"],
  
  "definitions": {
    "ast_node": {
      "type": "object",
      "required": ["type"],
      "oneOf": [
        { "$ref": "#/definitions/node_execute_tool" },
        { "$ref": "#/definitions/node_eval_condition" },
        { "$ref": "#/definitions/node_set_variable" },
        { "$ref": "#/definitions/node_end" }
      ]
    },
    
    "node_execute_tool": {
      "properties": {
        "type": { "const": "EXECUTE_TOOL" },
        "tool_name": { "type": "string" },
        "params": {
          "type": "object",
          "description": "Payload parameters. Can include [[...]] dynamic
interpolation syntax."
        },
        "returns_to": { "type": "string", "description": "Local variable to
store the result." },
        "next": { "type": "string", "description": "The ID of the next node to
execute." }
      },
      "required": ["type", "tool_name", "params", "returns_to", "next"],
      "additionalProperties": false
    },
    
    "node_eval_condition": {
      "properties": {
        "type": { "const": "EVAL_CONDITION" },
        "variable": { "type": ["string", "number", "boolean"] },
        "target_value": { "type": ["string", "number", "boolean"] },
        "next_true": { "type": "string" },
        "next_false": { "type": "string" }
      },
      "required": ["type", "variable", "target_value", "next_true",
"next_false"],
      "additionalProperties": false
    },
    
    "node_set_variable": {
      "properties": {
        "type": { "const": "SET_VARIABLE" },
        "assign_to": { "type": "string" },
        "value": { "type": ["string", "number", "boolean", "object", "array"]
},
        "next": { "type": "string" }
      },
      "required": ["type", "assign_to", "value", "next"],
      "additionalProperties": false
    },
    
    "node_end": {
      "properties": {
        "type": { "const": "END" }
      },
      "required": ["type"],
      "additionalProperties": false
    }
  }
}

```