Steps

The steps array contains the conversation as a sequence of LLM API calls. Each step follows the TAO (Thought-Action-Observation) pattern from ATIF.

Step Structure

{
  "step_index": 2,
  "role": "agent",
  "content": "I'll investigate the failing test...",
  "reasoning_content": "The user wants me to...",
  "model": "anthropic/claude-sonnet-4-20250514",
  "system_prompt_hash": "sp_a1b2c3",
  "agent_role": "main",
  "parent_step": null,
  "call_type": "main",
  "tools_available": ["bash", "read", "edit", "glob", "grep", "write", "agent"],
  "tool_calls": [],
  "observations": [],
  "snippets": [],
  "token_usage": {},
  "timestamp": "ISO8601"
}

Fields

Field	Type	Required	Description
`step_index`	integer	yes	Sequential step number
`role`	string	yes	`"system"`, `"user"`, or `"agent"`
`content`	string	no	Message content; may be empty for pure tool or warmup steps
`reasoning_content`	string	no	Thinking content
`model`	string	no	Model used (`provider/model-name`)
`system_prompt_hash`	string	no	Reference to `system_prompts` lookup table
`agent_role`	string	no	`"main"`, `"explore"`, `"plan"`, etc.
`parent_step`	integer	no	Step index of parent (for sub-agents)
`call_type`	string	no	`"main"`, `"subagent"`, or `"warmup"`
`tools_available`	string[]	no	Tools available at this step
`tool_calls`	ToolCall[]	no	Tool invocations made in the step
`observations`	Observation[]	no	Tool results linked back by `source_call_id`
`snippets`	Snippet[]	no	Extracted code blocks
`token_usage`	TokenUsage	no	Per-step token usage breakdown
`timestamp`	string	no	ISO8601 timestamp

`call_type` Values

Value	Description
`main`	Primary agent step
`subagent`	Sub-agent invocation
`warmup`	Cache priming call with no useful output

Tool Calls

{
  "tool_calls": [
    {
      "tool_call_id": "tc_001",
      "tool_name": "bash",
      "input": {
        "command": "npm test -- --grep parser"
      },
      "duration_ms": 3400
    }
  ]
}

Tool calls carry a tool_call_id. Observations link back via source_call_id.

Observations

{
  "observations": [
    {
      "source_call_id": "tc_001",
      "content": "FAIL src/parser.test.ts...",
      "output_summary": "1 test failed: parser.test.ts line 42 assertion error",
      "error": null
    }
  ]
}

output_summary is a lightweight preview so consumers can assess relevance without downloading full multi-KB outputs.

Snippets

Code blocks extracted from tool results and agent responses:

{
  "snippets": [
    {
      "file_path": "src/parser.ts",
      "start_line": 42,
      "end_line": 55,
      "language": "typescript",
      "text": "function parseToken(input: string)..."
    }
  ]
}

Token Usage

Per-step token breakdown:

{
  "token_usage": {
    "input_tokens": 12400,
    "output_tokens": 890,
    "cache_read_tokens": 11200,
    "cache_write_tokens": 1200,
    "prefix_reuse_tokens": 11200
  }
}

Sub-Agent Hierarchy

Sub-agent steps use parent_step to link back to the invoking step:

{
  "step_index": 5,
  "role": "agent",
  "agent_role": "explore",
  "parent_step": 3,
  "call_type": "subagent",
  "content": "Searching for related parser implementations..."
}

Sub-agent transcripts are linked by session_id reference to separate trajectory records, not embedded.

●HUMAN ○MACHINE