# HITL Step Recording Implementation - Complete Summary

## Overview
HITL (Human-In-The-Loop) checkpoint decisions are now recorded as separate steps in `trace.json`, making the full checkpoint lifecycle available for audit and review alongside existing events in `run_events.jsonl`.

## Changes Made

### Modified File
- **`src/data_agent_baseline/langgraph_agent/graph.py`**

### Implementation Details

#### 1. New Helper Function: `_record_hitl_step()`
Added function that:
- Creates a standardized HITL step object matching the trace.json format
- Captures decision type (approve/cancel/revise/timeout_auto_approve)
- Records original and revised plans
- Includes human steering instructions
- Preserves checkpoint configuration (timeout_seconds, default_action_on_timeout)
- Appends step to state.steps for inclusion in final trace.json
- Emits optional callback event for run_events.jsonl

**Location**: Lines ~44-107 in graph.py

#### 2. Integration Points
Function is called in `_maybe_handle_planner_checkpoint()` at 4 decision paths:

**A) APPROVE Decision** (Lines ~365-378)
```python
_record_hitl_step(
    state,
    checkpoint_id=checkpoint.checkpoint_id,
    decision=decision_record.decision,
    message="Checkpoint approved. Resuming execution.",
    original_plan=original_plan,
    revised_plan=original_plan,
    ...
)
```

**B) CANCEL Decision** (Lines ~403-416)
```python
_record_hitl_step(
    state,
    checkpoint_id=checkpoint.checkpoint_id,
    decision=decision_record.decision,
    message="Task cancelled by human at planner checkpoint.",
    original_plan=original_plan,
    revised_plan=None,
    human_instruction=decision_record.human_instruction,
    ...
)
```

**C) REVISE Decision** (Lines ~445-458)
```python
_record_hitl_step(
    state,
    checkpoint_id=checkpoint.checkpoint_id,
    decision=decision_record.decision,
    message="Revision submitted and replanning completed...",
    original_plan=original_plan,
    revised_plan=revised_plan,  # After replanning
    human_instruction=decision_record.human_instruction,
    ...
)
```

**D) TIMEOUT_AUTO_APPROVE Decision** (Lines ~315-327)
```python
_record_hitl_step(
    state,
    checkpoint_id=checkpoint.checkpoint_id,
    decision=InterventionDecision.TIMEOUT_AUTO_APPROVE.value,
    message=f"No human response within {policy.timeout_seconds}s...",
    original_plan=original_plan,
    revised_plan=original_plan,
    ...
)
```

## Result Format in trace.json

HITL steps appear in `trace.json["steps"]` as:

```json
{
  "step_index": <number>,
  "action": "planner_review",
  "phase": "planner_review",
  "thought": "Human-in-the-loop checkpoint review (checkpoint_id=cp_...)",
  "action_input": {
    "checkpoint_id": "cp_...",
    "decision": "approve|cancel|revise|timeout_auto_approve"
  },
  "raw_response": "(human decision)",
  "observation": {
    "ok": true,
    "tool": "planner_review",
    "content": {
      "checkpoint_id": "cp_...",
      "decision": "...",
      "message": "...",
      "original_plan": { /* Full plan object */ },
      "revised_plan": { /* Full plan object or null */ },
      "human_instruction": "...",
      "timeout_seconds": 60,
      "default_action_on_timeout": "continue"
    }
  },
  "ok": true
}
```

## Example Usage

### View HITL steps in trace.json
```bash
# View all HITL review steps
jq '.steps[] | select(.action == "planner_review")' trace.json

# View the decision for a specific checkpoint
jq '.steps[] | select(.action == "planner_review") | .observation.content' trace.json

# Count HITL interactions
jq '[.steps[] | select(.action == "planner_review")] | length' trace.json
```

### Review approval decisions
```bash
jq '.steps[] | select(.action == "planner_review" and .observation.content.decision == "approve")' trace.json
```

### Compare original vs revised plans
```bash
jq '.steps[] | select(.action == "planner_review" and .observation.content.decision == "revise") | {original: .observation.content.original_plan, revised: .observation.content.revised_plan}' trace.json
```

## Backward Compatibility

✅ **Fully backward compatible**:
- Existing non-HITL runs unaffected
- HITL steps appended to steps array (no structure changes)
- Existing event emission to run_events.jsonl unchanged
- All existing visualization tools continue to work

## Data Retention

The implementation ensures:
- **Immutable Audit Trail**: HITL decisions persisted in trace.json
- **Full Context**: Original and revised plans stored together
- **Human Intent**: Steering instructions preserved
- **Timing**: Checkpoint timeout configuration captured
- **Traceability**: checkpoint_id links to run_events.jsonl events

## Testing

Comprehensive test file validates all decision paths:
- ✅ Approval decisions
- ✅ Cancel decisions  
- ✅ Revision decisions with plan changes
- ✅ Timeout auto-approve scenarios
- ✅ Multiple HITL steps with proper indexing
- ✅ JSON serialization compatibility

**Test file**: `test_hitl_step_recording.py`

Run with: `python test_hitl_step_recording.py`

## Verification

To verify the implementation in a live run:

```bash
# 1. Run a guided task with HITL
cd /workspace/ainn-cm-poc-data-agent
python -m data_agent_baseline.cli run-lang-task --task-id task_145 --guided

# 2. Check trace.json for HITL step
cat artifacts/runs/*/task_145/trace.json | jq '.steps[-1]'

# 3. Verify it appears with correct structure
jq 'if .steps[-1].action == "planner_review" then "✅ HITL step found" else "❌ HITL step not found" end' trace.json
```

## Benefits

✨ **Key Advantages**:
1. **Audit & Compliance**: Complete record of human decisions
2. **Review**: Easy visualization of checkpoint lifecycle
3. **Analysis**: Patterns in human steering decisions
4. **Debugging**: Understand why plans changed
5. **Reproducibility**: Exact conditions for replanning captured
6. **Integration**: Works with existing observatory tools

## Notes

- HITL steps have `"ok": true` (they're decisions, not tool failures)
- `phase` is always `"planner_review"` (distinguishes from other actions)
- Multiple HITL steps per task are possible (e.g., approve, then revise)
- Each step has independent checkpoint_id for linking to events