# DES Design Session Checkpoint

**Date:** 2026-01-22
**Branch:** `determinism`
**Session Purpose:** Design deterministic execution system for Claude Code workflows

---

## Session Summary

This session focused on designing and empirically testing a Deterministic Execution System (DES) to ensure step execution, Outside-In TDD phases, and commits are always executed or explicitly skipped with documentation.

### Work Completed

1. **Initial Research** (3 parallel agents)
   - Researcher: Deterministic workflow patterns (FSM, guardrails, stage-gate)
   - Explorer: Current nWave implementation analysis
   - Product Owner: Requirements and acceptance criteria

2. **Design Document Created**
   - 4-layer architecture: Filtering → Templates → Lifecycle → Validation
   - Comprehensive failure mode analysis
   - Implementation roadmap

3. **Multi-Agent Review Completed**
   - Solution Architect: CONDITIONALLY APPROVED
   - Software Crafter: NEEDS WORK
   - Product Owner: BLOCKED (3/8 DoR)
   - Troubleshooter: NOT READY

4. **Empirical Testing**
   - Created SubagentStop hook discovery script
   - Tested hook firing (did NOT fire in VSCode context)
   - Discovered max_turns is CLI-only (not Task tool parameter)

---

## Critical Findings

### Finding 1: max_turns Doesn't Exist for Task Tool

```python
# THIS DOES NOT WORK
Task(prompt="...", max_turns=50)  # ❌ INVALID

# max_turns is CLI flag only
claude -p "..." --max-turns 3  # ✅ This works
```

**Impact:** Need alternative timeout strategy (prompt-based discipline, external watchdog)

### Finding 2: SubagentStop Hook May Need Session Restart

Hook configured but did not fire during testing. Possible causes:
- Settings need session restart to reload
- VSCode extension handles hooks differently
- May only fire for certain agent types

---

## Where We Left Off

The user asked to save the conversation because VSCode UI wasn't showing past conversations.

**Last user request:**
> "can you ensure this conversation is saved? Recently the vscode UI is not showing me the past conversations"
> "I need you also to save your last request so we can pick up from there"

**Recommended next steps:**

1. **Restart session** and re-test SubagentStop hook
2. **Revise DES design** based on findings:
   - Remove max_turns from Task tool references
   - Add alternative timeout strategies
   - Strengthen pre-commit as primary gate
3. **Add UAT scenarios** (Given/When/Then format) - required by Product Owner review
4. **Resolve Q1** (hook context access) before implementation

---

## Files Created This Session

| File | Purpose |
|------|---------|
| `docs/design/deterministic-execution-system-design.md` | Main design document |
| `docs/design/deterministic-execution-system-review-summary.md` | Multi-agent review |
| `docs/design/des-critical-finding-max-turns.md` | max_turns analysis |
| `docs/design/des-discovery-report.md` | Empirical testing results |
| `docs/design/des-session-checkpoint.md` | This checkpoint |
| `nWave/hooks/discover_subagent_context.py` | Hook discovery script |
| `data/research/workflow-patterns/deterministic-workflow-execution-llm-agents.md` | Research |
| `.claude/settings.local.json` | Updated with SubagentStop hook |

---

## To Resume This Work

```bash
# 1. Checkout the branch
git checkout determinism

# 2. Read the checkpoint
cat docs/design/des-session-checkpoint.md

# 3. Read the main design
cat docs/design/deterministic-execution-system-design.md

# 4. Read the review summary
cat docs/design/deterministic-execution-system-review-summary.md

# 5. Continue with next steps above
```

---

*Checkpoint saved to preserve session context.*
