working-on-delta

# Working on Delta Skill

Orchestrates the per-delta workflow from spec through implementation.

## When to Load

Load this skill when executing:
- `/katachi:spec-delta <ID>`
- `/katachi:design-delta <ID>`
- `/katachi:plan-delta <ID>`
- `/katachi:implement-delta <ID>`
- `/katachi:retrofit-design <ID>` (retrofit mode)

## Key References

**Guidance documents** (how to write each document type):
- `references/spec-template.md` - How to write delta specifications
- `references/design-template.md` - How to write design rationale
- `references/plan-template.md` - How to write implementation plans

**Document templates** (actual templates to follow):
- `references/delta-spec.md` - Delta specification template
- `references/delta-design.md` - Design document template
- `references/implementation-plan.md` - Implementation plan template

## Workflow

### 1. Pre-Check

Before starting any per-delta command:

```python
# Check delta exists in DELTAS.md
delta = get_delta(FEATURE_ID)
if not delta:
    error("Delta not found in DELTAS.md")

# Check dependencies are complete (for design/plan/implement)
if command in ["design", "plan", "implement"]:
    deps = get_dependencies(FEATURE_ID)
    incomplete = [d for d in deps if not is_complete(d)]
    if incomplete:
        warn(f"Dependencies not complete: {incomplete}")
```

### 2. Status Update (Start)

Update status when starting:

```bash
# spec-delta
python scripts/deltas.py status set FEATURE-ID "⧗ Spec"

# design-delta
python scripts/deltas.py status set FEATURE-ID "⧗ Design"

# plan-delta
python scripts/deltas.py status set FEATURE-ID "⧗ Plan"

# implement-delta
python scripts/deltas.py status set FEATURE-ID "⧗ Implementation"
```

### 3. Document Creation Workflow

For spec/design/plan commands:

1. **Research Phase (Silent)**
   - Read relevant context (DELTAS.md, DEPENDENCIES.md)
   - Read previous documents (spec before design, design before plan)
   - Read relevant ADRs and DES patterns
   - Research any libraries/APIs i