Grepai Trace Callees

# GrepAI Trace Callees

This skill covers using `grepai trace callees` to find all functions called by a specific function.

## When to Use This Skill

- Understanding function dependencies
- Mapping function behavior
- Finding deeply nested dependencies
- Code comprehension and documentation

## What is Trace Callees?

`grepai trace callees` answers: **"What does this function call?"**

```
func ProcessOrder(order) {
    validateOrder(order)
    calculateTotal(order)
    sendConfirmation(order.email)
}
        │
        ↓
┌───────┴───────────────────┐
│  What does ProcessOrder   │
│  call?                    │
├───────────────────────────┤
│ • validateOrder           │
│ • calculateTotal          │
│ • sendConfirmation        │
└───────────────────────────┘
```

## Basic Usage

```bash
grepai trace callees "FunctionName"
```

### Example

```bash
grepai trace callees "ProcessOrder"
```

Output:
```
🔍 Callees of "ProcessOrder"

Found 4 callees:

1. validateOrder
   File: services/order.go:45
   Context: validateOrder(order)

2. calculateTotal
   File: services/order.go:48
   Context: total := calculateTotal(order.Items)

3. applyDiscount
   File: services/order.go:51
   Context: total = applyDiscount(total, order.Coupon)

4. sendConfirmation
   File: services/order.go:55
   Context: sendConfirmation(order.Email, total)
```

## JSON Output

```bash
grepai trace callees "ProcessOrder" --json
```

Output:
```json
{
  "query": "ProcessOrder",
  "mode": "callees",
  "count": 4,
  "results": [
    {
      "file": "services/order.go",
      "line": 45,
      "callee": "validateOrder",
      "context": "validateOrder(order)"
    },
    {
      "file": "services/order.go",
      "line": 48,
      "callee": "calculateTotal",
      "context": "total := calculateTotal(order.Items)"
    },
    {
      "file": "services/order.go",
      "line": 51,
      "callee": "applyDiscount",
      "context": "total = applyDiscount(total, order.Coupon)"
    },
    {
      "file": "services/order.go",
      "line": 55,
      "callee": "sendConfirmation",
      "context": "sendConfirmation(order.Email, total)"
    }
  ]
}
```

## Compact JSON (AI Optimized)

```bash
grepai trace callees "ProcessOrder" --json --compact
```

Output:
```json
{
  "q": "ProcessOrder",
  "m": "callees",
  "c": 4,
  "r": [
    {"f": "services/order.go", "l": 45, "fn": "validateOrder"},
    {"f": "services/order.go", "l": 48, "fn": "calculateTotal"},
    {"f": "services/order.go", "l": 51, "fn": "applyDiscount"},
    {"f": "services/order.go", "l": 55, "fn": "sendConfirmation"}
  ]
}
```

## TOON Output (v0.26.0+)

TOON format offers ~50% fewer tokens than JSON:

```bash
grepai trace callees "ProcessOrder" --toon
```

> **Note:** `--json` and `--toon` are mutually exclusive.

## Extraction Modes

### Fast Mode (Default)

```bash
grepai trace callees "ProcessOrder" --mode fast
```

### Precise Mode

```bash
grepai trace callees "ProcessOrder" --mode precise
```

| Mode | Speed | Accuracy | Dependencies |
|------|-------|----------|--------------|
| `fast` | ⚡⚡⚡ | Good | None |
| `precise` | ⚡⚡ | Excellent | tree-sitter |

## Use Cases

### Understanding Function Behavior

```bash
# What does this complex function do?
grepai trace callees "handleRequest"

# Map the data flow
grepai trace callees "processPayment"
```

### Finding Dependencies

```bash
# What external services does this call?
grepai trace callees "syncData"

# What database operations happen?
grepai trace callees "saveUser"
```

### Code Review

```bash
# What side effects does this function have?
grepai trace callees "updateProfile"

# Is this function doing too much?
grepai trace callees "doEverything"  # Lots of callees = code smell
```

### Documentation

```bash
# Generate dependency list for docs
grepai trace callees "initialize" --json | jq '.results[]