# Module Dependency Diagram

```mermaid
graph TD
    NR[NetRunner] --> S[NetRunner.Stream]
    NR --> P[NetRunner.Process]
    S --> P
    P --> EX[Process.Exec]
    P --> ST[Process.State]
    P --> OP[Process.Operations]
    P --> PI[Process.Pipe]
    P --> NI[Process.Nif]
    P --> SIG[NetRunner.Signal]
    P --> STATS[Process.Stats]
    EX --> NI
    PI --> NI
    ST --> PI
    ST --> OP
    ST --> STATS
    W[NetRunner.Watcher] --> NI
    W --> SIG
    APP[NetRunner.Application] --> W
    D[NetRunner.Daemon] --> P

    subgraph "C Native"
        SH[shepherd.c]
        NIFC[net_runner_nif.c]
        PROTO[protocol.h]
        UTIL[utils.h]
    end

    NI -.->|loads| NIFC
    EX -.->|spawns| SH
    NIFC --> PROTO
    NIFC --> UTIL
    SH --> PROTO
```

## Module Reference

### Public API

| Module | Purpose |
|--------|---------|
| `NetRunner` | Top-level API: `run/2`, `stream!/2`, `stream/2` |
| `NetRunner.Process` | GenServer managing a single OS process lifecycle |
| `NetRunner.Stream` | `Stream.resource` wrapper for incremental I/O |
| `NetRunner.Daemon` | Supervised long-running process for supervision trees |
| NetRunner.Signal | Signal atom → platform-specific number resolution |

### Internal Modules

| Module | Purpose |
|--------|---------|
| NetRunner.Process.Exec | Process spawning: UDS, Port.open, SCM\_RIGHTS, FD wrapping |
| NetRunner.Process.Nif | NIF function stubs (@on\_load :load\_nifs) |
| NetRunner.Process.Pipe | Pipe struct wrapping a NIF FD resource |
| NetRunner.Process.State | GenServer state struct |
| NetRunner.Process.Operations | Pending operation queue (park on EAGAIN, retry on ready) |
| NetRunner.Process.Stats | I/O statistics accumulator |
| NetRunner.Watcher | DynamicSupervisor child that kills OS process on GenServer death |
| NetRunner.Application | OTP application: starts WatcherSupervisor |

### C Components

| File | Lines | Purpose |
|------|-------|---------|
| `c_src/shepherd.c` | ~600 | Persistent child watchdog: fork, FD pass, poll loop, kill escalation, PTY, cgroup |
| `c_src/net_runner_nif.c` | ~480 | NIF: read/write/close/create_fd/dup_fd/kill/signal_number with enif_select |
| `c_src/protocol.h` | ~35 | Shared protocol constants |
| `c_src/utils.h` | ~20 | Debug/error macros |