# Implementation Plan: Android FS5 Device Management

**Feature**: 001-android-fs5-management
**Created**: 2026-03-02
**Tech Stack**: Bash 5, ADB 1.0.41, Python 3 (for JSON output), ShellCheck

---

## Constitution Check

- [x] **Article I (Shell-First)**: Implemented as Bash CLI with Python for JSON formatting.
- [x] **Article II (ADB Interface)**: All device ops go through `adb -s $DEVICE_SERIAL`.
- [x] **Article III (Test-First)**: Tests written in `tests/` using bats-core before implementation.
- [x] **Article IV (Idempotency)**: All operations check state before mutating.
- [x] **Article V (Non-Destructive)**: Destructive ops require `--force`; all writes logged.
- [x] **Article VI (Device Identity)**: Serial loaded from `.env`, validated on every run.
- [x] **Article VII (Simplicity)**: 3 modules: `fs5` (entrypoint), `lib/adb.sh` (ADB helpers), `lib/output.sh` (formatting).
- [x] **Article VIII (Structured Output)**: `--json` flag on all commands via Python `json` module.
- [x] **Article IX (Config over Hardcoding)**: `.env` file with `DEVICE_SERIAL`, `LOG_FILE`, `DEFAULT_PUSH_PATH`.

---

## Architecture

```text
android-fs5/
├── fs5                    # Main entrypoint (Bash, chmod +x)
├── lib/
│   ├── adb.sh             # ADB wrapper functions
│   └── output.sh          # Human/JSON output formatting
├── tests/
│   ├── test_status.bats   # bats-core tests for status command
│   ├── test_transfer.bats # bats-core tests for push/pull
│   ├── test_app.bats      # bats-core tests for app management
│   ├── test_shell.bats    # bats-core tests for shell command
│   └── test_logs.bats     # bats-core tests for log capture
├── .env.example           # Template config (committed)
├── .env                   # Local config (gitignored)
├── .gitignore
├── README.md
└── fs5.log                # Operation log (gitignored)
```

---

## Module Design

### `fs5` — Main Entrypoint

```text
Usage: ./fs5 <command> [options]

Commands:
  status              Show device health and info
  push <src> <dst>    Push file/dir to device
  pull <src> <dst>    Pull file/dir from device
  app list            List installed apps
  app install <apk>   Install APK
  app uninstall <pkg> Uninstall package
  shell [cmd]         Execute shell command on device
  logs                Stream logcat output

Global Options:
  --json              Output as JSON
  --force             Allow destructive operations
  --help              Show help
```

### `lib/adb.sh` — ADB Helpers

Key functions:
- `adb_check_device()` — validates device is connected, exits 2 if not
- `adb_cmd()` — wraps `adb -s $DEVICE_SERIAL` with error handling
- `adb_get_prop(key)` — reads device property
- `adb_shell(cmd)` — executes shell command on device
- `adb_push(src, dst)` — pushes file with existence check
- `adb_pull(src, dst)` — pulls file
- `adb_log_op(op, detail)` — appends timestamped entry to `fs5.log`

### `lib/output.sh` — Output Formatting

Key functions:
- `out_human(msg)` — prints to stdout
- `out_json(data)` — formats key=value pairs as JSON via Python
- `out_error(msg)` — prints to stderr with red color
- `out_success(msg)` — prints with green checkmark

---

## Data Model

### Config (`.env`)

```bash
DEVICE_SERIAL=RD51QE202392
LOG_FILE=./fs5.log
DEFAULT_PUSH_PATH=/sdcard/
ADB_TIMEOUT=10
```

### Device Status Object (JSON)

```json
{
  "serial": "RD51QE202392",
  "model": "FS5",
  "manufacturer": "exone GmbH",
  "android_version": "9",
  "battery_level": 85,
  "battery_charging": true,
  "storage_total_kb": 54302616,
  "storage_used_kb": 18228852,
  "storage_free_kb": 35926308,
  "storage_percent_used": 34,
  "adb_state": "device",
  "timestamp": "2026-03-02T15:43:00+01:00"
}
```

### Log Entry Format

```text
2026-03-02T15:43:00+01:00 PUSH /home/ja/file.txt -> /sdcard/file.txt [OK]
2026-03-02T15:44:00+01:00 INSTALL /tmp/app.apk -> com.example.app [OK]
```

---

## Technical Decisions

### Why Bash over Python?

- ADB is a CLI tool — Bash is the natural glue language.
- No dependency installation required on the host.
- Python used only for JSON serialization (available on all Manjaro systems).

### Why bats-core for testing?

- Purpose-built for Bash script testing.
- Supports mocking ADB calls for offline testing.
- Integrates with CI/CD pipelines.

### JSON Output Strategy

Use Python one-liner to convert shell variables to JSON:

```bash
python3 -c "import json,sys; d={...}; print(json.dumps(d, indent=2))"
```

This avoids `jq` as a hard dependency while producing valid JSON.

### Exit Code Strategy

| Code | Meaning |
|------|---------|
| 0 | Success |
| 1 | General error (bad args, operation failed) |
| 2 | Device not found / ADB error |

---

## Dependencies

| Tool | Version | Required | Install |
|------|---------|----------|---------|
| adb | 1.0.41+ | YES | `sudo pacman -S android-tools` |
| bash | 5.x | YES | Pre-installed |
| python3 | 3.x | YES | Pre-installed |
| bats-core | 1.x | DEV | `sudo pacman -S bash-bats` |
| shellcheck | 0.9+ | DEV | `sudo pacman -S shellcheck` |

---

## Validation Scenarios (Quickstart)

```bash
# 1. Verify device connected
./fs5 status

# 2. Test JSON output
./fs5 status --json | python3 -m json.tool

# 3. Test file transfer
echo "test" > /tmp/fs5-test.txt
./fs5 push /tmp/fs5-test.txt /sdcard/fs5-test.txt
./fs5 pull /sdcard/fs5-test.txt /tmp/fs5-pulled.txt
diff /tmp/fs5-test.txt /tmp/fs5-pulled.txt && echo "PASS"

# 4. Test idempotency
./fs5 push /tmp/fs5-test.txt /sdcard/fs5-test.txt  # Should warn, not fail

# 5. Test app listing
./fs5 app list

# 6. Test shell passthrough
./fs5 shell "echo hello from device"

# 7. Test log capture
./fs5 logs --lines 5

# 8. Test disconnected behavior (unplug device first)
./fs5 status; echo "Exit code: $?"  # Should be 2
```