Add E2E tests, fix bugs

Made-with: Cursor

_docs/02_document/modules/hardware_service.md

@@ -0,0 +1,64 @@
+# Module: hardware_service
+
+## Purpose
+
+Collects a hardware fingerprint string from the host OS (CPU, GPU, memory, drive serial) for use in hardware-bound encryption key derivation.
+
+## Public Interface
+
+### Classes
+
+#### `HardwareService` (cdef class)
+
+| Method              | Signature                      | Description                                    |
+|---------------------|--------------------------------|------------------------------------------------|
+| `get_hardware_info` | `@staticmethod cdef str ()`    | Returns cached hardware fingerprint string     |
+
+### Module-level State
+
+| Name             | Type | Description                      |
+|------------------|------|----------------------------------|
+| `_CACHED_HW_INFO`| str  | Cached result (computed once)    |
+
+## Internal Logic
+
+### `get_hardware_info`
+
+1. If cached (`_CACHED_HW_INFO is not None`), return cached value immediately
+2. Detect OS via `os.name`:
+   - **Windows (`nt`)**: PowerShell command querying WMI (Win32_Processor, Win32_VideoController, Win32_OperatingSystem, Disk serial)
+   - **Linux/other**: shell commands (`lscpu`, `lspci`, `free`, block device serial)
+3. Parse output lines → extract CPU, GPU, memory, drive serial
+4. Format: `"CPU: {cpu}. GPU: {gpu}. Memory: {memory}. DriveSerial: {serial}"`
+5. Cache result in `_CACHED_HW_INFO`
+
+The function uses `subprocess.check_output(shell=True)` — platform-specific shell commands.
+
+## Dependencies
+
+- **Internal**: `constants` (for `log()`)
+- **External**: `os`, `subprocess` (stdlib)
+
+## Consumers
+
+- `api_client` — `load_bytes()` and `check_resource()` call `HardwareService.get_hardware_info()`
+
+## Data Models
+
+None.
+
+## Configuration
+
+None. Hardware detection commands are hardcoded per platform.
+
+## External Integrations
+
+- **OS commands**: Windows PowerShell (Get-CimInstance, Get-Disk) or Linux shell (lscpu, lspci, free, /sys/block)
+
+## Security
+
+Produces a hardware fingerprint used to bind encryption keys to specific machines. The fingerprint includes drive serial number, which acts as a machine-unique identifier.
+
+## Tests
+
+No tests found.