feat(inventory): show NVMe PCIe link gen/width, flag downtrains — 0.38.0

Each NVMe drive's Inventory entry now shows its negotiated PCIe link (e.g.
'· PCIe Gen4 x4') from sysfs (current/max link speed+width), and flags drives
running below their capability ('Gen3 x4 (capable of Gen4 x4)') — so you can
confirm a Gen4 SSD is in a Gen4 slot. SATA disks show no PCIe link. Renders in
the GUI Inventory, CLI, and the Markdown/JSON export automatically. +tests.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/rigdoctor/__init__.py

@@ -1,3 +1,3 @@
 """RigDoctor — modular hardware monitoring & crash diagnostics for Linux gamers."""
 
-__version__ = "0.37.1"
+__version__ = "0.38.0"

src/rigdoctor/core/inventory.py

@@ -9,6 +9,7 @@ from __future__ import annotations
 import json
 import os
 import platform
+import re
 import shutil
 import subprocess
 from dataclasses import dataclass
@@ -123,6 +124,46 @@ def _gpu() -> Section:
     return Section("GPU", [("Device", g) for g in gpus] or [("Device", "unknown")])
 
 
+# PCIe link speed (GT/s) → generation.
+_PCIE_GEN = {"2.5": 1, "5": 2, "5.0": 2, "8": 3, "8.0": 3, "16": 4, "16.0": 4, "32": 5, "32.0": 5}
+
+
+def _gen(speed: str) -> int | None:
+    """Map a sysfs link speed like '16.0 GT/s PCIe' to its PCIe generation (4)."""
+    tok = speed.strip().split()[0] if speed.strip() else ""
+    return _PCIE_GEN.get(tok)
+
+
+def _link_desc(dev: Path) -> str:
+    """Describe a PCI device's negotiated PCIe link, noting if it's below its max.
+
+    e.g. 'PCIe Gen4 x4', or 'PCIe Gen3 x4 (capable of Gen4 x4)' when downtrained / in a
+    slower slot.
+    """
+    def rd(name: str) -> str:
+        try:
+            return (dev / name).read_text().strip()
+        except OSError:
+            return ""
+
+    cur_g, cur_w = _gen(rd("current_link_speed")), rd("current_link_width")
+    max_g, max_w = _gen(rd("max_link_speed")), rd("max_link_width")
+    if not cur_g or not cur_w:
+        return ""
+    desc = f"PCIe Gen{cur_g} x{cur_w}"
+    if max_g and (cur_g < max_g or (max_w and cur_w != max_w)):
+        desc += f" (capable of Gen{max_g} x{max_w})"
+    return desc
+
+
+def _nvme_link(block_name: str) -> str:
+    """PCIe link for an NVMe block device (nvme0n1 → controller nvme0); '' for non-NVMe."""
+    m = re.match(r"(nvme\d+)", block_name)
+    if not m:
+        return ""
+    return _link_desc(Path("/sys/class/nvme") / m.group(1) / "device")
+
+
 def _storage() -> Section:
     items: list[tuple[str, str]] = []
     # TYPE first so MODEL (which can contain spaces) is the trailing field.
@@ -133,7 +174,11 @@ def _storage() -> Section:
             continue
         name, size = parts[1], parts[2]
         model = parts[3] if len(parts) > 3 else ""
-        items.append((name, f"{model} ({size})".strip()))
+        desc = f"{model} ({size})".strip()
+        link = _nvme_link(name)  # NVMe PCIe gen/width (e.g. Gen4 x4), flags downtrains
+        if link:
+            desc += f" · {link}"
+        items.append((name, desc))
     return Section("Storage", items or [("Disks", "unknown")])