feat(displays): monitors w/ resolution+refresh in Inventory; flag sub-max refresh in Health — 0.39.0

New core/displays.py reads connected monitors via GNOME Mutter DisplayConfig over
D-Bus (busctl --json; works on X11 + Wayland), falling back to xrandr on other X11
desktops. Inventory's Display section now lists each monitor's resolution + current
refresh (e.g. 'DP-1 · Samsung LC34G55T: 3440x1440 @ 165 Hz'). System Health
(check_displays) flags a monitor running below its max refresh AT THE CURRENT
resolution (e.g. 165 Hz panel set to 60 Hz) — never suggests lowering resolution.
+tests (Mutter JSON + xrandr parsers, health check).

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__ = "0.38.0"
+__version__ = "0.39.0"

src/rigdoctor/core/displays.py

@@ -0,0 +1,148 @@
+"""Connected displays (M5): resolution + current/max refresh per monitor.
+
+GNOME exposes the authoritative data over D-Bus (Mutter `DisplayConfig.GetCurrentState`),
+which works on both X11 and Wayland — read via `busctl --json`. Plain X11 desktops fall back
+to `xrandr`. Other Wayland compositors (sway/KDE) aren't covered yet and degrade to empty.
+Stdlib only; every probe fails soft. Max refresh is computed at the *current* resolution, so
+"can go faster" never suggests dropping resolution.
+"""
+
+from __future__ import annotations
+
+import json
+import re
+import shutil
+import subprocess
+from dataclasses import dataclass
+
+# A few common PNP monitor-vendor IDs → friendly names (best-effort; unknown codes pass through).
+_PNP = {
+    "SAM": "Samsung", "DEL": "Dell", "GSM": "LG", "LGD": "LG", "AUS": "ASUS", "ACR": "Acer",
+    "BNQ": "BenQ", "MSI": "MSI", "AOC": "AOC", "VSC": "ViewSonic", "HWP": "HP", "HPN": "HP",
+    "PHL": "Philips", "GBT": "Gigabyte", "APP": "Apple", "DGC": "Dell",
+}
+
+
+@dataclass
+class Monitor:
+    connector: str          # e.g. "DP-1"
+    name: str               # e.g. "Samsung LC34G55T" ("" if unknown, e.g. xrandr)
+    width: int
+    height: int
+    refresh: float          # current Hz
+    max_refresh: float      # max Hz available at the current resolution
+
+    @property
+    def can_go_faster(self) -> bool:
+        """True if a meaningfully higher refresh is available at the current resolution."""
+        return self.max_refresh - self.refresh > 1.0
+
+    def label(self) -> str:
+        return f"{self.connector} · {self.name}".rstrip(" ·") if self.name else self.connector
+
+
+def _run(cmd: list[str], timeout: float = 8.0) -> str:
+    try:
+        proc = subprocess.run(cmd, capture_output=True, text=True, timeout=timeout)
+        if proc.returncode == 0:
+            return proc.stdout
+    except (subprocess.SubprocessError, OSError):
+        pass
+    return ""
+
+
+def _parse_mutter(out: str) -> list[Monitor]:
+    """Parse `busctl --json` output of Mutter DisplayConfig.GetCurrentState.
+
+    data = [serial, monitors, logical_monitors, props]; each monitor is
+    [[connector, vendor, product, serial], [modes], props]; each mode is
+    [id, width, height, refresh, scale, [scales], {props}] where props may hold is-current.
+    """
+    try:
+        data = json.loads(out)["data"]
+        raw_monitors = data[1]
+    except (json.JSONDecodeError, KeyError, IndexError, TypeError):
+        return []
+    monitors: list[Monitor] = []
+    for mon in raw_monitors:
+        try:
+            connector, vendor, product = mon[0][0], mon[0][1], mon[0][2]
+            modes = mon[1]
+        except (IndexError, TypeError):
+            continue
+        current = None
+        for m in modes:
+            props = m[6] if len(m) > 6 and isinstance(m[6], dict) else {}
+            if (props.get("is-current") or {}).get("data"):
+                current = m
+                break
+        if current is None:
+            continue
+        w, h, r = int(current[1]), int(current[2]), float(current[3])
+        max_r = max((float(m[3]) for m in modes if int(m[1]) == w and int(m[2]) == h), default=r)
+        name = f"{_PNP.get(vendor, vendor)} {product}".strip()
+        monitors.append(Monitor(connector, name, w, h, r, max_r))
+    return monitors
+
+
+def _parse_xrandr(out: str) -> list[Monitor]:
+    """Parse `xrandr --query`: an output line with the active WxH+x+y, then indented mode lines
+    whose rates carry `*` for the current one."""
+    monitors: list[Monitor] = []
+    out_re = re.compile(r"^(\S+) connected.*?(\d+)x(\d+)\+\d+\+\d+")
+    mode_re = re.compile(r"^\s+(\d+)x(\d+)\s+(.+)$")
+    name = ""
+    cw = ch = 0
+    cur_r = max_r = 0.0
+
+    def flush() -> None:
+        if name and cw and cur_r:
+            monitors.append(Monitor(name, "", cw, ch, cur_r, max_r or cur_r))
+
+    for line in out.splitlines():
+        mo = out_re.match(line)
+        if mo:
+            flush()
+            name, cw, ch = mo.group(1), int(mo.group(2)), int(mo.group(3))
+            cur_r = max_r = 0.0
+            continue
+        mm = mode_re.match(line)
+        if mm and name and int(mm.group(1)) == cw and int(mm.group(2)) == ch:
+            for tok in mm.group(3).split():
+                try:
+                    rate = float(tok.rstrip("*+"))
+                except ValueError:
+                    continue
+                max_r = max(max_r, rate)
+                if "*" in tok:
+                    cur_r = rate
+    flush()
+    return monitors
+
+
+def _mutter() -> list[Monitor]:
+    exe = shutil.which("busctl")
+    if not exe:
+        return []
+    out = _run([exe, "--user", "--json=short", "call", "org.gnome.Mutter.DisplayConfig",
+                "/org/gnome/Mutter/DisplayConfig", "org.gnome.Mutter.DisplayConfig",
+                "GetCurrentState"])
+    return _parse_mutter(out) if out.strip() else []
+
+
+def _xrandr() -> list[Monitor]:
+    if not shutil.which("xrandr"):
+        return []
+    return _parse_xrandr(_run(["xrandr", "--query"]))
+
+
+def collect() -> list[Monitor]:
+    """Connected monitors, via the first backend that returns any (Mutter, then xrandr)."""
+    for backend in (_mutter, _xrandr):
+        try:
+            monitors = backend()
+        except Exception:
+            monitors = []
+        if monitors:
+            return monitors
+    return []

src/rigdoctor/core/health.py

@@ -283,6 +283,23 @@ def check_pcie_links() -> list[Finding]:
     return findings
 
 
+def check_displays() -> list[Finding]:
+    """Flag monitors running below their max refresh rate at the current resolution — e.g. a
+    165 Hz panel set to 60 Hz, a common and easily-missed gaming setting (read-only suggestion)."""
+    from . import displays
+
+    findings: list[Finding] = []
+    for m in displays.collect():
+        if m.can_go_faster:
+            findings.append(Finding(
+                INFO, "Display",
+                f"{m.connector} at {round(m.refresh)} Hz (supports {round(m.max_refresh)} Hz)",
+                f"{m.name or m.connector} is running at {round(m.refresh)} Hz at "
+                f"{m.width}x{m.height}, but supports {round(m.max_refresh)} Hz at that resolution.",
+                "Raise the refresh rate in your desktop's Display settings (GNOME: Settings → Displays)."))
+    return findings
+
+
 def run_health_checks(include_journal: bool = True) -> list[Finding]:
     """Run all checks and return findings sorted by severity (worst first).
 
@@ -306,5 +323,6 @@ def run_health_checks(include_journal: bool = True) -> list[Finding]:
         findings += check_smart()
     findings += check_live_temps()
     findings += check_pcie_links()
+    findings += check_displays()
     findings.sort(key=lambda f: _ORDER.get(f.severity, 9))
     return findings

src/rigdoctor/core/inventory.py

@@ -201,10 +201,18 @@ def _storage() -> Section:
 
 
 def _display() -> Section:
-    return Section("Display", [
+    from . import displays
+
+    items = [
         ("Session", os.environ.get("XDG_SESSION_TYPE", "unknown")),
         ("Desktop", os.environ.get("XDG_CURRENT_DESKTOP") or os.environ.get("DESKTOP_SESSION", "unknown")),
-    ])
+    ]
+    for m in displays.collect():
+        val = f"{m.width}x{m.height} @ {round(m.refresh)} Hz"
+        if m.can_go_faster:
+            val += f" (supports {round(m.max_refresh)} Hz)"
+        items.append((m.label(), val))
+    return Section("Display", items)
 
 
 def _dmidecode() -> dict: