Media build part 1 (unreleased): real restart (R-1026), media apps on every PRESENT drive via an owned compose override (R-1023), dead-drive check from mountinfo, removal never deletes shared/:ro binds (R-1027), safety list knows userdata (R-1032), no drive question for media apps (R-1031)

Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/system/mountdead_linux.go

@@ -0,0 +1,56 @@
+//go:build linux
+
+package system
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// MountIsShutdown reports whether the TOP mount at path is a dead filesystem — ext4's `shutdown` super option, set when
+// the device under it went away (a pulled drive). It reads /proc/self/mountinfo only: NO disk I/O, so it never hangs on
+// the dead device (gates.md: health checks issue no block I/O). A timed `stat` is NOT a substitute: it answered „ok" on
+// a dead drive from the cache (measured 2026-10-14, `15` §10 K4). Pinned by TestMountIsShutdown_*.
+func MountIsShutdown(path string) bool {
+	data, err := os.ReadFile(mountinfoPath)
+	if err != nil {
+		return false
+	}
+	return mountinfoShutdown(string(data), path)
+}
+
+var mountinfoPath = "/proc/self/mountinfo"
+
+// mountinfoShutdown: the LAST mountinfo line whose mount point is path (the top of a stack) carries `shutdown` in its
+// super options (the third field after " - ").
+func mountinfoShutdown(mountinfo, path string) bool {
+	path = filepath.Clean(path)
+	dead := false
+	found := false
+	for _, line := range strings.Split(mountinfo, "\n") {
+		f := strings.Fields(line)
+		if len(f) < 5 || unescapeMountinfo(f[4]) != path {
+			continue
+		}
+		found = true
+		dead = false
+		if i := strings.Index(line, " - "); i >= 0 {
+			tail := strings.Fields(line[i+3:])
+			if len(tail) >= 3 {
+				for _, o := range strings.Split(tail[2], ",") {
+					if o == "shutdown" {
+						dead = true
+					}
+				}
+			}
+		}
+	}
+	return found && dead
+}
+
+// unescapeMountinfo undoes mountinfo's octal escapes for space, tab, newline and backslash.
+func unescapeMountinfo(s string) string {
+	r := strings.NewReplacer(`\040`, " ", `\011`, "\t", `\012`, "\n", `\134`, `\`)
+	return r.Replace(s)
+}