probeRoots() ended the disagreement about what a root IS, but the card built
its own rows from the probe and left `ok` and `error` out. A denied or missing
root therefore arrived at the widget as null usage, which it drew as "—" free
and a 0%-full bar: the rendering that means an empty healthy mount, on the one
surface an operator glances at rather than reads. rootInfos() maps the probes
for both web surfaces now, so what a caller is told cannot drift the way what a
caller asked for used to.

The card says "unreadable" and the reason under it instead, and drops the bar —
a 0% bar on a root nobody can read is worse than no bar.

Two more things the same route had wrong:

- "N more roots" counted the rows the card had been sent, and the route sent a
  slice, so an operator with sixteen roots was told about one. It counts the
  configured roots now.
- The slice was four while the card renders three, so every load paid for a
  stat and a df on a root nobody draws — on a spun-down disk, in seconds. One
  constant, named for the card, decides both.

roots_test.ts covers the mapper: a failed probe keeps its `ok` and `error`, and
each root gets its own scan in the configured order. Its barrier df now clears
its timer in a `finally`, so a body that throws before the assertions reports
the throw rather than a leaked timer.

@@ -86,1 +91,3 @@
-      if (!walks) continue;
+      if (!line.includes("policy.roots") || lookup.test(line)) continue;
+      // the call may be several lines up: `probeRoots(c, usage, roots.slice())`
+      // is over fmt's column limit and lands one argument per line

@@ -667,0 +671,4 @@
+      // how many are configured, not how many were probed: the card counts the
+      // rest into "N more", and counting the slice told an operator with
+      // sixteen roots about one
+      total: policy.roots.length,

@@ -68,2 +72,2 @@
-            {root.scan ? `${formatBytes(root.scan.bytes)} · ${ago(root.scan.finishedAtMs)}` : ago(null)}
-          </div>
+          {#if root.ok}
+            <ProgressBar value={root.usage?.usedPct ?? 0} />

@@ -34,0 +47,4 @@
+  let at = source.indexOf(CALL);
+  while (at >= 0) {
+    let depth = 0;
+    for (let i = at + CALL.length - 1; i < chars.length; i++) {

@@ -79,1 +112,4 @@
+  // Asking how many there are or for one by name is not describing them.
+  const lookup =
+    /policy\.roots\.(length\b|find\(|findIndex\(|findLast\(|some\(|every\(|includes\(|indexOf\(|at\()|policy\.roots\[/;
   for (const file of ROUTE_FILES) {

@@ -87,3 +122,3 @@
       assert(
-        line.includes("probeRoots("),
+        !named.includes("policy.roots") || lookup.test(named),
         `${file}:${index + 1} walks the roots itself:\n  ${line.trim()}`,

@@ -34,3 +36,2 @@
 
-  const shown = $derived(data?.roots.slice(0, 3) ?? []);
-  const hidden = $derived(Math.max(0, (data?.roots.length ?? 0) - shown.length));
+  const shown = $derived(data?.roots ?? []);

@@ -70,0 +81,4 @@
+          {:else}
+            <!-- no bar: a 0%-full one on a root nobody can read says "empty",
+                 which is the opposite of what happened -->
+            <div class="meta why" title={root.error ?? ""}>

@@ -59,0 +62,4 @@
+  healthy mount. `rootInfos()` maps them for both web surfaces, and
+  `overviewRoots()` decides how many the card draws and how many it left out — a
+  route deciding that counted "N more" from the rows it sent. There are tests
+  for each, and route files may name `policy.roots` only inside a `probeRoots()`

@@ -34,0 +41,4 @@
+ * the arguments says what the window approximated, and every other character
+ * keeps its line and column.
+ */
+function withoutProbeArgs(source: string): string {

@@ -34,0 +51,4 @@
+      if (chars[i] === "(") depth++;
+      else if (chars[i] === ")") depth--;
+      else if (chars[i] !== "\n") chars[i] = " ";
+      if (depth === 0) break;

@@ -459,0 +488,4 @@
+ * — overflow is clipped, never scrolled — so the card shows this many and says
+ * how many it left out.
+ */
+export const OVERVIEW_ROOTS = 3;

@@ -70,0 +81,4 @@
+          {:else}
+            <!-- no bar: a 0%-full one on a root nobody can read says "empty",
+                 which is the opposite of what happened -->
+            <div class="meta why" title={root.error ?? ""}>