fix(directory-picker-browse): bot round 1 — pill cascade+corner, slow-scan close reset, asymmetry+calibration recorded

- .loadingFloat moved after the .status/.error block (its padding was
  losing the same-specificity race) and re-anchored bottom-right: the
  truncated/error rows own the bottom left and keep rendering through a
  scan, so the pill can never cover them; confirmCreate's relist now
  clears the stale failure text like every other scan launch.
- The close edge resets loading, so the slow-scan effect disarms while
  hidden and a reopened dialog waits out a fresh silence window
  (regression test added).
- The truncated note's survival through a scan is now asserted in the
  slow-scan test; the wait-bound test moved to fake timers with the
  200ms bound explicit.
- select()'s exemption from the one-frame rule and the constants' local
  calibration premise are recorded in JSDoc and the capability-seam
  Agent Note; the themed-scrollbars note's rebinding enumeration is
  replaced by a pointer to the mechanical gate (it had drifted twice).
  Both pairs re-recorded.

packages/host/directory-picker-browse/src/client/DirectoryBrowser.module.css

@@ -159,19 +159,6 @@
   padding: 16px 16px 16px 24px;
 }
 
-/* The slow-scan indicator floats over the content's bottom-left on the card
- * background instead of occupying a row: a scan must never shift the
- * columns' height, and the stale view keeps rendering beneath it (it only
- * appears at all once a scan outlives SLOW_SCAN_DELAY_MS). */
-.loadingFloat {
-  position: absolute;
-  left: 24px;
-  bottom: 8px;
-  padding: 2px 8px;
-  border-radius: 6px;
-  background: var(--dsw-alias-bg-layer-2);
-}
-
 /* Columns split the row evenly around the divider (a solo column takes the
  * whole row); 256px is the floor below which the row scrolls (scrollbar
  * hidden, the effect pins the child pane into view) instead of squeezing
@@ -267,6 +254,23 @@
   color: var(--dsw-alias-state-error-primary);
 }
 
+/* The slow-scan indicator floats over the content's bottom-RIGHT corner on
+ * the card background instead of occupying a row: a scan must never shift
+ * the columns' height, and the stale view keeps rendering beneath it (it
+ * only appears at all once a scan outlives SLOW_SCAN_DELAY_MS). Right,
+ * not left: the truncated/error status rows flow at the bottom LEFT and
+ * stay on screen through a scan, so the opposite corner keeps both
+ * legible. After .status in the cascade — the element carries both
+ * classes and this padding must win the same-specificity race. */
+.loadingFloat {
+  position: absolute;
+  right: 16px;
+  bottom: 8px;
+  padding: 2px 8px;
+  border-radius: 6px;
+  background: var(--dsw-alias-bg-layer-2);
+}
+
 /* Footer: l3 separator on top, symmetric padding so the row sits vertically
  * centered in the bar; New-folder and the show-hidden toggle pin left. */
 .footerBar {

packages/host/directory-picker-browse/src/client/DirectoryBrowser.tsx

@@ -331,7 +331,15 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
   const pathInputRef = useRef<HTMLInputElement | null>(null)
   const editZoneRef = useRef<HTMLButtonElement | null>(null)
 
-  /** Select a row of the listed level and preview its children on the right. */
+  /**
+   * Select a row of the listed level and preview its children on the right.
+   * Deliberately NOT one-frame like navigate(): a pick's first duty is the
+   * immediate selected state on the clicked row, and the pane split IS that
+   * feedback (aria-current pill, crumbs following the selection) — holding
+   * it back for the child listing would make clicks feel dropped. The quiet
+   * rule governs whole-view replacement, where nothing acknowledges the
+   * click but the swap itself.
+   */
   const select = useCallback((entry: DirectoryEntry) => {
     const { seq, scan } = launchListing(entry.path)
     // A pick while the path editor is open adopts the (filtered) row and
@@ -402,6 +410,11 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
       return
     }
     supersede()
+    // Closing mid-scan leaves nothing to load: without this edge the
+    // slow-scan effect keeps arming while hidden and the reopened dialog
+    // would show the indicator on its first frame instead of waiting out a
+    // fresh silence window (reopen's navigate() produces no loading edge).
+    setLoading(false)
     setError(null)
     setPathDraft(null)
     setFolderDraft(null)
@@ -438,6 +451,10 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
       // create target becomes the listed level and the new folder its selection.
       const { seq, scan } = launchListing(targetPath)
       setLoading(true)
+      // Symmetric with navigate/select: a launched scan clears the stale
+      // failure text (and keeps the floating indicator's corner the only
+      // occupant of the content's right edge while it shows).
+      setError(null)
       scan.then((level) => {
         /* v8 ignore next -- same fence as navigate/select; the modal blocks superseding input */
         if (seq !== requestSeq.current) return