fix(maestro): pin activity rail to left edge, drop active-state pulse

Rail now spans full row height flush to the left edge with square
corners, instead of a depth-shifted inset bar. Active state stays
solid green since colour alone already signals it; blink/flash stay
for awaiting-input/error.

docs/SIDEBAR.md

@@ -51,13 +51,15 @@ command. `<duration>` follows in the rail's colour when shown. There is no
 state word and no second badge: the rail exists so the state is still legible
 when a row is dimmed or the terminal renders the duration in the default fg.
 
-In the **web client** the rail is a 5px bar positioned inside the row's own
-indent gutter — it shifts outward with nesting depth exactly as the gutter
-does — spanning the full card height. It carries motion, reserved for states
-that need attention (DESIGN.md's "living signals" rule): a slow breathing
-opacity while `Active`, a hard blink while `AwaitingInput`, a fast flash while
-`Error`. `Idle` is solid and still, on purpose. `prefers-reduced-motion`
-leaves every state as a solid bar.
+In the **web client** the rail is a 5px bar pinned to the row's own left
+edge, square corners, spanning the full card height edge to edge — it
+shifts outward with nesting depth along with the row's own padding, since
+it is positioned relative to the row. It carries motion only for states that
+need attention (DESIGN.md's "living signals" rule): a hard blink while
+`AwaitingInput`, a fast flash while `Error`. `Active` and `Idle` are both
+solid and still — colour alone (green vs. the idle grey) is the signal for
+`Active`, so it does not also pulse. `prefers-reduced-motion` leaves every
+state as a solid bar.
 
 In the **TUI** the rail is a one-column-wide block glyph (`▌`) in the state's
 palette role, leading the existing indent gutter (`INDENT`/`META_INDENT`) on

web/src/catalog.ts

@@ -68,13 +68,11 @@ const STATE_WORDS: Record<string, string> = {
   error: "Error",
 };
 
-/** docs/SIDEBAR.md: the activity rail sits inside the row's own indent
- * gutter, so it shifts outward with nesting depth exactly as that gutter
- * does. `depth * 16 + 8` is the same expression `renderNode` uses for the
- * row's own padding — the rail sits just inside it. */
-function activityRailMarkup(slug: string, stateWord: string, depth: number): string {
-  const left = depth * 16 + 2;
-  return `<span class="activity-rail" data-activity="${slug}" style="left:${left}px" role="img" title="${escapeHtml(stateWord)}" aria-label="${escapeHtml(stateWord)}"></span>`;
+/** docs/SIDEBAR.md: the activity rail is pinned to the row's own left edge,
+ * full height. The row's own padding (`renderNode`) shifts outward with
+ * nesting depth, carrying the rail with it. */
+function activityRailMarkup(slug: string, stateWord: string): string {
+  return `<span class="activity-rail" data-activity="${slug}" role="img" title="${escapeHtml(stateWord)}" aria-label="${escapeHtml(stateWord)}"></span>`;
 }
 
 function metaLine(s: Session, now: number): string {
@@ -172,7 +170,7 @@ function renderNode(node: TreeNode, depth: number): HTMLElement {
   );
   // docs/SIDEBAR.md: line 1 reserves action width, and line 2 is unconditional.
   row.innerHTML = `
-    ${activityRailMarkup(slug, stateWord, depth)}
+    ${activityRailMarkup(slug, stateWord)}
     <span class="card-line1">
       <span class="leaf-name">${escapeHtml(name)}</span>
       <span class="leaf-actions">

web/src/styles.css

@@ -1393,23 +1393,21 @@ input.leaf-rename:focus {
   color: var(--danger);
 }
 
-/* docs/SIDEBAR.md: the activity rail replaces the old inline dot. It sits
-   inside the row's own indent gutter (`.tree-leaf` is already positioned),
-   at a `left` set inline per nesting depth — see `activityRailMarkup` in
+/* docs/SIDEBAR.md: the activity rail replaces the old inline dot. It is
+   pinned to the row's own left edge, full height, square corners — see
    catalog.ts. Idle stays solid and still on purpose: motion is reserved for
    states that need attention (DESIGN.md's "living signals" rule). */
 .activity-rail {
   position: absolute;
-  top: 4px;
-  bottom: 4px;
+  top: 0;
+  bottom: 0;
+  left: 0;
   width: 5px;
-  border-radius: 2px;
   background: currentColor;
 }
 
 .activity-rail[data-activity="active"] {
   color: var(--live);
-  animation: pulse 2.4s var(--ease-out) infinite;
 }
 .activity-rail[data-activity="idle"] {
   color: var(--border-strong);