feat(rail): sort the vertical tab rail by activity, and give its rows the home screen's card

The vertical rail lists exactly the sessions both home screens list, so it now
answers their question the same way instead of showing the raw tab order.

Order: new per-device `tabRailSort` (App Settings -> Appearance -> Tabs ->
Vertical Rail Order, default "By activity"). It runs `CodemanSessionOrder` over
rows classified by `_mobileOverviewState`, i.e. literally the home screens'
comparator, `lastSubmitAt`-anchored running group included.

It is applied as the flex `order` property, never by reordering the DOM.
`#sessionTabs` stays in `sessionOrder`, which is what keeps the Alt+N badge
honest (it names a shortcut, not a row position, so it deliberately does NOT
run 1,2,3 down a sorted rail), and keeps drag-and-drop, the arrow-key walk, the
sidebar filter and `_scrollActiveTabIntoView()` all reading the list they
always read. A session changing state then moves one inline style instead of
forcing the full rebuild that would restart every card's animation on every SSE
tick. The incremental render path re-applies it, since a state flip adds no tab
and never reaches the full rebuild, and an empty string is what clears it when
sorting stops. Web tabs are pinned past the cards by a CSS `order: 9999`, since
`renderWebviewTabs()` emits the same markup for every layout and the flex
default of 0 would interleave them. Drag is switched off while sorting (the
drop rewrites `sessionOrder` correctly and the sort puts the card straight
back, so the affordance would be a lie); 'manual' is the way back.

Cards: detailed rail rows become bordered cards on `--bg-card`, with the stamps
line on its own full-width row and the pill at its right end. The state dot
goes 6px to 9px, keeps its orbiting ring while working and gains the green
halo; idle mutes toward `--text-muted` as the home rail does. Needs/error/
waiting reuse `home-sessions-blink-red`/`-yellow` rather than a second copy.

These card rules are RAIL-SCOPED and deliberately absent from the comma-grouped
selectors that carry both vertical surfaces: the rail is an occasional,
resizable list you scan, while the sidebar is a permanently-docked nav column
where 20 stacked cards read as a wall. Every state-dot rule also excludes
`.tab-alert-action`/`.tab-alert-idle` by hand, because those alert rules are
only (0,3,0) and these are (0,5,1)+.

Lines: the lineage bracket already drew in the rail, but its track sat 6px from
the left edge, so half of its 11px outer glow was clipped by the window frame
and it read as a thread pinned to the frame. It now runs at 10px, mid-channel
in the gutter the rail already reserves.

Tests: test/tab-rail-order.test.ts (17) drives the real `isTabRailSorted()` and
`_tabRailSortOrder()` out of app.js, covering the row model (a WORKING row
ranked by `lastSubmitAt`, which would otherwise rank every running turn as
freshly started and fail no rendering test), the Alt+N badge, and the opt-out.

Verified in Chromium across sorted/manual/simple/header-strip/sidebar with the
setting flipped at runtime: no page errors, and the header strip and sidebar
render byte-identically to before.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/web/public/app.js

@@ -4027,6 +4027,71 @@ class CodemanApp {
     return this.isSessionSidebarRich() || this.isTabRailRich();
   }
 
+  /**
+   * True when the VERTICAL TAB RAIL orders its cards the way both home screens
+   * do — blocked on you first, then running longest-first, then quiet
+   * most-recently-quiet first (`CodemanSessionOrder`, constants.js) — instead of
+   * leaving them in the user's tab order.
+   *
+   * Read off <html> like the other two rail gates, because the render loop asks
+   * it once per pass and getSessionListLayout() re-parses localStorage.
+   * `tabRailSort: 'manual'` is the opt-out, and it is what a user who reorders
+   * by hand wants: a self-sorting list cannot also be drag-reorderable, so
+   * setupTabDragHandlers() drops the drag affordance while this is on rather
+   * than letting a card snap back to where the sort puts it.
+   *
+   * Deliberately NOT gated on `isTabRailRich()`: a simple rail lists the same
+   * sessions and answers the same question, it just says less about each one.
+   */
+  isTabRailSorted() {
+    const root = document.documentElement;
+    return root.getAttribute('data-tab-orientation') === 'vertical' && root.dataset.tabRailSort === 'activity';
+  }
+
+  /**
+   * Visual position per session id for the sorted rail, or null when the rail is
+   * not sorting.
+   *
+   * The sort is applied as the flex `order` property, NOT by reordering the DOM.
+   * That is the whole design: `#sessionTabs` stays in `sessionOrder`, so
+   * drag-and-drop, the Alt+N badges, the arrow-key walk, the sidebar filter and
+   * `_scrollActiveTabIntoView()` all keep reading the list they have always
+   * read, and a session changing state moves one inline style instead of
+   * forcing the full rebuild that would restart every card's animation.
+   *
+   * Rows are classified by `_mobileOverviewState()` and compared by
+   * `CodemanSessionOrder` — the same two helpers both home screens use, so the
+   * rail cannot disagree with them about what "working" means or what sorts
+   * first. `orderIndex` is the tab-strip position, which the comparator uses as
+   * its deterministic final tiebreak.
+   *
+   * Guarded like every other cross-file consumer: a stale cached constants.js or
+   * mobile-overview.js degrades to tab order rather than taking the strip down.
+   *
+   * @param {Array<string>} ids live session ids, in tab order
+   * @returns {Map<string, number>|null}
+   */
+  _tabRailSortOrder(ids) {
+    if (!this.isTabRailSorted()) return null;
+    if (!window.CodemanSessionOrder || typeof this._mobileOverviewState !== 'function') return null;
+    const rows = [];
+    for (let i = 0; i < ids.length; i++) {
+      const session = this.sessions.get(ids[i]);
+      if (!session) continue;
+      rows.push({
+        id: ids[i],
+        state: this._mobileOverviewState(session, this.pendingHooks?.get(ids[i])),
+        lastActivityAt: Number(session.lastActivityAt) || 0,
+        lastSubmitAt: Number(session.lastSubmitAt) || 0,
+        orderIndex: i,
+      });
+    }
+    const sorted = window.CodemanSessionOrder.sort(rows);
+    const out = new Map();
+    for (let i = 0; i < sorted.length; i++) out.set(sorted[i].id, i);
+    return out;
+  }
+
   /**
    * True where the sidebar is a MODAL off-canvas drawer over the terminal
    * instead of a docked column.
@@ -4648,11 +4713,21 @@ class CodemanApp {
       // Read once for the whole pass, like the full-rebuild path: this touches
       // the DOM and the loop below runs for every session on every SSE tick.
       const richRows = this.isRichTabRows();
+      // Sorted vertical rail: a state change moves a card, and this is the path
+      // that sees one — a session going working→idle never adds or removes a
+      // tab, so the full rebuild below is not reached. Recomputed per pass for
+      // the same reason the rich meta line is: the order IS the state.
+      const railSortOrder = this._tabRailSortOrder(this.sessionOrder.filter((sid) => this.sessions.has(sid)));
       // Incremental update - only modify changed properties
       for (const [id, session] of this.sessions) {
         const tab = container.querySelector(`.session-tab[data-id="${id}"]`);
         if (!tab) continue;
 
+        // An empty string clears the property, which is also what un-sorts the
+        // rail when the setting (or the layout) flips without a full rebuild.
+        const railOrder = railSortOrder?.has(id) ? String(railSortOrder.get(id)) : '';
+        if (tab.style.order !== railOrder) tab.style.order = railOrder;
+
         // A web tab owns the active state while one is open. activeSessionId stays
         // set (the terminal keeps streaming underneath, and switching back is
         // instant): only the highlight moves. Without this the debounced render
@@ -4959,10 +5034,17 @@ class CodemanApp {
     // Read once, not per session: isRichTabRows() touches the DOM and
     // this loop runs for every tab on every full rebuild.
     const richRows = this.isRichTabRows();
+    // The sorted vertical rail (tabRailSort) moves cards with the flex `order`
+    // property and leaves this loop iterating tab order, so the Alt+N badge
+    // below still counts the strip, not the sorted list. Null in every other
+    // layout, and the tabs then carry no inline order at all — the header
+    // strip's markup is byte-identical to before.
+    const railSortOrder = this._tabRailSortOrder(tabOrder.filter((id) => this.sessions.has(id)));
     let _tabIdx = 0;
     for (const id of tabOrder) {
       const session = this.sessions.get(id);
       if (!session) continue; // Skip if session was removed
+      const railOrderStyle = railSortOrder?.has(id) ? ` style="order:${railSortOrder.get(id)}"` : '';
 
       // See the note in the incremental path: a web tab owns the active highlight
       // while one is open, even though activeSessionId stays set.
@@ -5016,7 +5098,7 @@ class CodemanApp {
       const inlineSessionActions = this.shouldInlineSessionActions();
       const tabActionsHtml = `<span class="tab-actions"><span class="tab-gear" onclick="event.stopPropagation(); app.openSessionOptions(${escapeHtml(JSON.stringify(id))})" title="Session options" aria-label="Session options" tabindex="0">&#x2699;</span><span class="tab-detach" onclick="event.stopPropagation(); app.detachSession(${escapeHtml(JSON.stringify(id))})" title="Open in a new window" aria-label="Open session in a new window" tabindex="0">&#x29C9;</span><span class="tab-close" onclick="event.stopPropagation(); app.requestCloseSession(${escapeHtml(JSON.stringify(id))})" title="Close session" aria-label="Close session" tabindex="0">&times;</span><button type="button" class="tab-more" onclick="event.stopPropagation(); app.openTabRailActionMenu(event, ${escapeHtml(JSON.stringify(id))})" title="Session actions" aria-label="Session actions">&#x22EF;</button></span>`;
 
-      parts.push(`<div class="session-tab ${isActive ? 'active' : ''}${alertClass}${richClass}${loadState ? ' tab-loading' : ''}${this.hasTabDetachOverride(id) ? ' tab-show-detach' : ''}"${richData} data-id="${id}" data-color="${color}" ${loadState ? `data-load-phase="${escapeHtml(loadState.phase)}"` : ''} onclick="app.handleSessionTabClick(event, ${escapeHtml(JSON.stringify(id))})" oncontextmenu="event.preventDefault(); app.startInlineRename(${escapeHtml(JSON.stringify(id))})" tabindex="0" role="tab" aria-selected="${isActive ? 'true' : 'false'}" aria-busy="${loadState ? 'true' : 'false'}" aria-label="${escapeHtml(name)} session" ${tabTooltip ? `title="${escapeHtml(tabTooltip)}"` : ''}>
+      parts.push(`<div class="session-tab ${isActive ? 'active' : ''}${alertClass}${richClass}${loadState ? ' tab-loading' : ''}${this.hasTabDetachOverride(id) ? ' tab-show-detach' : ''}"${richData}${railOrderStyle} data-id="${id}" data-color="${color}" ${loadState ? `data-load-phase="${escapeHtml(loadState.phase)}"` : ''} onclick="app.handleSessionTabClick(event, ${escapeHtml(JSON.stringify(id))})" oncontextmenu="event.preventDefault(); app.startInlineRename(${escapeHtml(JSON.stringify(id))})" tabindex="0" role="tab" aria-selected="${isActive ? 'true' : 'false'}" aria-busy="${loadState ? 'true' : 'false'}" aria-label="${escapeHtml(name)} session" ${tabTooltip ? `title="${escapeHtml(tabTooltip)}"` : ''}>
           ${_tabIdx < 9 ? '<span class="tab-number">' + (_tabIdx + 1) + '</span>' : ''}
           ${loadState ? '<span class="tab-load-spinner" aria-hidden="true"></span>' : ''}
           <span class="tab-status ${status}" aria-hidden="true"></span>
@@ -5227,6 +5309,17 @@ class CodemanApp {
     const container = this.$('sessionTabs');
     const tabs = container.querySelectorAll('.session-tab[data-id]');
 
+    // A self-sorting list cannot also be hand-ordered: the drop below rewrites
+    // sessionOrder correctly, the sort then puts the card straight back where it
+    // was, and the user is left dragging a row that refuses to move. Drop the
+    // affordance instead of lying about it — `tabRailSort: 'manual'` is the way
+    // back to drag-reordering, and Alt+N / Ctrl+Shift+{ } still walk the strip
+    // order this list is no longer showing.
+    if (this.isTabRailSorted()) {
+      tabs.forEach((tab) => tab.setAttribute('draggable', 'false'));
+      return;
+    }
+
     tabs.forEach(tab => {
       tab.setAttribute('draggable', 'true');