fix(tabs): grouped rail editing review fixes

- Pointer drag: a press released outside the rail no longer lingers. The
  release is heard on window while a press is pending, a move with the
  primary button up cancels it, a new press cancels any previous drag, and
  an existing Escape listener is removed before another is added, so no
  orphaned capture listener can swallow Escape before the terminal.
- Inline group rename: a commit by blur leaves focus where the user put it;
  Enter and Escape still return focus to the header.
- A failed layout read while edits are pending keeps the held layout and the
  editor and re-reads once the write settles, so a 409 is still rebased.
  Dropping unsaved work now always says so in a toast.
- "Move to <group>" quotes the group name (with a matching zh-CN pattern), so
  a group named "New group" or "ungrouped" no longer reads or translates like
  the fixed entries.
- The group menu glyph stays visible under (hover: none).
- The sessionStorage replay copy carries { owner, baseVersion, savedAt } and is
  ignored for another owner, after 60 s, or against an older layout. A move
  with no anchor carries no index, so a replay keeps the row last.
- A 400 that survives the re-read is reported as "Could not save tab groups."
- closeTabRailActionMenu() no longer removes the group menu's DOM.
- Cancelling "Delete group" returns focus to the header.
- Stale comments updated.

docs/architecture-invariants.md

@@ -303,9 +303,9 @@ So: `_confirmIdle()` (session.ts) requires the pane to go quiet, and then asks t
 - **Collapse is per-device** (`codeman:tab-groups-collapsed` in localStorage, ids of deleted groups garbage-collected on adoption). A store that throws means all-expanded; a malformed stored VALUE reads as empty and is rewritten, so it can never disable collapse on that device for good. A collapsed group still SHOWS the active row, and `_updateActiveTabImmediate` falls through to a full render whenever the structure key changes, since a class toggle cannot reveal a hidden row.
 - **A collapsed header carries the most urgent alert it hides** (`hiddenGroupAlerts()`, applied by `_syncTabGroupHeaderAlerts` on BOTH render paths, since alerts change without a rebuild), in the tab alert language: `tab-alert-action` red, `tab-alert-idle` yellow. A permission prompt behind a collapse must never be invisible.
 - **Lineage arcs to a collapse-hidden session anchor to its group header** (`lineage-line--proxied`); two endpoints proxied to one header draw nothing.
-- **The upstream HTML5 drag stays off in the grouped rail**: a flat-order drop cannot express a group move, and the server re-ranks within the old group. The grouped rail has its OWN pointer drag instead (`_bindTabLayoutPointerDrag`, mouse/pen only, bound once on the container): rows move before/after a row or into a group, a header drag reorders groups, and the drop maps to ONE operation through the pure `dropOperation()`. Escape cancels a drag, and the click that ends one is swallowed. The flat rail and the header strip keep the HTML5 drag untouched. For the same reason Ctrl+Shift+{ / } only swaps with a neighbour in the active session's own section (`_canSwapActiveTabWith`, reading the projection's `sectionByRef`): a cross-group swap moves nothing on the server, gets no `session:orderChanged` back, and would leave this client's `sessionOrder` and Alt+N targets out of step with every other device.
-- **Edits are named operations, saved serially.** `createEditCoordinator` applies `createGroup` / `renameGroup` / `deleteGroup` / `reorderGroup` / `moveRef` to the rail at once, then sends ONE `PUT /api/tab-layout {baseVersion, layout}` at a time; edits made meanwhile wait and go out on the version that write returns. A 409 carries the server's layout: the in-flight operations are replayed onto it (an operation that no longer applies is dropped and reported) and re-sent, at most `maxAttempts` times; a 400 re-reads first; anything else reports and re-reads. A `moveRef` moves the session together with the sessions that still follow it and marks a hand-moved child `placement: 'manual'`, mirroring the server's `moveRef`, and `normalizeLayout` keeps `placement` because whole layouts are written back. `_onTabLayoutChanged` / `_applyTabLayout` defer a read while a write is in flight and rebase unsaved edits onto a read otherwise. On `pagehide`, unconfirmed operations go out in a `keepalive` PUT AND into sessionStorage; after reload they replay onto the fresh layout, which is a no-op when the keepalive landed.
-- **Every way in has a keyboard path.** The session row menu (Shift+F10 in the tree, the rail's overflow button) gains Move up/down, Move to <group>, Move to Ungrouped and Move to new group in the vertical rail (only "new group" before the first group exists; nothing on the strip). A group header opens its menu with Shift+F10 / ContextMenu, right-click or its hover glyph (a non-focusable, `aria-hidden` span: a treeitem holds no interactive children), and F2 renames it inline. The menu closes on Escape (which it consumes before the global Escape handler), a pointer outside, Tab, focus leaving it, a resize, a second open and any full re-render. The inline group editor shares `_activeRename` with the session rename, so only the CURRENT editor may release `_inlineRenameActive`.
+- **The upstream HTML5 drag stays off in the grouped rail**: a flat-order drop cannot express a group move, and the server re-ranks within the old group. The grouped rail has its OWN pointer drag instead (`_bindTabLayoutPointerDrag`, mouse/pen only, bound once on the container): rows move before/after a row or into a group, a header drag reorders groups, and the drop maps to ONE operation through the pure `dropOperation()`. Escape cancels a drag, and the click that ends one is swallowed. ⚠️ A press is only captured once it moves 6 px, so its release can land outside the rail: `pointerup`/`pointercancel` are heard on `window` while a press is pending, a move with the primary button up cancels it, and a new press cancels any previous one. Without that a stale press became a phantom drag on the next hover, and a replaced drag left its capture-phase Escape listener behind, swallowing every Escape before the terminal saw it. The flat rail and the header strip keep the HTML5 drag untouched. For the same reason Ctrl+Shift+{ / } only swaps with a neighbour in the active session's own section (`_canSwapActiveTabWith`, reading the projection's `sectionByRef`): a cross-group swap moves nothing on the server, gets no `session:orderChanged` back, and would leave this client's `sessionOrder` and Alt+N targets out of step with every other device.
+- **Edits are named operations, saved serially.** `createEditCoordinator` applies `createGroup` / `renameGroup` / `deleteGroup` / `reorderGroup` / `moveRef` to the rail at once, then sends ONE `PUT /api/tab-layout {baseVersion, layout}` at a time; edits made meanwhile wait and go out on the version that write returns. A 409 carries the server's layout: the in-flight operations are replayed onto it (an operation that no longer applies is dropped and reported) and re-sent, at most `maxAttempts` times; a 400 re-reads once (a second 400 is reported as a failed save, not as a race); anything else reports and re-reads. A `moveRef` moves the session together with the sessions that still follow it and marks a hand-moved child `placement: 'manual'`, mirroring the server's `moveRef`, and `normalizeLayout` keeps `placement` because whole layouts are written back. `_onTabLayoutChanged` / `_applyTabLayout` defer a read while a write is in flight and rebase unsaved edits onto a read otherwise. ⚠️ A FAILED read (`_applyTabLayout(null)`) while edits are pending keeps the held layout and the editor and re-reads after the write settles: disposing there would orphan the in-flight write, whose 409 then never gets its rebase. Any path that does drop unsaved work says so in a toast. On `pagehide`, unconfirmed operations go out in a `keepalive` PUT AND into sessionStorage as `{ owner, baseVersion, savedAt, operations }`; after reload they replay onto the fresh layout (a no-op when the keepalive landed), but only for the same owner, within `TAB_LAYOUT_PENDING_MAX_AGE_MS` (60 s), and never onto a layout older than the copy's base. A "Move to <group>" with no anchor carries no `index`, so a replay still puts the row last.
+- **Every way in has a keyboard path.** The session row menu (Shift+F10 in the tree, the rail's overflow button) gains Move up/down, Move to <group>, Move to Ungrouped and Move to new group in the vertical rail (only "new group" before the first group exists; nothing on the strip). A group header opens its menu with Shift+F10 / ContextMenu, right-click or its hover glyph (a non-focusable, `aria-hidden` span: a treeitem holds no interactive children), and F2 renames it inline (Enter commits and refocuses the header; a commit by BLUR leaves focus where it went, since refocusing from inside the blur handler overrides the user's click). The glyph stays visible under `@media (hover: none)`: a touch tablet has no hover and no long-press `contextmenu`. Group names in "Move to" labels are quoted, so a group named "New group" or "ungrouped" cannot read (or translate, case-insensitively) like the fixed entries. The menu closes on Escape (which it consumes before the global Escape handler), a pointer outside, Tab, focus leaving it, a resize, a second open and any full re-render. It borrows the `.tab-rail-action-menu` class for its look only: `closeTabRailActionMenu()` excludes `.tab-layout-group-action-menu`, so closing the row menu (every `session:deleted` does) cannot strand the group menu's listeners. The inline group editor shares `_activeRename` with the session rename, so only the CURRENT editor may release `_inlineRenameActive`.
 - **Only the grouped rail is a tree.** `#sessionTabs` ships as `role=tablist` with `role=tab` rows, and the header strip, sidebar and flat rail keep exactly that. While grouped, `_applyTabListRole` makes it `role=tree` (and restores `tablist` + its label when grouping ends), named-group headers are level-1 `treeitem`s that `aria-owns` their rows' `role=group` (rows sit beside the header, not inside it), and ungrouped rows plus a collapsed group's kept selection are level-1 items. A collapsed header owns nothing, a group with no open rows is a leaf (no `aria-expanded`, no owned group), and the "Ungrouped" heading is `aria-hidden`. Rows are re-roled in the DOM by `_applyTabTreeSemantics` after render, never by rewriting their markup, so a grouped row's content stays the flat row's.
 - **One tab stop in the tree.** Exactly one treeitem carries `tabindex=0` (the focused or selected item); every control inside a row drops to `-1`, which is why Shift+F10 / ContextMenu open a row's actions from the keyboard. Focus survives a full re-render by identity (`group:`/`session:`/`webview:`; a row a collapse just hid hands focus to its header), but only when focus was already inside the rail. The tree walk (`_tabTreeItems`) follows painted order WITHIN each group when the rail is sorted; the flat list keeps its own whole-list computed-order walk. `aria-posinset`/`aria-setsize` follow painted order too, so the incremental render path re-runs `_applyTabTreePositions` after it re-sorts rows in place. ⚠️ `_handleTabTreeKeydown` acts only when the key lands on the treeitem ITSELF: a key on a focused in-row control (close, overflow, the rename input) is that control's, or Enter on the overflow button re-selects the row instead of reopening its menu. ⚠️ The roving `tabindex=-1` also hides every item but the stop from the keyboard-dismiss selector's `[tabindex]` arm, which is why `MOBILE_KEYBOARD_DISMISS_EXEMPT_SELECTOR` lists `[role="treeitem"]` (see Dismissing the on-screen keyboard).