tracking(workbar): replace the hand-written tab strip with TabList, and close the panel gaps that are left

[Astro-Han]

Why this issue is being rewritten

The original body was written just after #2158 and described the workbar as "eight apps in a tab strip". Most of what it asked for has since landed through the panel PRs, so I re-checked every work item against main before rewriting it. Six of the eleven items were already done or rested on a premise that no longer held, so each of them would have opened as an empty PR.

Updated after #4789. PR 1 has landed and its four measured defects are closed. PR 2 shrank: the Task face is retired, so half of it no longer exists. PR 4's floor moved with the panel's. What is left is below, with the measurements that back it.

Everything marked measured comes from a live renderer or the built Storybook rather than from reading the CSS.

Problem

The workbar column is composed from Astryx primitives — panels already use Section, Banner, EmptyState, Toolbar, Collapsible, and the resize edges are Astryx ResizeHandle. The tab strip was the exception: .maka-workbar-tab* in styles/workbar/shell.css plus roughly 200 lines of workbar-surface.tsx re-implemented a tab strip that @astryxdesign/core/TabList already ships, and four measured defects were all consequences of that re-implementation.

That is done — see PR 1 below for what each defect measured before and after. The panel gaps that remain are the ones this tracker still exists for.

Goal

One tab strip, owned by TabList, and no panel left drawing chrome the design system already ships.

This supersedes the direction recorded as A3 in docs/frontend-architecture-astryx-review-2026-08-09.md ("keep custom tab strip (dnd + role=tab is justified)"). Both halves of that justification are gone: role=tab is TabList's, and drag-to-reorder was dropped rather than rebuilt — faces are opened from one menu and the strip's order is the order they were opened in.

Plan

Three PRs left. They open flat off main and touch disjoint files, so none blocks another. Each carries BEFORE/AFTER Storybook captures (light and dark) from the Product/Session Workbar story group.

PR 1 — Shell: the tab strip becomes TabList — done (#4789)

workbar-surface.tsx, styles/workbar/shell.css, workbar-toggle.tsx. WorkbarTabStrip and SortableWorkbarTab are gone, .maka-workbar-tab* with them, and dnd-kit left the dependency tree. Net deletion.

• .maka-workbar-tab* gone; neither WorkbarTabStrip nor SortableWorkbarTab exists.
• The strip scrolls inside itself instead of pushing the trailing controls off the edge. Measured: three faces at the 340px floor need 284px against 256px available, scrolls: true, [+] on screen. The "264px hole" was this defect's symptom — the strip's container had no min-width: 0, so it spilled rather than scrolled. [+] and the collapse toggle stay at the bar's trailing edge by design, the way the launcher mockups settled it.
• A hovered unselected tab is distinguishable from the selected tab, in both themes, and selection carries exactly one marker. Measured: selected is weight 600 with no fill plus TabList's rail; unselected is weight 400 and takes a background on hover. The old rule gave both --state-hover-bg.
• Tab, [+] and collapse report one height. Measured: 28 / 28 / 28 (was 28 / 28 / 32). WorkbarToggle was hard-wired to md; it takes a size now and the bar passes sm.
• Left and right padding are equal where the platform reserves nothing. Measured: 8px / 8px (was 8px / 24px). The right pad was --space-6, borrowed from the window titlebar strip, which measures from the window edge — this bar starts a content-area gap inside it.
• The renderer ledger does not rise.

Two things changed shape rather than being preserved, and both were deliberate:

• Drag-to-reorder, preview/pin and the tab context menu are gone. Tab renders endContent inside its own <button>, so a per-tab close would nest a button in a button; opening and closing share the [+] menu instead. Nothing in the renderer ever set preview: true, so that state was dead code with no producer.
• The Task face is retired, folded into Work Board separately. Its renderer read path went with it; todo:read and querySessionTodo stay as the boundary Work Board will read through.

PR 2 — Work Board rows on the List idiom

apps/desktop/src/renderer/work-board-panel.tsx and its CSS. This was a two-panel PR; the Tasks half is gone with the face, so what remains is Work Board alone — and with it, the shared-status-vocabulary requirement, which had only one consumer left.

Done when:

• The panel's rows are on the List idiom; the hand-written <ul>/<li> is gone, and .maka-work-board-archived-tag with it.
• Status is carried by StatusDot, whose label is required — so a screen reader reads every row's status, which today it cannot: the status is a lucide icon marked aria-hidden="true" beside plain text.
• The empty state is clean tier 2 per DESIGN.md §10 — icon + title + description, no action. It is missing description today, which lands it between tiers.

PR 3 — One failure vocabulary

session-terminal-panel.tsx, quote-companion-panel.tsx. Small and self-contained.

Done when:

• Terminal and Side Chat each state a failure as a Banner with a labelled retry beside it, the way Review already does.
• All panels' failure states have the same shape: a Banner, a status, and a way back.

PR 4 — Files at the panel's floor and at 400px

artifact-pane.tsx plus a new artifacts fixture scenario. The fixture and the verification are one change — without seeded artifacts the panel renders empty and neither defect can be observed.

Done when:

• An artifacts fixture scenario exists and renders a populated Files panel.
• At 340px — the floor since fix(desktop): rebuild the workbar shell on TabList and one open/close control #4789, up from 320 — the filename and size rects do not intersect, asserted rather than inspected.
• At 400px a diff scrolls inside its own container and the panel itself does not scroll horizontally.
• If both defects turn out to be already fixed, this PR is the fixture alone and the finding is recorded here.

Already done — removed from this tracker

Recorded here so nobody re-opens them.

Original item	Current state
Column plate on --surface-raised, one separator	Already so: --agents-content-area-bg resolves to var(--surface-raised) (reference-shell.css), with no fill+border+shadow stack
Resize handle on tokens; drop undeclared --maka-*	Astryx ResizeHandle; --maka-session-workbar-width and --maka-session-bottom-panel-height are set inline by workbar-host.tsx, --maka-plate-titlebar-clearance is declared in shell-layout.css. Nothing falls back
Review — rows on List/Item, header as MetadataList	CollapsibleGroup hasDividers density="compact" role="list" + Collapsible role="listitem", which List cannot replace: the row expands to a diff. Failure and empty states are Banner / EmptyState
Browser — audit URL field, loading, blocked	Toolbar + TextInput + EmptyState + Tooltip; loading swaps refresh for stop
Terminal — header and states, no bespoke chrome	There is no header to retire, and the states are Banner / EmptyState
Side Chat — close confirmation on Dialog/Button; quote chip overrides to themeProps	Confirmation is Dialog + DialogHeader + Layout + CheckboxInput. No xstyle or inline-style overrides remain on the quote chip
Tasks panel — rows on List, status on StatusDot	The face is retired (#4789). Its ledger is folded into Work Board, tracked there

Out of scope

Panel behaviour and data flow (apps/desktop/src/renderer/features/workbar/README.md); AppShell composition (#4582); WorkHub (#3492). Folding SessionTodo into Work Board needs its own issue — it is a schema change (Work Board has no session scope, agent_suggestion requires confirmedAt, and the two carry different state vocabularies), not a chrome one. Splitting static tool kinds from resource-backed tabs (terminal:*, side-chat:*) is the other half of A3 and also needs its own issue.

Refs #2158, #4400, #4582, #4679, #4789

[Phoenix500526]

Can I have a try on this ?