docs: UI-audit fixes in CLAUDE.md, API, OpenAPI, LANES and READMEs

New params and errors (agents session_ids, sessions awaiting/from/to,
stats tool counts, event labels, cleanup dry_run/INVALID_PURGE_DAYS, lane
start slot auto/ESESSIONLIVE/EUNSUPPORTED), terminal and pane shortcuts,
the shared UI primitives, accent vs accent-solid, lazy routes and the
Settings groups. openapi.yaml regenerated.

docs/LANES.md

@@ -404,8 +404,9 @@ The dashboard web UI merges workspaces and runs into a single **Workspace** page
 - **No header row** — the session view has no header of its own: the console's tab bar is it (status, the workspace's name and the back arrow are gone — the name is on the sidebar row and the home). Only a workspace with an installed pipeline template shows its time-on-stage, pipeline picker and feature picker above the console; there are no stage chips — the declared stage and the `auto: <stage>` detection both render in the PipelineMap. While one pane is shown, its split right/down menus sit at the right end of the tab bar; each offers **New terminal** and the same AI tools as the `+` menu. The detail block (the workspace card, the PipelineMap, the proof gallery) is always shown, and Delete lives in the sidebar row menu. There is no Tools menu any more: MCP sync and the sync-base check are the CLI's `agenthub lanes mcp sync` and `agenthub lanes sync-base`, and a readme refresh is a skill typed into a session.
 - **Detail panel** — the selected workspace's declared stage, its inferred stage when detection leads, a full-width pipeline map, and a legend naming all five node states plus the dashed-amber inferred treatment Hidden while no pipeline template is installed (see "Pipeline stages and the five node states").
 - **Terminal** — a real interactive terminal (xterm.js) displaying the tmux session's PTY output, with full support for interactive commands, editors, and pagers. A live run keeps its rendered history and scroll position when scrolling. It grabs the keyboard the moment it appears, so typing goes into the pane without clicking it first. A pane has **no run form of its own**: a session with a prompt starts from the workspace home's prompt box. There is no **New run** button: when a pane's process ends (a double Ctrl+C out of `claude`, `exit`, a crash) its pane closes; the last one shows the next open tab, or the home when none is left. A pane with nothing to show offers **New session**, which opens the home too.
+  Keyboard: the terminal keeps Tab and Shift+Tab (`claude` cycles its permission mode on Shift+Tab), so **Ctrl+M** toggles *Tab moves focus* — VS Code's way out of its terminal — and Tab then leaves the pane; **Cmd+F** (macOS) / **Ctrl+Shift+F** opens a find bar. URLs open in a new tab; a selection tmux copies (OSC 52) lands in the browser clipboard, and that path is write-only — nothing in the pane can read your clipboard. `agenthub.terminal.screenReader` = `"1"` in `localStorage` turns on xterm's screen-reader mode. While the socket is down a **Reconnecting…** overlay says keystrokes are not reaching the pane; it re-attaches by itself. In the session view, outside a terminal or a text field, `Alt+1`–`Alt+4` focuses pane 1–4, `Alt+\` splits the focused pane right with a new terminal, and `Alt+W` closes the focused pane (its session stays a tab).
 - **Clipboard in a pane** — the workspace's tmux session is started with the graphical session's own `DISPLAY`/`WAYLAND_DISPLAY`/`XAUTHORITY`/`XDG_RUNTIME_DIR` (read from `systemctl --user show-environment`, this process's own values winning; `server/lib/desktop-env.js`). The dashboard normally runs as a systemd *user* service, which has none of them, so a pane it started had no clipboard at all and `claude` answered "no image found in clipboard" on every image paste while the same CLI pasted fine in a terminal. Only those four names are forwarded, and only into panes this dashboard spawns — an already-running pane keeps the environment it was started with, so it needs a restart to gain one.
-- **Tabs** — the session view's console is a tab bar (`client/src/components/run/ConsoleTabs.tsx`), one tab per live tmux session of the workspace — at most four, its slots 0–3: slot 0 is the workspace's `agenthub-lane-<id>` (its `run_id`), slots 1–3 are `agenthub-lane-<id>-<slot>`. A tab shows its AI tool's icon and name (or **Terminal**); the active tab is the focused pane's, which is the URL's `?run=`, so the Changes panel and Analyst follow it, and a tab another pane shows carries a grey underline. A click shows a tab in the focused pane (or focuses the pane already showing it), **Ctrl/Cmd+click** — on a tab or on a `+` item — opens it in a split, and a tab drags onto the panes. Every tab with a live run stays mounted and those no pane shows are hidden with CSS, so switching tabs never drops a terminal. A tab's **×** stops its session (`DELETE /api/run/<runId>`) and closes its pane; with no pane left it moves to the next tab, or the home. The **+** menu opens a new tab in the first free slot: **New terminal** (your own default shell in the workspace folder — `POST /api/lanes/:id/start {slot, shell: true}`, recorded as tool `shell`; it is not an agent, so the workspace's `run_id`/`status` are left alone), each installed, enabled AI tool (started bare, on its default model, no prompt), and **Agent settings…** (Settings → Agents). With four tabs open **+** is disabled. EVERY tab is bound to the sidebar's selection. A tab has no header of its own (no title, no **Active runs** list, no **New run**): other sessions are opened from the sidebar or the home's Recents. (The old fixed 1/2/4 split layout and its `agenthub.workspace.splitView` key are gone; **Split panes** replaces them.)
+- **Tabs** — the session view's console is a tab bar (`client/src/components/run/ConsoleTabs.tsx`), one tab per live tmux session of the workspace — at most four, its slots 0–3: slot 0 is the workspace's `agenthub-lane-<id>` (its `run_id`), slots 1–3 are `agenthub-lane-<id>-<slot>`. A tab shows its AI tool's icon and name (or **Terminal**); the active tab is the focused pane's, which is the URL's `?run=`, so the Changes panel and Analyst follow it, and a tab another pane shows carries a grey underline. A click shows a tab in the focused pane (or focuses the pane already showing it), **Ctrl/Cmd+click** — on a tab or on a `+` item — opens it in a split, and a tab drags onto the panes. Every tab with a live run stays mounted and those no pane shows are hidden with CSS, so switching tabs never drops a terminal. A tab's **×** stops its session (`DELETE /api/run/<runId>`) and closes its pane; with no pane left it moves to the next tab, or the home. The **+** menu opens a new tab in the first free slot, which the server picks (`slot: "auto"`, under the workspace lock): **New terminal** (your own default shell in the workspace folder — `POST /api/lanes/:id/start {slot, shell: true}`, recorded as tool `shell`; it is not an agent, so the workspace's `run_id`/`status` are left alone), each installed, enabled AI tool (started bare, on its default model, no prompt), and **Agent settings…** (Settings → Agents). With four tabs open **+** is disabled. EVERY tab is bound to the sidebar's selection. A tab has no header of its own (no title, no **Active runs** list, no **New run**): other sessions are opened from the sidebar or the home's Recents. (The old fixed 1/2/4 split layout and its `agenthub.workspace.splitView` key are gone; **Split panes** replaces them.)
 
 - **Split panes** — the console splits like VS Code (`client/src/components/run/PaneGrid.tsx`, model in `client/src/lib/paneLayout.ts`): a binary tree of splits, each side by side or stacked at a ratio, whose leaves are the workspace's slots — at most four panes, one per live session, a session never shown twice. **Ctrl/Cmd+click** a tab, a `+` item or a sidebar session row opens it to the right of the focused pane (the intent rides on the navigation's state, never in the URL); with more than one pane each gets a slim header: **drag** it (or a tab) onto another pane — its edge splits there, its middle swaps the two —, its **▾** shows another live session in it (swapping with the pane that showed it), **Split right / Split down** puts a not-shown session or a **New terminal** beside it, and **×** closes the pane only (its session stays a tab). Dividers drag (or move by arrow keys) between 10% and 90%. Clicking in (or tabbing into) a pane focuses it, `?run=` follows — so the right panel, Analyst and the sidebar read the focused session — and the keyboard goes with it: only the focused pane's terminal takes it when it appears. A pane closes when its terminal reports that its session ended (exited, closed from another browser); the run list itself only prunes a remembered layout on a workspace's first read, and a pane opened here whose session never got listed — one empty read, which the server returns on any tmux error, never wipes a split. A session ending while the home or a replay is shown only closes its pane; the URL stays. The layout is a viewer preference kept per workspace in `localStorage` (`agenthub.workspace.paneLayout`), never on the server. Every pane is an absolutely placed sibling keyed by its slot, so splitting, swapping or resizing never re-parents — and so never remounts — a live terminal; the session view itself fills the page edge to edge, its tab bar and the right panel's activity bar one header strip.
 - **Workspace grid** — one card per workspace, 1 column, 2 at `md`, 3 at `xl`. Each card carries the workspace id, liveness dot and status, title, declared stage and time-on-stage, the `auto:` chip when detection leads, the kind and CI tags, the working-copy facts from `GET /api/lanes/:id/git`, and the action row. The needs-you message (`needs_action`) is on the workspace list tile only — the detail card no longer repeats it as a banner.
@@ -416,7 +417,9 @@ Run history is per workspace, queryable via `GET /api/run/history?laneId=<n>`.
 
 **Start and Resume are create-or-reuse, and never silently swallow the request.** When the workspace's `agenthub-lane-<id>` tmux session does not exist, it is created with the full argv. When it exists but its pane is sitting at a **shell prompt** (a `agenthub lanes shell` you opened, or a `claude` that has since exited), the argv is typed into that pane — so `--resume` really runs, and an initial prompt really lands, in the session you are already looking at. Only when the pane is running something (a live `claude`, an editor, a build) is the request adopted as-is: attaching shows you what is running rather than typing over it. Before this, an existing session was always adopted silently, so the first Resume after a `agenthub lanes shell` answered `200` while doing nothing at all.
 
-**A workspace whose `run_id` still points at a live run refuses a second Start/Resume outright** — `POST /api/lanes/:id/start` answers `409 ERUNLIVE` rather than typing a new prompt or `--resume` over a session that is still in flight. The dashboard starts a session only in a slot with no live run (the home, a resume and the tab bar's `+` all take the first free one), and a tab's **×** is what frees a slot (`DELETE /api/run/:id`); the workspace's own `run_id`/`status` self-heal to idle the next time anything reads the workspace (`healRunId` in `routes/lanes.js`), so no separate workspace-side call is needed.
+**A workspace whose `run_id` still points at a live run refuses a second Start/Resume outright** — `POST /api/lanes/:id/start` answers `409 ERUNLIVE` rather than typing a new prompt or `--resume` over a session that is still in flight. The dashboard starts a session only in a slot with no live run (the home, a resume and the tab bar's `+` all send `slot: "auto"`, so the SERVER picks the first free one under the workspace lock; `409 ERUNLIVE` when all four are busy), and a tab's **×** is what frees a slot (`DELETE /api/run/:id`); the workspace's own `run_id`/`status` self-heal to idle the next time anything reads the workspace (`healRunId` in `routes/lanes.js`), so no separate workspace-side call is needed.
+
+**A session is open in at most one tab.** A resume (`resumeSessionId`, or `resume`) of a session a live pane already holds answers `409 ESESSIONLIVE` with that pane's `run_id` instead of starting a second agent on the same transcript — open that pane instead. A **Fork** makes a new session and is allowed. A catalog tool other than Claude/Codex cannot resume a session by id (`400 EUNSUPPORTED`).
 
 The UI operates on a working directory (`cwd`), not a workspace id. Starting a run in a `cwd` that no workspace owns calls `POST /api/lanes/ensure` first, to idempotently find or adopt a workspace for that path; a `cwd` an existing workspace already owns is matched from the loaded workspace list without a round trip. Either way the run is then started through `POST /api/lanes/:id/start` rather than directly through `POST /api/run`.
 
@@ -601,7 +604,7 @@ the editor (Whole file toggles back to its diff; a commit still opens as a diff)
 Edit click, **Save**/**Cancel** stay and wake up once the text differs, Cancel
 restores the saved text) → closed (`agenthub.workspace.changesSize`
 alongside `agenthub.workspace.changesOpen`); the collapsed rail reopens it
-narrow. A stored size from an older build that no longer exists (`wide`) falls back to narrow. Reading a diff and watching a console want opposite amounts of room and
+narrow. Between the console and the open (not full-screen) panel sits a **splitter**: drag it, or move it with the arrow keys, to any width between 15% and 85%; that fraction is stored as a NUMBER in the same `agenthub.workspace.changesSize` key, and the header button still steps through the presets. A stored size from an older build that no longer exists (`wide`) falls back to narrow. Reading a diff and watching a console want opposite amounts of room and
 which one is "work" changes several times an hour, so the width is a step, not
 a setting — and one button beats a width button wedged beside a collapse button
 in the panel's tightest corner. It is icon-only, and the icon it draws is the