refactor: codebase audit cleanup — dead code, dedup, module splits

Multi-agent audit + aggressive cleanup across server/web/coder/booterm,
delivered behind a DEFER discipline so none of the in-flight files were
touched. Removes dead code/deps/columns, dedups server + coder helpers,
and splits the oversized modules (tools.ts, opencode-server.ts,
sentinel-summaries, turn.ts, TerminalPane.tsx) behind stable contracts.
Adds 78 parity/unit tests (server 587, coder 323); fixes two latent bugs
(ChatPane queue keys, FileViewerOverlay blank-line parity).

Intended tag: v2.7.12-audit-cleanup.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/src/components/Workspace.tsx

@@ -2,7 +2,7 @@ import { useEffect, useMemo, useState } from 'react';
 import { Terminal, Clipboard } from 'lucide-react';
 import { api } from '@/api/client';
 import type { Chat, Project, Session, WorkspacePane } from '@/api/types';
-import { MAX_PANES, activePaneChatId, type UseWorkspacePanesResult } from '@/hooks/useWorkspacePanes';
+import { activePaneChatId, type UseWorkspacePanesResult } from '@/hooks/useWorkspacePanes';
 import type { UseSessionChatsResult } from '@/hooks/useSessionChats';
 import { useViewport } from '@/hooks/useViewport';
 import { terminalsRegistry } from '@/lib/events';
@@ -32,7 +32,6 @@ interface Props {
   project: Project | null;
   /** New BooCode opens a fresh coder session; chat/terminal split in-place. */
   onAddPane: (kind: 'chat' | 'terminal' | 'coder') => void;
-  onCoderConnectedChange?: (paneId: string, connected: boolean) => void;
 }
 
 export function Workspace({
@@ -44,7 +43,6 @@ export function Workspace({
   chatsHook,
   session,
   project,
-  onCoderConnectedChange,
   onAddPane,
 }: Props) {
   const {
@@ -141,10 +139,6 @@ export function Workspace({
     return out;
   }, [panes]);
 
-  // Per-coder-pane WS connection (status dot lives in the pane header).
-  const [coderConnected, setCoderConnected] = useState<Record<string, boolean>>({});
-  const [coderLabels, setCoderLabels] = useState<Record<string, string>>({});
-
   return (
     <div className="flex flex-col h-full min-h-0">
       <div
@@ -195,41 +189,21 @@ export function Workspace({
               onDragStart={!isMobile && !isChromeless && panes.length > 1 ? handlePaneDragStart(idx) : undefined}
               onDragEnd={!isMobile && !isChromeless && panes.length > 1 ? handlePaneDragEnd : undefined}
             >
-              {/* Hidden on mobile per v1.8; settings + terminal panes own
-                  their own header (no chats, so no ChatTabBar). */}
-              {!isMobile && !isChromeless && (
+              {/* Hidden on mobile; settings/terminal/artifact panes own their
+                  own header. Chat and coder panes share this strip — tabKind
+                  and onNewTab differ between the two. */}
+              {!isMobile && (isCoder || !isChromeless) && (
                 <ChatTabBar
                   pane={pane}
                   tabs={chatsForPane(pane)}
+                  tabKind={isCoder ? 'coder' : undefined}
                   tabNumbers={tabNumbers}
                   onSwitchTab={(tabIdx) => switchTab(idx, tabIdx)}
                   onRemoveTab={(chatId) => removeTab(idx, chatId)}
                   onCloseOthers={(chatId) => closeOtherTabs(idx, chatId)}
                   onCloseToRight={(chatId) => closeTabsToRight(idx, chatId)}
                   onCloseAll={() => closeAllTabs(idx)}
-                  onNewTab={() => void createChat(idx)}
-                  onSplitPane={(kind) => onAddPane(kind)}
-                  onReopenPane={hasClosedPanes ? reopenPane : undefined}
-                  onShowHistory={() => showLandingPage(idx)}
-                  onRename={renameChat}
-                  onRemovePane={panes.length > 1 ? () => removePane(idx) : undefined}
-                />
-              )}
-              {/* Coder panes host BooCode tabs (one chat = one agent context,
-                  all sharing the session worktree). "+" adds a tab; the split
-                  button adds a pane. Same tab strip as chat panes (tabKind). */}
-              {isCoder && !isMobile && (
-                <ChatTabBar
-                  pane={pane}
-                  tabs={chatsForPane(pane)}
-                  tabKind="coder"
-                  tabNumbers={tabNumbers}
-                  onSwitchTab={(tabIdx) => switchTab(idx, tabIdx)}
-                  onRemoveTab={(chatId) => removeTab(idx, chatId)}
-                  onCloseOthers={(chatId) => closeOtherTabs(idx, chatId)}
-                  onCloseToRight={(chatId) => closeTabsToRight(idx, chatId)}
-                  onCloseAll={() => closeAllTabs(idx)}
-                  onNewTab={() => void createCoderTab(idx)}
+                  onNewTab={isCoder ? () => void createCoderTab(idx) : () => void createChat(idx)}
                   onSplitPane={(kind) => onAddPane(kind)}
                   onReopenPane={hasClosedPanes ? reopenPane : undefined}
                   onShowHistory={() => showLandingPage(idx)}
@@ -296,17 +270,6 @@ export function Workspace({
                   chatId={activePaneChatId(pane)}
                   chatPending={isPaneChatPending(pane.id)}
                   projectPath={project?.path}
-                  onConnectedChange={(connected) => {
-                    setCoderConnected((prev) =>
-                      prev[pane.id] === connected ? prev : { ...prev, [pane.id]: connected },
-                    );
-                    onCoderConnectedChange?.(pane.id, connected);
-                  }}
-                  onAgentLabelChange={(label) =>
-                    setCoderLabels((prev) =>
-                      prev[pane.id] === label ? prev : { ...prev, [pane.id]: label },
-                    )
-                  }
                 />
               ) : pane.kind === 'markdown_artifact' && pane.markdown_artifact_state ? (
                 <MarkdownArtifactPane