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.

apps/web/src/components/ToolCallLine.tsx

@@ -1,8 +1,7 @@
 import { useState } from 'react';
-import type { ReactNode } from 'react';
 import { Check, ChevronRight, Loader2, X } from 'lucide-react';
 import type { ToolCall, ToolResult } from '@/api/types';
-import { sessionEvents } from '@/hooks/sessionEvents';
+import { linkifyPaths } from '@/lib/linkify-paths';
 
 // v1.8.2: cap on the inline arg-summary length. Expanded view shows full
 // args + full result, so this is purely a single-line render budget.
@@ -22,7 +21,7 @@ function truncate(s: string, n: number): string {
 // Per-tool argument summary mapping from the v1.8.2 spec. Goal is a single
 // scannable line that surfaces the *what* (path / pattern) without
 // overwhelming the chat with full JSON.
-export function formatToolArgs(name: string, args: Record<string, unknown>): string {
+function formatToolArgs(name: string, args: Record<string, unknown>): string {
   if (name === 'view_file') {
     const path = String(args.path ?? '');
     const start = args.start_line;
@@ -98,36 +97,8 @@ export function runStatus(run: ToolRun): 'pending' | 'success' | 'error' {
   return 'success';
 }
 
-// Path-shaped paths in tool output text get a click handler so users can
-// jump to the file. Same heuristic as MessageBubble.linkifyPaths.
-const PATH_REGEX = /([a-zA-Z0-9._/-]+\.[a-zA-Z0-9]+)/g;
-function linkifyOutput(text: string): ReactNode[] {
-  const out: ReactNode[] = [];
-  let lastIdx = 0;
-  let idx = 0;
-  for (const match of text.matchAll(PATH_REGEX)) {
-    const matchedText = match[0];
-    const start = match.index ?? 0;
-    if (!matchedText.includes('/')) continue;
-    if (start > lastIdx) out.push(text.slice(lastIdx, start));
-    out.push(
-      <button
-        key={idx}
-        type="button"
-        onClick={() =>
-          sessionEvents.emit({ type: 'open_file_in_browser', path: matchedText })
-        }
-        className="text-primary underline cursor-pointer hover:text-primary/80"
-      >
-        {matchedText}
-      </button>
-    );
-    lastIdx = start + matchedText.length;
-    idx += 1;
-  }
-  if (lastIdx < text.length) out.push(text.slice(lastIdx));
-  return out.length > 0 ? out : [text];
-}
+// Path-shaped substrings in tool output get a click handler via the shared
+// linkifyPaths util (lib/linkify-paths.tsx).
 
 interface Props {
   run: ToolRun;
@@ -189,7 +160,7 @@ export function ToolCallLine({ run, insideGroup }: Props) {
               {run.result.error ? (
                 <span className="text-destructive">{run.result.error}</span>
               ) : (
-                linkifyOutput(
+                linkifyPaths(
                   typeof run.result.output === 'string'
                     ? run.result.output
                     : JSON.stringify(run.result.output, null, 2)