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/MarkdownRenderer.tsx

@@ -2,53 +2,13 @@
 // in-chat bubble renderer and the MarkdownArtifactPane share the same Shiki +
 // remark-gfm + path-linkifier pipeline. Behavior preserved byte-for-byte from
 // the original MessageBubble.MarkdownBody helper (and its linkify helpers).
-import { Children, cloneElement, isValidElement } from 'react';
+import { memo, Children, cloneElement, isValidElement } from 'react';
 import type { ReactElement, ReactNode } from 'react';
 import Markdown from 'react-markdown';
+import type { Components } from 'react-markdown';
 import remarkGfm from 'remark-gfm';
 import { CodeBlock } from './CodeBlock';
-import { sessionEvents } from '@/hooks/sessionEvents';
-
-// Match path-shaped substrings ending in `.ext`. Additionally require a `/`
-// in the match to reduce false positives in prose (e.g. plain `foo.ts` won't
-// match, but `src/foo.ts` will). False positives at the edges are accepted
-// per Sam's design decision (2026-05-14).
-const PATH_REGEX = /([a-zA-Z0-9._/-]+\.[a-zA-Z0-9]+)/g;
-
-function isPathLike(s: string): boolean {
-  return s.includes('/');
-}
-
-function emitOpenFile(path: string): void {
-  sessionEvents.emit({ type: 'open_file_in_browser', path });
-}
-
-function linkifyPaths(text: string, keyPrefix: 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 (!isPathLike(matchedText)) continue;
-    if (start > lastIdx) out.push(text.slice(lastIdx, start));
-    out.push(
-      <button
-        key={`${keyPrefix}-${idx}`}
-        type="button"
-        onClick={() => emitOpenFile(matchedText)}
-        className="text-primary underline cursor-pointer hover:text-primary/80"
-      >
-        {matchedText}
-      </button>
-    );
-    lastIdx = start + matchedText.length;
-    idx += 1;
-  }
-  if (out.length === 0) return text;
-  if (lastIdx < text.length) out.push(text.slice(lastIdx));
-  return out;
-}
+import { linkifyPaths } from '@/lib/linkify-paths';
 
 function linkifyChildren(children: ReactNode, keyPrefix = 'l'): ReactNode {
   const arr = Children.toArray(children);
@@ -92,57 +52,58 @@ const codeRenderer = (props: { children?: unknown; className?: string }) => {
   );
 };
 
-export function MarkdownRenderer({ content }: { content: string }) {
-  return (
-    <Markdown
-      remarkPlugins={[remarkGfm]}
-      components={{
-        pre: ({ children }) => <>{children}</>,
-        code: codeRenderer,
-        a: ({ children, href }) => (
-          <a
-            href={href}
-            target="_blank"
-            rel="noreferrer"
-            className="underline decoration-muted-foreground/40 underline-offset-2 hover:decoration-foreground"
-          >
-            {children}
-          </a>
-        ),
-        ul: ({ children }) => (
-          <ul className="list-disc pl-5 space-y-1">{children}</ul>
-        ),
-        ol: ({ children }) => (
-          <ol className="list-decimal pl-5 space-y-1">{children}</ol>
-        ),
-        li: ({ children }) => <li>{linkifyChildren(children)}</li>,
-        p: ({ children }) => (
-          <p className="leading-relaxed">{linkifyChildren(children)}</p>
-        ),
-        h1: ({ children }) => <h1 className="text-base font-semibold mt-2">{children}</h1>,
-        h2: ({ children }) => <h2 className="text-sm font-semibold mt-2">{children}</h2>,
-        h3: ({ children }) => <h3 className="text-sm font-semibold mt-1">{children}</h3>,
-        blockquote: ({ children }) => (
-          <blockquote className="border-l-2 border-border pl-3 text-muted-foreground">
-            {children}
-          </blockquote>
-        ),
-        table: ({ children }) => (
-          <div className="overflow-x-auto">
-            <table className="border-collapse text-xs">{children}</table>
-          </div>
-        ),
-        th: ({ children }) => (
-          <th className="border border-border px-2 py-1 text-left font-medium">{children}</th>
-        ),
-        td: ({ children }) => (
-          <td className="border border-border px-2 py-1">
-            {linkifyChildren(children)}
-          </td>
-        ),
-      }}
+// Hoisted to module level — closes over nothing render-scoped, so a stable
+// reference avoids react-markdown reconstructing its vdom on every token delta.
+const MARKDOWN_COMPONENTS: Components = {
+  pre: ({ children }) => <>{children}</>,
+  code: codeRenderer,
+  a: ({ children, href }) => (
+    <a
+      href={href}
+      target="_blank"
+      rel="noreferrer"
+      className="underline decoration-muted-foreground/40 underline-offset-2 hover:decoration-foreground"
     >
+      {children}
+    </a>
+  ),
+  ul: ({ children }) => (
+    <ul className="list-disc pl-5 space-y-1">{children}</ul>
+  ),
+  ol: ({ children }) => (
+    <ol className="list-decimal pl-5 space-y-1">{children}</ol>
+  ),
+  li: ({ children }) => <li>{linkifyChildren(children)}</li>,
+  p: ({ children }) => (
+    <p className="leading-relaxed">{linkifyChildren(children)}</p>
+  ),
+  h1: ({ children }) => <h1 className="text-base font-semibold mt-2">{children}</h1>,
+  h2: ({ children }) => <h2 className="text-sm font-semibold mt-2">{children}</h2>,
+  h3: ({ children }) => <h3 className="text-sm font-semibold mt-1">{children}</h3>,
+  blockquote: ({ children }) => (
+    <blockquote className="border-l-2 border-border pl-3 text-muted-foreground">
+      {children}
+    </blockquote>
+  ),
+  table: ({ children }) => (
+    <div className="overflow-x-auto">
+      <table className="border-collapse text-xs">{children}</table>
+    </div>
+  ),
+  th: ({ children }) => (
+    <th className="border border-border px-2 py-1 text-left font-medium">{children}</th>
+  ),
+  td: ({ children }) => (
+    <td className="border border-border px-2 py-1">
+      {linkifyChildren(children)}
+    </td>
+  ),
+};
+
+export const MarkdownRenderer = memo(function MarkdownRenderer({ content }: { content: string }) {
+  return (
+    <Markdown remarkPlugins={[remarkGfm]} components={MARKDOWN_COMPONENTS}>
       {content}
     </Markdown>
   );
-}
+});