perf(hooks,tools): optimize string operations and reduce redundant iterations

- output-renderer, hashline-edit-diff: replace str += with array join (H2)
- auto-slash-command: single-pass Map grouping instead of 6x filter (M1)
- comment-checker: hoist Zod schema to module scope (M2)
- session-last-agent: reverse iterate sorted array instead of sort+reverse (L2)

src/hooks/atlas/session-last-agent.ts

@@ -18,9 +18,9 @@ function getLastAgentFromMessageDir(messageDir: string): string | null {
     const files = readdirSync(messageDir)
       .filter((fileName) => fileName.endsWith(".json"))
       .sort()
-      .reverse()
 
-    for (const fileName of files) {
+    for (let i = files.length - 1; i >= 0; i--) {
+      const fileName = files[i]
       try {
         const content = readFileSync(join(messageDir, fileName), "utf-8")
         const parsed = JSON.parse(content) as { agent?: unknown }

src/hooks/auto-slash-command/executor.ts

@@ -44,12 +44,6 @@ export interface ExecutorOptions {
   agent?: string
 }
 
-function filterDiscoveredCommandsByScope(
-  commands: DiscoveredCommandInfo[],
-  scope: DiscoveredCommandInfo["scope"],
-): DiscoveredCommandInfo[] {
-  return commands.filter(command => command.scope === scope)
-}
 
 async function discoverAllCommands(options?: ExecutorOptions): Promise<CommandInfo[]> {
   const discoveredCommands = discoverCommandsSync(process.cwd(), {
@@ -60,14 +54,18 @@ async function discoverAllCommands(options?: ExecutorOptions): Promise<CommandIn
   const skills = options?.skills ?? await discoverAllSkills()
   const skillCommands = skills.map(skillToCommandInfo)
 
+  const scopeOrder: DiscoveredCommandInfo["scope"][] = ["project", "user", "opencode-project", "opencode", "builtin", "plugin"]
+  const grouped = new Map<string, DiscoveredCommandInfo[]>()
+  for (const cmd of discoveredCommands) {
+    const list = grouped.get(cmd.scope) ?? []
+    list.push(cmd)
+    grouped.set(cmd.scope, list)
+  }
+  const orderedCommands = scopeOrder.flatMap((scope) => grouped.get(scope) ?? [])
+
   return [
     ...skillCommands,
-    ...filterDiscoveredCommandsByScope(discoveredCommands, "project"),
-    ...filterDiscoveredCommandsByScope(discoveredCommands, "user"),
-    ...filterDiscoveredCommandsByScope(discoveredCommands, "opencode-project"),
-    ...filterDiscoveredCommandsByScope(discoveredCommands, "opencode"),
-    ...filterDiscoveredCommandsByScope(discoveredCommands, "builtin"),
-    ...filterDiscoveredCommandsByScope(discoveredCommands, "plugin"),
+    ...orderedCommands,
   ]
 }
 

src/hooks/comment-checker/hook.ts

@@ -3,6 +3,18 @@ import type { CommentCheckerConfig } from "../../config/schema"
 
 import z from "zod"
 
+const ApplyPatchMetadataSchema = z.object({
+  files: z.array(
+    z.object({
+      filePath: z.string(),
+      movePath: z.string().optional(),
+      before: z.string(),
+      after: z.string(),
+      type: z.string().optional(),
+    }),
+  ),
+})
+
 import {
   initializeCommentCheckerCli,
   getCommentCheckerCliPathPromise,
@@ -104,17 +116,6 @@ export function createCommentCheckerHooks(config?: CommentCheckerConfig) {
         return
       }
 
-      const ApplyPatchMetadataSchema = z.object({
-        files: z.array(
-          z.object({
-            filePath: z.string(),
-            movePath: z.string().optional(),
-            before: z.string(),
-            after: z.string(),
-            type: z.string().optional(),
-          }),
-        ),
-      })
 
       if (toolLower === "apply_patch") {
         const parsed = ApplyPatchMetadataSchema.safeParse(output.metadata)