Consolidate duplicate patterns and simplify codebase (#1317)

* refactor(shared): unify binary downloader and session path storage

- Create binary-downloader.ts for common download/extract logic
- Create session-injected-paths.ts for unified path tracking
- Refactor comment-checker, ast-grep, grep downloaders to use shared util
- Consolidate directory injector types into shared module

* feat(shared): implement unified model resolution pipeline

- Create ModelResolutionPipeline for centralized model selection
- Refactor model-resolver to use pipeline
- Update delegate-task and config-handler to use unified logic
- Ensure consistent model resolution across all agent types

* refactor(agents): simplify agent utils and metadata management

- Extract helper functions for config merging and env context
- Register prompt metadata for all agents
- Simplify agent variant detection logic

* cleanup: inline utilities and remove unused exports

- Remove case-insensitive.ts (inline with native JS)
- Simplify opencode-version helpers
- Remove unused getModelLimit, createCompactionContextInjector exports
- Inline transcript entry creation in claude-code-hooks
- Update tests accordingly

---------

Co-authored-by: justsisyphus <justsisyphus@users.noreply.github.com>

src/tools/ast-grep/downloader.ts

@@ -1,8 +1,15 @@
-import { existsSync, mkdirSync, chmodSync, unlinkSync } from "fs"
+import { existsSync } from "fs"
 import { join } from "path"
 import { homedir } from "os"
 import { createRequire } from "module"
-import { extractZip } from "../../shared"
+import {
+  cleanupArchive,
+  downloadArchive,
+  ensureCacheDir,
+  ensureExecutable,
+  extractZipArchive,
+  getCachedBinaryPath as getCachedBinaryPathShared,
+} from "../../shared/binary-downloader"
 import { log } from "../../shared/logger"
 
 const REPO = "ast-grep/ast-grep"
@@ -53,8 +60,7 @@ export function getBinaryName(): string {
 }
 
 export function getCachedBinaryPath(): string | null {
-  const binaryPath = join(getCacheDir(), getBinaryName())
-  return existsSync(binaryPath) ? binaryPath : null
+  return getCachedBinaryPathShared(getCacheDir(), getBinaryName())
 }
 
 
@@ -83,29 +89,12 @@ export async function downloadAstGrep(version: string = DEFAULT_VERSION): Promis
   log(`[oh-my-opencode] Downloading ast-grep binary...`)
 
   try {
-    if (!existsSync(cacheDir)) {
-      mkdirSync(cacheDir, { recursive: true })
-    }
-
-    const response = await fetch(downloadUrl, { redirect: "follow" })
-
-    if (!response.ok) {
-      throw new Error(`HTTP ${response.status}: ${response.statusText}`)
-    }
-
     const archivePath = join(cacheDir, assetName)
-    const arrayBuffer = await response.arrayBuffer()
-    await Bun.write(archivePath, arrayBuffer)
-
-    await extractZip(archivePath, cacheDir)
-
-    if (existsSync(archivePath)) {
-      unlinkSync(archivePath)
-    }
-
-    if (process.platform !== "win32" && existsSync(binaryPath)) {
-      chmodSync(binaryPath, 0o755)
-    }
+    ensureCacheDir(cacheDir)
+    await downloadArchive(downloadUrl, archivePath)
+    await extractZipArchive(archivePath, cacheDir)
+    cleanupArchive(archivePath)
+    ensureExecutable(binaryPath)
 
     log(`[oh-my-opencode] ast-grep binary ready.`)