refactor: wave 2 - split atlas, auto-update-checker, session-recovery, todo-enforcer, background-task hooks

- Extract atlas/ into 15 focused modules (hook, event handler, tool policies, types, etc.)
- Split auto-update-checker into checker/ and hook/ subdirectories with single-purpose files
- Decompose session-recovery into separate recovery strategy files per error type
- Extract todo-continuation-enforcer from monolith to directory with dedicated modules
- Split background-task/tools.ts into individual tool creator files
- Extract command-executor, tmux-utils into focused sub-modules
- Split config/schema.ts into domain-specific schema files
- Decompose cli/config-manager.ts into focused modules
- Rollback skill-mcp-manager, model-availability, index.ts splits that broke tests
- Fix all import path depths for moved files (../../ -> ../../../)
- Add explicit type annotations to resolve TS7006 implicit any errors

Typecheck: 0 errors
Tests: 2359 pass, 5 fail (all pre-existing)

src/hooks/auto-update-checker/hook/background-update-check.ts

@@ -0,0 +1,79 @@
+import type { PluginInput } from "@opencode-ai/plugin"
+import { runBunInstall } from "../../../cli/config-manager"
+import { log } from "../../../shared/logger"
+import { invalidatePackage } from "../cache"
+import { PACKAGE_NAME } from "../constants"
+import { extractChannel } from "../version-channel"
+import { findPluginEntry, getCachedVersion, getLatestVersion, updatePinnedVersion } from "../checker"
+import { showAutoUpdatedToast, showUpdateAvailableToast } from "./update-toasts"
+
+async function runBunInstallSafe(): Promise<boolean> {
+  try {
+    return await runBunInstall()
+  } catch (err) {
+    const errorMessage = err instanceof Error ? err.message : String(err)
+    log("[auto-update-checker] bun install error:", errorMessage)
+    return false
+  }
+}
+
+export async function runBackgroundUpdateCheck(
+  ctx: PluginInput,
+  autoUpdate: boolean,
+  getToastMessage: (isUpdate: boolean, latestVersion?: string) => string
+): Promise<void> {
+  const pluginInfo = findPluginEntry(ctx.directory)
+  if (!pluginInfo) {
+    log("[auto-update-checker] Plugin not found in config")
+    return
+  }
+
+  const cachedVersion = getCachedVersion()
+  const currentVersion = cachedVersion ?? pluginInfo.pinnedVersion
+  if (!currentVersion) {
+    log("[auto-update-checker] No version found (cached or pinned)")
+    return
+  }
+
+  const channel = extractChannel(pluginInfo.pinnedVersion ?? currentVersion)
+  const latestVersion = await getLatestVersion(channel)
+  if (!latestVersion) {
+    log("[auto-update-checker] Failed to fetch latest version for channel:", channel)
+    return
+  }
+
+  if (currentVersion === latestVersion) {
+    log("[auto-update-checker] Already on latest version for channel:", channel)
+    return
+  }
+
+  log(`[auto-update-checker] Update available (${channel}): ${currentVersion} → ${latestVersion}`)
+
+  if (!autoUpdate) {
+    await showUpdateAvailableToast(ctx, latestVersion, getToastMessage)
+    log("[auto-update-checker] Auto-update disabled, notification only")
+    return
+  }
+
+  if (pluginInfo.isPinned) {
+    const updated = updatePinnedVersion(pluginInfo.configPath, pluginInfo.entry, latestVersion)
+    if (!updated) {
+      await showUpdateAvailableToast(ctx, latestVersion, getToastMessage)
+      log("[auto-update-checker] Failed to update pinned version in config")
+      return
+    }
+    log(`[auto-update-checker] Config updated: ${pluginInfo.entry} → ${PACKAGE_NAME}@${latestVersion}`)
+  }
+
+  invalidatePackage(PACKAGE_NAME)
+
+  const installSuccess = await runBunInstallSafe()
+
+  if (installSuccess) {
+    await showAutoUpdatedToast(ctx, currentVersion, latestVersion)
+    log(`[auto-update-checker] Update installed: ${currentVersion} → ${latestVersion}`)
+  } else {
+    await showUpdateAvailableToast(ctx, latestVersion, getToastMessage)
+    log("[auto-update-checker] bun install failed; update not installed (falling back to notification-only)")
+  }
+}