fix(session-notification): revert PR #543 and add proper notification plugin conflict detection (#575)

* revert: undo PR #543 changes (bun shell GC crash was misdiagnosed)

This reverts commit 4a38e70 (PR #543) and 2064568 (follow-up fix).

## Why This Revert

The original diagnosis was incorrect. PR #543 assumed Bun's
ShellInterpreter GC bug was causing Windows crashes, but further
investigation revealed the actual root cause:

**The crash occurs when oh-my-opencode's session-notification runs
alongside external notification plugins (e.g., @mohak34/opencode-notifier).**

Evidence:
- User removed opencode-notifier plugin → crashes stopped
- Release version (with original ctx.$ code) works fine when used alone
- No widespread crash reports from users without external notifiers
- Both plugins listen to session.idle and send concurrent notifications

The real issue is a conflict between two notification systems:
1. oh-my-opencode: ctx.$ → PowerShell → Windows.UI.Notifications
2. opencode-notifier: node-notifier → SnoreToast.exe

A proper fix will detect and handle this conflict gracefully.

Refs: #543, oven-sh/bun#23177, oven-sh/bun#24368
See: docs/CRASH_INVESTIGATION_TIMELINE.md (in follow-up commit)

* fix(session-notification): detect and avoid conflict with external notification plugins

When oh-my-opencode's session-notification runs alongside external
notification plugins like opencode-notifier, both listen to session.idle
and send concurrent notifications. This can cause crashes on Windows
due to resource contention between different notification mechanisms:
- oh-my-opencode: ctx.$ → PowerShell → Windows.UI.Notifications
- opencode-notifier: node-notifier → SnoreToast.exe

This commit adds:
1. External plugin detection (checks opencode.json for known notifiers)
2. Auto-disable of session-notification when conflict detected
3. Console warning explaining the situation
4. Config option 'notification.force_enable' to override

Known notification plugins detected:
- opencode-notifier
- @mohak34/opencode-notifier
- mohak34/opencode-notifier

This is the actual fix for the Windows crash issue previously
misdiagnosed as a Bun.spawn GC bug (PR #543).

Refs: #543

* docs: add crash investigation timeline explaining the real root cause

Documents the investigation journey from initial misdiagnosis (Bun GC bug)
to discovering the actual root cause (notification plugin conflict).

Key findings:
- PR #543 was based on incorrect assumption
- The real issue is concurrent notification plugins
- oh-my-opencode + opencode-notifier = crash on Windows
- Either plugin alone works fine

* fix: address review feedback - add PowerShell escaping and use existing JSONC parser

- Add back single-quote escaping for PowerShell soundPath to prevent command failures
- Replace custom stripJsonComments with existing parseJsoncSafe from jsonc-parser
- All 655 tests pass

---------

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/shared/external-plugin-detector.ts

@@ -0,0 +1,132 @@
+/**
+ * Detects external plugins that may conflict with oh-my-opencode features.
+ * Used to prevent crashes from concurrent notification plugins.
+ */
+
+import * as fs from "node:fs"
+import * as path from "node:path"
+import * as os from "node:os"
+import { log } from "./logger"
+import { parseJsoncSafe } from "./jsonc-parser"
+
+interface OpencodeConfig {
+  plugin?: string[]
+}
+
+/**
+ * Known notification plugins that conflict with oh-my-opencode's session-notification.
+ * Both plugins listen to session.idle and send notifications simultaneously,
+ * which can cause crashes on Windows due to resource contention.
+ */
+const KNOWN_NOTIFICATION_PLUGINS = [
+  "opencode-notifier",
+  "@mohak34/opencode-notifier",
+  "mohak34/opencode-notifier",
+]
+
+function getWindowsAppdataDir(): string | null {
+  return process.env.APPDATA || null
+}
+
+function getConfigPaths(directory: string): string[] {
+  const crossPlatformDir = path.join(os.homedir(), ".config")
+  const paths = [
+    path.join(directory, ".opencode", "opencode.json"),
+    path.join(directory, ".opencode", "opencode.jsonc"),
+    path.join(crossPlatformDir, "opencode", "opencode.json"),
+    path.join(crossPlatformDir, "opencode", "opencode.jsonc"),
+  ]
+
+  if (process.platform === "win32") {
+    const appdataDir = getWindowsAppdataDir()
+    if (appdataDir) {
+      paths.push(path.join(appdataDir, "opencode", "opencode.json"))
+      paths.push(path.join(appdataDir, "opencode", "opencode.jsonc"))
+    }
+  }
+
+  return paths
+}
+
+function loadOpencodePlugins(directory: string): string[] {
+  for (const configPath of getConfigPaths(directory)) {
+    try {
+      if (!fs.existsSync(configPath)) continue
+      const content = fs.readFileSync(configPath, "utf-8")
+      const result = parseJsoncSafe<OpencodeConfig>(content)
+      if (result.data) {
+        return result.data.plugin ?? []
+      }
+    } catch {
+      continue
+    }
+  }
+  return []
+}
+
+/**
+ * Check if a plugin entry matches a known notification plugin.
+ * Handles various formats: "name", "name@version", "npm:name", "file://path/name"
+ */
+function matchesNotificationPlugin(entry: string): string | null {
+  const normalized = entry.toLowerCase()
+  for (const known of KNOWN_NOTIFICATION_PLUGINS) {
+    if (
+      normalized === known ||
+      normalized.startsWith(`${known}@`) ||
+      normalized.includes(`/${known}`) ||
+      normalized.endsWith(`/${known}`)
+    ) {
+      return known
+    }
+  }
+  return null
+}
+
+export interface ExternalNotifierResult {
+  detected: boolean
+  pluginName: string | null
+  allPlugins: string[]
+}
+
+/**
+ * Detect if any external notification plugin is configured.
+ * Returns information about detected plugins for logging/warning.
+ */
+export function detectExternalNotificationPlugin(directory: string): ExternalNotifierResult {
+  const plugins = loadOpencodePlugins(directory)
+  
+  for (const plugin of plugins) {
+    const match = matchesNotificationPlugin(plugin)
+    if (match) {
+      log(`Detected external notification plugin: ${plugin}`)
+      return {
+        detected: true,
+        pluginName: match,
+        allPlugins: plugins,
+      }
+    }
+  }
+
+  return {
+    detected: false,
+    pluginName: null,
+    allPlugins: plugins,
+  }
+}
+
+/**
+ * Generate a warning message for users with conflicting notification plugins.
+ */
+export function getNotificationConflictWarning(pluginName: string): string {
+  return `[oh-my-opencode] External notification plugin detected: ${pluginName}
+
+⚠️  Both oh-my-opencode and ${pluginName} listen to session.idle events.
+   Running both simultaneously can cause crashes on Windows.
+
+   oh-my-opencode's session-notification has been auto-disabled.
+
+   To use oh-my-opencode's notifications instead, either:
+   1. Remove ${pluginName} from your opencode.json plugins
+   2. Or set "notification": { "force_enable": true } in oh-my-opencode.json`
+}