Add auto-slash-command hook for intercepting and replacing slash commands

This hook intercepts user messages starting with '/' and REPLACES them with the actual command template output instead of injecting instructions. The implementation includes:

- Slash command detection (detector.ts) - identifies messages starting with '/'
- Command discovery and execution (executor.ts) - loads templates from ~/.claude/commands/ or similar
- Hook integration (index.ts) - registers with chat.message event to replace output.parts
- Comprehensive test coverage - 37 tests covering detection, replacement, error handling, and command exclusions
- Configuration support in HookNameSchema

Key features:
- Supports excluded commands to skip processing
- Loads command templates from user's command directory
- Replaces user input before reaching the LLM
- Tests all edge cases including missing files, malformed templates, and special commands

🤖 Generated with assistance of OhMyOpenCode (https://github.com/code-yeongyu/oh-my-opencode)

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

@@ -0,0 +1,82 @@
+import {
+  detectSlashCommand,
+  extractPromptText,
+} from "./detector"
+import { executeSlashCommand } from "./executor"
+import { log } from "../../shared"
+import {
+  AUTO_SLASH_COMMAND_TAG_OPEN,
+  AUTO_SLASH_COMMAND_TAG_CLOSE,
+} from "./constants"
+import type {
+  AutoSlashCommandHookInput,
+  AutoSlashCommandHookOutput,
+} from "./types"
+
+export * from "./detector"
+export * from "./executor"
+export * from "./constants"
+export * from "./types"
+
+const sessionProcessedCommands = new Set<string>()
+
+export function createAutoSlashCommandHook() {
+  return {
+    "chat.message": async (
+      input: AutoSlashCommandHookInput,
+      output: AutoSlashCommandHookOutput
+    ): Promise<void> => {
+      const promptText = extractPromptText(output.parts)
+
+      if (
+        promptText.includes(AUTO_SLASH_COMMAND_TAG_OPEN) ||
+        promptText.includes(AUTO_SLASH_COMMAND_TAG_CLOSE)
+      ) {
+        return
+      }
+
+      const parsed = detectSlashCommand(promptText)
+
+      if (!parsed) {
+        return
+      }
+
+      const commandKey = `${input.sessionID}:${input.messageID}:${parsed.command}`
+      if (sessionProcessedCommands.has(commandKey)) {
+        return
+      }
+      sessionProcessedCommands.add(commandKey)
+
+      log(`[auto-slash-command] Detected: /${parsed.command}`, {
+        sessionID: input.sessionID,
+        args: parsed.args,
+      })
+
+      const result = await executeSlashCommand(parsed)
+
+      const idx = output.parts.findIndex((p) => p.type === "text" && p.text)
+      if (idx < 0) {
+        return
+      }
+
+      if (result.success && result.replacementText) {
+        const taggedContent = `${AUTO_SLASH_COMMAND_TAG_OPEN}\n${result.replacementText}\n${AUTO_SLASH_COMMAND_TAG_CLOSE}`
+        output.parts[idx].text = taggedContent
+
+        log(`[auto-slash-command] Replaced message with command template`, {
+          sessionID: input.sessionID,
+          command: parsed.command,
+        })
+      } else {
+        const errorMessage = `${AUTO_SLASH_COMMAND_TAG_OPEN}\n[AUTO-SLASH-COMMAND ERROR]\n${result.error}\n\nOriginal input: ${parsed.raw}\n${AUTO_SLASH_COMMAND_TAG_CLOSE}`
+        output.parts[idx].text = errorMessage
+
+        log(`[auto-slash-command] Command not found, showing error`, {
+          sessionID: input.sessionID,
+          command: parsed.command,
+          error: result.error,
+        })
+      }
+    },
+  }
+}