fix: use path.join for cross-platform compatibility in Codex FILE_PATHS

Fixes #132

The FILE_PATHS constant was using hardcoded forward slashes, which caused
path.basename() to fail on Windows. On Windows, path.basename() expects
backslashes as path separators, so it would return the entire string
instead of just the filename.

This broke Codex detection on Windows during init/update because the
resolveAbsolutePath() method would construct incorrect paths, causing
file existence checks to fail.

Changed FILE_PATHS to use path.join() which automatically uses the
correct platform-specific path separators (backslashes on Windows,
forward slashes on Unix).

.changeset/release-minor-update.md

@@ -1,5 +0,0 @@
----
-"@fission-ai/openspec": minor
----
-
-Add support for Codex and GitHub Copilot slash commands with YAML frontmatter and $ARGUMENTS

CHANGELOG.md

@@ -1,5 +1,11 @@
 # @fission-ai/openspec
 
+## 0.9.0
+
+### Minor Changes
+
+- efbbf3b: Add support for Codex and GitHub Copilot slash commands with YAML frontmatter and $ARGUMENTS
+
 ## Unreleased
 
 ### Minor Changes

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@fission-ai/openspec",
-  "version": "0.8.1",
+  "version": "0.9.0",
   "description": "AI-native system for spec-driven development",
   "keywords": [
     "openspec",

src/core/configurators/slash/codex.ts

@@ -6,9 +6,9 @@ import { FileSystemUtils } from "../../../utils/file-system.js";
 import { OPENSPEC_MARKERS } from "../../config.js";
 
 const FILE_PATHS: Record<SlashCommandId, string> = {
-  proposal: ".codex/prompts/openspec-proposal.md",
-  apply: ".codex/prompts/openspec-apply.md",
-  archive: ".codex/prompts/openspec-archive.md",
+  proposal: path.join(".codex", "prompts", "openspec-proposal.md"),
+  apply: path.join(".codex", "prompts", "openspec-apply.md"),
+  archive: path.join(".codex", "prompts", "openspec-archive.md"),
 };
 
 export class CodexSlashCommandConfigurator extends SlashCommandConfigurator {