fix: use correct 'skills' directory path and respect OPENCODE_CONFIG_DIR

- Change skill directory from 'skill' (singular) to 'skills' (plural) to match OpenCode standard
- Use getOpenCodeConfigDir() to respect OPENCODE_CONFIG_DIR environment variable
- Update documentation and tests to reflect correct paths

Fixes #810

src/features/opencode-skill-loader/loader.ts

@@ -1,11 +1,11 @@
 import { promises as fs } from "fs"
 import { join, basename } from "path"
-import { homedir } from "os"
 import yaml from "js-yaml"
 import { parseFrontmatter } from "../../shared/frontmatter"
 import { sanitizeModelField } from "../../shared/model-sanitizer"
 import { resolveSymlinkAsync, isMarkdownFile } from "../../shared/file-utils"
 import { getClaudeConfigDir } from "../../shared"
+import { getOpenCodeConfigDir } from "../../shared/opencode-config-dir"
 import type { CommandDefinition } from "../claude-code-command-loader/types"
 import type { SkillScope, SkillMetadata, LoadedSkill, LazyContentLoader } from "./types"
 import type { SkillMcpConfig } from "../skill-mcp-manager/types"
@@ -187,13 +187,14 @@ export async function loadProjectSkills(): Promise<Record<string, CommandDefinit
 }
 
 export async function loadOpencodeGlobalSkills(): Promise<Record<string, CommandDefinition>> {
-  const opencodeSkillsDir = join(homedir(), ".config", "opencode", "skill")
+  const configDir = getOpenCodeConfigDir({ binary: "opencode" })
+  const opencodeSkillsDir = join(configDir, "skills")
   const skills = await loadSkillsFromDir(opencodeSkillsDir, "opencode")
   return skillsToRecord(skills)
 }
 
 export async function loadOpencodeProjectSkills(): Promise<Record<string, CommandDefinition>> {
-  const opencodeProjectDir = join(process.cwd(), ".opencode", "skill")
+  const opencodeProjectDir = join(process.cwd(), ".opencode", "skills")
   const skills = await loadSkillsFromDir(opencodeProjectDir, "opencode-project")
   return skillsToRecord(skills)
 }
@@ -249,11 +250,12 @@ export async function discoverProjectClaudeSkills(): Promise<LoadedSkill[]> {
 }
 
 export async function discoverOpencodeGlobalSkills(): Promise<LoadedSkill[]> {
-  const opencodeSkillsDir = join(homedir(), ".config", "opencode", "skill")
+  const configDir = getOpenCodeConfigDir({ binary: "opencode" })
+  const opencodeSkillsDir = join(configDir, "skills")
   return loadSkillsFromDir(opencodeSkillsDir, "opencode")
 }
 
 export async function discoverOpencodeProjectSkills(): Promise<LoadedSkill[]> {
-  const opencodeProjectDir = join(process.cwd(), ".opencode", "skill")
+  const opencodeProjectDir = join(process.cwd(), ".opencode", "skills")
   return loadSkillsFromDir(opencodeProjectDir, "opencode-project")
 }