fix(skill): unify skill resolution to support user custom skills

sisyphus_task was only loading builtin skills via resolveMultipleSkills().
Now uses resolveMultipleSkillsAsync() which merges discoverSkills() + builtin skills.

- Add getAllSkills(), extractSkillTemplate(), resolveMultipleSkillsAsync()
- Update sisyphus_task to use async skill resolution
- Refactor skill tool to reuse unified getAllSkills()
- Add async skill resolution tests

src/tools/sisyphus-task/tools.ts

@@ -6,8 +6,8 @@ import type { SisyphusTaskArgs } from "./types"
 import type { CategoryConfig, CategoriesConfig, GitMasterConfig } from "../../config/schema"
 import { SISYPHUS_TASK_DESCRIPTION, DEFAULT_CATEGORIES, CATEGORY_PROMPT_APPENDS } from "./constants"
 import { findNearestMessageWithFields, findFirstMessageWithAgent, MESSAGE_STORAGE } from "../../features/hook-message-injector"
-import { resolveMultipleSkills } from "../../features/opencode-skill-loader/skill-content"
-import { createBuiltinSkills } from "../../features/builtin-skills/skills"
+import { resolveMultipleSkillsAsync } from "../../features/opencode-skill-loader/skill-content"
+import { discoverSkills } from "../../features/opencode-skill-loader"
 import { getTaskToastManager } from "../../features/task-toast-manager"
 import type { ModelFallbackInfo } from "../../features/task-toast-manager/types"
 import { subagentSessions, getSessionAgent } from "../../features/claude-code-session-state"
@@ -196,9 +196,10 @@ export function createSisyphusTask(options: SisyphusTaskToolOptions): ToolDefini
 
       let skillContent: string | undefined
       if (args.skills.length > 0) {
-        const { resolved, notFound } = resolveMultipleSkills(args.skills, { gitMasterConfig })
+        const { resolved, notFound } = await resolveMultipleSkillsAsync(args.skills, { gitMasterConfig })
         if (notFound.length > 0) {
-          const available = createBuiltinSkills().map(s => s.name).join(", ")
+          const allSkills = await discoverSkills({ includeClaudeCodePaths: true })
+          const available = allSkills.map(s => s.name).join(", ")
           return `❌ Skills not found: ${notFound.join(", ")}. Available: ${available}`
         }
         skillContent = Array.from(resolved.values()).join("\n\n")

src/tools/skill/tools.ts

@@ -1,10 +1,9 @@
 import { dirname } from "node:path"
-import { readFileSync } from "node:fs"
 import { tool, type ToolDefinition } from "@opencode-ai/plugin"
 import { TOOL_DESCRIPTION_NO_SKILLS, TOOL_DESCRIPTION_PREFIX } from "./constants"
 import type { SkillArgs, SkillInfo, SkillLoadOptions } from "./types"
-import { discoverSkills, type LoadedSkill } from "../../features/opencode-skill-loader"
-import { parseFrontmatter } from "../../shared/frontmatter"
+import type { LoadedSkill } from "../../features/opencode-skill-loader"
+import { getAllSkills, extractSkillTemplate } from "../../features/opencode-skill-loader/skill-content"
 import type { SkillMcpManager, SkillMcpClientInfo, SkillMcpServerContext } from "../../features/skill-mcp-manager"
 import type { Tool, Resource, Prompt } from "@modelcontextprotocol/sdk/types.js"
 
@@ -48,9 +47,7 @@ async function extractSkillBody(skill: LoadedSkill): Promise<string> {
   }
 
   if (skill.path) {
-    const content = readFileSync(skill.path, "utf-8")
-    const { body } = parseFrontmatter(content)
-    return body.trim()
+    return extractSkillTemplate(skill)
   }
 
   const templateMatch = skill.definition.template?.match(/<skill-instruction>([\s\S]*?)<\/skill-instruction>/)
@@ -135,7 +132,7 @@ export function createSkillTool(options: SkillLoadOptions = {}): ToolDefinition
   const getSkills = async (): Promise<LoadedSkill[]> => {
     if (options.skills) return options.skills
     if (cachedSkills) return cachedSkills
-    cachedSkills = await discoverSkills({ includeClaudeCodePaths: !options.opencodeOnly })
+    cachedSkills = await getAllSkills()
     return cachedSkills
   }