Allow loading skills dynamically

Author: jahooma

common/src/tools/params/tool/skill.ts

@@ -34,9 +34,11 @@ export const AVAILABLE_SKILLS_PLACEHOLDER = '{{AVAILABLE_SKILLS}}'
 // Base description - the full description with available skills is generated dynamically
 const baseDescription = `Load a skill by name to get its full instructions. Skills provide reusable behaviors and domain-specific knowledge that you can use to complete tasks.
 
-The following are the only skills that are currently available (do not try to use any other skills):
+The following are the pre-loaded skills available at session start:
 ${AVAILABLE_SKILLS_PLACEHOLDER}
 
+Note: You can also load any skill that was created during this session by specifying its name. The skill will be loaded dynamically from disk.
+
 Example:
 ${$getNativeToolCallExampleString({
   toolName,

packages/agent-runtime/src/tools/handlers/tool/skill.ts

@@ -1,4 +1,10 @@
 import { jsonToolResult } from '@codebuff/common/util/messages'
+import { SKILLS_DIR_NAME, SKILL_FILE_NAME } from '@codebuff/common/constants/skills'
+import { SkillFrontmatterSchema, type SkillDefinition } from '@codebuff/common/types/skill'
+import fs from 'fs'
+import path from 'path'
+import os from 'os'
+import matter from 'gray-matter'
 
 import type { CodebuffToolHandlerFunction } from '../handler-function-type'
 import type {
@@ -7,6 +13,73 @@ import type {
 } from '@codebuff/common/tools/list'
 import type { ProjectFileContext } from '@codebuff/common/util/file'
 
+/**
+ * Dynamically load a single skill from disk.
+ * Used when a skill is not found in the pre-loaded cache but may have been created during the session.
+ */
+async function loadSkillFromDisk(
+  projectRoot: string,
+  skillName: string,
+): Promise<SkillDefinition | null> {
+  const home = os.homedir()
+  const skillsDirs = [
+    // Global directories first
+    path.join(home, '.agents', SKILLS_DIR_NAME),
+    path.join(home, '.claude', SKILLS_DIR_NAME),
+    // Project directories (later takes precedence for overwriting)
+    path.join(projectRoot, '.agents', SKILLS_DIR_NAME),
+    path.join(projectRoot, '.claude', SKILLS_DIR_NAME),
+  ]
+
+  for (const skillsDir of skillsDirs) {
+    const skillDir = path.join(skillsDir, skillName)
+    const skillFilePath = path.join(skillDir, SKILL_FILE_NAME)
+
+    try {
+      // Check if the skill directory and file exist
+      const stat = fs.statSync(skillDir)
+      if (!stat.isDirectory()) continue
+
+      fs.statSync(skillFilePath) // Will throw if file doesn't exist
+
+      // Read and parse the skill file
+      const content = fs.readFileSync(skillFilePath, 'utf8')
+      const parsed = matter(content)
+
+      if (!parsed.data || Object.keys(parsed.data).length === 0) {
+        continue
+      }
+
+      // Validate frontmatter
+      const result = SkillFrontmatterSchema.safeParse(parsed.data)
+      if (!result.success) {
+        continue
+      }
+
+      const frontmatter = result.data
+
+      // Verify name matches directory name
+      if (frontmatter.name !== skillName) {
+        continue
+      }
+
+      return {
+        name: frontmatter.name,
+        description: frontmatter.description,
+        content,
+        license: frontmatter.license,
+        filePath: skillFilePath,
+        metadata: frontmatter.metadata,
+      }
+    } catch {
+      // Skill doesn't exist in this directory, try the next one
+      continue
+    }
+  }
+
+  return null
+}
+
 type ToolName = 'skill'
 
 export const handleSkill = (async (params: {
@@ -20,14 +93,24 @@ export const handleSkill = (async (params: {
   await previousToolCallFinished
 
   const skills = fileContext.skills ?? {}
-  const skill = skills[name]
+  const cachedSkill = skills[name]
+
+  // If skill not in cache, try to load it dynamically from disk
+  // This supports skills created during the session
+  const diskSkill = cachedSkill
+    ? null
+    : fileContext.projectRoot
+      ? await loadSkillFromDisk(fileContext.projectRoot, name)
+      : null
+
+  const skill = cachedSkill ?? diskSkill
 
   if (!skill) {
     const availableSkills = Object.keys(skills)
     const suggestion =
       availableSkills.length > 0
-        ? ` Available skills: ${availableSkills.join(', ')}`
-        : ' No skills are currently available.'
+        ? ` Available skills: ${availableSkills.join(', ')}. You can also load skills created during this session by name.`
+        : ' No skills are currently available. You can load skills created during this session by name.'
 
     return {
       output: jsonToolResult({