fix(shared): add ancestor project discovery helpers

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/index.ts

@@ -67,5 +67,6 @@ export * from "./session-directory-resolver"
 export * from "./prompt-tools"
 export * from "./internal-initiator-marker"
 export * from "./plugin-command-discovery"
+export * from "./project-discovery-dirs"
 export { SessionCategoryRegistry } from "./session-category-registry"
 export * from "./plugin-identity"

src/shared/project-discovery-dirs.test.ts

@@ -0,0 +1,74 @@
+import { afterEach, beforeEach, describe, expect, it } from "bun:test"
+import { mkdirSync, rmSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import {
+  findProjectAgentsSkillDirs,
+  findProjectClaudeSkillDirs,
+  findProjectOpencodeCommandDirs,
+  findProjectOpencodeSkillDirs,
+} from "./project-discovery-dirs"
+
+const TEST_DIR = join(tmpdir(), `project-discovery-dirs-${Date.now()}`)
+
+describe("project-discovery-dirs", () => {
+  beforeEach(() => {
+    mkdirSync(TEST_DIR, { recursive: true })
+  })
+
+  afterEach(() => {
+    rmSync(TEST_DIR, { recursive: true, force: true })
+  })
+
+  it("#given nested .opencode skill directories #when finding project opencode skill dirs #then returns nearest-first with aliases", () => {
+    // given
+    const projectDir = join(TEST_DIR, "project")
+    const childDir = join(projectDir, "apps", "cli")
+    mkdirSync(join(projectDir, ".opencode", "skill"), { recursive: true })
+    mkdirSync(join(projectDir, ".opencode", "skills"), { recursive: true })
+    mkdirSync(join(TEST_DIR, ".opencode", "skills"), { recursive: true })
+
+    // when
+    const directories = findProjectOpencodeSkillDirs(childDir)
+
+    // then
+    expect(directories).toEqual([
+      join(projectDir, ".opencode", "skills"),
+      join(projectDir, ".opencode", "skill"),
+      join(TEST_DIR, ".opencode", "skills"),
+    ])
+  })
+
+  it("#given nested .opencode command directories #when finding project opencode command dirs #then returns nearest-first with aliases", () => {
+    // given
+    const projectDir = join(TEST_DIR, "project")
+    const childDir = join(projectDir, "packages", "tool")
+    mkdirSync(join(projectDir, ".opencode", "commands"), { recursive: true })
+    mkdirSync(join(TEST_DIR, ".opencode", "command"), { recursive: true })
+
+    // when
+    const directories = findProjectOpencodeCommandDirs(childDir)
+
+    // then
+    expect(directories).toEqual([
+      join(projectDir, ".opencode", "commands"),
+      join(TEST_DIR, ".opencode", "command"),
+    ])
+  })
+
+  it("#given ancestor claude and agents skill directories #when finding project compatibility dirs #then discovers both scopes", () => {
+    // given
+    const projectDir = join(TEST_DIR, "project")
+    const childDir = join(projectDir, "src", "nested")
+    mkdirSync(join(projectDir, ".claude", "skills"), { recursive: true })
+    mkdirSync(join(TEST_DIR, ".agents", "skills"), { recursive: true })
+
+    // when
+    const claudeDirectories = findProjectClaudeSkillDirs(childDir)
+    const agentsDirectories = findProjectAgentsSkillDirs(childDir)
+
+    // then
+    expect(claudeDirectories).toEqual([join(projectDir, ".claude", "skills")])
+    expect(agentsDirectories).toEqual([join(TEST_DIR, ".agents", "skills")])
+  })
+})

src/shared/project-discovery-dirs.ts

@@ -0,0 +1,52 @@
+import { existsSync } from "node:fs"
+import { dirname, join, resolve } from "node:path"
+
+function findAncestorDirectories(
+  startDirectory: string,
+  targetPaths: ReadonlyArray<ReadonlyArray<string>>,
+): string[] {
+  const directories: string[] = []
+  const seen = new Set<string>()
+  let currentDirectory = resolve(startDirectory)
+
+  while (true) {
+    for (const targetPath of targetPaths) {
+      const candidateDirectory = join(currentDirectory, ...targetPath)
+      if (!existsSync(candidateDirectory) || seen.has(candidateDirectory)) {
+        continue
+      }
+
+      seen.add(candidateDirectory)
+      directories.push(candidateDirectory)
+    }
+
+    const parentDirectory = dirname(currentDirectory)
+    if (parentDirectory === currentDirectory) {
+      return directories
+    }
+
+    currentDirectory = parentDirectory
+  }
+}
+
+export function findProjectClaudeSkillDirs(startDirectory: string): string[] {
+  return findAncestorDirectories(startDirectory, [[".claude", "skills"]])
+}
+
+export function findProjectAgentsSkillDirs(startDirectory: string): string[] {
+  return findAncestorDirectories(startDirectory, [[".agents", "skills"]])
+}
+
+export function findProjectOpencodeSkillDirs(startDirectory: string): string[] {
+  return findAncestorDirectories(startDirectory, [
+    [".opencode", "skills"],
+    [".opencode", "skill"],
+  ])
+}
+
+export function findProjectOpencodeCommandDirs(startDirectory: string): string[] {
+  return findAncestorDirectories(startDirectory, [
+    [".opencode", "commands"],
+    [".opencode", "command"],
+  ])
+}