fix(skills): require fresh bundle staging

docs/agent-skill-sharing-implementation-checklist.md

@@ -206,7 +206,7 @@ does not mean the surrounding phase is complete.
       user explicitly approves replacement.
 - [x] Package ingestion rejects unsafe archives before any destination mutation.
 - [x] Interrupted operations recover to a complete previous or requested version.
-- [ ] Private package bytes remain access-controlled, published versions persist until deletion,
+- [x] Private package bytes remain access-controlled, published versions persist until deletion,
       and incomplete uploads expire automatically.
 - [x] Mixed-version clients and remote hosts fail safely through capability negotiation.
 - [ ] Cloud resources are Terraform-owned, monitored, recoverable, and protected by independent
@@ -305,8 +305,10 @@ does not mean the surrounding phase is complete.
       digest.
 - [x] Validate Agent Plugins 1.0.0 `plugin.json` fields from independently authored local rules;
       never fetch a schema during loading.
-- [ ] Create fresh staging roots and reject unknown, malformed, or conflicting imported
-      `dev.orca.skill-sharing` namespaces without overwriting them.
+- [x] Create fresh staging roots and reject unknown, malformed, or conflicting imported
+      `dev.orca.skill-sharing` namespaces without overwriting them. The extractor now exclusively
+      creates its staging root, preserves a pre-existing namespace on conflict, rejects unknown
+      top-level extension entries, and removes only staging it created.
 - [x] Keep the detailed manifest inside the archive for export, remote/SSH transport, and offline
       validation; keep GCS metadata compact and PostgreSQL limited to exact link/ownership lookup.
 - [x] Add selected skill IDs and per-skill conflict choices to preview/install requests.
@@ -394,12 +396,13 @@ does not mean the surrounding phase is complete.
 - [x] Include only `skill/` contents in the eventual installed directory.
 - [x] Bind the user-visible share preview to the final staged digest.
 - [x] Clean staging files on success, cancellation, source drift, and error.
-- [ ] Accept a non-empty ordered selection of skill directories and support at least 30 within the
-      global entry/file/byte limits.
+- [x] Accept a non-empty ordered selection of skill directories and support at least 30 within the
+      global entry/file/byte limits. Focused local creation/extraction now covers one 30-skill
+      archive; staging load run `31585710645` finalized the same maximum selection through Cloud.
 - [ ] Reject duplicate normalized skill names and preserve selection across search/filter changes
       in the caller.
 - [x] Generate deterministic `plugin.json`, `skills/`, and Orca extension metadata.
-- [ ] Bind the share review to every staged skill digest and the final bundle digest.
+- [x] Bind the share review to every staged skill digest and the final bundle digest.
 
 ### Bounded extraction
 

src/main/skills/skill-bundle-creation.test.ts

@@ -1,10 +1,14 @@
-import { mkdir, mkdtemp, readFile, rm, writeFile } from 'node:fs/promises'
+import { mkdir, mkdtemp, readFile, rm, stat, writeFile } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, describe, expect, it } from 'vitest'
-import { AGENT_PLUGIN_SCHEMA_V1 } from '../../shared/skill-bundle-manifest'
+import {
+  AGENT_PLUGIN_MANIFEST_PATH,
+  AGENT_PLUGIN_SCHEMA_V1
+} from '../../shared/skill-bundle-manifest'
 import { createSkillBundleArchive } from './skill-bundle-creation'
 import { extractSkillBundleArchive } from './skill-bundle-extraction'
+import { writeSkillTarGzip } from './skill-package-tar'
 
 const temporaryDirectories: string[] = []
 
@@ -92,6 +96,91 @@ describe('skill bundle creation and extraction', () => {
     expect(await readFile(first.archivePath)).toEqual(await readFile(second.archivePath))
   })
 
+  it('packages and extracts thirty selected skills within the shared limits', async () => {
+    const root = await temporaryDirectory()
+    const names = Array.from(
+      { length: 30 },
+      (_, index) => `skill-${String(index).padStart(2, '0')}`
+    )
+    const sources = await Promise.all(
+      names.map(async (name) => ({
+        sourceDirectory: await createSkill(root, name, `Description for ${name}`)
+      }))
+    )
+    const created = await createSkillBundleArchive({
+      sources: sources.toReversed(),
+      archivePath: join(root, 'thirty-skills.tar.gz'),
+      packageId: 'package_30',
+      versionId: 'version_30',
+      bundleName: 'thirty-skills'
+    })
+
+    const extracted = await extractSkillBundleArchive({
+      archivePath: created.archivePath,
+      destinationDirectory: join(root, 'thirty-skills'),
+      expectedBundleDigest: created.manifest.bundleDigest
+    })
+
+    expect(extracted.manifest.skills.map((skill) => skill.name)).toEqual(names)
+    expect(extracted.manifest.skills).toHaveLength(30)
+    await expect(
+      readFile(join(extracted.skillsDirectory, 'skill-29', 'notes.txt'), 'utf8')
+    ).resolves.toBe('skill-29 notes\n')
+  })
+
+  it('rejects conflicting staging roots without changing their imported namespace', async () => {
+    const root = await temporaryDirectory()
+    const source = await createSkill(root, 'alpha-skill', 'Alpha')
+    const created = await createSkillBundleArchive({
+      sources: [{ sourceDirectory: source }],
+      archivePath: join(root, 'bundle.tar.gz'),
+      packageId: 'package_1',
+      versionId: 'version_1',
+      bundleName: 'team-skills'
+    })
+    const destination = join(root, 'conflicting-staging')
+    const importedManifest = join(destination, 'dev.orca.skill-sharing', 'manifest.json')
+    await mkdir(join(destination, 'dev.orca.skill-sharing'), { recursive: true })
+    await writeFile(importedManifest, 'unowned\n')
+
+    await expect(
+      extractSkillBundleArchive({
+        archivePath: created.archivePath,
+        destinationDirectory: destination
+      })
+    ).rejects.toMatchObject({ code: 'EEXIST' })
+    await expect(readFile(importedManifest, 'utf8')).resolves.toBe('unowned\n')
+  })
+
+  it('rejects unknown top-level extension namespaces and removes fresh staging', async () => {
+    const root = await temporaryDirectory()
+    const plugin = Buffer.from(
+      JSON.stringify({ $schema: AGENT_PLUGIN_SCHEMA_V1, name: 'team-skills' })
+    )
+    const unknown = Buffer.from('{}')
+    const archivePath = join(root, 'unknown-extension.tar.gz')
+    await writeSkillTarGzip(archivePath, [
+      {
+        path: AGENT_PLUGIN_MANIFEST_PATH,
+        size: plugin.length,
+        executable: false,
+        bytes: plugin
+      },
+      {
+        path: 'dev.orca.unexpected/manifest.json',
+        size: unknown.length,
+        executable: false,
+        bytes: unknown
+      }
+    ])
+    const destination = join(root, 'unknown-extension-staging')
+
+    await expect(
+      extractSkillBundleArchive({ archivePath, destinationDirectory: destination })
+    ).rejects.toThrow('skill-bundle-manifest-envelope-invalid')
+    await expect(stat(destination)).rejects.toMatchObject({ code: 'ENOENT' })
+  })
+
   it('rejects duplicate names and source drift without publishing an archive', async () => {
     const root = await temporaryDirectory()
     const first = await createSkill(root, 'same-skill', 'First')

src/main/skills/skill-bundle-extraction.ts

@@ -142,6 +142,8 @@ export async function extractSkillBundleArchive(input: {
   const archive = await openSkillTarGzip(input.archivePath)
   let destinationCreated = false
   try {
+    await mkdir(input.destinationDirectory, { mode: 0o700 })
+    destinationCreated = true
     const pluginManifest = parseAgentPluginManifest(
       await readJsonEntry(archive.reader, AGENT_PLUGIN_MANIFEST_PATH)
     )
@@ -158,8 +160,7 @@ export async function extractSkillBundleArchive(input: {
       throw new Error('skill-bundle-identity-mismatch')
     }
     const skillsDirectory = join(input.destinationDirectory, 'skills')
-    await mkdir(skillsDirectory, { recursive: true, mode: 0o700 })
-    destinationCreated = true
+    await mkdir(skillsDirectory, { mode: 0o700 })
     for (const skill of manifest.skills) {
       for (const file of skill.files) {
         const archivePath = `skills/${skill.name}/${file.path}`