fix(review): validate skill roots at mount and isolate provider default roots

ds-review-bot round 1 on the repository-plugin runtime:
- a manifest-declared skill root absent or non-directory in the installed
  package now fails the plugin load (skill-local treats a missing root as
  legitimately empty, which silently mounted a skill-less plugin)
- includeDefaultRoots: false no longer inherits $DSH_BUNDLED_SKILL_DIR, so
  isolated repository providers see only their explicit roots
- prepared wrapper baseUrl schema requires the file: scheme, failing hostile
  URLs at the declared validation boundary
- preparedPath reuses format.ts's isOutside; SERVER_NAME_PATTERN is exported
  and pinned equal to dsh-mcp-client's, with the restatement justified (the
  prepare bin keeps a zod-only module graph); the unexplained `as never`
  cast now carries its schemastery rationale
- the import-free wrapper assertion also rejects dynamic import(
- the headless fixture wrapper is regenerated by the real prepareDshPlugin
  and a drift test pins fixture == generator output
- prepareDshPlugin JSDoc states the non-atomic publish repair contract

examples/headless-agent/tests/fixtures/repository-plugin/dsh-plugin.mjs

@@ -1,9 +1,9 @@
 // Generated by dsh-plugin-prepare. Do not edit.
-const manifest = { "name": "headless-repository-fixture", "skills": ["dsh-plugin-assets/skills/0"] }
-export const name = 'headless-repository-fixture'
-export const inject = ['loader']
+const manifest = {"name":"headless-repository-fixture","skills":["dsh-plugin-assets/skills/0"]}
+export const name = "headless-repository-fixture"
+export const inject = ["loader","skills"]
 export async function apply(ctx) {
-  const runtime = ctx.loader.builtins['dsh-repository-plugin']
-  if (runtime === undefined) throw new Error('missing Cordis builtin dsh-repository-plugin')
+  const runtime = ctx.loader.builtins["dsh-repository-plugin"]
+  if (runtime === undefined) throw new Error("missing Cordis builtin dsh-repository-plugin")
   await ctx.plugin(runtime, { baseUrl: import.meta.url, manifest })
 }

examples/headless-agent/tests/keyless-smoke.e2e.ts

@@ -1,10 +1,12 @@
-import { readFile, readdir } from 'node:fs/promises'
+import { cp, mkdir, mkdtemp, readFile, readdir, rm, writeFile } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
 import { zstdDecompress } from 'node:zlib'
 import { promisify } from 'node:util'
 import { join } from 'node:path'
 import { fileURLToPath } from 'node:url'
 import { describe, expect, it } from 'vitest'
 import { LOADER_SMOKE_TEST_TIMEOUT_MS, runLoaderSmoke } from '@deepseek-ai/dsh-loader-smoke'
+import { PREPARED_ENTRY_FILENAME, prepareDshPlugin } from '@deepseek-ai/dsh-repository-plugin'
 import type { SessionEvent } from '@deepseek-ai/dsh-session'
 
 const binScript = fileURLToPath(new URL('../../../packages/examples/cli-demo/src/bin.ts', import.meta.url))
@@ -59,4 +61,28 @@ describe('headless-agent keyless smoke', () => {
     expect(String(result?.['result'])).toContain('CLI_TOOL_ROUND_TRIP')
     expect(persistedHeader).toMatchObject({ type: 'session' })
   }, LOADER_SMOKE_TEST_TIMEOUT_MS)
+
+  it('keeps the checked-in prepared wrapper identical to the generator output for its manifest', async () => {
+    // The fixture claims "Generated by dsh-plugin-prepare"; this pin makes the
+    // claim true — a wrapper-template change fails here until the fixture is
+    // regenerated, so the assembled smoke can never exercise a stale shape.
+    const fixture = fileURLToPath(new URL('./fixtures/repository-plugin/', import.meta.url))
+    const root = await mkdtemp(join(tmpdir(), 'dsh-fixture-drift-'))
+    try {
+      const plugin = join(root, '.dsh-plugin')
+      await mkdir(plugin, { recursive: true })
+      await cp(join(fixture, 'dsh-plugin-assets/skills/0'), join(root, 'skills'), { recursive: true })
+      await writeFile(join(plugin, 'package.json'), `${JSON.stringify({
+        name: 'headless-repository-fixture',
+        version: '0.0.0',
+        dsh: { skills: ['../skills'] },
+      }, undefined, 2)}\n`)
+      await prepareDshPlugin(plugin)
+      const generated = await readFile(join(plugin, PREPARED_ENTRY_FILENAME), 'utf8')
+      const checkedIn = await readFile(join(fixture, PREPARED_ENTRY_FILENAME), 'utf8')
+      expect(checkedIn).toBe(generated)
+    } finally {
+      await rm(root, { recursive: true, force: true })
+    }
+  })
 })