workflow: forward TSX_TSCONFIG_PATH through the worker env scrub

The empty-env hardening wiped the one variable the UNBUILT worker's
loader depends on: tsx finds a tsconfig by searching up from the
worker's cwd, and a parent running outside the repo (the ACP snapshot
harness pins the repo tsconfig through TSX_TSCONFIG_PATH exactly
because its child cwd is a temp dir) lost the dsh-* paths map - the
worker then resolved workspace imports to unbuilt lib/ bundles and died
on CI with ERR_MODULE_NOT_FOUND (green locally only because stale built
lib/ masked the wrong resolution).

Forward exactly that variable when the parent carries it - loader
plumbing, not a secret; the built shape stays fully empty - and pin the
whole contract with an escape-based test: the worker env is exactly
{TSX_TSCONFIG_PATH}, the credential canary still never crosses.

packages/workflow/workflow-workerthread/tests/workflow-workerthread.spec.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it, vi } from 'vitest'
+import { fileURLToPath } from 'node:url'
 import { Context } from 'cordis'
 import Loader from '@cordisjs/plugin-loader'
 import { AgentId } from '@deepseek-ai/dsh-agent'
@@ -272,6 +273,28 @@ describe('dsh-workflow-workerthread', () => {
         delete process.env.WORKFLOW_ENV_CANARY
       }
     })
+
+    it('the unbuilt worker forwards exactly TSX_TSCONFIG_PATH through the scrub: the paths-map pin survives, secrets do not', async () => {
+      const { ctx, parent } = await setup()
+      // The ACP snapshot harness runs the parent with its cwd OUTSIDE the
+      // repo and pins the repo tsconfig through this variable; the worker
+      // must inherit the pin (or its dsh-* imports silently resolve to
+      // unbuilt lib/ bundles) while every other variable stays scrubbed.
+      const tsconfig = fileURLToPath(new URL('../../../../tsconfig.json', import.meta.url))
+      process.env.TSX_TSCONFIG_PATH = tsconfig
+      process.env.WORKFLOW_ENV_CANARY = 'leak me'
+      try {
+        const result = await run(ctx, parent, scripted(`
+          const proc = ${ESCAPE}
+          return { keys: Object.keys(proc.env), tsconfig: proc.env.TSX_TSCONFIG_PATH }
+        `))
+        expect(result.stopReason).toBe('completed')
+        expect(result.value).toEqual({ keys: ['TSX_TSCONFIG_PATH'], tsconfig })
+      } finally {
+        delete process.env.TSX_TSCONFIG_PATH
+        delete process.env.WORKFLOW_ENV_CANARY
+      }
+    })
   })
 
   describe('lifecycle: parse errors, cancellation, termination, disposal', () => {