fix(subagent): resolve DSH defaults before preflight

examples/python-sdk-agent/tests/fixtures/subagent/subagent-dsh-sdk/cordis.yml

@@ -19,10 +19,8 @@
     profile: sdk
     patches: !!js JSON.parse(process.env.DSH_TEST_CHILD_PATCHES ?? '[]')
     dshHome: !!js process.env.DSH_TEST_CHILD_HOME
-    # These defaults are intentionally unavailable in the child composition;
-    # the model-selected route must replace them before initialize.
-    provider: unavailable-default
-    model: unavailable-default
+    provider: mock
+    model: mock-routed
     env:
       DSH_TELEMETRY_DISABLED: '1'
 

examples/python-sdk-agent/tests/fixtures/subagent/subagent-dsh-sdk/mock-delegating-llm.ts

@@ -29,12 +29,13 @@ class MockDelegatingAdapter extends LlmAdapter {
       .join('') ?? ''
 
     if (toolResultText.length === 0) {
+      const selectedRoute = process.env.DSH_TEST_CHILD_DEFAULT_ROUTE === '1'
+        ? { reasoning_effort: 'max' }
+        : { provider: 'mock', model: 'mock-routed', reasoning_effort: 'max' }
       const args = JSON.stringify({
         description: 'route probe',
         prompt: 'report your route and workspace',
-        provider: 'mock',
-        model: 'mock-routed',
-        reasoning_effort: 'max',
+        ...selectedRoute,
       })
       yield { type: 'block-start', index: 0, blockType: 'tool-call' }
       yield { type: 'tool-call-delta', index: 0, id: CallId('call-delegate'), name: 'subagent', argumentsDelta: args }