Model routing: an omitted allowed-models means any model when merging imports

[Copilot]

When imported workflows also set routing for the same engine, the compiler combines their allowed-models lists. An omitted list means "no shortlist" (any model allowed by models.allowed/models.blocked), but the merge treated it as empty. So one workflow's list silently narrowed another's "any model". For example, a main workflow without allowed-models that imports allowed-models: [claude-sonnet-5] was compiled to candidateModels: ["github-copilot/claude-sonnet-5"].

Changes

• Merge rule (mergeImportedModelRoutingConfigs in pkg/workflow/compiler_orchestrator_engine.go): when an import's routing settings are merged into existing ones and either side's AllowedModels is nil, the result is nil. It stays nil for later imports. When every side has a list, the deduplicated union is unchanged. Two things are untouched:

  • When the main workflow has no routing settings, the first import's settings are still copied as is.
  • The main workflow's goal and mode still win.

  if engineConfig.ModelRouting.AllowedModels == nil || importedConfig.ModelRouting.AllowedModels == nil {
      engineConfig.ModelRouting.AllowedModels = nil
      continue
  }

• Tests (TestImportedWorkflowModelRoutingOmittedAllowedModelsMeansAnyModel): a table-driven test, run through ParseWorkflowFile and BuildAWFConfigJSON. For each case it checks AllowedModels and whether apiProxy.routing.candidateModels is present.

  Main allowed-models	Imports	Result
  Omitted	[claude-sonnet-5]	No shortlist
  [gpt-6-sol]	Omitted	No shortlist
  No routing	Omitted, then [claude-sonnet-5]	No shortlist
  No routing	[claude-sonnet-5], then omitted	No shortlist
  No routing	[claude-sonnet-5]	[claude-sonnet-5]
  [gpt-6-sol]	[claude-sonnet-5, gpt-6-sol]	[gpt-6-sol, claude-sonnet-5]

  The test workflows don't pin sandbox.agent.version. With a pinned version, compiling routing that has no list fails with "missing model-routing candidates".

• Docs:

  • model-routing.md, "Shared routing settings": the old "chooses from only the imported entries" sentence is replaced with the new rule.
  • main_workflow_schema.json: one sentence added to the allowed-models description; frontmatter-full.md is regenerated.
  • A patch changeset is added.

Out of scope

These are tracked separately:

• An import's goal/mode are dropped without a warning when they differ from the main workflow's.
• A main workflow using the short form engine: copilot can't import routing settings.

• Fixes Model routing: an omitted allowed-models is narrowed to an imported workflow's list instead of meaning any model #68877

[Copilot]

🟢 Approval recommended

The localized fix has focused regression coverage, and the remaining documentation clarification is nonblocking.

1 open finding

• Clarify no-shortlist rule applies only to routing-enabled workflows · New

What changed in this PR

Fixes gh-aw’s routing import merge so an omitted allowed-models list remains unrestricted instead of inheriting another workflow’s shortlist.

Changes:

• Preserve unrestricted routing while retaining explicit-list unions.
• Add regression cases for omissions, inheritance, and import order.
• Update routing documentation and add a patch changeset.

File	Description
pkg/​workflow/​model_routing_subagents_test.go	Tests merged lists and emitted routing candidates.
pkg/​workflow/​compiler_orchestrator_engine.go	Preserves omitted lists during routing merges.
pkg/​parser/​schemas/​main_workflow_schema.json	Documents routing merge semantics.
docs/​src/​content/​docs/​reference/​model-routing.md	Updates shared-routing guidance.
docs/​src/​content/​docs/​reference/​frontmatter-full.md	Refreshes generated field descriptions.
.changeset/​model-routing-omitted-allowed-models-import-merge.md	Records the patch release fix.

🧠 Review effort: Max

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[gh-aw-bot]

@copilot address the following outstanding work in one pass:

1. Update this branch with the latest main using make merge-main, resolving any conflicts and preserving the intended changes.
2. Review (pkg/parser/schemas/main_workflow_schema.json:15228): Limit the no-shortlist rule to workflows that enable routing for the same engine. A main workflow without model-routing still inherits an import's explicit list, as the new main without routing, import lists models test confirms. Imports without routing are skipped. The current wording incorrectly implies that either case clears the shortlist. - Model routing: an omitted allowed-models means any model when merging imports #68883 (comment)

Push the necessary fixes, reply to each listed review thread and resolve it when addressed. Ignore feedback already answered or resolved. Use the pr-finisher skill and stop when only human review or CI remains; do not trigger CI.

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[Copilot]

@copilot address the following outstanding work in one pass:

1. Update this branch with the latest main using make merge-main, resolving any conflicts and preserving the intended changes....

Pushed 4a294ab with the wording clarification and regenerated schema docs. make merge-main confirmed this branch already includes latest main and completed its build/recompile/format steps. The focused regression test, final progress gate, and secret scan passed. Replied to the linked review thread; marking it resolved requires a maintainer because no authenticated thread-resolution tool is available. No CI was triggered; checks on the new HEAD remain unverified. Automated review was unavailable; a separate read-only review found no significant issues.

[github-actions]

🎉 This pull request is included in a new release.

Release: v0.92.0