Fix imported engine.model silently dropped when max-ai-credits is set

[Copilot]

When a workflow sets max-ai-credits at the top level and sources engine.model from an import, the model pin is silently discarded — the compiled lock falls back to ${{ vars.GH_AW_MODEL_AGENT_COPILOT || ... }} with zero compiler warnings.

Root cause

max-ai-credits at the top level causes ExtractEngineConfig to return a non-nil engineConfig (to carry the budget). In resolveEngineFromIncludesAndImports, model extraction from allEngines was gated on engineConfig == nil, so a budget-only engineConfig caused the import's engine.model to be skipped entirely. The applyEngineImportDefaults path that handles MergedEngineModel is not exercised here because an engine with an id goes into MergedEngines, not MergedEngineModel.

Fix

• compiler_orchestrator_engine.go — add an else if branch in resolveEngineFromIncludesAndImports that extracts the model from allEngines[0] when model == "" and engineConfig != nil:

} else if model == "" && len(allEngines) > 0 {
    _, extractedModel, extractErr := c.extractEngineConfigFromJSON(allEngines[0])
    if extractErr == nil && extractedModel != "" {
        model = extractedModel
    }
}

• compiler_orchestrator_engine_test.go — regression test TestSetupEngineAndImports_ImportedModelPreservedWithTopLevelMaxAICredits covering the exact failure scenario: max-ai-credits: 1500 in the main workflow + engine: { id: copilot, model: gpt-5.6-sol } in an import.

• Fixes Imported engine.model is silently dropped when max-ai-credits is set #48441

[github-actions]

✅ Test Quality Sentinel completed test quality analysis.

[github-actions]

✅ Design Decision Gate 🏗️ completed the design decision gate check.

[github-actions]

🧠 Matt Pocock Skills Reviewer has completed the skills-based review. ✅

[github-actions]

✅ PR Code Quality Reviewer completed the code quality review.

[Copilot]

Pull request overview

Fixes imported engine model pins being dropped when top-level AI credit limits create a partial engine configuration.

Changes:

• Preserves imported engine.model values.
• Adds regression coverage for max-ai-credits.
• Refreshes the generated smoke workflow lock.

Show a summary per file

File	Description
pkg/workflow/compiler_orchestrator_engine.go	Extracts the imported model when needed.
pkg/workflow/compiler_orchestrator_engine_test.go	Tests model and budget preservation.
.github/workflows/smoke-copilot-auto.lock.yml	Refreshes generated model-cost metadata.

Review details

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• Files reviewed: 3/3 changed files
• Comments generated: 0
• Review effort level: Medium

[pelikhan]

@copilot resolve the merge conflicts on this branch.

[Copilot]

@copilot resolve the merge conflicts on this branch.

Resolved. I merged origin/main into this branch, fixed the conflict in .github/workflows/smoke-copilot-auto.lock.yml, and pushed commit d904707.