TSP Template script creates `const` for envvars - suggest `alias` to support string interpolation

[andrewconnell]

Describe the bug
When declared as a constant, the envvar can't be used in string concatenation (string interpolation). For example, say you have an authenticated endpoint. When envvars are constants, you can't use it when creating an alias.

The problem is the script in the template, ./scripts/generate-env.js, generates const for each envvar, but it should be an alias.

To Reproduce
Steps to reproduce the behavior:

1. In a new DA - TSP project, try to concat an envvar with a string... observe error

   

2. Change the variable to a constant, but when used in some TSP objects, like OAuth2Auth... observe error

   

Expected behavior
If the envvar generated was an alias, all works:

VS Code Extension Information (please complete the following information):

• OS: macOS
• Version v26.1

[m365-agent-toolkit-assistant]

👋 Hi @andrewconnell,

Thank you for reporting this issue! We want to let you know that:

⏱️ Our team will personally review your issue
🎯 You can expect a response within 2 business days

✨ This is an AI-generated initial response
🤖 AI-Generated Preliminary Analysis:

This is a valid issue—similar cases haven’t been found in public GitHub or Stack Overflow channels for the DA - TSP script, but environment variable handling (especially supporting string interpolation and aliasing) is a common pain point in many app templates.

Actionable guidance:

• The script ./scripts/generate-env.js currently generates const for envvars. Consider adjusting the code to generate them as TypeSpec alias instead, which allows for string interpolation and use in expressions.
• As a workaround, manually update the generated output to use alias for those envvars until template authors update the script.
• If this needs centralized support, you might propose this as a feature or bug to the toolkit maintainers.

Recent related issues have focused on:

• Envvars in manifests (issue #6640)
• Using dotenv over older libraries (issue #7904)

If you'd like to pursue this as a feature request:

• Apologies for the inconvenience—suggest opening a GitHub issue describing your use case and workaround, to help toolkit authors prioritize an update!

✨We'd love your feedback! Please take a moment to fill out our survey.

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Note: This is an automated first response generated by AI. A human team member will review your issue and provide a more detailed response soon. We appreciate your patience!

[wh-alice]

The issue is in-active for at least 3 months. If this is still relevant or cared in latest ATK release, please comment to provide updated repro details. Otherwise it will be marked as close-candidate after 7 days.