Why @workspace matters in Copilot Chat

@workspace is a Copilot Chat context selector that enables Copilot to use files from your currently opened project as grounding context.

When you chat with a domain agent like the @ecl participant, it can be highly knowledgeable about ECL concepts, syntax, and documentation. But that does not automatically mean it can read your local files.

That is the key difference:

• Without @workspace: the agent answers from its built-in knowledge, documentation context, and tools, but not your local project files unless you paste content.
• With @workspace: you explicitly grant access to your open workspace context, so Copilot can read referenced files and use nearby project structure as context.

What this looks like in practice

Example 1 (no workspace context)

@ecl explain #file:initfiles/examples/TutorialYourName/BWR_ProcessRawData.ecl in the context of initfiles/examples/TutorialYourName

Typical result:

“I can only answer questions about ECL based on the documentation and tools available to me. The file you referenced is a local workspace file that I don’t have access to view.”

Why this happens:

• You asked for a local file explanation.
• The agent was not given workspace scope.
• So it could not open or inspect that file, even though your prompt referenced it.

Example 2 (workspace context enabled)

@workspace @ecl explain #file:initfiles/examples/TutorialYourName/BWR_ProcessRawData.ecl in the context of initfiles/examples/TutorialYourName

Typical result:

Now Copilot explains the file clearly and specifically.

Why this happens

• @workspace tells Copilot to use your workspace as an allowed source of truth.
• The #file reference can now be resolved to the actual file.
• The agent can combine ECL knowledge with the real code in your project folder.

Simple mental model

Think of @ecl as the specialist and @workspace as the permission slip.

• @ecl = “I know ECL.”
• @workspace = “You may read my project files.”
• Together = “Explain my real ECL code, in my real repo context.”

When to add @workspace

Use @workspace whenever your question depends on:

• A specific local file
• Project-relative imports/includes
• Folder-level conventions
• Cross-file behavior in your repo

If your question is purely conceptual (for example, “What is a SuperFile?”), @workspace is often unnecessary.

Practical prompt pattern

A reliable pattern is:

@workspace @ecl explain #file:path/to/file.ecl in the context of path/to/folder

This gives Copilot three things at once:

• Permission to read files
• The exact file to inspect
• The surrounding folder context to interpret intent

Bottom line

Adding @workspace is what turns a general expert response into a code-aware explanation of your actual files. In the example above, that single addition is exactly why the second prompt works and the first one doesn't.