Claude Opus inserting spaces after decimals and after variable/property dots in Copilot

[aliattia02]

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Bug

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Bug: When using Claude Opus 4.5 inside GitHub Copilot, the generated code contains random unwanted spaces, for example:

After decimals: 1. 000 instead of 1.000

After dots in property access: element. getAttribute, button. addEventListener

After hyphenated names: tab- button

This breaks JavaScript code and formatting.

Important:
The same prompts tested directly on Claude.ai do not show these issues, and Claude in Copilot cannot “see” the spacing error, suggesting a Copilot rendering bug, not a model bug.

Steps to reproduce:
Generate code with decimals, property access (.getAttribute, .addEventListener), or hyphenated class names (tab-button) using Claude Opus in Copilot.

Expected: No extra spaces.
Actual: Copilot inserts random spaces.

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[bturner-cpacket]

Pasting here what I also put in issue: https://github.com/orgs/community/discussions/180736

I can confirm I just had this happen in 6 places in a single GitHub action workflow file I had Claude Opus 4.5 modify from the GitHub web page.

It took lines like this:

run: echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u ${{ github.actor }} --password-stdin

And gave me back this, with no other changes to this line except the new space after ghcr.:

run: echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr. io -u ${{ github.actor }} --password-stdin