fix(upstream-sync): multi-line prompt env var and MCP config token expansion

[Copilot]

Two bugs in upstream-sync.yml caused the workflow to fail when attempting to read the agent prompt from a file.

Changes

• $GITHUB_ENV multi-line value — echo "PROMPT=$PROMPT" >> "$GITHUB_ENV" is invalid when the value contains newlines. Replaced with the required GitHub Actions heredoc format:

  {
    echo 'PROMPT<<UPSTREAM_PROMPT_DELIMITER'
    printf 'REPO: %s\n\n' '${{ github.repository }}'
    cat '.github/_upstream_agent_prompt.md'
    echo 'UPSTREAM_PROMPT_DELIMITER'
  } >> "$GITHUB_ENV"

  Also fixes \n\n being written literally instead of as actual newlines.

• MCP config token expansion — << 'EOF' (single-quoted heredoc) suppresses variable expansion, so $GHTOKEN was written literally into the JSON auth header. Changed to << EOF so ${GHTOKEN} resolves to the actual PAT value.

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[Copilot]

Pull request overview

This PR fixes upstream-sync.yml so the upstream-sync workflow can (a) correctly export a multi-line agent prompt into $GITHUB_ENV, and (b) correctly expand the PAT token when generating the MCP config JSON used by the Claude action.

Changes:

• Writes PROMPT to $GITHUB_ENV using GitHub Actions’ multiline heredoc format (preserving real newlines).
• Updates the MCP config heredoc to allow ${GHTOKEN} expansion and uses ${GHTOKEN} in the Authorization header.

Comments suppressed due to low confidence (1)

.github/workflows/upstream-sync.yml:111

• The heredoc terminator for the MCP config appears to be indented relative to the cat << EOF line. In GitHub Actions run: | blocks, YAML strips only the minimum indentation, so an extra couple leading spaces before EOF will prevent the heredoc from terminating (the shell will read until end-of-file). Align the closing EOF at the same indentation level as the cat > ... << EOF line (or use a <<-EOF + tab-indented terminator) so the delimiter is matched exactly.

                  }
                }
              }
            }
            EOF

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-actions]

👋 Hey @Copilot,

Thanks for your contribution to codeweaver! 🧵

You need to agree to the CLA first... 🖊️

Before we can accept your contribution, you need to agree to our Contributor License Agreement (CLA).

To agree to the CLA, please comment:

I read the contributors license agreement and I agree to it.

Those exact words are important¹, so please don't change them. 😉

You can read the full CLA here: Contributor License Agreement

---

✅ @Copilot has signed the CLA.

---

0 out of 2 committers have signed the CLA.
❌ @Copilot
❌ @bashandbone
_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}

Footnotes

1. Our bot needs those exact words to recognize that you agree to the CLA. ↩