fix(attach): read OPENCODE_SERVER_USERNAME instead of hardcoding opencode

[ernestodeoliveira]

Issue for this PR

Closes #18611

Type of change

• Bug fix

What does this PR do?

opencode attach builds the Basic auth header hardcoding "opencode" as the username:

const auth = `Basic ${Buffer.from(`opencode:${password}`).toString("base64")}`

This ignores OPENCODE_SERVER_USERNAME, so authentication fails when the server is configured with a non-default username. opencode run already reads the env var correctly (line 659 in run.ts). This PR applies the same pattern to attach.

How did you verify your code works?

Code inspection — the fix mirrors the existing pattern in run.ts exactly.

Screenshots / recordings

N/A — CLI-only change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍

[atharvau]

Code Review for PR #18641: Duplicate Fix

⚠️ Notice: Duplicate PR

This PR is identical to PR #18646 by @kevinWangSheng, which implements the exact same fix:

• Both add OPENCODE_SERVER_USERNAME environment variable support
• Both use "opencode" as the fallback default
• Both modify the same file with identical changes

📋 Recommendation

Since PR #18646 was submitted first and has already been reviewed, I recommend:

1. Close this PR in favor of #18646
2. Credit @ernestodeoliveira in #18646 for also identifying this issue
3. Merge #18646 which has the same fix

This is a common situation where multiple contributors identify the same issue. Both solutions are correct, but we should avoid duplicate merges.

✅ Technical Assessment

The code change itself is excellent - same quality as #18646:

• Backwards compatible
• Follows established patterns
• Clean implementation

Recommendation: CLOSE (Duplicate of #18646)