fix(tui): add null check for local.agent.current()

[wydrox]

fix(tui): add null check for local.agent.current()

The local.agent.current() function can return undefined when no agents are
available (empty agents list). This caused a TypeError when trying to access
.name property on undefined.

Fix by adding optional chaining and nullish coalescing for safe access:

• local.agent.current()?.name ?? "build" for agent names
• local.agent.current()?.name ?? "" for UI display

Affected files:

• packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx (6 locations)
• packages/opencode/src/cli/cmd/tui/component/dialog-agent.tsx (1 location)

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate PRs Found

Several PRs address similar or overlapping issues with local.agent.current() null checks:

1. PR fix(tui): handle undefined agent.current() to prevent fatal TypeError #7689 - fix(tui): handle undefined agent.current() to prevent fatal TypeError

   • Directly addresses the same TypeError issue from undefined agent.current()

2. PR fix(tui): handle undefined agent.current() to prevent crash on startup #7748 - fix(tui): handle undefined agent.current() to prevent crash on startup

   • Handles undefined agent.current() to prevent crashes, similar scope to current PR

3. PR fix(opencode): add null checks for agent.current() in prompt #7920 - fix(opencode): add null checks for agent.current() in prompt

   • Explicitly adds null checks for agent.current() in prompt component

4. PR fix(tui): handle undefined agent during login/bootstrap transition #7940 - fix(tui): handle undefined agent during login/bootstrap transition

   • Addresses undefined agent handling in TUI context

5. PR Fix TUI crashes from undefined values (#8588, #8579, #8580) #8635 - Fix TUI crashes from undefined values (#8588, #8579, #8580)

   • Broader fix for TUI crashes from undefined values, may include agent.current() handling

6. PR fix(tui): guard local.agent.current() after oauth redirect (fixes #7727) #7747 - fix(tui): guard local.agent.current() after oauth redirect (fixes #7727)

   • Guards local.agent.current() in specific context

Recommendation: Check if PR #8745 is addressing a newly discovered case or if it's duplicating work from earlier PRs, particularly #7920 (prompt-specific) or #7748/#7689 (general agent.current() handling).