Fix/issue 16982 agent current undefined

[SOUMITRO-SAHA]

Issue for this PR

Closes #16982

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Problem:
The TUI was crashing with TypeError: undefined is not an object (evaluating 'local.agent.current().name') when the agent list was empty or filtered out (e.g., only subagents/hidden agents available).

The root cause was in src/cli/cmd/tui/context/local.tsx where agent.current() used a non-null assertion (!) but could actually return undefined:

current() {
  return agents().find((x) => x.name === agentStore.current)!  // ❌ unsafe
}

Fix:

1. Removed the unsafe non-null assertion
2. Added proper null checks in all places that access agent.current().name or its properties
3. Added early return with error toast in the prompt submit handler
4. Added fallback values in reactive memos (highlight, spinnerDef)

Files changed:

• src/cli/cmd/tui/context/local.tsx: Removed !, added 4 null checks
• src/cli/cmd/tui/component/prompt/index.tsx: Added agent validation before submit, safe property access in memos
• src/cli/cmd/tui/component/dialog-agent.tsx: Added optional chaining

How did you verify your code works?

1. Created comprehensive unit tests (test/cli/tui/context/local.test.ts):

   • 5 tests covering the bug scenario, null safety patterns, filtering logic, and all property access contexts
   • All tests pass ✓
   • Tests verify that undefined agent doesn't cause crashes

2. TypeScript compilation:

   • bun typecheck passes with no errors
   • All unsafe type assertions removed

3. Manual verification:

   • No more unsafe .current()! calls remain in the codebase
   • All 11 code changes have corresponding test coverage

Screenshots / recordings

N/A - This is a bug fix, no visual UI changes.

Checklist

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

[github-actions]

Hey! Your PR title Fix/issue 16982 agent current undefined doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

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

Potential Duplicate/Related PRs Found:

This issue has been addressed multiple times historically. While these are older PRs, they tackle the same root cause - the unsafe agent.current() access returning undefined:

1. fix(tui): handle undefined agent.current() to prevent fatal TypeError #7689 - fix(tui): handle undefined agent.current() to prevent fatal TypeError
2. fix(tui): handle undefined agent.current() to prevent crash on startup #7748 - fix(tui): handle undefined agent.current() to prevent crash on startup
3. fix(opencode): add null checks for agent.current() in prompt #7920 - fix(opencode): add null checks for agent.current() in prompt
4. fix(tui): guard local.agent.current() after oauth redirect (fixes #7727) #7747 - fix(tui): guard local.agent.current() after oauth redirect (fixes opentui: fatal: undefined is not an object (evaluating 'local.agent.current().name') #7727)
5. fix(tui): guard default agent selection #7796 - fix(tui): guard default agent selection
6. fix(tui): handle undefined agent during login/bootstrap transition #7940 - fix(tui): handle undefined agent during login/bootstrap transition
7. fix(tui): add null check for local.agent.current() #8745 - fix(tui): add null check for local.agent.current()
8. fix: add fallback for current agent in TUI to prevent crashes #9877 - fix: add fallback for current agent in TUI to prevent crashes

These PRs suggest this is a recurring issue in the codebase. You may want to check if any of these previous fixes were reverted or if this is a regression, and consider why the same crash pattern keeps appearing.

[github-actions]

Closing this pull request because it has had no updates for more than 60 days. If you plan to continue working on it, feel free to reopen or open a new PR.