fix(agent, cli): Gemini bugfixes, add fallback if pty isn't available

[ddupont808]

Summary by CodeRabbit

• Bug Fixes
  • Enhanced error resilience in AI model response handling when critical data is missing or incomplete.
  • Shell command execution now automatically falls back to non-interactive mode when interactive mode is unavailable, ensuring commands continue to function properly.

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	Feb 26, 2026 2:52pm

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📦 Publishable packages changed

• pypi/agent
• pypi/cli

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📝 Walkthrough

Walkthrough

The changes strengthen resilience in Gemini response parsing with guarded candidate and parts extraction, early returns for missing data, and expanded browser action name support; and introduce graceful PTY fallback to non-interactive execution when remote PTY initialization fails.

Changes

Cohort / File(s)	Summary
Gemini Response Resilience libs/python/agent/agent/loops/gemini.py	Replaced direct candidate/parts access with guarded retrieval, added early returns for missing data, enhanced function_call extraction with safe attribute access, and expanded browser action mapping to support both "open_web_browser" and "open_browser" names.
PTY Fallback Mechanism libs/python/cua-cli/cua_cli/commands/do.py	Added _PtyUnavailable exception class; modified _shell_remote_pty to raise this exception on PTY creation failure; updated _cmd_shell to catch the exception and gracefully fallback to non-interactive run_command execution.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• fix(agent): route cua/ prefix Gemini models through correct agent loop #1117: Directly related changes to Gemini SDK response parsing logic and function call mapping to internal computer_call actions including browser action names.
• feat: Add interactive terminal (PTY) support w/ tests to cua-auto, computer-server, computer, and the cua CLI #1114: Introduces PTY features that are extended with failure mode handling and fallback logic in this PR.

Poem

🐰 A rabbit hops through code so fine,
With guards and catches in each line,
When Gemini speaks without a sound,
Or PTY fails on shaky ground,
We fall back gracefully, bounce around!

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the two main changes: Gemini bugfixes in the agent module and a PTY fallback mechanism in the CLI, matching the actual changeset content.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch ddupont/ci-bugfixes

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[sentry]

Codecov Report

❌ Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
libs/python/agent/agent/loops/gemini.py	0.00%	10 Missing ⚠️

📢 Thoughts on this report? Let us know!

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@libs/python/agent/agent/loops/gemini.py`:
- Around line 840-842: The long chained getattr that builds _dbg_parts is
causing Black to fail; break the expression into smaller, Black-friendly
statements by first assigning _dbg_candidates = getattr(response, "candidates",
None) or [], then compute candidate = _dbg_candidates[0] if _dbg_candidates else
None, then content = getattr(candidate, "content", None), and finally set
_dbg_parts = getattr(content, "parts", None) or []; keep the subsequent for p in
_dbg_parts loop unchanged so the logic remains identical but formatted across
multiple lines for Black compatibility.

In `@libs/python/cua-cli/cua_cli/commands/do.py`:
- Around line 1466-1468: When catching _PtyUnavailable, handle the case where
command is empty by invoking the interactive fallback instead of
_cmd_shell_noninteractive; specifically, check if command is falsy in the except
block and call the interactive handler (e.g., _cmd_shell_interactive(...)) with
the same args, otherwise call _cmd_shell_noninteractive(command, args);
reference _PtyUnavailable, command, args, _cmd_shell_noninteractive and
_cmd_shell_interactive to locate and update the except block.

---

ℹ️ Review info

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 4e21930 and cfe3802.

📒 Files selected for processing (2)

• libs/python/agent/agent/loops/gemini.py
• libs/python/cua-cli/cua_cli/commands/do.py

[github-actions]

📦 Publishable packages changed

• pypi/agent
• pypi/cli

Add release:<service> labels to auto-release on merge (+ optional bump:minor or bump:major, default is patch).
Or add no-release to skip.