fix: add UTF-8 encoding for subprocess calls on Windows

[cabana8471-arch]

Summary

• Fix Windows UTF-8 encoding issue in subprocess calls
• Add encoding="utf-8" and errors="replace" to all subprocess calls that use text=True

Problem

Windows users experience UnicodeDecodeError when running parallel mode because subprocess.Popen with text=True defaults to CP1252 encoding instead of UTF-8.

Solution

Explicitly specify UTF-8 encoding for all subprocess calls that process text output from Claude agents.

Files Modified

• parallel_orchestrator.py (3 locations)
• start.py (2 locations)
• start_ui.py (1 location)

Testing

• Verified ruff linting passes: ruff check parallel_orchestrator.py start.py start_ui.py
• The fix is low-risk and only explicitly specifies UTF-8 encoding which is already the expected behavior on non-Windows systems

Notes

• Files quality_gates.py, git_workflow.py, review_agent.py, and security_scanner.py mentioned in issue Encoding issue with CP1252 / UTF-8 #138 don't exist on master - they are only in feature branches. This PR fixes all affected files on master.
• PR Merge 15+ PRs: Security, Windows fixes, Knowledge files, Chat persistence, and more #117 (mega merge) may have merge conflicts with this change

Closes#138

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Enhanced text encoding handling across system operations to improve Windows platform compatibility and prevent character encoding failures.
  • Improved error resilience during system initialization and background operations to ensure reliable text output processing.
  • Strengthened encoding error handling throughout critical system processes for more robust and stable operation.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds explicit UTF-8 encoding and error replacement parameters to subprocess invocations across three initialization and startup modules to resolve Windows CP1252 encoding issues. No control flow changes; parameters ensure robust text I/O handling on Windows environments.

Changes

Cohort / File(s)	Summary
Subprocess Encoding Robustness parallel_orchestrator.py, start.py, start_ui.py	Added encoding="utf-8" and errors="replace" parameters to subprocess.Popen and subprocess.run calls to handle Windows CP1252 encoding conflicts and prevent UnicodeDecodeError exceptions on non-ASCII byte sequences.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• leonvarzyl/autocoder#89: Both PRs modify subprocess invocation parameters (Popen/run kwargs) in parallel_orchestrator.py and start.py for improved Windows compatibility and encoding robustness.

Poem

🐰✨ A little rabbit hops with glee,
UTF-8 flows so wild and free,
CP1252 troubles now fade away,
Windows encodes the proper way! 🖥️💨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding UTF-8 encoding to subprocess calls on Windows to fix encoding issues.
Linked Issues check	✅ Passed	The PR directly addresses issue #138 by adding encoding='utf-8' and errors='replace' to all subprocess calls across three files, matching the exact solution proposed.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to the encoding fix in subprocess calls; no unrelated modifications were introduced.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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