Ensure `shellExecutionService.ts` respects `enableInteractiveShell: false` and implements high-fidelity native bridge stability by handling non-UTF-8 bytes in the string serialization layer or when the buffer exceeds heap limits for string conversion

[stevescherer-sherpa]

What happened?

Describe the Bug

We have identified three critical issues in the ShellExecutionService that affect stability, correctness, and security in automated or non-interactive environments (such as agent loops):

1. Hangs in Non-Interactive Loops: When enableInteractiveShell: false is set, the terminal environment is not fully restricted. Pagers (like less) and terminal colorizers can still trigger and block execution indefinitely waiting for manual user keypresses.
2. Native Bridge Crashes / OOM on Large Outputs: When a command produces a high-volume telemetry surge (e.g., >10MB), converting the massive buffer to string all at once in the native TTY bridge or child process stream triggers process-level segmentation faults or heap overflows.
3. Security Leak (GIT_CONFIG_ Bypass)*: In non-interactive mode, GIT_CONFIG_* environment variables are bypassed and restored directly from raw process.env even if they were correctly redacted by the sanitization layer due to sensitive content (e.g., GitHub OAuth tokens).

Expected Behavior

1. Non-interactive configuration should strictly enforce TERM=dumb, PAGER=cat, and GIT_PAGER=cat to prevent blocking pagers.
2. Output streams should be processed incrementally in stable 1MB chunks (without truncating or discarding data) to maintain native bridge stability and prevent OOMs.
3. Environment variable sanitization should be respected for all variables, including GIT_CONFIG_*, without any bypass loops.

Additional Context

We have prepared a complete fix for this including robust unit tests for chunking and split UTF-8 boundary decoding, and a native PTY integration test harness. I will link a Pull Request shortly.

What did you expect to happen?

Expected Behavior

1. Non-interactive configuration should strictly enforce TERM=dumb, PAGER=cat, and GIT_PAGER=cat to prevent blocking pagers.
2. Output streams should be processed incrementally in stable 1MB chunks (without truncating or discarding data) to maintain native bridge stability and prevent OOMs.
3. Environment variable sanitization should be respected for all variables, including GIT_CONFIG_*, without any bypass loops.

Client information

\u2502 About Gemini CLI                                                                                               \u2502
\u2502                                                                                                                \u2502
\u2502 CLI Version                            0.45.0-nightly.20260521.g854f811be-git.3cc7e5b                          \u2502
\u2502 Git Commit                             3cc7e5b                                                                 \u2502
\u2502 Model                                  Auto (Gemini 3)                                                         \u2502
\u2502 Sandbox                                no sandbox                                                              \u2502
\u2502 OS                                     linux  

Login information

No response

Anything else we need to know?

No response

[gemini-cli]

Found possible duplicate issues:

• gemini-cli hang calling git due to use of pager #13590

If you believe this is not a duplicate, please remove the status/possible-duplicate label.

[gemini-cli]

Effort Analysis:
The ShellExecutionService in packages/core/src/services/shellExecutionService.ts currently hardcodes TERM=xterm-256color in its prepareExecution method, which causes hangs in non-interactive environments as tools incorrectly detect a fully-capable terminal. Furthermore, the executeWithPty method uses a headlessTerminal (xterm.js) with a SCROLLBACK_LIMIT of 300,000 lines. High-volume telemetry surges (>10MB) lead to heap overflows or segmentation faults when serializeTerminalToObject or getFullBufferText attempts to convert massive internal buffers into strings for serialization across the IPC bridge to the React/Ink UI. Additionally, both ShellExecutionService.ts and packages/core/src/services/environmentSanitization.ts explicitly bypass redaction for GIT_CONFIG_* variables (lines 450 and 150 respectively), creating a documented security leak for sensitive credentials. Fixing these requires refactoring low-level process environment management, implementing incremental chunk-based streaming to avoid OOMs, and tightening the security sanitization logic—all of which fall under the effort/large criteria for PTY/Signals and Performance/Memory optimizations.

[Keesan12]

This sounds like the shell bridge needs a byte-safe path, not a more opinionated string conversion. If enableInteractiveShell is false, the execution layer should stay in non-interactive mode all the way down and preserve raw bytes until the caller asks for text. That would avoid both accidental interactivity and corruption on non-UTF-8 output.