fix(cli): resolve double rendering in shpool and address vscode lint warnings

[braddux]

This commit fixes rendering artifacts (specifically double rendering of the footer
and settings menu) when running Gemini CLI within an shpool session.

Key changes for shpool:

• Detected shpool sessions via the SHPOOL_SESSION_NAME environment variable.
• Added a 100ms delay before initial TUI rendering in shpool to allow terminal
  state and size to stabilize.
• Disabled incrementalRendering for shpool sessions, which prevents frame
  replay artifacts common in multiplexed environments.
• Removed redundant manual enterAlternateScreen() and disableLineWrapping()
  calls in the boot sequence, delegating alternate buffer management entirely
  to the ink library.
• Ensured line wrapping is disabled after alternate buffer entry and properly
  restored on exit via registered cleanup functions.

VS Code Companion refactorings:

• Addressed unsafe type assertions in diff-manager.ts and ide-server.ts by
  using proper type guards (instanceof vscode.TabInputTextDiff) and safer
  header extraction logic. This removes the need for eslint-disable directives
  and ensures compliance with root linting rules.

Test updates:

• Updated unit tests to account for additional cleanup registrations and
  ensured consistent environment variable handling.

Fixes #18703

[gemini-code-assist]

Summary of Changes

Hello @braddux, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves critical rendering issues within the Gemini CLI when operating in an shpool environment, preventing visual glitches like double rendering. Concurrently, it enhances the robustness and type safety of the VS Code Companion by eliminating unsafe type assertions and improving header parsing, aligning the codebase with stricter linting standards. These changes collectively improve the user experience in specific terminal multiplexer setups and bolster the overall code quality of the VS Code integration.

Highlights

• Shpool Rendering Fixes: Implemented specific logic to address rendering artifacts in shpool sessions, including detecting shpool via environment variables, introducing a 100ms delay before TUI rendering, and disabling incremental rendering to prevent frame replay issues.
• Alternate Buffer Management Refinement: Removed redundant manual calls for enterAlternateScreen() and disableLineWrapping(), delegating alternate buffer management entirely to the Ink library and ensuring proper line wrapping restoration via cleanup functions.
• VS Code Companion Type Safety Improvements: Refactored diff-manager.ts and ide-server.ts to replace unsafe type assertions with proper type guards (e.g., instanceof vscode.TabInputTextDiff) and safer header extraction logic, eliminating the need for eslint-disable directives.
• Unit Test Updates: Adjusted unit tests to correctly handle the new cleanup registrations and ensure consistent environment variable management, specifically for SHPOOL_SESSION_NAME.

Changelog

• packages/cli/src/gemini.test.tsx
  • Added originalEnvShpool variable to store and restore the SHPOOL_SESSION_NAME environment variable.
  • Ensured SHPOOL_SESSION_NAME is cleared before each test and restored afterwards.
  • Introduced vi.unstubAllEnvs() to clean up environment stubs.
  • Updated the expected number of registerCleanup calls in tests from 3 to 4.
• packages/cli/src/gemini.tsx
  • Removed direct imports and calls for enterAlternateScreen and added enableLineWrapping.
  • Introduced isShpool detection based on SHPOOL_SESSION_NAME environment variable.
  • Added a 100ms delay before TUI rendering when running in an shpool session.
  • Conditionally disabled incrementalRendering for shpool sessions.
  • Managed disableLineWrapping and enableLineWrapping via registerCleanup when using an alternate buffer.
  • Removed manual alternate screen and line wrapping management from the main function, relying on Ink's capabilities.
• packages/vscode-ide-companion/src/diff-manager.ts
  • Replaced an unsafe type assertion for tab.input with a type guard using instanceof vscode.TabInputTextDiff.
• packages/vscode-ide-companion/src/ide-server.ts
  • Refactored header extraction for MCP_SESSION_ID_HEADER to safely handle array or string values.
  • Removed an unsafe type assertion for this.server.address() by capturing the server instance locally.
  • Assigned the local server instance to this.server after it has started listening.

Activity

• No human activity has occurred on this pull request yet.

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[gemini-code-assist]

Code Review

This pull request introduces several valuable improvements. It effectively resolves rendering artifacts in shpool by detecting the session and adjusting rendering parameters, including adding a short delay and disabling incremental rendering. The refactoring of terminal screen management to better leverage the ink library is a good cleanup. Furthermore, the changes in the VS Code companion are excellent, replacing unsafe type assertions with proper type guards (instanceof) in diff-manager.ts and ide-server.ts. This significantly improves type safety and code clarity, removing the need for eslint-disable directives. The test suite has also been updated accordingly to reflect these changes. Overall, this is a high-quality contribution that improves both functionality and code health.

[jacob314]