fix: inherit process environment variables in terminal shells

[roomote]

Fixes #7094

Problem

When Roo Code creates terminals (especially in remote SSH environments), it was not inheriting the user's PATH customizations and other environment variables from their shell configuration files. This meant that tools and commands available in the user's normal shell were not accessible in Roo's integrated terminal.

Solution

Modified Terminal.getEnv() to start with process.env and then apply Roo-specific overrides. This ensures that:

• User PATH customizations are preserved
• Shell aliases and custom environment variables are available
• Roo-specific requirements (like VTE_VERSION, PAGER) are still properly set

Changes

• Modified Terminal.getEnv() to inherit from process.env while filtering out undefined values
• Added comprehensive tests for environment variable inheritance
• Updated existing tests to use expect.objectContaining() for more flexible environment checks

Testing

• Added new test suite Terminal.env.spec.ts with 11 tests covering environment inheritance
• All existing terminal tests pass
• TypeScript compilation successful
• Linting passes

This change ensures that users working in remote SSH environments or with custom shell configurations will have their full environment available when Roo executes commands.

---

Important

Terminal.getEnv() now inherits user environment variables, preserving PATH and custom settings while applying Roo-specific overrides, with comprehensive tests added.

• Behavior:
  • Terminal.getEnv() now starts with process.env to inherit user environment variables, preserving PATH and custom variables.
  • Roo-specific overrides like VTE_VERSION and PAGER are applied after inheriting user environment.
• Testing:
  • Added Terminal.env.spec.ts with 11 tests for environment variable inheritance.
  • Updated tests in TerminalRegistry.spec.ts to use expect.objectContaining() for environment checks.
• Misc:
  • Ensures full environment availability in remote SSH and custom shell configurations.

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[roomote]

Reviewing my own code is like debugging in a mirror - everything looks backwards but the bugs are still mine.

[roomote]

Security consideration: We're now inheriting ALL environment variables from process.env. While this solves the PATH issue perfectly, should we consider adding a whitelist/blacklist mechanism to filter out potentially sensitive variables like API keys or tokens? Some users might have secrets in their environment that shouldn't be exposed to terminal processes.

[roomote]

Performance thought: Would using Object.assign() with spread operator be more performant here? Something like:

Suggested change

	const env: Record<string, string> = {}
	// Start with the current process environment to inherit user's PATH and other customizations
	// Filter out undefined values to satisfy the return type
	const env: Record<string, string> = { ...process.env }
	for (const key in env) {
	if (env[key] === undefined) {
	delete env[key]
	}
	}

Though the current approach is clear and works well.

[roomote]

Nice edge case testing! Though I wonder if we should set sensible defaults for essential variables like PATH when they're undefined? Some shell operations might fail without these critical variables.

[roomote]

Could we make this comment more explicit about WHY we filter undefined values? Something like: "Filter out undefined values to satisfy TypeScript's Record<string, string> return type"