fix(core): respect .gitignore and .geminiignore in session_context directory tree

[KirtiRamchandani]

Summary

Ensures the <session_context> directory tree honors the same ignore rules as the rest of the CLI.

Fixes #27787

Problem

getDirectoryContextString() builds the folder tree shown inside <session_context>. It calls getFolderStructure() with only fileService, but does not pass fileFilteringOptions from config.

getFolderStructure() only applies .gitignore / .geminiignore filtering when both are available:

1. fileService.shouldIgnoreFile() / shouldIgnoreDirectory()
2. Matching fileFilteringOptions.respectGitIgnore / respectGeminiIgnore flags

Without (2), ignored paths can still appear in the session bootstrap context — wasting tokens and potentially leaking files the user intentionally excluded.

Root cause

// Before
getFolderStructure(dir, {
  fileService: config.getFileService(),
});

Other tools (ls, glob, read-many-files, etc.) already pass config.getFileFilteringOptions(). Session context generation was the missing call site.

Fix

Pass the configured filtering options alongside the file service:

getFolderStructure(dir, {
  fileService: config.getFileService(),
  fileFilteringOptions: config.getFileFilteringOptions(),
});

This aligns session context generation with the ignore behavior used elsewhere in core.

Testing

Updated environmentContext.test.ts expectations and mocked getFileFilteringOptions().

cd packages/core && npx vitest run src/utils/environmentContext.test.ts
# 8 passed

[gemini-code-assist]

Summary of Changes

Hello, 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 addresses an issue where the session context directory tree was failing to respect user-defined ignore rules. By passing the configured file filtering options to the folder structure generation logic, the system now consistently applies .gitignore and .geminiignore settings, preventing unnecessary token usage and potential file exposure.

Highlights

• Session Context Filtering: Updated the session context generation to correctly pass file filtering options, ensuring that .gitignore and .geminiignore rules are respected.
• Test Coverage: Updated environment context tests to mock filtering options and verify that the folder structure generation correctly applies ignore rules.

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[github-actions]

📊 PR Size: size/S

• Lines changed: 16
• Additions: +16
• Deletions: -0
• Files changed: 2

[gemini-code-assist]

Code Review

This pull request updates getDirectoryContextString in environmentContext.ts to pass fileFilteringOptions from the configuration to getFolderStructure. The corresponding unit tests in environmentContext.test.ts have been updated to mock getFileFilteringOptions and verify that the options are correctly passed. There are no review comments, so I have no feedback to provide.

[KirtiRamchandani]

Thanks for reviewing.

This wires config.getFileFilteringOptions() into getFolderStructure() for session directory trees, matching how ls, glob, and read-many-files already honor .gitignore / .geminiignore.

Unit tests assert the options object is forwarded. Happy to add an integration test if you'd like.