feat: handle multiple dynamic context filenames in system prompt

[NTaylorMullen]

Summary

This PR updates the system prompt to dynamically reflect the configured context filename(s). It replaces the hardcoded GEMINI.md string with the actual filename(s) from the configuration, supporting both single strings and arrays of filenames.

Details

• Modified packages/core/src/prompts/snippets.ts to support contextFilenames as an array of strings in SystemPromptOptions and CoreMandatesOptions.
• Updated renderCoreMandates to format multiple filenames as a natural language list (e.g., "GEMINI.md, CUSTOM.md or ANOTHER.md").
• Updated renderUserMemory and renderFinalShell to propagate and display multiple filenames in the contextual instructions header.
• Updated packages/core/src/prompts/promptProvider.ts to retrieve all configured filenames using getAllGeminiMdFilenames() and pass them to the rendering functions.
• Removed an unused import getCurrentGeminiMdFilename in promptProvider.ts that was causing build failures.
• Added comprehensive unit tests in packages/core/src/prompts/promptProvider.test.ts to verify prompt generation with multiple context filenames.

Related Issues

None.

How to Validate

1. Run the new prompt provider tests:

   npm test -w @google/gemini-cli-core -- src/prompts/promptProvider.test.ts

2. Run existing core prompt tests:

   npm test -w @google/gemini-cli-core -- src/core/prompts.test.ts

3. (Optional) Manually verify by setting a custom context filename in config.yaml and checking the generated system prompt via GEMINI_WRITE_SYSTEM_MD=true.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[gemini-code-assist]

Summary of Changes

Hello @NTaylorMullen, 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 significantly enhances the system's prompt generation mechanism by introducing support for multiple dynamic context filenames. Previously, the system relied on a hardcoded filename for contextual instructions. This change allows the system prompt to accurately reflect all configured context files, improving the flexibility and accuracy of the instructions provided to the underlying model and making the system more adaptable to diverse project structures.

Highlights

• Dynamic Context Filenames: The system prompt now dynamically reflects configured context filenames, replacing the previously hardcoded GEMINI.md string with actual filenames.
• Array Support for Filenames: The configuration now supports an array of filenames for context, allowing for greater flexibility in defining contextual instructions.
• Natural Language Formatting: Multiple context filenames are formatted into natural language lists (e.g., "GEMINI.md, CUSTOM.md or ANOTHER.md") within the system prompt for improved readability.
• Prompt Rendering Updates: Functions such as renderCoreMandates, renderUserMemory, and renderFinalShell have been updated to correctly propagate and display these multiple filenames throughout the prompt.
• Configuration Retrieval: The promptProvider.ts file now utilizes getAllGeminiMdFilenames() to retrieve all relevant context filenames from the configuration.
• Improved Test Coverage: Comprehensive unit tests have been added to promptProvider.test.ts to ensure correct prompt generation with various context filename configurations, including single and multiple files.

Changelog

• packages/core/src/prompts/promptProvider.test.ts
  • Added new test cases to verify the correct handling and display of multiple context filenames in both the core system prompt and the user memory section.
• packages/core/src/prompts/promptProvider.ts
  • Imported getAllGeminiMdFilenames to retrieve all configured context filenames.
  • Modified getCoreSystemPrompt to pass the retrieved contextFilenames array to the activeSnippets.getCoreSystemPrompt and activeSnippets.renderFinalShell functions.
• packages/core/src/prompts/snippets.ts
  • Updated SystemPromptOptions and CoreMandatesOptions interfaces to include an optional contextFilenames property (array of strings).
  • Modified renderFinalShell to accept contextFilenames as an argument and pass it to renderUserMemory.
  • Updated renderCoreMandates to dynamically format and display the contextFilenames array in the "Contextual Precedence" section, handling single and multiple filenames with natural language conjunctions.
  • Modified renderUserMemory to accept contextFilenames and use them to generate the header for the "Contextual Instructions" section.

Activity

• The pull request was created by NTaylorMullen.
• New unit tests were added to validate the changes.
• The author performed self-validation on MacOS using npm run.

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[gemini-code-assist]

Code Review

This pull request effectively adds support for multiple dynamic context filenames in the system prompt. There are opportunities to enhance code clarity and maintainability by removing a redundant property and replacing a hardcoded string with its corresponding constant.

[github-actions]

Size Change: +640 B (0%)

Total Size: 23.9 MB

ℹ️ View Unchanged

Filename	Size	Change
./bundle/gemini.js	23.9 MB	+640 B (0%)
./bundle/sandbox-macos-permissive-closed.sb	1.03 kB	0 B
./bundle/sandbox-macos-permissive-open.sb	890 B	0 B
./bundle/sandbox-macos-permissive-proxied.sb	1.31 kB	0 B
./bundle/sandbox-macos-restrictive-closed.sb	3.29 kB	0 B
./bundle/sandbox-macos-restrictive-open.sb	3.36 kB	0 B
./bundle/sandbox-macos-restrictive-proxied.sb	3.56 kB	0 B

_{compressed-size-action}

[abhipatel12]

LGTM, w/ small nit on date