Feature Request: Auto-detect and suggest ignoring heavy build directories (e.g. .next, dist)

[aniruddhaadak80]

What would you like to be added?

Add a mechanism to automatically detect and suggest ignoring heavy, generated build directories (like .next, node_modules, dist, build, .out) when they are not explicitly ignored via .gitignore or .geminiignore.

Approach:
Upon CLI initialization or when traversing files (e.g., using read-many-files or globbing), if the tool detects high file counts from known boilerplate directories, it could print a light, transient warning or automatically inject a default ignore template locally.

Why is this needed?

Tokens are precious. If a user runs the CLI in a repository where they haven't properly configured ignore behaviors, the agent might aggressively ingest thousands of minified JS files from dist or chunks from .next. This can:

1. Instantly blow up the user's token budget constraint.
2. Severely degrade prompt contextual quality and latency.
3. Potentially cause the TokenBudgetWarning to fire immediately.

Having a smart, default set of ignored paths out of the box will significantly improve the onboarding experience for JavaScript / TypeScript / Build-heavy project users.

Suggested File Paths / Context

• packages/core/src/indexing/ignoreUtils.ts
• Or packages/core/src/tools/read-many-files.ts