Lower Brotli default compression level to 4

[loks0n]

Summary

• Brotli default lowered from library default (11, near-max) to 4 — a sensible, fast setting for an HTTP response path.
• Added explicit Zstd default of 3 (matches the library default; set explicitly for clarity).
• Audited GZIP and Deflate: no public level setter in utopia-php/compression 0.1.4, both use PHP default level 6 — left as-is.

New constants on Http:

• COMPRESSION_BROTLI_LEVEL_DEFAULT = 4
• COMPRESSION_ZSTD_LEVEL_DEFAULT = 3

Applied in Response::send() via instanceof checks against Brotli / Zstd after algorithm selection.

Test plan

• composer check (phpstan) passes
• composer test passes
• Existing compression e2e tests still pass (response body decompresses correctly at the new level)

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR lowers the Brotli compression level from the library default (11) to 4 for better HTTP response throughput, and explicitly sets Zstd to its library default of 3 for clarity. Two new constants are added to Http and applied in Response::send() via instanceof checks before calling compress().

Confidence Score: 5/5

Safe to merge — changes are minimal, well-scoped, and follow existing patterns in the codebase.

No logic errors or correctness issues found. The level values are within valid ranges for both algorithms, the instanceof guards are correct, setLevel is called before compress(), and the new constants follow the established COMPRESSION_MIN_SIZE_DEFAULT pattern. All remaining observations are P2 or below.

No files require special attention.

Important Files Changed

Filename	Overview
src/Http/Http.php	Adds COMPRESSION_BROTLI_LEVEL_DEFAULT = 4 and COMPRESSION_ZSTD_LEVEL_DEFAULT = 3 constants, following the existing COMPRESSION_MIN_SIZE_DEFAULT pattern.
src/Http/Response.php	Applies the new compression level defaults in send() via instanceof checks on the selected algorithm before calling compress(); logic and ordering are correct.

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