Optimize(Web): gzip pre-compression

[Marc-Andrieu]

Description

Summary

The web version can be unbearably slow. One way to fix it is compression.

• Compression = fewer data is transferred over the network = faster loading times (even more blatant in slow networks)
• Pre-compression = compressed once (here I included this in the building of the Docker image), served instantly from disk, no CPU overhead, and allows more aggressive levels without downsides for the client (source: the creator of gzip himself said so on StackOverflow) = even faster
• gzip = already in Nginx by default. Brotli may be even faster to decompress, and supported everywhere as well, but building a Nginx+Brotli image really is unmaintainable for us.

Sources:

• https://stackoverflow.com/a/37892135/30331616

Before/after

A video is better than 1000 words: ~30% faster with a fast connection.
Can go up to 2x faster in slower networks.
Consistently 12.0-12.2s for https://titan.dev.eclair.ec-lyon.fr and 8.7-9.0s for https://titan-1.dev.eclair.ec-lyon.fr

Enregistrement.de.l.ecran.2026-02-07.204811.mp4

Issues/PR dependencies

Subset of the draft #646 for Nginx pre-compression.

Changes Made

• Nginx config: gzip config: gzip & gunzip, static, level 9, >512 bytes, mime types to take text-based files & avoid images,
• Dockerfile: include the compression there, for >512 bytes file, take text-based files & avoid image
• Consistent params between the Nginx config and the compression during image build.
• Re-run flutter pub run pdfx:install_web to regenerate the PDF script

Classification

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 🔨 Refactor (non-breaking change that neither fixes a bug nor adds a feature)
• 🔧 Infra CI/CD (changes to configs of workflows)
• 💥 BREAKING CHANGE (fix or feature that require a new minimal version of the front-end)
• 😶‍🌫️ No impact for the end-users
• Optimization

Impact & Scope

• Core functionality changes
• Single module changes
• Multiple modules changes
• Other: Dockerfile, Nginx config, index.html

Testing

• 1. Tested this locally: built and run my Docker image
• 2. Added/modified tests that pass the CI (or tested in a downstream fork)
• 3. Tested in a local client using a pre-prod backend
• 4. Created the 1st Titan pre-prod for the occasion
• 0. Untestable (exceptionally), will be tested in prod directly

Documentation

• Updated the docs accordingly :
• // Comments
• No documentation needed

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 50.88%. Comparing base (27a10d9) to head (cf1ad2c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #653   +/-   ##
=======================================
  Coverage   50.88%   50.88%           
=======================================
  Files         167      167           
  Lines        3797     3797           
=======================================
  Hits         1932     1932           
  Misses       1865     1865           

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