Selective warning-code suppression in Astro CI pipelines

Context

Teams running astro build in CI need actionable alerts — such as Content Collections validation failures or missing image alt text — without drowning in noisy warnings from integrations like @astrojs/sitemap or @astrojs/prefetch. Astro 4.x provides a global --log-level flag and experimental --log-format json output, yet no first-party mechanism exists to suppress individual warning codes (for example, "unused-content-entry") while retaining other warnings of the same severity.

Constraints

• Vite's logLevel and Astro's --log-level interact unpredictably when both are configured.
• JSON log structure is marked experimental and may change without a major version bump.
• The astro:build:done hook receives warnings only after the build exits, so it cannot alter the exit code.
• Third-party integrations may write directly to stdout/stderr, bypassing Astro's logger entirely.

Questions

1. What is the recommended pattern for allow-listing or block-listing specific warning codes in CI today without wrapping the build in a custom parsing script?
2. Does Astro's roadmap include a stable, per-warning-code filter or a warnings configuration section in astro.config.mjs?
3. Can the validate: 'error' option for Content Collections be extended to other built-in warning categories to achieve similar fail-fast behavior?