Temporarily override Miniflare Sharp security advisory

[kcsfelty]

Summary

• pin a root npm override from Miniflare's exact development-only sharp@0.34.5 to patched sharp@0.35.3
• regenerate only the Sharp/libvips portion of the lockfile; keep Miniflare 4.20260714.0 and Wrangler 4.112.0 unchanged
• preserve the raw npm audit --audit-level=high gate instead of suppressing the advisory
• document that the override is outside Miniflare's declared dependency contract, that Images/AVIF are not a Diamond support claim, and the exact removal trigger

Tracks #49. Upstream supported resolution: cloudflare/workers-sdk#14493.

Qualification evidence

Windows x64 and Linux x64 Node 22:

• clean npm ci
• npm ls sharp miniflare wrangler --all resolves sharp@0.35.3 overridden
• npm audit --audit-level=high reports zero vulnerabilities
• complete npm run check passes all 159 main-branch tests plus real workerd D1, bundled/local Worker, packed consumer, licensing, coverage, and readiness
• npm run conformance passes 490/490
• npm run conformance:earl writes 490 passing assertions

Windows Node 24 also passed. An isolated cross-platform compatibility probe confirmed that Miniflare itself dynamically loaded the 0.35.3 native addon and transformed a known 4×3 PNG to a checked 3×2 WebP. This is override qualification, not an Images feature claim.

AVIF/HEIF boundary

No AVIF regression is claimed. Sharp 0.35 reports AVIF metadata as heif, and pinned Miniflare lacks Cloudflare's corresponding mapping fix. Upstream #14493 updates the dependency and mapping together. Miniflare Images remain outside Diamond's supported package surface.

Removal trigger

Remove this override and regenerate the lock as soon as a released Miniflare/Wrangler pair declares a non-vulnerable Sharp version and the unchanged audit, real-D1, Worker, packed-consumer, and W3C gates pass.

Strongest counterargument

Miniflare pins exactly 0.34.5 rather than a compatible range, so this override is outside upstream's tested contract. The risk is bounded to development tooling, qualified on the two CI operating-system families and supported Node lines, explicitly excludes Images/AVIF, and is temporary. Independent review should reject this PR if that evidence is not sufficient.