--- title: Changelog: build-time flake inputs and unauthenticated... description: Determinate Nix 3.9.0 introduces build-time flake inputs as an experimental feature, allowing Nix to defer fetching certain inputs (like non-Nix Git repos)... canonical: https://daily.dev/posts/changelog-build-time-flake-inputs-and-unauthenticated-upgrades-c1qietjk3 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Changelog: build-time flake inputs and unauthenticated upgrades | daily.dev og:description: Determinate Nix 3.9.0 introduces build-time flake inputs as an experimental feature, allowing Nix to defer fetching certain inputs (like non-Nix Git repos)... og:url: https://daily.dev/posts/changelog-build-time-flake-inputs-and-unauthenticated-upgrades-c1qietjk3 og:image: https://api.daily.dev/og/posts/c1qietJK3.png og:image:alt: Changelog: build-time flake inputs and unauthenticated upgrades og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Changelog: build-time flake inputs and unauthenticated upgrades **[Determinate Systems](https://daily.dev/sources/determinate-systems)** · 4 min read · 0 upvotes · 0 comments ## Summary Determinate Nix 3.9.0 introduces build-time flake inputs as an experimental feature, allowing Nix to defer fetching certain inputs (like non-Nix Git repos) until build time rather than evaluation time. This significantly speeds up evaluation for users with large numbers of flake inputs. The release also removes the requirement to be logged into FlakeHub when running upgrades, fixes inconsistent behavior in `nix flake check`, and improves the installer with automatic retry logic for stalled downloads (restarting if transfer drops below 250kb/sec over 15 seconds). ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Changelog: a new upstream base, GC roots for nix eval, and a faster nix copy](https://daily.dev/posts/changelog-a-new-upstream-base-gc-roots-for-nix-eval-and-a-faster-nix-copy-a9ytihpvx) · Determinate Systems · 0 upvotes · 0 comments - [The Great Nix Flake Check](https://daily.dev/posts/the-great-nix-flake-check-joelq4xlg) · Lobsters · 0 upvotes · 0 comments - [Changelog: FlakeHub Cache edge routing and a few crash fixes](https://daily.dev/posts/changelog-flakehub-cache-edge-routing-and-a-few-crash-fixes-umodwxeoj) · Determinate Systems · 0 upvotes · 0 comments - [Dependabot version updates now support the Nix ecosystem](https://daily.dev/posts/dependabot-version-updates-now-support-the-nix-ecosystem-77socdz4m) · GitHub Changelog · 0 upvotes · 0 comments - [One flake to rule them all](https://daily.dev/posts/one-flake-to-rule-them-all-oyz5p8fiz) · Farid Zakaria’s Blog · 1 upvotes · 1 comments --- [View this post on daily.dev](https://daily.dev/posts/changelog-build-time-flake-inputs-and-unauthenticated-upgrades-c1qietjk3) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Changelog: build-time flake inputs and unauthenticated upgrades","url":"https://daily.dev/posts/changelog-build-time-flake-inputs-and-unauthenticated-upgrades-c1qietjk3","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/changelog-build-time-flake-inputs-and-unauthenticated-upgrades-c1qietjk3"},"datePublished":"2026-07-26T07:48:26.306Z","dateModified":"2026-07-26T07:51:16.669Z","description":"Determinate Nix 3.9.0 introduces build-time flake inputs as an experimental feature, allowing Nix to defer fetching certain inputs (like non-Nix Git repos)...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/3c1225b91b553781eff09d7d50a2fd3e?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/3c1225b91b553781eff09d7d50a2fd3e?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Determinate Systems","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Determinate Systems","logo":"https://media.daily.dev/image/upload/s--E2qrkc9w--/c_limit,w_256/f_auto,q_auto/v1785052094/logos/determinate-systems?_a=BAMAMicg0","url":"https://daily.dev/sources/determinate-systems"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/changelog-build-time-flake-inputs-and-unauthenticated-upgrades-c1qietjk3","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Determinate Systems","item":"https://daily.dev/sources/determinate-systems"},{"@type":"ListItem","position":3,"name":"Changelog: build-time flake inputs and unauthenticated upgrades"}]} ```