From d4ca2c252454695768f15cba20d69cad94e7d504 Mon Sep 17 00:00:00 2001
From: Jeremy Daer <jeremy@37signals.com>
Date: Mon, 24 Aug 2026 01:50:56 -0700
Subject: [PATCH] Use cached Go 1.27 from nixpkgs

Refresh nixpkgs-unstable now that it carries stable Go 1.27.0, then remove the temporary source-toolchain override so cold Nix stores substitute Go from cache.nixos.org.
---
 flake.lock |  6 +++---
 nix/go.nix | 30 +++++-------------------------
 2 files changed, 8 insertions(+), 28 deletions(-)

diff --git a/flake.lock b/flake.lock
index fe0dde09..30d0a9a3 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1787414105,
-        "narHash": "sha256-WncT27+3BOkgTaJZLnCsf3LcYf9RXMuR9ONSN4rzQ7s=",
+        "lastModified": 1787394516,
+        "narHash": "sha256-pRGOQSClnXNI2iLUG6DYpsGvYcuw0drOutVZFTJNw90=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a9e6d84f9c2f9012f5fe7d964a7851352300e61a",
+        "rev": "c8f90650c15282fa8656a041bfbbd2403997a9a7",
         "type": "github"
       },
       "original": {
diff --git a/nix/go.nix b/nix/go.nix
index b92a75e1..04fe8168 100644
--- a/nix/go.nix
+++ b/nix/go.nix
@@ -1,28 +1,8 @@
-{ lib, fetchurl, go_1_27 }:
+{ go_1_27 }:
 
 # The Go toolchain shared by the package build and the dev shell.
 #
-# go.mod's `go` directive is the floor; nixpkgs-unstable lagged it at 1.27rc3
-# when go.mod moved to 1.27.0, so the toolchain is rebuilt from the upstream
-# source tarball until nixpkgs catches up. The override is conditional and
-# drops itself once go_1_27 reaches 1.27.0 — delete this file's override and
-# return go_1_27 directly after a `nix flake update` that makes
-# `lib.versionOlder` false. Keep minGo in step with go.mod: a toolchain bump
-# that outpaces flake.lock breaks the build without touching go.mod or go.sum,
-# which is why the nix-build CI job runs on every go.mod change and on tags.
-#
-# Both consumers must use this one derivation. The dev shell once listed
-# the nixpkgs Go directly, which handed `nix develop` a Go older than go.mod's
-# directive — `make build` then failed under GOTOOLCHAIN=local or offline.
-let
-  minGo = "1.27.0";
-in
-if lib.versionOlder go_1_27.version minGo
-then go_1_27.overrideAttrs (_: {
-  version = minGo;
-  src = fetchurl {
-    url = "https://go.dev/dl/go${minGo}.src.tar.gz";
-    hash = "sha256-cAJAPXzERSnvbSb2mkSBgmM5Xq18FsBaWAiuBH6+sOU=";
-  };
-})
-else go_1_27
+# Both consumers use this one derivation so the package and `nix develop`
+# cannot drift. Keep flake.lock new enough that go_1_27 satisfies go.mod;
+# the nix-build CI job covers every go.mod change and every release tag.
+go_1_27