Build failure: Bun version mismatch (expects 1.3.5, system has 1.3.6)

[MBanucu]

The NixOS build fails with a Bun version check error.

Full error log:

Using versionCheckHook
Running phase: unpackPhase
@nix { "action": "setPhase", "phase": "unpackPhase" }
unpacking source archive /nix/store/6fxp8p37c292692r01favj5lk4a0npyi-source
source root is source
Running phase: patchPhase
@nix { "action": "setPhase", "phase": "patchPhase" }
Running phase: updateAutotoolsGnuConfigScriptsPhase
@nix { "action": "setPhase", "phase": "updateAutotoolsGnuConfigScriptsPhase" }
Running phase: configurePhase
@nix { "action": "setPhase", "phase": "configurePhase" }
Running phase: buildPhase
@nix { "action": "setPhase", "phase": "buildPhase" }
 8 | if (!expectedBunVersion) {
 9 |   throw new Error("packageManager field not found in root package.json")
10 | }
11 | 

12 | if (process.versions.bun !== expectedBunVersion) {
13 |   throw new Error(\`This script requires bun@\${expectedBunVersion}, but you are using bun@\${process.versions.bun}\`)
                 ^
error: This script requires bun@1.3.5, but you are using bun@1.3.6
       at /build/source/packages/script/src/index.ts:13:13

Bun v1.3.6 (Linux x64)

This occurs during sudo nixos-rebuild switch --flake . on NixOS.

System: NixOS 25.11.20260118.77ef7a2

The script in packages/script/src/index.ts checks for exact Bun version 1.3.5, but Nix provides 1.3.6.

[github-actions]

This issue is related to Nix build failures. Please check:

• Nix build fails when shell completion generation produces empty output #9285: Nix build fails when shell completion generation produces empty output

While #9285 addresses shell completion failures, both issues involve Nix build processes failing during the build phase. This might help understand the broader Nix compatibility issues affecting this project.

[MBanucu]

Additional details for the build failure:

Nix Version:

nix (Nix) 2.31.2

NixOS Version:
25.11.20260118.77ef7a2

Flake.nix:

{
  description = "NixOS configuration";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
    nixpkgsUnstable.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixpkgsUnstableSmall.url = "github:NixOS/nixpkgs/nixos-unstable-small"; # New: faster unstable channel
    mcp-grok = {
      url = "github:MBanucu/mcp-grok";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    opencode = {
      url = "github:anomalyco/opencode";
    };

    home-manager = {
      url = "github:nix-community/home-manager/release-25.11";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs =
    {
      self,
      nixpkgs,
      nixpkgsUnstable,
      nixpkgsUnstableSmall, # New
      mcp-grok,
      opencode,

      home-manager,
    }:
    let
      system = "x86_64-linux";
      unstableSmall = import nixpkgsUnstableSmall {
        inherit system;
        config.allowUnfree = true;
      };
    in
    {
      nixosConfigurations.nixos = nixpkgs.lib.nixosSystem {
        inherit system;
        specialArgs = {
          inherit
            nixpkgs
            mcp-grok
            nixpkgsUnstable
            nixpkgsUnstableSmall # New
            opencode

            home-manager
            ;
          inherit system;
        };
        modules = [
          ./configuration.nix
          home-manager.nixosModules.default
        ];
      };

      devShells.${system}.default = unstableSmall.mkShell {
        packages = with unstableSmall; [
          vscode
        ];

        shellHook = ''
          sudo HOME="$HOME" code . --no-sandbox --user-data-dir=$(pwd)/.config/Code
        '';
      };
    };
}

Flake.lock:

{
  "nodes": {
    "home-manager": {
      "inputs": {
        "nixpkgs": [
          "nixpkgs"
        ]
      },
      "locked": {
        "lastModified": 1768603898,
        "narHash": "sha256-vRV1dWJOCpCal3PRr86wE2WTOMfAhTu6G7bSvOsryUo=",
        "owner": "nix-community",
        "repo": "home-manager",
        "rev": "2a63d0e9d2c72ac4d4150ebb242cf8d86f488c8c",
        "type": "github"
      },
      "original": {
        "owner": "nix-community",
        "ref": "release-25.11",
        "repo": "home-manager",
        "type": "github"
      }
    },
    "mcp-grok": {
      "inputs": {
        "nixpkgs": [
          "nixpkgs"
        ]
      },
      "locked": {
        "lastModified": 1767368186,
        "narHash": "sha256-H8k/fjB7JI7Ev4btGBlU7q3u02KV0gvX6EKqDcoesos=",
        "owner": "MBanucu",
        "repo": "mcp-grok",
        "rev": "57e14b586049e640da63fdcf76efc0e3b9b9d0af",
        "type": "github"
      },
      "original": {
        "owner": "MBanucu",
        "repo": "mcp-grok",
        "type": "github"
      }
    },
    "nixpkgs": {
      "locked": {
        "lastModified": 1768773494,
        "narHash": "sha256-XsM7GP3jHlephymxhDE+/TKKO1Q16phz/vQiLBGhpF4=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "77ef7a29d276c6d8303aece3444d61118ef71ac2",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixos-25.11",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "nixpkgsUnstable": {
      "locked": {
        "lastModified": 1768564909,
        "narHash": "sha256-Kell/SpJYVkHWMvnhqJz/8DqQg2b6PguxVWOuadbHCc=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "e4bae1bd10c9c57b2cf517953ab70060a828ee6f",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixos-unstable",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "nixpkgsUnstableSmall": {
      "locked": {
        "lastModified": 1768886240,
        "narHash": "sha256-C2TjvwYZ2VDxYWeqvvJ5XPPp6U7H66zeJlRaErJKoEM=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "80e4adbcf8992d3fd27ad4964fbb84907f9478b0",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixos-unstable-small",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "nixpkgs_2": {
      "locked": {
        "lastModified": 1768569498,
        "narHash": "sha256-bB6Nt99Cj8Nu5nIUq0GLmpiErIT5KFshMQJGMZwgqUo=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "be5afa0fcb31f0a96bf9ecba05a516c66fcd8114",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixpkgs-unstable",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "opencode": {
      "inputs": {
        "nixpkgs": "nixpkgs_2"
      },
      "locked": {
        "lastModified": 1768890796,
        "narHash": "sha256-AjNhwKfud2tLYhmDLqrNMCFbvp6BywgKbIeUW/ApQqs=",
        "owner": "anomalyco",
        "repo": "opencode",
        "rev": "616329ae97c975f21687f6c8c9c6d4d8018e6fd9",
        "type": "github"
      },
      "original": {
        "owner": "anomalyco",
        "repo": "opencode",
        "type": "github"
      }
    },
    "root": {
      "inputs": {
        "home-manager": "home-manager",
        "mcp-grok": "mcp-grok",
        "nixpkgs": "nixpkgs",
        "nixpkgsUnstable": "nixpkgsUnstable",
        "nixpkgsUnstableSmall": "nixpkgsUnstableSmall",
        "opencode": "opencode"
      }
    }
  },
  "root": "root",
  "version": 7
}

[MBanucu]

Workaround Solution: Override Bun Version in Nix Flake

I've successfully resolved the Bun version mismatch locally by overriding the OpenCode flake's nixpkgs input to use a commit that includes Bun 1.3.5.

Problem

The OpenCode build script strictly checks for Bun 1.3.5, but the current nixpkgs-unstable used by OpenCode provides Bun 1.3.6, causing the build to fail.

Solution

Pin OpenCode's nixpkgs to a specific commit that has Bun 1.3.5.

Steps

1. Add a pinned nixpkgs input for Bun 1.3.5:

   nixpkgsBun135.url = "github:NixOS/nixpkgs/f665af0cdb70ed27e1bd8f9fdfecaf451260fc55";
   

2. Modify the opencode input to follow this nixpkgs:

   opencode = {
     url = "github:anomalyco/opencode";
     inputs = {
       nixpkgs.follows = "nixpkgsBun135";
     };
   };

3. Update the outputs function to include the new input:

   outputs = { self, nixpkgs, nixpkgsUnstable, nixpkgsUnstableSmall, nixpkgsBun135, mcp-grok, opencode, home-manager }:

4. Update flake lock:

   nix flake update nixpkgsBun135
   

5. Rebuild:

   sudo nixos-rebuild switch --flake .
   

Verification

After applying this, the OpenCode derivation builds successfully with Bun 1.3.5.

Recommendation

This is a temporary workaround. The proper fix would be to update the OpenCode script to allow compatible Bun versions (e.g., >= 1.3.5) or use a version range check.

[bogorad]

I wonder how did it even build in CI.

[MBanucu]

I wonder how did it even build in CI.

Let's find out?

[MBanucu]

The failing OpenCode version is 1.1.26 (commit 616329a), as seen in the derivation path: /nix/store/7w5y9vk3i4zmslrhvxwj00riv8vqifgm-opencode-1.1.26-616329a.drv

[MBanucu]

Update: Tested overlay approach - it does not work because system overlays cannot affect flake inputs' internal nixpkgs evaluations. The proper solution is the input override method (pinning opencode's nixpkgs to a Bun 1.3.5 commit), which successfully resolves the build failure.

[MBanucu]

Temporary Workaround: Use Forked Branch

While waiting for PR #9597 to merge, you can temporarily use the fixed branch from the fork.

Update flake.nix

Change your opencode input to:

opencode = {
  url = "github:MBanucu/opencode/fix/bun-version-range";
};

Rebuild

1. Update lock: nix flake update opencode
2. Rebuild: sudo nixos-rebuild switch --flake .

Revert Later

Once PR #9597 merges, change back to:

opencode = {
  url = "github:anomalyco/opencode";
};

This has been tested and resolves the Bun 1.3.6 issue. No changes needed in configuration.nix.

[MBanucu]

"I wonder how did it even build in CI." (#9583 (comment))

@ bogorad It didn't build successfully in CI. The nix-desktop workflow failed after the flake.lock update in PR #9238 introduced Bun 1.3.6. See the checks for PR #9238: the build-desktop jobs failed on all platforms due to the strict Bun version check.

[MBanucu]

Apparently there are no branch protection rules, at least not what we expect from such a repository.