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9th chunk of `src/nix/flake.md`
4f3aa5853f998b3737f413835752442e014cab3ba81cf46b0000000100000847
        "type": "github",
        "lastModified": 1580555482,
        "narHash": "sha256-OnpEWzNxF/AU4KlqBXM2s5PWvfI5/BS6xQrPvkF5tO8="
      },
      "original": {
        "id": "nixpkgs",
        "type": "indirect"
      }
    },
    "n3": {
      "inputs": {},
      "locked": {
        "owner": "edolstra",
        "repo": "import-cargo",
        "rev": "8abf7b3a8cbe1c8a885391f826357a74d382a422",
        "type": "github",
        "lastModified": 1567183309,
        "narHash": "sha256-wIXWOpX9rRjK5NDsL6WzuuBJl2R0kUCnlpZUrASykSc="
      },
      "original": {
        "owner": "edolstra",
        "repo": "import-cargo",
        "type": "github"
      }
    },
    "n4": {
      "inputs": {},
      "locked": {
        "owner": "mozilla",
        "repo": "grcov",
        "rev": "989a84bb29e95e392589c4e73c29189fd69a1d4e",
        "type": "github",
        "lastModified": 1580729070,
        "narHash": "sha256-235uMxYlHxJ5y92EXZWAYEsEb6mm+b069GAd+BOIOxI="
      },
      "original": {
        "owner": "mozilla",
        "repo": "grcov",
        "type": "github"
      },
      "flake": false
    }
  }
}
```

This graph has 4 nodes: the root flake, and its 3 dependencies. The
nodes have arbitrary labels (e.g. `n1`). The label of the root node of
the graph is specified by the `root` attribute. Nodes contain the
following fields:

* `inputs`: The dependencies of this node, as a mapping from input
  names (e.g. `nixpkgs`) to node labels (e.g. `n2`).

* `original`: The original input specification from `flake.nix`, as a
  set of `builtins.fetchTree` arguments.

* `locked`: The locked input specification, as a set of
  `builtins.fetchTree` arguments. Thus, in the example above, when we
  build this flake, the input `nixpkgs` is mapped to revision
  `7f8d4b088e2df7fdb6b513bc2d6941f1d422a013` of the `edolstra/nixpkgs`
  repository on GitHub.

  It also includes the attribute `narHash`, specifying the expected
  contents of the tree in the Nix store (as computed by `nix
  hash-path`), and may include input-type-specific attributes such as
  the `lastModified` or `revCount`. The main reason for these
Title: Nix Flake Lock File Structure and Fields
Summary
This chunk concludes an example of a `flake.lock` JSON file and proceeds to explain its underlying graph structure. The graph consists of nodes with arbitrary labels, where the `root` attribute points to the main flake node. Each node contains three primary fields: `inputs`, which maps input names to other node labels (representing dependencies); `original`, detailing the initial, unlocked input specification from `flake.nix`; and `locked`, which provides the exact, reproducible input specification. The `locked` field includes attributes like `owner`, `repo`, `rev` (revision hash), `type`, and crucially, `narHash`, which specifies the expected content hash of the input in the Nix store, along with other input-type-specific metadata like `lastModified`.