diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..bbbf04e
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1787070829,
+        "narHash": "sha256-vXNVDVtvfiQuXthP0NHPFdNvvMTkGpx0UP8oddIWbNk=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "0ae2bc1419c3f345984c2629e72e7a631820fa4d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..f6944cb
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,241 @@
+{
+  description = "Nix package and development shell for agent-tty";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs = {
+    self,
+    nixpkgs,
+    ...
+  }: let
+    systems = [
+      "x86_64-linux"
+      "aarch64-linux"
+      "aarch64-darwin"
+    ];
+    forAllSystems = nixpkgs.lib.genAttrs systems;
+  in {
+    packages = forAllSystems (system: let
+      pkgs = import nixpkgs {inherit system;};
+      lib = pkgs.lib;
+      nodejs = pkgs.nodejs_26;
+
+      dependencySource = lib.fileset.toSource {
+        root = ./.;
+        fileset = lib.fileset.unions [
+          ./package.json
+          ./aube-lock.yaml
+          ./pnpm-workspace.yaml
+        ];
+      };
+
+      packageSource = lib.fileset.toSource {
+        root = ./.;
+        fileset = lib.fileset.unions [
+          ./package.json
+          ./aube-lock.yaml
+          ./pnpm-workspace.yaml
+          ./tsconfig.json
+          ./tsconfig.build.json
+          ./src
+          ./scripts
+          ./skills
+          ./skill-data
+        ];
+      };
+
+      # Aube's lockfile contains integrity hashes for every package, while this
+      # fixed-output derivation pins the complete downloaded cache. The package
+      # derivation below must then install with --offline.
+      dependencyCache = pkgs.stdenvNoCC.mkDerivation {
+        pname = "agent-tty-aube-cache";
+        version = "0.5.0";
+        src = dependencySource;
+
+        nativeBuildInputs = [
+          pkgs.aube
+          pkgs.cacert
+        ];
+
+        dontConfigure = true;
+        dontFixup = true;
+
+        buildPhase = ''
+          runHook preBuild
+
+          # Use Nixpkgs' pinned Aube. Package-manager self-switching would make
+          # the fetched tool another undeclared dependency of the build.
+          substituteInPlace package.json \
+            --replace-fail '  "packageManager": "aube@1.2.0",' ""
+
+          export HOME="$TMPDIR/home"
+          export XDG_CACHE_HOME="$TMPDIR/cache"
+          export XDG_DATA_HOME="$TMPDIR/data"
+          mkdir -p "$HOME" "$XDG_CACHE_HOME" "$XDG_DATA_HOME"
+
+          aube fetch --frozen-lockfile --reporter append-only
+
+          runHook postBuild
+        '';
+
+        installPhase = ''
+          runHook preInstall
+          mkdir -p "$out/cache" "$out/data"
+          cp -R "$XDG_CACHE_HOME"/. "$out/cache"/
+          cp -R "$XDG_DATA_HOME"/. "$out/data"/
+          runHook postInstall
+        '';
+
+        outputHashMode = "recursive";
+        outputHashAlgo = "sha256";
+        outputHash = "sha256-U5oksqBtoQTDwVKwEXjgc9z3WRaMv7MVPyeK3/195oc=";
+      };
+
+      agent-tty = pkgs.stdenvNoCC.mkDerivation {
+        pname = "agent-tty";
+        version = "0.5.0";
+        src = packageSource;
+
+        nativeBuildInputs = [
+          pkgs.aube
+          nodejs
+          pkgs.python3
+          pkgs.stdenv.cc
+          pkgs.gnumake
+          pkgs.pkg-config
+          pkgs.node-gyp
+          pkgs.makeWrapper
+        ];
+
+        dontConfigure = true;
+
+        buildPhase = ''
+          runHook preBuild
+
+          substituteInPlace package.json \
+            --replace-fail '  "packageManager": "aube@1.2.0",' ""
+
+          export HOME="$TMPDIR/home"
+          export XDG_CACHE_HOME="$TMPDIR/cache"
+          export XDG_DATA_HOME="$TMPDIR/data"
+          mkdir -p "$HOME" "$XDG_CACHE_HOME" "$XDG_DATA_HOME"
+          cp -R ${dependencyCache}/cache/. "$XDG_CACHE_HOME"/
+          cp -R ${dependencyCache}/data/. "$XDG_DATA_HOME"/
+          chmod -R u+w "$XDG_CACHE_HOME" "$XDG_DATA_HOME"
+
+          aube install \
+            --offline \
+            --frozen-lockfile \
+            --ignore-scripts \
+            --disable-global-virtual-store \
+            --package-import-method copy \
+            --reporter append-only
+
+          # node-pty has no Linux prebuild in the locked package. Build it with
+          # Nixpkgs' node-gyp so Aube never bootstraps a tool from the network.
+          (
+            cd node_modules/node-pty
+            node-gyp rebuild
+          )
+          npm run build
+
+          runHook postBuild
+        '';
+
+        installPhase = ''
+          runHook preInstall
+
+          app="$out/lib/agent-tty"
+          production="$TMPDIR/production"
+          mkdir -p "$app" "$out/bin"
+
+          # Build tools are devDependencies, so compile first and then create a
+          # fresh production graph. Aube's in-place prune currently leaves
+          # dangling virtual-store links behind.
+          mkdir -p "$production"
+          cp package.json aube-lock.yaml pnpm-workspace.yaml "$production"/
+          (
+            cd "$production"
+            aube install \
+              --prod \
+              --offline \
+              --frozen-lockfile \
+              --ignore-scripts \
+              --disable-global-virtual-store \
+              --package-import-method copy \
+              --reporter append-only
+
+            cd node_modules/node-pty
+            node-gyp rebuild
+          )
+
+          cp -R dist package.json skills skill-data "$app"/
+          cp -R "$production/node_modules" "$app"/
+
+          makeWrapper ${nodejs}/bin/node "$out/bin/agent-tty" \
+            --add-flags "$app/dist/cli/main.js"
+
+          runHook postInstall
+        '';
+
+        meta = {
+          description = "Drive, inspect, and record terminal sessions from the CLI";
+          homepage = "https://github.com/coder/agent-tty";
+          license = lib.licenses.asl20;
+          mainProgram = "agent-tty";
+          platforms = systems;
+        };
+      };
+    in {
+      default = agent-tty;
+      inherit agent-tty;
+    });
+
+    checks = forAllSystems (system: let
+      pkgs = import nixpkgs {inherit system;};
+      package = self.packages.${system}.default;
+    in {
+      inherit package;
+
+      smoke =
+        pkgs.runCommand "agent-tty-smoke" {
+          nativeBuildInputs = [
+            package
+            pkgs.jq
+          ];
+        } ''
+            export HOME="$TMPDIR/home"
+          mkdir -p "$HOME"
+
+          agent-tty version --json > version.json
+          doctor_exit=0
+          agent-tty --home "$TMPDIR/agent-tty-home" doctor --json > doctor.json || doctor_exit=$?
+          printf '%s\n' "$doctor_exit" > doctor-exit-status
+          jq -e '.result.checks.environment[] | select(.name == "pty-spawn" and .status == "pass")' doctor.json
+
+          mkdir -p "$out"
+          cp version.json doctor.json doctor-exit-status "$out"/
+        '';
+    });
+
+    devShells = forAllSystems (system: let
+      pkgs = import nixpkgs {inherit system;};
+    in {
+      default = pkgs.mkShell {
+        packages = [
+          pkgs.nodejs_26
+          pkgs.aube
+          pkgs.zig_0_15
+          pkgs.python3
+          pkgs.stdenv.cc
+          pkgs.gnumake
+          pkgs.pkg-config
+          pkgs.git
+          pkgs.cacert
+        ];
+      };
+    });
+
+    formatter = forAllSystems (system: (import nixpkgs {inherit system;}).alejandra);
+  };
+}