feat: package the claude ACP adapter for aoe

aoe's structured view spawns `claude-agent-acp` off $PATH. npm's global
prefix here is the read-only nodejs store path, so `npm install -g` cannot
provide it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

pkgs/claude-agent-acp/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "claude-agent-acp-env",
+  "version": "0.70.0",
+  "private": true,
+  "dependencies": {
+    "@agentclientprotocol/claude-agent-acp": "0.70.0"
+  }
+}

pkgs/claude-agent-acp/package.nix

@@ -0,0 +1,51 @@
+{
+  lib,
+  buildNpmPackage,
+  makeWrapper,
+  nodejs_26,
+}:
+# The ACP adapter aoe spawns for its structured view (`aoe acp doctor` calls it
+# "claude"). Upstream only publishes it to npm, and `npm install -g` cannot work
+# here: npm's prefix is the read-only nodejs derivation in the store.
+#
+# The sources here are a one-dependency wrapper project, not upstream's repo.
+# To bump: set the version in package.json, run
+#   npm install --package-lock-only --ignore-scripts
+#   nix run nixpkgs#prefetch-npm-deps -- package-lock.json
+# and paste the hash into npmDepsHash.
+buildNpmPackage {
+  pname = "claude-agent-acp";
+  version = "0.70.0";
+
+  src = lib.cleanSource ./.;
+
+  npmDepsHash = "sha256-+q0Va1VvyImKqyWyOBYVmSFDC8TpKViikdYhE1VwGAE=";
+
+  nodejs = nodejs_26;
+
+  dontNpmBuild = true;
+  npmFlags = [ "--ignore-scripts" ];
+
+  nativeBuildInputs = [ makeWrapper ];
+
+  installPhase = ''
+    runHook preInstall
+
+    mkdir -p $out/lib/claude-agent-acp
+    cp -r node_modules $out/lib/claude-agent-acp/
+
+    # The adapter's shebang is `env node`; aoe spawns it from a systemd unit
+    # whose PATH need not carry one.
+    makeWrapper ${nodejs_26}/bin/node $out/bin/claude-agent-acp \
+      --add-flags $out/lib/claude-agent-acp/node_modules/@agentclientprotocol/claude-agent-acp/dist/index.js
+
+    runHook postInstall
+  '';
+
+  meta = {
+    description = "Agent Client Protocol adapter for Claude Code, spawned by aoe's structured view";
+    homepage = "https://www.npmjs.com/package/@agentclientprotocol/claude-agent-acp";
+    license = lib.licenses.asl20;
+    mainProgram = "claude-agent-acp";
+  };
+}