feat(agents): add Qwen Code and use OpenCode V2 as opencode

Expose llm-agents' opencode2 package under the normal opencode command and persist Qwen Code's ~/.qwen state on the ephemeral-root hosts.

home/base/tui/agents/README.md

@@ -13,12 +13,12 @@ Markdown with no Nix dependency; this module only wires it into place.
 - `skills.nix`: links the global skills into `~/.agents/skills/<name>`, from pinned flake inputs and
   from `agents/skills/`; the inventory is
   [agents/skills/README.md](../../../../agents/skills/README.md).
-- `packages.nix`: agent CLIs (`codex`, `opencode2`, `pi`) from the `llm-agents` flake input, dsh
-  from `nur-ryan4yin`, `pkgs.ctx7` for the `find-docs` skill, and `pkgs.mcp-grafana` for the Grafana
-  MCP server. dsh's Nushell-only shell is selected when the package is built, via `dsh.withPlugins`
-  with the plugin from the `dsh-nu` flake input, so it is a derivation choice rather than runtime
-  state; profile patches live in `~/.dsh/profiles/<name>/cordis.patch.yml`. See [dsh.md](./dsh.md)
-  for the layer order and the settings that bite.
+- `packages.nix`: agent CLIs (`codex`, `opencode`, `qwen-code`, `pi`) from the `llm-agents` flake
+  input, dsh from `nur-ryan4yin`, `pkgs.ctx7` for the `find-docs` skill, and `pkgs.mcp-grafana` for
+  the Grafana MCP server. dsh's Nushell-only shell is selected when the package is built, via
+  `dsh.withPlugins` with the plugin from the `dsh-nu` flake input, so it is a derivation choice
+  rather than runtime state; profile patches live in `~/.dsh/profiles/<name>/cordis.patch.yml`. See
+  [dsh.md](./dsh.md) for the layer order and the settings that bite.
 - `env.nix`: telemetry and auto-update opt-outs for the agents.
 
 ## Deployed rule targets

home/base/tui/agents/packages.nix

@@ -12,12 +12,21 @@ let
     inherit pkgs;
     inherit (pkgs) dsh;
   };
+  # llm-agents.nix still exposes OpenCode V2 as `opencode2` so it can coexist
+  # with the v1 package. Re-expose its binary under the normal command name.
+  opencode = pkgs.linkFarm "opencode" [
+    {
+      name = "bin/opencode";
+      path = "${agentPackages.opencode2}/bin/opencode2";
+    }
+  ];
 in
 {
   home.packages = [
     # Agents
     agentPackages.codex
-    agentPackages.opencode2
+    opencode
+    agentPackages.qwen-code
     agentPackages.pi
     # dsh from nur-packages: llm-agents.nix's dsh cannot boot on nixpkgs node
     # (node-addon-require-builtin probe), this one shims it. The Nushell-only

hosts/idols-ai/preservation.nix

@@ -178,6 +178,12 @@ in
         ".codex"
         ".dsh" # DeepSeek Harness
         ".pi"
+        # Qwen Code keeps settings, credentials, history, sessions, and logs
+        # under ~/.qwen; keep the whole directory private and persistent.
+        {
+          directory = ".qwen";
+          mode = "0700";
+        }
         ".config/opencode"
         ".local/share/opencode"
         ".local/state/opencode"

hosts/idols-aquamarine/preservation.nix

@@ -100,6 +100,12 @@ in
         ".codex"
         ".dsh" # DeepSeek Harness
         ".pi"
+        # Qwen Code keeps settings, credentials, history, sessions, and logs
+        # under ~/.qwen; keep the whole directory private and persistent.
+        {
+          directory = ".qwen";
+          mode = "0700";
+        }
         ".config/opencode"
         ".local/share/opencode"
         ".local/state/opencode"

outputs/x86_64-linux/tests/agent-profile/expected.nix

@@ -2,6 +2,7 @@
 let
   common = {
     agentsFromHome = true;
+    qwenInstalled = true;
     devToolsFromHome = true;
     nushellSecrets = false;
     nixLd = true;

outputs/x86_64-linux/tests/agent-profile/expr.nix

@@ -23,6 +23,7 @@ lib.genAttrs hosts (
   {
     # home role: home/linux/tui.nix
     agentsFromHome = hasPackage "codex" home.home.packages;
+    qwenInstalled = hasPackage "qwen-code" home.home.packages;
     devToolsFromHome = hasPackage "kubectl" home.home.packages;
     # ~/.secrets is synced to the desktops only; sourcing it would break nushell.
     nushellSecrets = home.modules.shell.secrets.enable;

outputs/x86_64-linux/tests/idols-ai-gpu/expected.nix

@@ -19,4 +19,5 @@
   wivrnImportsOpenXRToSteam = true;
   wivrnStatePreserved = true;
   adbStatePreserved = true;
+  qwenStatePreserved = true;
 }

outputs/x86_64-linux/tests/idols-ai-gpu/expr.nix

@@ -54,4 +54,5 @@ in
     cfg.environment.sessionVariables.PRESSURE_VESSEL_IMPORT_OPENXR_1_RUNTIMES == "1";
   wivrnStatePreserved = privatelyPreserved ".config/wivrn";
   adbStatePreserved = privatelyPreserved ".android";
+  qwenStatePreserved = privatelyPreserved ".qwen";
 }

outputs/x86_64-linux/tests/idols-aquamarine/expr.nix

@@ -102,6 +102,7 @@ in
       ".local/state/home-manager"
       ".local/state/nix/profiles"
       ".codex"
+      ".qwen"
       ".config/opencode"
     ];
   pythonInstalled = builtins.any (