feat(app-boot): register cordis:group beside cordis:include

A composition that shares one `isolate` realm across rows needs a
`cordis:group` row, and a preset living outside this workspace — the
authored ones under the Harness home — cannot resolve
`@cordisjs/plugin-group` by name: Node's upward `node_modules` walk
never reaches the harness from there. Registering it as a loader builtin
beside `cordis:include` loads both through the ambient module pipeline
instead.

Record it in the preset Agent Note, which leans on the realm vocabulary
without saying where the group row comes from, and drop the preset
README's limitation claiming this builtin is unavailable — it described
the state this change ends.

The test's assertion had a vacuous escape: `provide` mints the root
symbol unconditionally, so the `rootKey === undefined` disjunct could
never hold and the comment claiming the root realm never learned the
name was wrong. Pin both halves — the symbol exists, nothing is stored
under it — and clean up the global the fixture writes.

packages/ui/app-boot/README.md

@@ -14,7 +14,7 @@ Shared boot glue for the app bins ([`dsh`](../../../apps/cli/README.md), [`dsh-c
 | `assertEntriesActivated(ctx, binName)` | Include the `assertEntriesLoaded` check, then await every enabled entry after the Loader settles; throw with each failed plugin's original stack or each pending plugin's unresolved services |
 | `loadOptionalPatches(binName, file)` | Parse an optional patch-list file (a profile's `cordis.patch.yml`) — a top-level YAML array of include `PatchOptions` (id-targeted config overrides, `insert` lists, `!!js` allowed); absent file → `undefined`, an unreadable/unparsable/non-array file throws |
 | `loadOverlayPatches(binName, file)` | Parse a required patch-list file with the same shape; a missing file also throws, because the caller named it |
-| `mountRootInclude(ctx, absoluteConfigPath, patches?)` | Mount the statically imported Include builtin and retain the exact root entry used by user patch-layer HMR |
+| `mountRootInclude(ctx, absoluteConfigPath, patches?)` | Register the statically imported `cordis:include` and `cordis:group` builtins, mount the include, and retain the exact root entry used by user patch-layer HMR |
 | `watchUserPatches(ctx, options)` | Register the named patch file with the existing Cordis HMR service; each add/change/removal transactionally recomposes the full patch list through the caller's `compose` closure (app-owned layers around the current user layer) and returns an async disposer |
 | `resolveProfileDir` / `initProfile` / `loadProfile` / `readProfileManifest` / `writeProfileManifest` / `resolveBundleDir` / `composeEntries` / `healProfilesModuleFallback` / `PROFILE_TEMPLATES` / `DEFAULT_PROFILE_BUNDLES` / `PROFILES_DIR` / `PROFILE_PATCH_FILENAME` | Profile machinery (see [Profiles](#profiles)) |
 | `boot(binName, absoluteConfigPath, patches?, prepare?)` | Create the root context, expose `dshHomePath(...segments)` to Loader `!!js` config expressions, install Loader, run optional host preparation before config-tree entries mount (`prepare` may use Loader and provide launcher-owned context slots), then mount and await the include tree, assert entries loaded and activated, and return the root context — or dispose the partial context and reject a labelled error |
@@ -26,6 +26,8 @@ Loader settlement rejects import and lifecycle failures with the failing entry a
 
 The Loader mounts entries concurrently, so a surface can already own the terminal when something else fails: exiting without the tree's own teardown would leave raw mode, bracketed paste, and the keyboard protocol set on the user's shell, and an in-flight terminal query's reply would land as literal text at the next prompt. A config-tree failure settles through `boot()`, whose disposal of the partial context runs the surface's own shutdown before the labelled rejection. For the rejections `boot()` cannot see — a plugin's detached async work rejecting during or after mounting — a terminal-owning bin passes `release` to dispose the tree before the exit commits; `dsh` captures the root context in `boot()`'s `prepare` hook rather than from its return value so the hook covers the whole mounting window. While a release is in flight the handler stays installed and latched: the first rejection is the reported one, and later rejections (teardown's own included) are swallowed rather than becoming uncaught and killing the process mid-teardown.
 
+`cordis:group` is registered beside `cordis:include` so a composition can give one `isolate` realm to a provider and its consumers together. Both load through the ambient module pipeline rather than the included tree's own specifier resolution, which is what lets a composition outside this workspace — an agent preset under the Harness home — use a group row at all.
+
 Bare plugin specifiers in a config (`@deepseek-ai/dsh-*`, npm packages) resolve through the Cordis Loader's internal module loader. Repository bins install Loader's optional `node-addon-require-builtin` peer; external callers must supply it or install plugins where plain Node import resolution can find them. Relative specifiers resolve against the config directory without the native helper. The built `dsh-app-boot` artifact embeds the statically mounted Include implementation while leaving Loader external, so the include tree and host bind to one Loader peer. The `dsh` source launcher additionally maps manifest-declared workspace packages to their TypeScript source; its configuration gate requires every shipped raw/Web bare plugin to appear in the resolver manifest's `dependencies`.
 
 This package carries no loader hooks and no dev-mode surface. The [`dsh` app](../../../apps/cli/README.md) owns its Node source-launch hook and consumes these helpers for the boot sequence; built consumers continue to use plain Node package resolution.