diff --git a/apps/cli/config/agent-presets/core-web/agent.cordis.yml b/apps/cli/config/agent-presets/core-web/agent.cordis.yml
index 9a251461c5..e9003aa975 100644
--- a/apps/cli/config/agent-presets/core-web/agent.cordis.yml
+++ b/apps/cli/config/agent-presets/core-web/agent.cordis.yml
@@ -15,20 +15,12 @@
     text: >-
       You are a coding agent powered by the {{model}} model. Your working directory is {{cwd}}.
 
-# `tool-bash` provides the `bashEnv` service, so it needs a realm even alone.
-- id: shell
-  name: cordis:group
-  group: true
-  isolate:
-    bashEnv: true
-  config:
-    # The registry and its consumer share the realm: a consumer left outside
-    # would resolve the host's `bashEnv`, which this plane no longer provides.
-    - id: bash-env
-      name: '@deepseek-ai/dsh-bash-env'
-
-    - id: tool-bash
-      name: '@deepseek-ai/dsh-tool-bash'
+# `bash-env` stays in the HOST composition: `apps/cli/src/web.ts` injects it to
+# publish `DSH_WEB_URL`/`DSH_WEB_MODE`, and a host row that injects a service is
+# the criterion for host-plane ownership. `tool-bash` consumes that host
+# registry from here.
+- id: tool-bash
+  name: '@deepseek-ai/dsh-tool-bash'
 
 - id: tool-str-replace-editor
   name: '@deepseek-ai/dsh-tool-str-replace-editor'
diff --git a/apps/cli/config/agent-presets/standard/agent.cordis.yml b/apps/cli/config/agent-presets/standard/agent.cordis.yml
index 407e4d7d27..0a211bc97f 100644
--- a/apps/cli/config/agent-presets/standard/agent.cordis.yml
+++ b/apps/cli/config/agent-presets/standard/agent.cordis.yml
@@ -31,22 +31,15 @@
 
 # ── shell ───────────────────────────────────────────────────────────────────
 
-# `tool-bash` reads as a tool but provides the `bashEnv` service, so it needs a
-# realm like any other provider. The executor behind it (`bash-sandbox`) stays
-# in the host composition, where the sandbox policy owns it.
-- id: shell
-  name: cordis:group
-  group: true
-  isolate:
-    bashEnv: true
-  config:
-    # The registry and its consumer share the realm: a consumer left outside
-    # would resolve the host's `bashEnv`, which this plane no longer provides.
-    - id: bash-env
-      name: '@deepseek-ai/dsh-bash-env'
-
-    - id: tool-bash
-      name: '@deepseek-ai/dsh-tool-bash'
+# `bash-env` stays in the HOST composition: `apps/cli/src/web.ts` injects it to
+# publish `DSH_WEB_URL`/`DSH_WEB_MODE`, and a host row that injects a service is
+# the criterion for host-plane ownership — injection resolves before any session
+# exists, so there is no agent to key by. Behind a preset realm those variables
+# never reached the model's shell at all. `tool-bash` consumes the host registry
+# from here; the executor behind it (`bash-sandbox`) is host-plane too, where the
+# sandbox policy owns it.
+- id: tool-bash
+  name: '@deepseek-ai/dsh-tool-bash'
 
 # ── filesystem ──────────────────────────────────────────────────────────────
 
@@ -172,29 +165,21 @@
 
 # ── delegation and workflows ────────────────────────────────────────────────
 
-# Every backend and every tool that reaches `subagents` or `workflows` shares
-# one realm: a consumer left outside it would resolve the host's registry
-# instead, which this preset does not populate.
+# The `subagents` registry and its spawn/fork backends live in the HOST
+# composition: the registry is a process singleton whose cross-session queries
+# the api-proxy serves to the browser, and a provider name may only be
+# registered once. This preset contributes the delegation TOOLS, which resolve
+# that host registry.
+#
+# `workflows` is different — nothing outside an agent reads it — so every row
+# that reaches it shares one entry-local realm here, and a consumer left
+# outside would resolve a host registry this preset does not populate.
 - id: delegation
   name: cordis:group
   group: true
   isolate:
-    subagents: true
     workflows: true
   config:
-    - id: subagent
-      name: '@deepseek-ai/dsh-subagent'
-
-    - id: subagent-spawn
-      name: '@deepseek-ai/dsh-subagent-spawn'
-      config:
-        providerName: spawn
-
-    - id: subagent-fork
-      name: '@deepseek-ai/dsh-subagent-fork'
-      config:
-        providerName: fork
-
     - id: tool-subagent-control
       name: '@deepseek-ai/dsh-tool-subagent-control'
 
@@ -215,8 +200,11 @@
         toolName: subagent_fork
         backgroundMode: continuable
 
-    - id: tool-subagent-report
-      name: '@deepseek-ai/dsh-tool-subagent-report'
+    # `tool-subagent-report` is host-plane for the same reason as the registry,
+    # not because a preset may not want it: it registers a CONTINUABLE SETUP on
+    # that singleton rather than a tool this agent calls, and the setup list is
+    # not scope-aware — one copy per mounted preset means every child gets
+    # `report` registered once per live session, which throws on the second.
 
     - id: workflow-workerthread
       name: '@deepseek-ai/dsh-workflow-workerthread'
diff --git a/apps/web/tests/scaffold.ts b/apps/web/tests/scaffold.ts
index 8d8f866740..b1c6d66bf9 100644
--- a/apps/web/tests/scaffold.ts
+++ b/apps/web/tests/scaffold.ts
@@ -240,6 +240,31 @@ export async function launchWebScaffold(options: LaunchOptions = {}): Promise<We
   // paths at load, and an in-process boot must NEVER touch the developer's
   // real ~/.dsh document or credential file.
   const harnessHome = join(workspaceCwd, '.dsh-home')
+  // Skill discovery is model-visible input, and its roots now resolve inside a
+  // PRESET — a subtree this lane's include patches cannot reach, because the
+  // roster mounts it directly per session rather than as a row of the booted
+  // tree. The row's documented fallback is the environment, so pin that: the
+  // whole scaffold lifetime, not just the boot, since presets mount when a
+  // session is created. Without this a developer's real ~/.dsh/skills silently
+  // enters replay requests and goldens while CI sees none.
+  const skillRootEnvironment = {
+    DSH_HOME: join(workspaceCwd, '.dsh-home'),
+    DSH_AGENTS_HOME: join(workspaceCwd, '.agents-home'),
+    DSH_BUNDLED_SKILL_DIR: join(workspaceCwd, '.bundled-skills'),
+  }
+  const originalSkillRootEnvironment = Object.fromEntries(
+    Object.keys(skillRootEnvironment).map(key => [key, process.env[key]]),
+  )
+  let skillRootEnvironmentRestored = false
+  const restoreSkillRootEnvironment = (): void => {
+    if (skillRootEnvironmentRestored) return
+    skillRootEnvironmentRestored = true
+    for (const [key, value] of Object.entries(originalSkillRootEnvironment)) {
+      if (value === undefined) Reflect.deleteProperty(process.env, key)
+      else process.env[key] = value
+    }
+  }
+  Object.assign(process.env, skillRootEnvironment)
   let persistenceRoot: string
   try {
     persistenceRoot = await mkdtemp(join(tmpdir(), 'dsh-web-e2e-sessions-'))
@@ -415,6 +440,7 @@ export async function launchWebScaffold(options: LaunchOptions = {}): Promise<We
     if (process.cwd() !== originalCwd) process.chdir(originalCwd)
     const cleanupFailures = await cleanupScaffoldWorld(ctx, workspaceCwd, persistenceRoot)
     restoreCredentialEnvironment()
+    restoreSkillRootEnvironment()
     if (cleanupFailures.length > 0) {
       throw new AggregateError([error, ...cleanupFailures], 'web scaffold setup failed and cleanup was incomplete')
     }
@@ -462,6 +488,7 @@ export async function launchWebScaffold(options: LaunchOptions = {}): Promise<We
         failures.push(...await cleanupScaffoldWorld(ctx, workspaceCwd, persistenceRoot))
       } finally {
         restoreCredentialEnvironment()
+        restoreSkillRootEnvironment()
       }
       if (failures.length > 0) throw new AggregateError(failures, 'web scaffold teardown failed')
     },
diff --git a/packages/bundle/web-app/cordis.patch.yml b/packages/bundle/web-app/cordis.patch.yml
index 356d0a95a7..2fe73e7dd5 100644
--- a/packages/bundle/web-app/cordis.patch.yml
+++ b/packages/bundle/web-app/cordis.patch.yml
@@ -204,8 +204,11 @@
 # absent from a surface overlay would silently reappear the day someone reorders
 # the composition.
 
-- id: bash-env
-  disabled: true
+# `bash-env` STAYS in the host plane: `apps/cli/src/web.ts` injects it to
+# publish `DSH_WEB_URL`/`DSH_WEB_MODE`, and a host row that injects a service is
+# the criterion for host-plane ownership — injection resolves before any session
+# exists, so there is no agent to key by. Behind a preset realm those variables
+# would never reach the model's shell at all.
 
 - id: tool-bash
   disabled: true
@@ -261,14 +264,12 @@
 - id: tool-result-prune
   disabled: true
 
-- id: subagent
-  disabled: true
-
-- id: subagent-spawn
-  disabled: true
-
-- id: subagent-fork
-  disabled: true
+# The subagent registry and its backends STAY in the host plane. `subagents` is
+# a process singleton with a cross-session query surface (`listChildren`,
+# `followup`) that the host api-proxy serves to the browser, and a provider
+# registers under a globally unique name, so a per-session copy would both
+# starve that host row and collide on the second session. What a preset
+# chooses is which delegation TOOLS its agent sees, below.
 
 - id: tool-subagent-control
   disabled: true
@@ -282,8 +283,11 @@
 - id: tool-subagent-fork
   disabled: true
 
-- id: tool-subagent-report
-  disabled: true
+# `tool-subagent-report` is host-plane for the same reason as the registry, not
+# because a preset may not want it: it registers a CONTINUABLE SETUP on that
+# singleton rather than a tool this agent calls, and the setup list is not
+# scope-aware — one copy per mounted preset means every child gets `report`
+# registered once per live session, which throws on the second.
 
 - id: workflow-workerthread
   disabled: true