From bf7020ade24b7490ef4801cac59f6160f353aab5 Mon Sep 17 00:00:00 2001
From: Dudu-0223 <fsyo0223@gmail.com>
Date: Wed, 26 Aug 2026 13:06:38 +0800
Subject: [PATCH] test(subagent): migrate model selection fixtures

---
 .../tests/fixtures/loader/cordis.yml          | 11 +++-
 .../fixtures/loader/scoped-tool-subagent.ts   | 19 ++++++
 .../tool-schemas.expected.json                | 31 +---------
 .../subagent-dsh-sdk-dynamic-route/cordis.yml | 11 +++-
 .../notifications.expected.jsonl              | 54 ++++++++--------
 .../session.jsonl                             |  9 +--
 .../tool-schemas.1.expected.json              | 31 +---------
 .../tool-schemas.expected.json                | 62 +------------------
 .../tool-schemas.expected.json                | 62 +------------------
 .../tool-schemas.expected.json                | 31 +---------
 snapshots/session/text-turn/cordis.yml        |  1 -
 11 files changed, 76 insertions(+), 246 deletions(-)
 create mode 100644 packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/scoped-tool-subagent.ts

diff --git a/packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/cordis.yml b/packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/cordis.yml
index a72b5fd79e..f0234ffdf7 100644
--- a/packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/cordis.yml
+++ b/packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/cordis.yml
@@ -25,12 +25,19 @@
       DSH_TELEMETRY_DISABLED: '1'
       DSH_TEST_CHILD_FAILURE: !!js String(process.env.DSH_TEST_CHILD_FAILURE ?? '')
 
+- id: subagent-model-selection-settings
+  name: '@deepseek-ai/dsh-tool-subagent/model-selection-settings'
+  config:
+    enabled: true
+    allowedModels:
+      - provider: mock
+        model: mock-routed
+
 - id: tool-subagent
-  name: '@deepseek-ai/dsh-tool-subagent'
+  name: './scoped-tool-subagent.ts'
   config:
     provider: dsh-sdk
     toolName: subagent
-    enableModelSelection: true
     agentOptions:
       maxTokens: 777
     # The SDK backend advertises no depthLimit: the child harness owns its own
diff --git a/packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/scoped-tool-subagent.ts b/packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/scoped-tool-subagent.ts
new file mode 100644
index 0000000000..5083694807
--- /dev/null
+++ b/packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/scoped-tool-subagent.ts
@@ -0,0 +1,19 @@
+/** Mount the SDK delegation tool in each fixture Agent's scope. */
+
+import type { Context } from '@deepseek-ai/cordis'
+import * as ToolSubagent from '@deepseek-ai/dsh-tool-subagent'
+import type { Config } from '@deepseek-ai/dsh-tool-subagent'
+
+export const name = 'scoped-tool-subagent'
+export const inject = ['agents', 'subagentModelSelection']
+
+/**
+ * Install the configured delegation tool before a published Agent starts its loop.
+ * @param ctx - fixture Host context carrying Agent lifecycle events.
+ * @param config - delegation-tool configuration forwarded into each Agent scope.
+ */
+export function apply(ctx: Context, config: Config): void {
+  ctx.on('agent/created', ({ agent }) => {
+    agent.ctx.plugin(ToolSubagent, { ...config, modelSelectionSettings: true })
+  })
+}
diff --git a/snapshots/sdk/subagent-dsh-sdk-diagnostic/tool-schemas.expected.json b/snapshots/sdk/subagent-dsh-sdk-diagnostic/tool-schemas.expected.json
index 2e0fc2b44b..b3a1813e8b 100644
--- a/snapshots/sdk/subagent-dsh-sdk-diagnostic/tool-schemas.expected.json
+++ b/snapshots/sdk/subagent-dsh-sdk-diagnostic/tool-schemas.expected.json
@@ -260,23 +260,6 @@
         }
       }
     },
-    {
-      "name": "list_subagent_models",
-      "description": "Discover LLM routes for subagents without changing the current Agent. Call with no arguments to list registered providers, with `provider` to list its advertised models, or with `provider` and `model` to inspect that exact model and its reasoning efforts. Catalog membership is advisory: an adapter may accept an unlisted model id. Use the returned ids with a delegation tool's `provider`, `model`, and `reasoning_effort` fields.",
-      "parameters": {
-        "type": "object",
-        "properties": {
-          "provider": {
-            "type": "string",
-            "description": "Registered LLM provider id. Omit to list providers."
-          },
-          "model": {
-            "type": "string",
-            "description": "Exact model id to inspect. Requires provider; omit to list that provider's advertised models."
-          }
-        }
-      }
-    },
     {
       "name": "ralph",
       "description": "Run a foreground fresh-agent Ralph loop toward one immutable objective. Use only when the direct human explicitly asks for Ralph or fresh-agent iteration. Each round opens a new child with no parent conversation or prior child session; the shared workspace is long-term memory, and only a bounded structured report crosses rounds. The call returns when a worker reports completion or a concrete blocker, or at the round limit. Ordinary long-running same-session work belongs to goal tools.",
@@ -461,7 +444,7 @@
     },
     {
       "name": "subagent",
-      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort.",
+      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result.",
       "parameters": {
         "type": "object",
         "properties": {
@@ -473,18 +456,6 @@
             "type": "string",
             "description": "The complete, self-contained task for the subagent. It does not share this conversation's context, so include everything it needs."
           },
-          "provider": {
-            "type": "string",
-            "description": "LLM provider route for the child. Supply together with model; omit both to use configured child defaults or inherit the parent route."
-          },
-          "model": {
-            "type": "string",
-            "description": "Model id interpreted by provider. Supply together with provider; omit both to use configured child defaults or inherit the parent route."
-          },
-          "reasoning_effort": {
-            "type": "string",
-            "description": "Adapter-owned reasoning effort for the effective child route. Omit to inherit a compatible configured/parent effort or use a newly selected model's default."
-          },
           "run_in_background": {
             "type": "boolean",
             "description": "Whether to run in the background and return a durable subagent id immediately. Defaults to true. Set false to wait for the result when your next action depends on it."
diff --git a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/cordis.yml b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/cordis.yml
index 100c7c20aa..4b6e415081 100644
--- a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/cordis.yml
+++ b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/cordis.yml
@@ -35,12 +35,19 @@
         env:
           DSH_TELEMETRY_DISABLED: '1'
 
+    - id: subagent-model-selection-settings
+      name: '@deepseek-ai/dsh-tool-subagent/model-selection-settings'
+      config:
+        enabled: true
+        allowedModels:
+          - provider: mock
+            model: mock-routed
+
     - id: tool-subagent-dsh-sdk
-      name: '@deepseek-ai/dsh-tool-subagent'
+      name: '../../../packages/subagent/subagent-dsh-sdk/tests/fixtures/loader/scoped-tool-subagent.ts'
       config:
         provider: dsh-sdk
         toolName: subagent
-        enableModelSelection: true
         enableRunInBackground: false
         agentOptions:
           maxTokens: 777
diff --git a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/notifications.expected.jsonl b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/notifications.expected.jsonl
index 9dee99a052..315ff76482 100644
--- a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/notifications.expected.jsonl
+++ b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/notifications.expected.jsonl
@@ -1,29 +1,29 @@
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"agent/inbox/spliced","seq":3,"time":0,"data":{"target":"next-turn","start":0,"inserted":[{"content":[{"type":"text","text":"Delegate once using the requested child route."}],"source":{"kind":"user"},"role":"user","id":"{{sessionId}}"}]}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"agent/inbox/spliced","seq":4,"time":0,"data":{"target":"next-turn","start":0,"inserted":[{"content":[{"type":"text","text":"Delegate once using the requested child route."}],"source":{"kind":"user"},"role":"user","id":"{{sessionId}}"}]}}}}
 {"method":"session.status","params":{"sessionId":"{{sessionId}}","status":"running"}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"turn/start","seq":4,"time":0,"data":{"turn":1}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"agent/inbox/spliced","seq":5,"time":0,"data":{"target":"next-turn","start":0,"removedCount":1,"inserted":[]}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":6,"time":0,"data":{"turn":1,"step":1}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"user/message","seq":7,"time":0,"data":{"content":[{"type":"text","text":"Delegate once using the requested child route."}],"source":{"kind":"user"},"role":"user","id":"{{sessionId}}"},"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"user/message","seq":8,"time":0,"data":{"content":[{"type":"text","text":"Current runtime context. This snapshot supersedes earlier runtime-context snapshots.\n\nCurrent DSH file policy: workspace-write. Any available operation enforced by the DSH file sandbox may modify files under the session workspace: \"{{cwd}}\". Some platform temporary areas may also be writable.\n\nApproval policy: ask. Operations that require approval may ask through the configured answerers; without an available answerer, the request fails closed."}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt","form":"snapshot","sections":[{"name":"sandbox:policy","text":"Current DSH file policy: workspace-write. Any available operation enforced by the DSH file sandbox may modify files under the session workspace: \"{{cwd}}\". Some platform temporary areas may also be writable."},{"name":"approval:policy","text":"Approval policy: ask. Operations that require approval may ask through the configured answerers; without an available answerer, the request fails closed."}]},"role":"user","id":"{{sessionId}}"},"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"session/title","seq":9,"time":0,"data":{"title":"Delegate once using the requested","messageSeqs":[7],"source":{"kind":"fallback"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"request/header","seq":10,"time":0,"data":{"header":{"config":{"provider":"deepseek-official","model":"mock-delegate"},"system":"{{system}}","tools":"{{tools}}"},"reason":"initial"}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"request/context","seq":11,"time":0,"data":{"provider":"deepseek-official","model":"mock-delegate"}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":12,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":13,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"tool-call-delta","index":0,"id":"call-delegate","name":"subagent","argumentsDelta":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":14,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":15,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":16,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":17,"time":0,"data":{"turn":1,"step":1,"message":{"role":"assistant","content":[{"type":"tool-call","id":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[12,13,14,15,16],"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":18,"time":0,"data":{"turn":1,"step":1,"callId":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/result","seq":19,"time":0,"data":{"turn":1,"step":1,"message":{"source":{"kind":"tool","callId":"call-delegate"},"content":[{"type":"tool-result","toolCallId":"call-delegate","content":[{"type":"text","text":"child route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"isError":false}],"role":"user","id":"{{sessionId}}"}},"sourceEventSeqs":[18],"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":20,"time":0,"data":{"turn":1,"step":1}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":21,"time":0,"data":{"turn":1,"step":2}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":22,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"text"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":23,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"text-delta","index":0,"text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":24,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"block-end","index":0,"block":{"type":"text","text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":25,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":26,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"finish","reason":{"kind":"stop"}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":27,"time":0,"data":{"turn":1,"step":2,"message":{"role":"assistant","content":[{"type":"text","text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[22,23,24,25,26],"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":28,"time":0,"data":{"turn":1,"step":2}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"turn/end","seq":29,"time":0,"data":{"turn":1,"reason":{"kind":"completed"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"turn/start","seq":5,"time":0,"data":{"turn":1}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"agent/inbox/spliced","seq":6,"time":0,"data":{"target":"next-turn","start":0,"removedCount":1,"inserted":[]}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":7,"time":0,"data":{"turn":1,"step":1}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"user/message","seq":8,"time":0,"data":{"content":[{"type":"text","text":"Delegate once using the requested child route."}],"source":{"kind":"user"},"role":"user","id":"{{sessionId}}"},"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"user/message","seq":9,"time":0,"data":{"content":[{"type":"text","text":"Current runtime context. This snapshot supersedes earlier runtime-context snapshots.\n\nCurrent DSH file policy: workspace-write. Any available operation enforced by the DSH file sandbox may modify files under the session workspace: \"{{cwd}}\". Some platform temporary areas may also be writable.\n\nApproval policy: ask. Operations that require approval may ask through the configured answerers; without an available answerer, the request fails closed."}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt","form":"snapshot","sections":[{"name":"sandbox:policy","text":"Current DSH file policy: workspace-write. Any available operation enforced by the DSH file sandbox may modify files under the session workspace: \"{{cwd}}\". Some platform temporary areas may also be writable."},{"name":"approval:policy","text":"Approval policy: ask. Operations that require approval may ask through the configured answerers; without an available answerer, the request fails closed."}]},"role":"user","id":"{{sessionId}}"},"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"session/title","seq":10,"time":0,"data":{"title":"Delegate once using the requested","messageSeqs":[8],"source":{"kind":"fallback"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"request/header","seq":11,"time":0,"data":{"header":{"config":{"provider":"deepseek-official","model":"mock-delegate"},"system":"{{system}}","tools":"{{tools}}"},"reason":"initial"}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"request/context","seq":12,"time":0,"data":{"provider":"deepseek-official","model":"mock-delegate"}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":13,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":14,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"tool-call-delta","index":0,"id":"call-delegate","name":"subagent","argumentsDelta":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":15,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":16,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":17,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":18,"time":0,"data":{"turn":1,"step":1,"message":{"role":"assistant","content":[{"type":"tool-call","id":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[13,14,15,16,17],"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":19,"time":0,"data":{"turn":1,"step":1,"callId":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/result","seq":20,"time":0,"data":{"turn":1,"step":1,"message":{"source":{"kind":"tool","callId":"call-delegate"},"content":[{"type":"tool-result","toolCallId":"call-delegate","content":[{"type":"text","text":"child route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"isError":false}],"role":"user","id":"{{sessionId}}"}},"sourceEventSeqs":[19],"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":21,"time":0,"data":{"turn":1,"step":1}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":22,"time":0,"data":{"turn":1,"step":2}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":23,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"text"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":24,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"text-delta","index":0,"text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":25,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"block-end","index":0,"block":{"type":"text","text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":26,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":27,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"finish","reason":{"kind":"stop"}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":28,"time":0,"data":{"turn":1,"step":2,"message":{"role":"assistant","content":[{"type":"text","text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[23,24,25,26,27],"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":29,"time":0,"data":{"turn":1,"step":2}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"turn/end","seq":30,"time":0,"data":{"turn":1,"reason":{"kind":"completed"}}}}}
 {"method":"session.status","params":{"sessionId":"{{sessionId}}","status":"idle"}}
diff --git a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/session.jsonl b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/session.jsonl
index cc800a84cb..9402e19672 100644
--- a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/session.jsonl
+++ b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/session.jsonl
@@ -2,13 +2,14 @@
 {"type":"permission/preset","data":{"preset":"workspace-write"}}
 {"type":"sandbox/mode","data":{"mode":"workspace-write"}}
 {"type":"approval/policy","data":{"policy":"ask"}}
+{"type":"subagent/model-selection-policy","data":{"allowedModels":[{"provider":"mock","model":"mock-routed"}]}}
 {"type":"agent/inbox/spliced","data":{"target":"next-turn","start":0,"inserted":[{"content":[{"type":"text","text":"Delegate once using the requested child route."}],"source":{"kind":"user"},"role":"user","id":"{{message:1}}"}]}}
 {"type":"turn/start","data":{"turn":1}}
 {"type":"agent/inbox/spliced","data":{"target":"next-turn","start":0,"removedCount":1,"inserted":[]}}
 {"type":"step/start","data":{"turn":1,"step":1}}
 {"type":"user/message","data":{"content":[{"type":"text","text":"Delegate once using the requested child route."}],"source":{"kind":"user"},"role":"user","id":"{{message:1}}"},"surfaceOp":"append"}
 {"type":"user/message","data":{"content":[{"type":"text","text":"Current runtime context. This snapshot supersedes earlier runtime-context snapshots.\n\nCurrent DSH file policy: workspace-write. Any available operation enforced by the DSH file sandbox may modify files under the session workspace: \"{{cwd}}\". Some platform temporary areas may also be writable.\n\nApproval policy: ask. Operations that require approval may ask through the configured answerers; without an available answerer, the request fails closed."}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt","form":"snapshot","sections":[{"name":"sandbox:policy","text":"Current DSH file policy: workspace-write. Any available operation enforced by the DSH file sandbox may modify files under the session workspace: \"{{cwd}}\". Some platform temporary areas may also be writable."},{"name":"approval:policy","text":"Approval policy: ask. Operations that require approval may ask through the configured answerers; without an available answerer, the request fails closed."}]},"role":"user","id":"{{message:2}}"},"surfaceOp":"append"}
-{"type":"session/title","data":{"title":"Delegate once using the requested","messageSeqs":[7],"source":{"kind":"fallback"}}}
+{"type":"session/title","data":{"title":"Delegate once using the requested","messageSeqs":[8],"source":{"kind":"fallback"}}}
 {"type":"request/header","data":{"header":{"config":{"provider":"deepseek-official","model":"mock-delegate"},"system":"{{system}}","tools":"{{tools}}"},"reason":"initial"}}
 {"type":"request/context","data":{"provider":"deepseek-official","model":"mock-delegate"}}
 {"type":"assistant/chunk","data":{"turn":1,"step":1,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}
@@ -16,9 +17,9 @@
 {"type":"assistant/chunk","data":{"turn":1,"step":1,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":1,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
-{"type":"assistant/message","data":{"turn":1,"step":1,"message":{"role":"assistant","content":[{"type":"tool-call","id":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{message:3}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[12,13,14,15,16],"surfaceOp":"append"}
+{"type":"assistant/message","data":{"turn":1,"step":1,"message":{"role":"assistant","content":[{"type":"tool-call","id":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{message:3}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[13,14,15,16,17],"surfaceOp":"append"}
 {"type":"tool/call","data":{"turn":1,"step":1,"callId":"call-delegate","name":"subagent","arguments":"{\"description\":\"route probe\",\"prompt\":\"report your route and workspace\",\"provider\":\"mock\",\"model\":\"mock-routed\",\"reasoning_effort\":\"max\"}"}}
-{"type":"tool/result","data":{"turn":1,"step":1,"message":{"source":{"kind":"tool","callId":"call-delegate"},"content":[{"type":"tool-result","toolCallId":"call-delegate","content":[{"type":"text","text":"child route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"isError":false}],"role":"user","id":"{{message:4}}"}},"sourceEventSeqs":[18],"surfaceOp":"append"}
+{"type":"tool/result","data":{"turn":1,"step":1,"message":{"source":{"kind":"tool","callId":"call-delegate"},"content":[{"type":"tool-result","toolCallId":"call-delegate","content":[{"type":"text","text":"child route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"isError":false}],"role":"user","id":"{{message:4}}"}},"sourceEventSeqs":[19],"surfaceOp":"append"}
 {"type":"step/end","data":{"turn":1,"step":1}}
 {"type":"step/start","data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"text"}}}
@@ -26,6 +27,6 @@
 {"type":"assistant/chunk","data":{"turn":1,"step":2,"chunk":{"type":"block-end","index":0,"block":{"type":"text","text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":2,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":2,"chunk":{"type":"finish","reason":{"kind":"stop"}}}}
-{"type":"assistant/message","data":{"turn":1,"step":2,"message":{"role":"assistant","content":[{"type":"text","text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{message:5}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[22,23,24,25,26],"surfaceOp":"append"}
+{"type":"assistant/message","data":{"turn":1,"step":2,"message":{"role":"assistant","content":[{"type":"text","text":"child reported:\nchild route: mock/mock-routed/max/777; cwd: {{cwd}}"}],"source":{"kind":"model","provider":"deepseek-official","model":"mock-delegate"},"id":"{{message:5}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[23,24,25,26,27],"surfaceOp":"append"}
 {"type":"step/end","data":{"turn":1,"step":2}}
 {"type":"turn/end","data":{"turn":1,"reason":{"kind":"completed"}}}
diff --git a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/tool-schemas.1.expected.json b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/tool-schemas.1.expected.json
index ba1d2e415d..fe0882fe53 100644
--- a/snapshots/sdk/subagent-dsh-sdk-dynamic-route/tool-schemas.1.expected.json
+++ b/snapshots/sdk/subagent-dsh-sdk-dynamic-route/tool-schemas.1.expected.json
@@ -260,23 +260,6 @@
         }
       }
     },
-    {
-      "name": "list_subagent_models",
-      "description": "Discover LLM routes for subagents without changing the current Agent. Call with no arguments to list registered providers, with `provider` to list its advertised models, or with `provider` and `model` to inspect that exact model and its reasoning efforts. Catalog membership is advisory: an adapter may accept an unlisted model id. Use the returned ids with a delegation tool's `provider`, `model`, and `reasoning_effort` fields.",
-      "parameters": {
-        "type": "object",
-        "properties": {
-          "provider": {
-            "type": "string",
-            "description": "Registered LLM provider id. Omit to list providers."
-          },
-          "model": {
-            "type": "string",
-            "description": "Exact model id to inspect. Requires provider; omit to list that provider's advertised models."
-          }
-        }
-      }
-    },
     {
       "name": "ralph",
       "description": "Run a foreground fresh-agent Ralph loop toward one immutable objective. Use only when the direct human explicitly asks for Ralph or fresh-agent iteration. Each round opens a new child with no parent conversation or prior child session; the shared workspace is long-term memory, and only a bounded structured report crosses rounds. The call returns when a worker reports completion or a concrete blocker, or at the round limit. Ordinary long-running same-session work belongs to goal tools.",
@@ -461,7 +444,7 @@
     },
     {
       "name": "subagent",
-      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort.",
+      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result.",
       "parameters": {
         "type": "object",
         "properties": {
@@ -473,18 +456,6 @@
             "type": "string",
             "description": "The complete, self-contained task for the subagent. It does not share this conversation's context, so include everything it needs."
           },
-          "provider": {
-            "type": "string",
-            "description": "LLM provider route for the child. Supply together with model; omit both to use configured child defaults or inherit the parent route."
-          },
-          "model": {
-            "type": "string",
-            "description": "Model id interpreted by provider. Supply together with provider; omit both to use configured child defaults or inherit the parent route."
-          },
-          "reasoning_effort": {
-            "type": "string",
-            "description": "Adapter-owned reasoning effort for the effective child route. Omit to inherit a compatible configured/parent effort or use a newly selected model's default."
-          },
           "run_in_background": {
             "type": "boolean",
             "description": "Whether to run in the background and return a durable subagent id immediately. Defaults to true. Set false to wait for the result when your next action depends on it."
diff --git a/snapshots/session/agent-instructions/tool-schemas.expected.json b/snapshots/session/agent-instructions/tool-schemas.expected.json
index 0d475b2d80..36df7a0481 100644
--- a/snapshots/session/agent-instructions/tool-schemas.expected.json
+++ b/snapshots/session/agent-instructions/tool-schemas.expected.json
@@ -260,23 +260,6 @@
         }
       }
     },
-    {
-      "name": "list_subagent_models",
-      "description": "Discover LLM routes for subagents without changing the current Agent. Call with no arguments to list registered providers, with `provider` to list its advertised models, or with `provider` and `model` to inspect that exact model and its reasoning efforts. Catalog membership is advisory: an adapter may accept an unlisted model id. Use the returned ids with a delegation tool's `provider`, `model`, and `reasoning_effort` fields.",
-      "parameters": {
-        "type": "object",
-        "properties": {
-          "provider": {
-            "type": "string",
-            "description": "Registered LLM provider id. Omit to list providers."
-          },
-          "model": {
-            "type": "string",
-            "description": "Exact model id to inspect. Requires provider; omit to list that provider's advertised models."
-          }
-        }
-      }
-    },
     {
       "name": "ralph",
       "description": "Run a foreground fresh-agent Ralph loop toward one immutable objective. Use only when the direct human explicitly asks for Ralph or fresh-agent iteration. Each round opens a new child with no parent conversation or prior child session; the shared workspace is long-term memory, and only a bounded structured report crosses rounds. The call returns when a worker reports completion or a concrete blocker, or at the round limit. Ordinary long-running same-session work belongs to goal tools.",
@@ -461,7 +444,7 @@
     },
     {
       "name": "subagent",
-      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort.",
+      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result.",
       "parameters": {
         "type": "object",
         "properties": {
@@ -473,18 +456,6 @@
             "type": "string",
             "description": "The complete, self-contained task for the subagent. It does not share this conversation's context, so include everything it needs."
           },
-          "provider": {
-            "type": "string",
-            "description": "LLM provider route for the child. Supply together with model; omit both to use configured child defaults or inherit the parent route."
-          },
-          "model": {
-            "type": "string",
-            "description": "Model id interpreted by provider. Supply together with provider; omit both to use configured child defaults or inherit the parent route."
-          },
-          "reasoning_effort": {
-            "type": "string",
-            "description": "Adapter-owned reasoning effort for the effective child route. Omit to inherit a compatible configured/parent effort or use a newly selected model's default."
-          },
           "run_in_background": {
             "type": "boolean",
             "description": "Whether to run in the background and return a durable subagent id immediately. Defaults to true. Set false to wait for the result when your next action depends on it."
@@ -990,23 +961,6 @@
           }
         }
       },
-      {
-        "name": "list_subagent_models",
-        "description": "Discover LLM routes for subagents without changing the current Agent. Call with no arguments to list registered providers, with `provider` to list its advertised models, or with `provider` and `model` to inspect that exact model and its reasoning efforts. Catalog membership is advisory: an adapter may accept an unlisted model id. Use the returned ids with a delegation tool's `provider`, `model`, and `reasoning_effort` fields.",
-        "parameters": {
-          "type": "object",
-          "properties": {
-            "provider": {
-              "type": "string",
-              "description": "Registered LLM provider id. Omit to list providers."
-            },
-            "model": {
-              "type": "string",
-              "description": "Exact model id to inspect. Requires provider; omit to list that provider's advertised models."
-            }
-          }
-        }
-      },
       {
         "name": "ralph",
         "description": "Run a foreground fresh-agent Ralph loop toward one immutable objective. Use only when the direct human explicitly asks for Ralph or fresh-agent iteration. Each round opens a new child with no parent conversation or prior child session; the shared workspace is long-term memory, and only a bounded structured report crosses rounds. The call returns when a worker reports completion or a concrete blocker, or at the round limit. Ordinary long-running same-session work belongs to goal tools.",
@@ -1191,7 +1145,7 @@
       },
       {
         "name": "subagent",
-        "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort.",
+        "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result.",
         "parameters": {
           "type": "object",
           "properties": {
@@ -1203,18 +1157,6 @@
               "type": "string",
               "description": "The complete, self-contained task for the subagent. It does not share this conversation's context, so include everything it needs."
             },
-            "provider": {
-              "type": "string",
-              "description": "LLM provider route for the child. Supply together with model; omit both to use configured child defaults or inherit the parent route."
-            },
-            "model": {
-              "type": "string",
-              "description": "Model id interpreted by provider. Supply together with provider; omit both to use configured child defaults or inherit the parent route."
-            },
-            "reasoning_effort": {
-              "type": "string",
-              "description": "Adapter-owned reasoning effort for the effective child route. Omit to inherit a compatible configured/parent effort or use a newly selected model's default."
-            },
             "run_in_background": {
               "type": "boolean",
               "description": "Whether to run in the background and return a durable subagent id immediately. Defaults to true. Set false to wait for the result when your next action depends on it."
diff --git a/snapshots/session/compaction-recovery/tool-schemas.expected.json b/snapshots/session/compaction-recovery/tool-schemas.expected.json
index 0d475b2d80..36df7a0481 100644
--- a/snapshots/session/compaction-recovery/tool-schemas.expected.json
+++ b/snapshots/session/compaction-recovery/tool-schemas.expected.json
@@ -260,23 +260,6 @@
         }
       }
     },
-    {
-      "name": "list_subagent_models",
-      "description": "Discover LLM routes for subagents without changing the current Agent. Call with no arguments to list registered providers, with `provider` to list its advertised models, or with `provider` and `model` to inspect that exact model and its reasoning efforts. Catalog membership is advisory: an adapter may accept an unlisted model id. Use the returned ids with a delegation tool's `provider`, `model`, and `reasoning_effort` fields.",
-      "parameters": {
-        "type": "object",
-        "properties": {
-          "provider": {
-            "type": "string",
-            "description": "Registered LLM provider id. Omit to list providers."
-          },
-          "model": {
-            "type": "string",
-            "description": "Exact model id to inspect. Requires provider; omit to list that provider's advertised models."
-          }
-        }
-      }
-    },
     {
       "name": "ralph",
       "description": "Run a foreground fresh-agent Ralph loop toward one immutable objective. Use only when the direct human explicitly asks for Ralph or fresh-agent iteration. Each round opens a new child with no parent conversation or prior child session; the shared workspace is long-term memory, and only a bounded structured report crosses rounds. The call returns when a worker reports completion or a concrete blocker, or at the round limit. Ordinary long-running same-session work belongs to goal tools.",
@@ -461,7 +444,7 @@
     },
     {
       "name": "subagent",
-      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort.",
+      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result.",
       "parameters": {
         "type": "object",
         "properties": {
@@ -473,18 +456,6 @@
             "type": "string",
             "description": "The complete, self-contained task for the subagent. It does not share this conversation's context, so include everything it needs."
           },
-          "provider": {
-            "type": "string",
-            "description": "LLM provider route for the child. Supply together with model; omit both to use configured child defaults or inherit the parent route."
-          },
-          "model": {
-            "type": "string",
-            "description": "Model id interpreted by provider. Supply together with provider; omit both to use configured child defaults or inherit the parent route."
-          },
-          "reasoning_effort": {
-            "type": "string",
-            "description": "Adapter-owned reasoning effort for the effective child route. Omit to inherit a compatible configured/parent effort or use a newly selected model's default."
-          },
           "run_in_background": {
             "type": "boolean",
             "description": "Whether to run in the background and return a durable subagent id immediately. Defaults to true. Set false to wait for the result when your next action depends on it."
@@ -990,23 +961,6 @@
           }
         }
       },
-      {
-        "name": "list_subagent_models",
-        "description": "Discover LLM routes for subagents without changing the current Agent. Call with no arguments to list registered providers, with `provider` to list its advertised models, or with `provider` and `model` to inspect that exact model and its reasoning efforts. Catalog membership is advisory: an adapter may accept an unlisted model id. Use the returned ids with a delegation tool's `provider`, `model`, and `reasoning_effort` fields.",
-        "parameters": {
-          "type": "object",
-          "properties": {
-            "provider": {
-              "type": "string",
-              "description": "Registered LLM provider id. Omit to list providers."
-            },
-            "model": {
-              "type": "string",
-              "description": "Exact model id to inspect. Requires provider; omit to list that provider's advertised models."
-            }
-          }
-        }
-      },
       {
         "name": "ralph",
         "description": "Run a foreground fresh-agent Ralph loop toward one immutable objective. Use only when the direct human explicitly asks for Ralph or fresh-agent iteration. Each round opens a new child with no parent conversation or prior child session; the shared workspace is long-term memory, and only a bounded structured report crosses rounds. The call returns when a worker reports completion or a concrete blocker, or at the round limit. Ordinary long-running same-session work belongs to goal tools.",
@@ -1191,7 +1145,7 @@
       },
       {
         "name": "subagent",
-        "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort.",
+        "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result.",
         "parameters": {
           "type": "object",
           "properties": {
@@ -1203,18 +1157,6 @@
               "type": "string",
               "description": "The complete, self-contained task for the subagent. It does not share this conversation's context, so include everything it needs."
             },
-            "provider": {
-              "type": "string",
-              "description": "LLM provider route for the child. Supply together with model; omit both to use configured child defaults or inherit the parent route."
-            },
-            "model": {
-              "type": "string",
-              "description": "Model id interpreted by provider. Supply together with provider; omit both to use configured child defaults or inherit the parent route."
-            },
-            "reasoning_effort": {
-              "type": "string",
-              "description": "Adapter-owned reasoning effort for the effective child route. Omit to inherit a compatible configured/parent effort or use a newly selected model's default."
-            },
             "run_in_background": {
               "type": "boolean",
               "description": "Whether to run in the background and return a durable subagent id immediately. Defaults to true. Set false to wait for the result when your next action depends on it."
diff --git a/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json b/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json
index 2f46955ebd..796bac1779 100644
--- a/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json
+++ b/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json
@@ -260,23 +260,6 @@
         }
       }
     },
-    {
-      "name": "list_subagent_models",
-      "description": "Discover LLM routes for subagents without changing the current Agent. Call with no arguments to list registered providers, with `provider` to list its advertised models, or with `provider` and `model` to inspect that exact model and its reasoning efforts. Catalog membership is advisory: an adapter may accept an unlisted model id. Use the returned ids with a delegation tool's `provider`, `model`, and `reasoning_effort` fields.",
-      "parameters": {
-        "type": "object",
-        "properties": {
-          "provider": {
-            "type": "string",
-            "description": "Registered LLM provider id. Omit to list providers."
-          },
-          "model": {
-            "type": "string",
-            "description": "Exact model id to inspect. Requires provider; omit to list that provider's advertised models."
-          }
-        }
-      }
-    },
     {
       "name": "ralph",
       "description": "Run a foreground fresh-agent Ralph loop toward one immutable objective. Use only when the direct human explicitly asks for Ralph or fresh-agent iteration. Each round opens a new child with no parent conversation or prior child session; the shared workspace is long-term memory, and only a bounded structured report crosses rounds. The call returns when a worker reports completion or a concrete blocker, or at the round limit. Ordinary long-running same-session work belongs to goal tools.",
@@ -461,7 +444,7 @@
     },
     {
       "name": "subagent",
-      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort.",
+      "description": "Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result.",
       "parameters": {
         "type": "object",
         "properties": {
@@ -473,18 +456,6 @@
             "type": "string",
             "description": "The complete, self-contained task for the subagent. It does not share this conversation's context, so include everything it needs."
           },
-          "provider": {
-            "type": "string",
-            "description": "LLM provider route for the child. Supply together with model; omit both to use configured child defaults or inherit the parent route."
-          },
-          "model": {
-            "type": "string",
-            "description": "Model id interpreted by provider. Supply together with provider; omit both to use configured child defaults or inherit the parent route."
-          },
-          "reasoning_effort": {
-            "type": "string",
-            "description": "Adapter-owned reasoning effort for the effective child route. Omit to inherit a compatible configured/parent effort or use a newly selected model's default."
-          },
           "run_in_background": {
             "type": "boolean",
             "description": "Whether to run in the background and return a durable subagent id immediately. Defaults to true. Set false to wait for the result when your next action depends on it."
diff --git a/snapshots/session/text-turn/cordis.yml b/snapshots/session/text-turn/cordis.yml
index 2c8ffef06f..ea97cc0616 100644
--- a/snapshots/session/text-turn/cordis.yml
+++ b/snapshots/session/text-turn/cordis.yml
@@ -51,7 +51,6 @@
   config:
     provider: spawn
     toolName: subagent
-    enableModelSelection: true
     backgroundMode: continuable
     maxDepth: 1