fix(core): ignore blank subagent options (#50977)

Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>

packages/core/src/tool/plugin/subagent.ts

@@ -3,7 +3,7 @@ export * as SubagentTool from "./subagent.js"
 import { ToolFailure } from "@opencode/ai"
 import type { Context } from "@opencode/plugin/effect/plugin"
 import type { SessionHooks } from "@opencode/plugin/effect/session"
-import { Effect, Schema } from "effect"
+import { Effect, Predicate, Schema } from "effect"
 import { Agent } from "../../agent.js"
 import { Config } from "../../config.js"
 import { Job } from "../../job.js"
@@ -268,6 +268,17 @@ export const Plugin = {
       )
       .pipe(Effect.orDie)
 
+    yield* ctx.tool.hook("execute.before", (event) =>
+      Effect.sync(() => {
+        if (event.tool !== name || !Predicate.isObject(event.input)) return
+        if (event.input.model !== "" && event.input.sessionID !== "") return
+        const input = { ...event.input }
+        if (input.model === "") delete input.model
+        if (input.sessionID === "") delete input.sessionID
+        event.input = input
+      }),
+    )
+
     const hook = (event: SessionHooks["context"]) =>
       Effect.gen(function* () {
         const tool = event.tools[name]

packages/core/test/lib/tool.ts

@@ -60,6 +60,7 @@ export const registerToolPlugin = <R>(
     readonly effect: (context: Context) => Effect.Effect<void, never, R>
   },
   overrides: Parameters<typeof host>[0] = {},
+  hook?: Context["tool"]["hook"],
 ): Effect.Effect<void, never, R | Tool.Service | Scope.Scope> =>
   Effect.gen(function* () {
     const tools = yield* Tool.Service
@@ -73,7 +74,7 @@ export const registerToolPlugin = <R>(
         transform: tools.transform,
         reload: tools.reload,
         list: tools.list,
-        hook: () => Effect.die("registerToolPlugin does not support tool hooks"),
+        hook: hook ?? (() => Effect.die("registerToolPlugin does not support tool hooks")),
       },
     })
     yield* plugin.effect(context)

packages/core/test/tool-subagent.test.ts

@@ -30,6 +30,7 @@ import { SessionMessage } from "@opencode/core/session/message"
 import { SessionRunnerModel } from "@opencode/core/session/runner/model"
 import { SessionStore } from "@opencode/core/session/store"
 import { Plugin } from "@opencode/core/plugin"
+import { PluginHooks } from "@opencode/core/plugin/hooks"
 import { PluginSupervisor } from "@opencode/core/plugin/supervisor"
 import { Permission } from "@opencode/core/permission"
 import { SubagentTool } from "@opencode/core/tool/plugin/subagent"
@@ -112,8 +113,13 @@ const executionNode = makeGlobalNode({
 
 const subagentPluginSupervisor = makeLocationNode({
   name: "test/subagent-plugins",
-  layer: Layer.effectDiscard(registerToolPlugin(SubagentTool.Plugin)),
-  deps: [Agent.node, Config.node, Model.node, Permission.node, Session.node, Job.node, Tool.node],
+  layer: Layer.effectDiscard(
+    Effect.gen(function* () {
+      const hooks = yield* PluginHooks.Service
+      yield* registerToolPlugin(SubagentTool.Plugin, {}, (name, callback) => hooks.register("tool", name, callback))
+    }),
+  ),
+  deps: [Agent.node, Config.node, Model.node, Permission.node, Session.node, Job.node, Tool.node, PluginHooks.node],
 })
 
 const nodes = LayerNode.group([
@@ -407,7 +413,7 @@ describe("SubagentTool", () => {
               type: "tool-call",
               id: "call-subagent",
               name: SubagentTool.name,
-              input: { agent: "reviewer", description: "review", prompt: "review this" },
+              input: { agent: "reviewer", description: "review", prompt: "review this", model: "", sessionID: "" },
             },
           })
 
@@ -484,6 +490,7 @@ describe("SubagentTool", () => {
                 description: "follow up",
                 prompt: "continue this",
                 sessionID: childID,
+                model: "",
               },
             },
           })
@@ -600,6 +607,28 @@ describe("SubagentTool", () => {
               message: `Subagent session not found: ${missing}`,
             },
           })
+          expect(
+            yield* executeTool(registry, {
+              sessionID: parent.id,
+              ...toolIdentity,
+              call: {
+                type: "tool-call",
+                id: "call-malformed-child-id",
+                name: SubagentTool.name,
+                input: { agent: "reviewer", description: "follow up", prompt: "continue", sessionID: "placeholder" },
+              },
+            }),
+          ).toMatchObject({
+            status: "error",
+            error: { message: expect.stringContaining('sessionID: Expected a string starting with "ses"') },
+          })
+          expect(yield* call(parent.id, "call-parent-id")).toEqual({
+            status: "error",
+            error: {
+              type: "tool.execution",
+              message: `Session ${parent.id} is not a child of the current session`,
+            },
+          })
           expect(yield* call(unrelated.id, "call-unrelated-child")).toEqual({
             status: "error",
             error: {
@@ -655,7 +684,7 @@ describe("SubagentTool", () => {
             })
 
           // The requested model beats the agent's configured model.
-          const spawned = yield* call("call-override", { model: "test/override#fast" })
+          const spawned = yield* call("call-override", { model: "test/override#fast", sessionID: "" })
           expect(spawned).toMatchObject({ status: "completed", metadata: { status: "completed" } })
           const child = yield* sessions.get(outputSessionID(spawned.metadata))
           expect(child).toMatchObject({ agent: "reviewer", model: overrideModel })