refactor(delegate-task): remove AI slop from supporting files

Tighten resolve-metadata-model runtime guards, tidy tool-argument-preparation
subagent-type override logging, and trim a redundant literal in the
metadata-model-unification test. Behavior preserved (328 tests pass).

src/tools/delegate-task/metadata-model-unification.test.ts

@@ -1,4 +1,4 @@
-const { describe, test, expect, mock } = require("bun:test")
+const { describe, test, expect } = require("bun:test")
 
 import type { DelegateTaskArgs, ToolContextWithMetadata } from "./types"
 import type { ParentContext } from "./executor-types"
@@ -90,7 +90,7 @@ describe("metadata model unification", () => {
           id: "bg_unstable", description: "test", agent: "explore",
           status: "completed", sessionID: "ses_unstable", model: MODEL,
         }
-        const result = await executeUnstableAgentTask(
+        await executeUnstableAgentTask(
           args, ctx,
           {
             manager: {

src/tools/delegate-task/resolve-metadata-model.ts

@@ -18,11 +18,16 @@ function isModelLike(value: unknown): value is ModelLike {
 }
 
 function toMetadataModel(model: ModelLike): MetadataModel {
-  return {
+  const metadataModel: MetadataModel = {
     providerID: model.providerID,
     modelID: model.modelID,
-    ...("variant" in model && model.variant ? { variant: model.variant } : {}),
   }
+
+  if ("variant" in model && model.variant) {
+    metadataModel.variant = model.variant
+  }
+
+  return metadataModel
 }
 
 export function resolveMetadataModel(

src/tools/delegate-task/tool-argument-preparation.ts

@@ -8,13 +8,14 @@ export async function prepareDelegateTaskArgs(args: Record<string, unknown>, ctx
   const originalSubagentType = typeof args.subagent_type === "string" ? args.subagent_type : undefined
   let subagentType = originalSubagentType
 
+  if (category && subagentType && subagentType !== SISYPHUS_JUNIOR_AGENT) {
+    log("[task] category provided - overriding subagent_type to sisyphus-junior", {
+      category,
+      subagent_type: subagentType,
+    })
+  }
+
   if (category) {
-    if (subagentType && subagentType !== SISYPHUS_JUNIOR_AGENT) {
-      log("[task] category provided - overriding subagent_type to sisyphus-junior", {
-        category,
-        subagent_type: subagentType,
-      })
-    }
     subagentType = SISYPHUS_JUNIOR_AGENT
   }