refactor: extract model selection logic from delegate-task into focused modules

- Create available-models.ts for model availability checking
- Create model-selection.ts for category-to-model resolution logic
- Update category-resolver, subagent-resolver, and sync modules to import
  from new focused modules instead of monolithic sources

src/tools/delegate-task/available-models.ts

@@ -0,0 +1,64 @@
+import type { OpencodeClient } from "./types"
+import { log } from "../../shared/logger"
+import { readConnectedProvidersCache, readProviderModelsCache } from "../../shared/connected-providers-cache"
+
+function addFromProviderModels(
+  out: Set<string>,
+  providerID: string,
+  models: Array<string | { id?: string }> | undefined
+): void {
+  if (!models) return
+  for (const item of models) {
+    const modelID = typeof item === "string" ? item : item?.id
+    if (!modelID) continue
+    out.add(`${providerID}/${modelID}`)
+  }
+}
+
+export async function getAvailableModelsForDelegateTask(client: OpencodeClient): Promise<Set<string>> {
+  const providerModelsCache = readProviderModelsCache()
+
+  if (providerModelsCache?.models) {
+    const connected = new Set(providerModelsCache.connected)
+
+    const out = new Set<string>()
+    for (const [providerID, models] of Object.entries(providerModelsCache.models)) {
+      if (!connected.has(providerID)) continue
+      addFromProviderModels(out, providerID, models as Array<string | { id?: string }> | undefined)
+    }
+    return out
+  }
+
+  const connectedProviders = readConnectedProvidersCache()
+
+  if (!connectedProviders || connectedProviders.length === 0) {
+    return new Set()
+  }
+
+  const modelList = (client as unknown as { model?: { list?: () => Promise<unknown> } })
+    ?.model
+    ?.list
+
+  if (!modelList) {
+    return new Set()
+  }
+
+  try {
+    const result = await modelList()
+    const rows = Array.isArray(result)
+      ? result
+      : ((result as { data?: unknown }).data as Array<{ provider?: string; id?: string }> | undefined) ?? []
+
+    const connected = new Set(connectedProviders)
+    const out = new Set<string>()
+    for (const row of rows) {
+      if (!row?.provider || !row?.id) continue
+      if (!connected.has(row.provider)) continue
+      out.add(`${row.provider}/${row.id}`)
+    }
+    return out
+  } catch (err) {
+    log("[delegate-task] client.model.list failed", { error: String(err) })
+    return new Set()
+  }
+}