refactor: wave 1 - extract leaf modules, rename catch-all files, split index.ts hooks

- Split 25+ index.ts files into hook.ts + extracted modules
- Rename all catch-all utils.ts/helpers.ts to domain-specific names
- Split src/tools/lsp/ into ~15 focused modules
- Split src/tools/delegate-task/ into ~18 focused modules
- Separate shared types from implementation
- 155 files changed, 60+ new files created
- All typecheck clean, 61 tests pass

src/tools/delegate-task/sync-prompt-sender.ts

@@ -0,0 +1,59 @@
+import type { DelegateTaskArgs, OpencodeClient } from "./types"
+import { isPlanAgent } from "./constants"
+import { promptWithModelSuggestionRetry } from "../../shared"
+import { formatDetailedError } from "./error-formatting"
+
+export async function sendSyncPrompt(
+  client: OpencodeClient,
+  input: {
+    sessionID: string
+    agentToUse: string
+    args: DelegateTaskArgs
+    systemContent: string | undefined
+    categoryModel: { providerID: string; modelID: string; variant?: string } | undefined
+    toastManager: { removeTask: (id: string) => void } | null | undefined
+    taskId: string | undefined
+  }
+): Promise<string | null> {
+  try {
+    const allowTask = isPlanAgent(input.agentToUse)
+    await promptWithModelSuggestionRetry(client, {
+      path: { id: input.sessionID },
+      body: {
+        agent: input.agentToUse,
+        system: input.systemContent,
+        tools: {
+          task: allowTask,
+          call_omo_agent: true,
+          question: false,
+        },
+        parts: [{ type: "text", text: input.args.prompt }],
+        ...(input.categoryModel ? { model: { providerID: input.categoryModel.providerID, modelID: input.categoryModel.modelID } } : {}),
+        ...(input.categoryModel?.variant ? { variant: input.categoryModel.variant } : {}),
+      },
+    })
+  } catch (promptError) {
+    if (input.toastManager && input.taskId !== undefined) {
+      input.toastManager.removeTask(input.taskId)
+    }
+    const errorMessage = promptError instanceof Error ? promptError.message : String(promptError)
+    if (errorMessage.includes("agent.name") || errorMessage.includes("undefined")) {
+      return formatDetailedError(new Error(`Agent "${input.agentToUse}" not found. Make sure the agent is registered in your opencode.json or provided by a plugin.`), {
+        operation: "Send prompt to agent",
+        args: input.args,
+        sessionID: input.sessionID,
+        agent: input.agentToUse,
+        category: input.args.category,
+      })
+    }
+    return formatDetailedError(promptError, {
+      operation: "Send prompt",
+      args: input.args,
+      sessionID: input.sessionID,
+      agent: input.agentToUse,
+      category: input.args.category,
+    })
+  }
+
+  return null
+}