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/subagent-resolver.ts

@@ -0,0 +1,87 @@
+import type { DelegateTaskArgs } from "./types"
+import type { ExecutorContext } from "./executor-types"
+import { isPlanAgent } from "./constants"
+import { SISYPHUS_JUNIOR_AGENT } from "./sisyphus-junior-agent"
+
+export async function resolveSubagentExecution(
+  args: DelegateTaskArgs,
+  executorCtx: ExecutorContext,
+  parentAgent: string | undefined,
+  categoryExamples: string
+): Promise<{ agentToUse: string; categoryModel: { providerID: string; modelID: string } | undefined; error?: string }> {
+  const { client } = executorCtx
+
+  if (!args.subagent_type?.trim()) {
+    return { agentToUse: "", categoryModel: undefined, error: `Agent name cannot be empty.` }
+  }
+
+  const agentName = args.subagent_type.trim()
+
+  if (agentName.toLowerCase() === SISYPHUS_JUNIOR_AGENT.toLowerCase()) {
+    return {
+      agentToUse: "",
+      categoryModel: undefined,
+      error: `Cannot use subagent_type="${SISYPHUS_JUNIOR_AGENT}" directly. Use category parameter instead (e.g., ${categoryExamples}).
+
+Sisyphus-Junior is spawned automatically when you specify a category. Pick the appropriate category for your task domain.`,
+    }
+  }
+
+  if (isPlanAgent(agentName) && isPlanAgent(parentAgent)) {
+    return {
+      agentToUse: "",
+      categoryModel: undefined,
+    error: `You are prometheus. You cannot delegate to prometheus via task.
+
+Create the work plan directly - that's your job as the planning agent.`,
+    }
+  }
+
+  let agentToUse = agentName
+  let categoryModel: { providerID: string; modelID: string } | undefined
+
+  try {
+    const agentsResult = await client.app.agents()
+    type AgentInfo = { name: string; mode?: "subagent" | "primary" | "all"; model?: { providerID: string; modelID: string } }
+    const agents = (agentsResult as { data?: AgentInfo[] }).data ?? agentsResult as unknown as AgentInfo[]
+
+    const callableAgents = agents.filter((a) => a.mode !== "primary")
+
+    const matchedAgent = callableAgents.find(
+      (agent) => agent.name.toLowerCase() === agentToUse.toLowerCase()
+    )
+    if (!matchedAgent) {
+      const isPrimaryAgent = agents
+        .filter((a) => a.mode === "primary")
+        .find((agent) => agent.name.toLowerCase() === agentToUse.toLowerCase())
+
+      if (isPrimaryAgent) {
+        return {
+          agentToUse: "",
+          categoryModel: undefined,
+    error: `Cannot call primary agent "${isPrimaryAgent.name}" via task. Primary agents are top-level orchestrators.`,
+        }
+      }
+
+      const availableAgents = callableAgents
+        .map((a) => a.name)
+        .sort()
+        .join(", ")
+      return {
+        agentToUse: "",
+        categoryModel: undefined,
+        error: `Unknown agent: "${agentToUse}". Available agents: ${availableAgents}`,
+      }
+    }
+
+    agentToUse = matchedAgent.name
+
+    if (matchedAgent.model) {
+      categoryModel = matchedAgent.model
+    }
+  } catch {
+    // Proceed anyway - session.prompt will fail with clearer error if agent doesn't exist
+  }
+
+  return { agentToUse, categoryModel }
+}