refactor(look-at): split tools.ts into argument parsing and extraction modules

Extract multimodal look-at tool internals:
- look-at-arguments.ts: argument validation and parsing
- assistant-message-extractor.ts: response extraction
- mime-type-inference.ts: file type detection
- multimodal-agent-metadata.ts: agent metadata constants

src/tools/look-at/multimodal-agent-metadata.ts

@@ -0,0 +1,56 @@
+import type { PluginInput } from "@opencode-ai/plugin"
+import { MULTIMODAL_LOOKER_AGENT } from "./constants"
+import { log } from "../../shared"
+
+type AgentModel = { providerID: string; modelID: string }
+
+type ResolvedAgentMetadata = {
+  agentModel?: AgentModel
+  agentVariant?: string
+}
+
+type AgentInfo = {
+  name?: string
+  model?: AgentModel
+  variant?: string
+}
+
+function isObject(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null
+}
+
+function toAgentInfo(value: unknown): AgentInfo | null {
+  if (!isObject(value)) return null
+  const name = typeof value["name"] === "string" ? value["name"] : undefined
+  const variant = typeof value["variant"] === "string" ? value["variant"] : undefined
+  const modelValue = value["model"]
+  const model =
+    isObject(modelValue) &&
+    typeof modelValue["providerID"] === "string" &&
+    typeof modelValue["modelID"] === "string"
+      ? { providerID: modelValue["providerID"], modelID: modelValue["modelID"] }
+      : undefined
+  return { name, model, variant }
+}
+
+export async function resolveMultimodalLookerAgentMetadata(
+  ctx: PluginInput
+): Promise<ResolvedAgentMetadata> {
+  try {
+    const agentsResult = await ctx.client.app?.agents?.()
+    const agentsRaw = isObject(agentsResult) ? agentsResult["data"] : undefined
+    const agents = Array.isArray(agentsRaw) ? agentsRaw.map(toAgentInfo).filter(Boolean) : []
+
+    const matched = agents.find(
+      (agent) => agent?.name?.toLowerCase() === MULTIMODAL_LOOKER_AGENT.toLowerCase()
+    )
+
+    return {
+      agentModel: matched?.model,
+      agentVariant: matched?.variant,
+    }
+  } catch (error) {
+    log("[look_at] Failed to resolve multimodal-looker model info", error)
+    return {}
+  }
+}