refactor(ralph-loop): split hook into state controller and event handler modules

Extract Ralph loop lifecycle management:
- loop-state-controller.ts: start/stop/recovery state machine
- ralph-loop-event-handler.ts: event handling logic
- continuation-prompt-builder.ts, continuation-prompt-injector.ts
- completion-promise-detector.ts, loop-session-recovery.ts
- message-storage-directory.ts

src/hooks/ralph-loop/continuation-prompt-injector.ts

@@ -0,0 +1,61 @@
+import type { PluginInput } from "@opencode-ai/plugin"
+import { log } from "../../shared/logger"
+import { findNearestMessageWithFields } from "../../features/hook-message-injector"
+import { getMessageDir } from "./message-storage-directory"
+
+type MessageInfo = {
+	agent?: string
+	model?: { providerID: string; modelID: string }
+	modelID?: string
+	providerID?: string
+}
+
+export async function injectContinuationPrompt(
+	ctx: PluginInput,
+	options: { sessionID: string; prompt: string; directory: string },
+): Promise<void> {
+	let agent: string | undefined
+	let model: { providerID: string; modelID: string } | undefined
+
+	try {
+		const messagesResp = await ctx.client.session.messages({
+			path: { id: options.sessionID },
+		})
+		const messages = (messagesResp.data ?? []) as Array<{ info?: MessageInfo }>
+		for (let i = messages.length - 1; i >= 0; i--) {
+			const info = messages[i]?.info
+			if (info?.agent || info?.model || (info?.modelID && info?.providerID)) {
+				agent = info.agent
+				model =
+					info.model ??
+					(info.providerID && info.modelID
+						? { providerID: info.providerID, modelID: info.modelID }
+						: undefined)
+				break
+			}
+		}
+	} catch {
+		const messageDir = getMessageDir(options.sessionID)
+		const currentMessage = messageDir ? findNearestMessageWithFields(messageDir) : null
+		agent = currentMessage?.agent
+		model =
+			currentMessage?.model?.providerID && currentMessage?.model?.modelID
+				? {
+					providerID: currentMessage.model.providerID,
+					modelID: currentMessage.model.modelID,
+				}
+				: undefined
+	}
+
+	await ctx.client.session.promptAsync({
+		path: { id: options.sessionID },
+		body: {
+			...(agent !== undefined ? { agent } : {}),
+			...(model !== undefined ? { model } : {}),
+			parts: [{ type: "text", text: options.prompt }],
+		},
+		query: { directory: options.directory },
+	})
+
+	log("[ralph-loop] continuation injected", { sessionID: options.sessionID })
+}