feat: add conversation storage (#140)

apps/freya-backend/src/agent/session-manager.ts

@@ -0,0 +1,188 @@
+import { SessionManager } from "@earendil-works/pi-coding-agent"
+import { tmpdir } from "node:os"
+
+import type { ConversationStorageEntry } from "./conversation-recording-query-agent.ts"
+
+import {
+	AssistantMessagePayload,
+	ContextSummaryPayload,
+	ConversationEntryKind,
+	UserMessagePayload,
+} from "../conversations/types.ts"
+
+type PiMessage = Parameters<SessionManager["appendMessage"]>[0]
+type PiAssistantMessage = Extract<PiMessage, { role: "assistant" }>
+
+export interface CreateSessionManagerInput {
+	cwd?: string
+	entries: ConversationStorageEntry[]
+	modelProvider: string
+	modelId: string
+	onMessageEntryAppended?: (piEntryId: string, entry: ConversationStorageEntry) => void
+}
+
+export function createSessionManager(input: CreateSessionManagerInput): SessionManager {
+	const sessionManager = SessionManager.inMemory(input.cwd ?? tmpdir())
+	const context = buildContextFromEntries(input.entries)
+
+	if (context.summary) {
+		sessionManager.appendCompaction(
+			context.summary.text,
+			"freya-db-context-start",
+			0,
+			{
+				conversationEntryId: context.summary.entry.id,
+				covers: context.summary.covers,
+			},
+			true,
+		)
+	}
+
+	for (const entry of context.entries) {
+		const message = messageForEntry(entry, input.modelProvider, input.modelId)
+		if (message) {
+			const piEntryId = sessionManager.appendMessage(message)
+			input.onMessageEntryAppended?.(piEntryId, entry)
+		}
+	}
+
+	return sessionManager
+}
+
+function buildContextFromEntries(entries: ConversationStorageEntry[]): {
+	summary?: { entry: ConversationStorageEntry; text: string; covers: unknown }
+	entries: ConversationStorageEntry[]
+} {
+	const orderedEntries = [...entries].sort((left, right) => left.sequence - right.sequence)
+	const summaryEntry = latestContextSummaryEntry(orderedEntries)
+	if (!summaryEntry || summaryEntry.kind !== ConversationEntryKind.ContextSummary) {
+		return { entries: orderedEntries }
+	}
+
+	const payload = ContextSummaryPayload.assert(summaryEntry.payload)
+	const text = contextSummaryText(payload.summary)
+	const rawStartSequence = payload.covers.endSequence + 1
+
+	return {
+		summary: {
+			entry: summaryEntry,
+			text,
+			covers: payload.covers,
+		},
+		entries: orderedEntries.filter((entry) => entry.sequence >= rawStartSequence),
+	}
+}
+
+function latestContextSummaryEntry(
+	entries: ConversationStorageEntry[],
+): ConversationStorageEntry | undefined {
+	let latest: ConversationStorageEntry | undefined
+
+	for (const entry of entries) {
+		if (entry.kind !== ConversationEntryKind.ContextSummary) continue
+		if (!latest || entry.sequence > latest.sequence) {
+			latest = entry
+		}
+	}
+
+	return latest
+}
+
+function messageForEntry(
+	entry: ConversationStorageEntry,
+	modelProvider: string,
+	modelId: string,
+): PiMessage | null {
+	switch (entry.kind) {
+		case ConversationEntryKind.UserMessage: {
+			const payload = UserMessagePayload.assert(entry.payload)
+			return {
+				role: "user",
+				content: messagePartsText(payload.parts),
+				timestamp: entry.createdAt.getTime(),
+			}
+		}
+		case ConversationEntryKind.AssistantMessage: {
+			const payload = AssistantMessagePayload.assert(entry.payload)
+			return {
+				role: "assistant",
+				content: [{ type: "text", text: messagePartsText(payload.parts) }],
+				api: "anthropic-messages",
+				provider: entry.metadata.modelRun?.provider ?? modelProvider,
+				model: entry.metadata.modelRun?.model ?? modelId,
+				usage: zeroUsage(),
+				stopReason: "stop",
+				timestamp: entry.createdAt.getTime(),
+			} satisfies PiAssistantMessage
+		}
+		case ConversationEntryKind.Attachment:
+		case ConversationEntryKind.ContextSummary:
+		case ConversationEntryKind.SystemNote:
+		case ConversationEntryKind.ToolCall:
+		case ConversationEntryKind.ToolResult:
+			return null
+	}
+}
+
+function messagePartsText(
+	parts: Array<{ type: "text"; text: string } | { type: "json"; value: unknown }>,
+): string {
+	return parts.map(messagePartText).join("\n")
+}
+
+function messagePartText(
+	part: { type: "text"; text: string } | { type: "json"; value: unknown },
+): string {
+	switch (part.type) {
+		case "text":
+			return part.text
+		case "json":
+			return stringifyJson(part.value)
+	}
+}
+
+function contextSummaryText(summary: {
+	userIntent?: string
+	durableFacts: string[]
+	preferences: string[]
+	decisions: string[]
+	openTasks: string[]
+	importantDetails: string[]
+}): string {
+	const sections: string[] = []
+	pushSection(sections, "User intent", summary.userIntent ? [summary.userIntent] : [])
+	pushSection(sections, "Durable facts", summary.durableFacts)
+	pushSection(sections, "Preferences", summary.preferences)
+	pushSection(sections, "Decisions", summary.decisions)
+	pushSection(sections, "Open tasks", summary.openTasks)
+	pushSection(sections, "Important details", summary.importantDetails)
+	return sections.join("\n\n")
+}
+
+function pushSection(sections: string[], title: string, values: string[]): void {
+	const trimmedValues = values.map((value) => value.trim()).filter(Boolean)
+	if (trimmedValues.length === 0) return
+
+	sections.push(`${title}:\n${trimmedValues.map((value) => `- ${value}`).join("\n")}`)
+}
+
+function stringifyJson(value: unknown): string {
+	return JSON.stringify(value, null, 2) ?? String(value)
+}
+
+function zeroUsage(): PiAssistantMessage["usage"] {
+	return {
+		input: 0,
+		output: 0,
+		cacheRead: 0,
+		cacheWrite: 0,
+		totalTokens: 0,
+		cost: {
+			input: 0,
+			output: 0,
+			cacheRead: 0,
+			cacheWrite: 0,
+			total: 0,
+		},
+	}
+}