feat: project durable agent conversations

packages/backend/convex/conversationProjections.ts

@@ -0,0 +1,145 @@
+import type { Id } from "./_generated/dataModel";
+import type { MutationCtx } from "./_generated/server";
+
+interface ProjectionContext {
+  readonly assistantMessageId: Id<"conversationMessages"> | null;
+  readonly turnId: Id<"conversationTurns"> | null;
+}
+
+const parseStringField = (record: unknown, key: string): string | undefined => {
+  if (typeof record !== "object" || record === null) {
+    return undefined;
+  }
+  const value = (record as Record<string, unknown>)[key];
+  return typeof value === "string" ? value : undefined;
+};
+
+const resolveContext = async (
+  ctx: MutationCtx,
+  submissionId: string | undefined
+): Promise<ProjectionContext> => {
+  if (submissionId === undefined) {
+    return { assistantMessageId: null, turnId: null };
+  }
+  const turn = await ctx.db
+    .query("conversationTurns")
+    .withIndex("by_submissionId", (q) => q.eq("submissionId", submissionId))
+    .unique();
+  if (turn === null) {
+    return { assistantMessageId: null, turnId: null };
+  }
+  const assistant = await ctx.db
+    .query("conversationMessages")
+    .withIndex("by_turnId_and_role", (q) =>
+      q.eq("turnId", turn._id).eq("role", "assistant")
+    )
+    .unique();
+  return {
+    assistantMessageId: assistant?._id ?? null,
+    turnId: turn._id,
+  };
+};
+
+const terminalError = (record: unknown): string => {
+  if (typeof record !== "object" || record === null) {
+    return "Flue submission failed";
+  }
+  const value = (record as Record<string, unknown>).error;
+  if (typeof value === "string") {
+    return value.slice(0, 2000);
+  }
+  if (typeof value === "object" && value !== null) {
+    const { message } = value as Record<string, unknown>;
+    if (typeof message === "string") {
+      return message.slice(0, 2000);
+    }
+  }
+  return "Flue submission failed";
+};
+
+/**
+ * Project the small product view from Flue's canonical conversation stream.
+ * The raw stream remains authoritative; this function only updates the existing
+ * assistant message and turn row that the web already reads.
+ */
+export const projectConversationRecords = async (
+  ctx: MutationCtx,
+  recordsJson: string,
+  submissionId: string | undefined
+): Promise<void> => {
+  let records: unknown[];
+  try {
+    const parsed = JSON.parse(recordsJson) as unknown;
+    if (!Array.isArray(parsed)) {
+      return;
+    }
+    records = parsed;
+  } catch {
+    return;
+  }
+
+  const projection = await resolveContext(ctx, submissionId);
+  if (projection.turnId === null) {
+    return;
+  }
+
+  for (const record of records) {
+    const type = parseStringField(record, "type");
+    if (type === "assistant_text_delta" && projection.assistantMessageId) {
+      const delta = parseStringField(record, "delta");
+      if (delta !== undefined) {
+        const assistant = await ctx.db.get(projection.assistantMessageId);
+        if (assistant !== null) {
+          await ctx.db.patch(assistant._id, {
+            content: `${assistant.content}${delta}`,
+          });
+        }
+      }
+      continue;
+    }
+
+    if (type !== "submission_settled") {
+      continue;
+    }
+
+    const turn = await ctx.db.get(projection.turnId);
+    if (
+      turn === null ||
+      turn.status === "completed" ||
+      turn.status === "failed" ||
+      turn.status === "aborted"
+    ) {
+      continue;
+    }
+
+    const outcome = parseStringField(record, "outcome");
+    if (outcome === "completed" && projection.assistantMessageId) {
+      const result =
+        typeof record === "object" && record !== null
+          ? (record as Record<string, unknown>).result
+          : undefined;
+      const text =
+        typeof result === "object" && result !== null
+          ? (result as Record<string, unknown>).text
+          : undefined;
+      if (typeof text === "string") {
+        await ctx.db.patch(projection.assistantMessageId, { content: text });
+      }
+    }
+
+    let status: "aborted" | "completed" | "failed" = "failed";
+    if (outcome === "completed") {
+      status = "completed";
+    } else if (outcome === "aborted") {
+      status = "aborted";
+    }
+
+    await ctx.db.patch(turn._id, {
+      completedAt: Date.now(),
+      error: outcome === "failed" ? terminalError(record) : undefined,
+      leaseExpiresAt: undefined,
+      leaseOwner: undefined,
+      status,
+    });
+  }
+};