From 98aefb0b121543d97a787caf2d484e726a0d068a Mon Sep 17 00:00:00 2001
From: Naomi Carrigan <commits@nhcarrigan.com>
Date: Tue, 23 Dec 2025 14:37:26 -0800
Subject: [PATCH] feat: include cost in announcements

---
 server/src/modules/generateAnnouncements.ts | 17 +++++++----
 server/src/routes/announcement.ts           |  5 ++--
 server/src/utils/getAiCost.ts               | 31 +++++++++++++++++++++
 3 files changed, 45 insertions(+), 8 deletions(-)
 create mode 100644 server/src/utils/getAiCost.ts

diff --git a/server/src/modules/generateAnnouncements.ts b/server/src/modules/generateAnnouncements.ts
index d15f852..32bb17e 100644
--- a/server/src/modules/generateAnnouncements.ts
+++ b/server/src/modules/generateAnnouncements.ts
@@ -10,8 +10,8 @@ import {
   announcementJsonSchema,
   announcementSystemMessage,
 } from "../config/announcements.js";
-import type { AnnouncementResponse }
-  from "../interfaces/announcementResponse.js";
+import { getAiCost } from "../utils/getAiCost.js";
+import type { AnnouncementResponse } from "../interfaces/announcementResponse.js";
 
 /**
  * Generates announcements for all platforms using AI.
@@ -20,7 +20,7 @@ import type { AnnouncementResponse }
  */
 export const generateAnnouncements = async(
   content: string,
-): Promise<AnnouncementResponse | null> => {
+): Promise<{ cost: string; response: AnnouncementResponse } | null> => {
   if (process.env.ANTHROPIC_KEY === undefined) {
     return null;
   }
@@ -46,12 +46,17 @@ export const generateAnnouncements = async(
     },
     system: announcementSystemMessage,
   });
-  const text = response.content.find((m) => {
+  const { usage, content: responseContent } = response;
+  const text = responseContent.find((m) => {
     return m.type === "text";
   });
   if (text?.text === undefined) {
     return null;
   }
-  // eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- Being lazy.
-  return JSON.parse(text.text) as AnnouncementResponse;
+
+  return {
+    cost:     getAiCost(usage),
+    // eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- Being lazy.
+    response: JSON.parse(text.text) as AnnouncementResponse,
+  };
 };
diff --git a/server/src/routes/announcement.ts b/server/src/routes/announcement.ts
index 2dbb403..5a4fd0f 100644
--- a/server/src/routes/announcement.ts
+++ b/server/src/routes/announcement.ts
@@ -86,7 +86,7 @@ export const announcementRoutes: FastifyPluginAsync = async(server) => {
         });
       }
 
-      const { bluesky, discord, reddit, twitter } = announcement;
+      const { bluesky, discord, reddit, twitter } = announcement.response;
       const { title: discordTitle, content: discordContent } = discord;
       const { title: redditTitle, content: redditContent } = reddit;
 
@@ -111,8 +111,9 @@ export const announcementRoutes: FastifyPluginAsync = async(server) => {
       const blueskyPost = await announceOnBluesky(bluesky);
       const twitterPost = await announceOnTwitter(twitter);
       return await reply.status(201).send({
+        cost:    announcement.cost,
         message: `Announcement processed. Discord: ${discordPost}, Reddit: ${redditPost}, Bluesky: ${blueskyPost}, Twitter: ${twitterPost}`,
-        rawPost: announcement,
+        rawPost: announcement.response,
       });
     },
   );
diff --git a/server/src/utils/getAiCost.ts b/server/src/utils/getAiCost.ts
new file mode 100644
index 0000000..265a38b
--- /dev/null
+++ b/server/src/utils/getAiCost.ts
@@ -0,0 +1,31 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import type { BetaUsage } from "@anthropic-ai/sdk/resources/beta.js";
+
+/**
+ * Calculates the cost of an AI response.
+ * @param usage - The usage payload from Anthropic.
+ * @returns A description of the cost of the AI response.
+ */
+export const getAiCost = (usage: BetaUsage): string => {
+  const { input_tokens: inputTokens, output_tokens: outputTokens } = usage;
+  const costPerInputToken = 5 / 1_000_000;
+  const costPerOutputToken = 25 / 1_000_000;
+  const inputCost = inputTokens * costPerInputToken;
+  const outputCost = outputTokens * costPerOutputToken;
+  const totalCost = inputCost + outputCost;
+  return `Input cost: ${inputCost.toLocaleString("en-GB", {
+    currency: "USD",
+    style:    "currency",
+  })} Output cost: ${outputCost.toLocaleString("en-GB", {
+    currency: "USD",
+    style:    "currency",
+  })} Total cost: ${totalCost.toLocaleString("en-GB", {
+    currency: "USD",
+    style:    "currency",
+  })}`;
+};