fix: Ensure message is never longer than 280 chars (#10)

Author: nzakas

src/post-generator.js

@@ -21,6 +21,14 @@ import { dirname, join } from "node:path";
 /** @typedef {import("./types.js").GptMessage} GptMessage */
 /** @typedef {import("./types.js").GptChatCompletionResponse} GptChatCompletionResponse */
 
+//-----------------------------------------------------------------------------
+// Constants
+//-----------------------------------------------------------------------------
+
+const MAX_CHARACTERS = 280;
+const MAX_RETRIES = 3;
+const URL_LENGTH = 27; // Bluesky counts URLs as 27 characters
+
 //-----------------------------------------------------------------------------
 // Helpers
 //-----------------------------------------------------------------------------
@@ -53,6 +61,17 @@ function validateGptRole(role) {
 	}
 }
 
+/**
+ * Measures the length of a social media post in characters using Bluesky rules.
+ * @param {string} text The text to measure.
+ * @returns {number} The length in characters.
+ */
+function getPostLength(text) {
+	// URLs count as exactly 27 characters on Bluesky
+	const urlRegex = /https?:\/\/[^\s]+/g;
+	return text.replace(urlRegex, "x".repeat(URL_LENGTH)).length;
+}
+
 //-----------------------------------------------------------------------------
 // Exports
 //-----------------------------------------------------------------------------
@@ -132,27 +151,50 @@ export class PostGenerator {
 	}
 
 	/**
-	 * Generates a tweet summary using OpenAI.
+	 * Generates a tweet summary using OpenAI with retry logic for length.
 	 * @param {string} projectName The name of the project.
 	 * @param {ReleaseInfo} release The release information.
 	 * @returns {Promise<string>} The generated tweet
+	 * @throws {Error} If unable to generate a valid post within retries
 	 */
 	async generateSocialPost(projectName, release) {
 		const systemPrompt = this.#prompt || (await readPrompt());
-
 		const { details, url, version } = release;
 
-		const completion = await this.#fetchCompletion({
-			model: "gpt-4o-mini",
-			messages: [
-				{ role: "system", content: systemPrompt },
-				{
-					role: "user",
-					content: `Create a post summarizing this release for ${projectName} ${version}: ${details}\n\nURL is ${url}`,
-				},
-			],
-		});
+		let attempts = 0;
+
+		while (attempts < MAX_RETRIES) {
+			const completion = await this.#fetchCompletion({
+				model: "gpt-4o-mini",
+				messages: [
+					{
+						role: "system",
+						content:
+							attempts > 0
+								? `${systemPrompt}\n\nPREVIOUS ATTEMPT WAS TOO LONG. Make it shorter!`
+								: systemPrompt,
+					},
+					{
+						role: "user",
+						content: `Create a post summarizing this release for ${projectName} ${version}: ${details}\n\nURL is ${url}`,
+					},
+				],
+			});
+
+			const post = completion.choices[0]?.message?.content;
+			if (!post) {
+				throw new Error("No content received from OpenAI");
+			}
+
+			if (getPostLength(post) <= MAX_CHARACTERS) {
+				return post;
+			}
+
+			attempts++;
+		}
 
-		return completion.choices[0]?.message?.content;
+		throw new Error(
+			`Failed to generate post within ${MAX_CHARACTERS} characters after ${MAX_RETRIES} attempts`,
+		);
 	}
 }

src/prompt.txt

@@ -1,30 +1,31 @@
-You are a professional social media manager specializing in technical content. Your task is to convert a GitHub project changelog written in Markdown into an engaging social media post.
+You are a professional social media manager specializing in technical content. Your task is to convert a GitHub project changelog written in Markdown into an engaging social media post that works across Twitter, Mastodon, and Bluesky. The tone should be professional and friendly, assuming technical knowledge of the reader.
 
-Guidelines:
-- Keep the tone professional yet friendly and approachable
-- Highlight the most important changes that users would care about
-- Prioritize mentioning features, then bug fixes, then everything else
-- Use appropriate technical terminology without being overly complex
+STRICT REQUIREMENT: The complete post MUST be 280 characters or less (URLs count as 27 characters each).
+
+Guidelines for staying within 280 characters:
+- Keep the intro very brief (project + version + max 3 more words)
+- List maximum 3 most important changes (prioritize features over bug fixes)
+- Use short emojis (✨ not ✨sparkles✨)
+- Keep the "Details:" line short
+- Remember URLs count as 27 characters
 - Do not use hash tags
-- Keep posts within 280 characters
-- Limit to one exclamation point
-- If the changelog is just the initial commit, then state that this is the first release
 
-Each post should have the following format:
+Format:
+"[Project] [version] has been released!
+
+✨ Major feature
+🔧 Notable change
+🐞 Important fix
 
-1. Short intro mentioning the project name and version numbers
-2. A blank line
-3. A bullet list of updates (do not include a bullet, use an Emoji instead)
-4. A blank line
-5. A call to read more
-6. A link to the changelog
+Details:
+[url]"
 
-Example output:
-"Mentoss v0.5.0 is released!
+Example that fits within limits:
+"Mentoss v0.5.0 has been released!
 
 🍪 Credentialed requests
 🚀 Use functions to generate responses
 🐞 Fixed errors related to forbidden headers
 
-Read more about it here:
-https://github.com/humanwhocodes/mentoss/releases/tag/mentoss-v0.5.0"
+Details:
+https://github.com/humanwhocodes/mentoss/releases/v0.5.0"

tests/post-generator.test.js

@@ -150,18 +150,157 @@ describe("PostGenerator", () => {
 				prompt: MOCK_PROMPT,
 			});
 
+			await assert.rejects(
+				() => generator.generateSocialPost("testproject", MOCK_RELEASE),
+				/No content received from OpenAI/,
+			);
+		});
+
+		it("should throw when completion response has no content", async () => {
+			server.post("/v1/chat/completions", {
+				status: 200,
+				body: { choices: [] },
+			});
+
+			const generator = new PostGenerator(OPENAI_TOKEN, {
+				prompt: MOCK_PROMPT,
+			});
+
+			await assert.rejects(
+				() => generator.generateSocialPost("testproject", MOCK_RELEASE),
+				{
+					name: "Error",
+					message: "No content received from OpenAI",
+				},
+			);
+		});
+	});
+
+	describe("generateSocialPost() character limits", () => {
+		it("should retry when post is too long", async () => {
+			const longResponse = {
+				choices: [
+					{
+						message: {
+							content: "x".repeat(281),
+						},
+					},
+				],
+			};
+
+			const goodResponse = {
+				choices: [
+					{
+						message: {
+							content: "Short enough response",
+						},
+					},
+				],
+			};
+
+			server.post("/v1/chat/completions", {
+				status: 200,
+				body: longResponse,
+			});
+
+			server.post("/v1/chat/completions", {
+				status: 200,
+				body: goodResponse,
+			});
+
+			const generator = new PostGenerator(OPENAI_TOKEN, {
+				prompt: MOCK_PROMPT,
+			});
+
+			const post = await generator.generateSocialPost(
+				"testproject",
+				MOCK_RELEASE,
+			);
+			assert.strictEqual(post, "Short enough response");
+		});
+
+		it("should count URLs as 27 characters", async () => {
+			const response = {
+				choices: [
+					{
+						message: {
+							content: `Test message with URL: https://example.com/very/long/url/that/would/normally/be/longer and another https://test.com/url`,
+						},
+					},
+				],
+			};
+
+			server.post("/v1/chat/completions", {
+				status: 200,
+				body: response,
+			});
+
+			const generator = new PostGenerator(OPENAI_TOKEN, {
+				prompt: MOCK_PROMPT,
+			});
+
+			// This should pass because URLs count as 27 chars
 			const post = await generator.generateSocialPost(
 				"testproject",
 				MOCK_RELEASE,
 			);
-			assert.strictEqual(post, undefined);
+			assert.strictEqual(post, response.choices[0].message.content);
+		});
+
+		it("should throw after MAX_RETRIES attempts", async () => {
+			const longResponse = {
+				choices: [
+					{
+						message: {
+							content: "x".repeat(281),
+						},
+					},
+				],
+			};
+
+			// Setup three different responses for three retries
+			server.post("/v1/chat/completions", {
+				status: 200,
+				body: longResponse,
+				headers: {
+					"content-type": "application/json",
+				},
+			});
+
+			server.post("/v1/chat/completions", {
+				status: 200,
+				body: longResponse,
+				headers: {
+					"content-type": "application/json",
+				},
+			});
+
+			server.post("/v1/chat/completions", {
+				status: 200,
+				body: longResponse,
+				headers: {
+					"content-type": "application/json",
+				},
+			});
+
+			const generator = new PostGenerator(OPENAI_TOKEN, {
+				prompt: MOCK_PROMPT,
+			});
+
+			await assert.rejects(
+				() => generator.generateSocialPost("testproject", MOCK_RELEASE),
+				/Failed to generate post within 280 characters after 3 attempts/,
+			);
+
+			// Verify all three attempts were made
+			server.assertAllRoutesCalled();
 		});
 	});
 });
 
 describe("readPrompt()", () => {
 	it("should read the prompt from a file", async () => {
-		const prompt = await readPrompt("./tests/fixtures/prompt.txt");
+		const prompt = await readPrompt();
 		assert.ok(prompt.length > 0);
 	});
 });