refactor: enhance version bump detection using AI analysis of PR diffs

scripts/detect-bump-type.js

@@ -0,0 +1,158 @@
+#!/usr/bin/env node
+"use strict";
+
+/**
+ * Uses the GitHub Models API (gpt-4o-mini, no extra secrets required —
+ * GITHUB_TOKEN is enough when running inside GitHub Actions) to analyse
+ * a PR diff and decide whether the release is a patch, minor, or major bump.
+ *
+ * Versioning rules (from public/versioning.js):
+ *   MAJOR — incompatible changes that break existing .map files
+ *   MINOR — backward-compatible additions or changes that may require
+ *            old .map files to be updated / migrated
+ *   PATCH — backward-compatible bug fixes and small features that do
+ *            NOT affect the .map file format at all
+ *
+ * Usage (called by bump-version.yml):
+ *   node scripts/detect-bump-type.js --diff-file <path>
+ *
+ * Output:  prints exactly one of:  patch  |  minor  |  major
+ * Exit 0 always (falls back to "patch" on any error).
+ */
+
+const fs = require("fs");
+const https = require("https");
+const path = require("path");
+
+// ---------------------------------------------------------------------------
+// Config
+// ---------------------------------------------------------------------------
+
+const MODEL = "gpt-4o-mini";
+const ENDPOINT_HOST = "models.inference.ai.azure.com";
+const ENDPOINT_PATH = "/chat/completions";
+// Keep the diff under ~20 000 chars to stay within the model's context window.
+const MAX_DIFF_CHARS = 20_000;
+
+// ---------------------------------------------------------------------------
+// System prompt — contains the project-specific versioning rules
+// ---------------------------------------------------------------------------
+
+const SYSTEM_PROMPT = `\
+You are a semantic-version expert for Azgaar's Fantasy Map Generator.
+
+The project uses semantic versioning where the PUBLIC API is the .map save-file format.
+
+Rules:
+• MAJOR — any change that makes existing .map files incompatible or unreadable
+  (e.g. removing or renaming top-level save-data fields, changing data types of
+  stored values, restructuring the save format)
+• MINOR — backward-compatible additions or changes that may require old .map
+  files to be silently migrated on load (e.g. adding new optional fields to the
+  save format, changing default values that affect saved maps, adding new
+  generators that store new data)
+• PATCH — everything else: UI improvements, bug fixes, refactors, new features
+  that do not touch the .map file format at all, dependency updates, docs
+
+Respond with EXACTLY one lowercase word: patch  |  minor  |  major
+No explanation, no punctuation, no extra words.`;
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function httpsPost(host, pathStr, headers, body) {
+  return new Promise((resolve, reject) => {
+    const data = JSON.stringify(body);
+    const req = https.request(
+      {host, path: pathStr, method: "POST", headers: {...headers, "Content-Length": Buffer.byteLength(data)}},
+      res => {
+        let raw = "";
+        res.on("data", c => (raw += c));
+        res.on("end", () => {
+          if (res.statusCode >= 200 && res.statusCode < 300) resolve(raw);
+          else reject(new Error(`HTTP ${res.statusCode}: ${raw.slice(0, 300)}`));
+        });
+      }
+    );
+    req.on("error", reject);
+    req.write(data);
+    req.end();
+  });
+}
+
+// ---------------------------------------------------------------------------
+// Main
+// ---------------------------------------------------------------------------
+
+async function main() {
+  const args = process.argv.slice(2);
+  const diffFileIdx = args.indexOf("--diff-file");
+  const diffFile = diffFileIdx !== -1 ? args[diffFileIdx + 1] : null;
+
+  if (!diffFile || !fs.existsSync(diffFile)) {
+    console.error("[detect-bump-type] --diff-file <path> is required and must exist.");
+    process.stdout.write("patch\n");
+    process.exit(0);
+  }
+
+  const token = process.env.GITHUB_TOKEN;
+  if (!token) {
+    console.error("[detect-bump-type] GITHUB_TOKEN not set — falling back to patch.");
+    process.stdout.write("patch\n");
+    process.exit(0);
+  }
+
+  let diff = fs.readFileSync(diffFile, "utf8").trim();
+  if (!diff) {
+    console.error("[detect-bump-type] Diff is empty — falling back to patch.");
+    process.stdout.write("patch\n");
+    process.exit(0);
+  }
+
+  // Trim diff to avoid exceeding context window
+  if (diff.length > MAX_DIFF_CHARS) {
+    diff = diff.slice(0, MAX_DIFF_CHARS) + "\n\n[diff truncated]";
+    console.error(`[detect-bump-type] Diff truncated to ${MAX_DIFF_CHARS} chars.`);
+  }
+
+  const userMessage = `Analyse this git diff and respond with exactly one word (patch, minor, or major):\n\n${diff}`;
+
+  try {
+    const raw = await httpsPost(
+      ENDPOINT_HOST,
+      ENDPOINT_PATH,
+      {
+        "Content-Type": "application/json",
+        Authorization: `Bearer ${token}`
+      },
+      {
+        model: MODEL,
+        messages: [
+          {role: "system", content: SYSTEM_PROMPT},
+          {role: "user", content: userMessage}
+        ],
+        temperature: 0,
+        max_tokens: 5
+      }
+    );
+
+    const json = JSON.parse(raw);
+    const answer = json.choices?.[0]?.message?.content?.trim().toLowerCase() ?? "patch";
+
+    if (answer === "major" || answer === "minor" || answer === "patch") {
+      console.error(`[detect-bump-type] AI decision: ${answer}`);
+      process.stdout.write(`${answer}\n`);
+    } else {
+      console.error(`[detect-bump-type] Unexpected AI response "${answer}" — defaulting to patch.`);
+      process.stdout.write("patch\n");
+    }
+  } catch (err) {
+    console.error(`[detect-bump-type] API error: ${err.message} — falling back to patch.`);
+    process.stdout.write("patch\n");
+  }
+
+  process.exit(0);
+}
+
+main();