The forge announces every merge, whoever made it

The merge tool emitted at the instant it acted; a merge made in the forge's own
pages or over its API emitted nothing, and the mesh went on believing every module
current with its source (novox/hq 04-ISSUES/131). Merged pull requests are now
watched the way repositories are: what the forge holds, asked for on a tick,
announced once, with the merge commit and the clone URL a build needs. What has
been announced is kept beside the module's state, so a restart does not announce
the whole history again, and a first tick with no record announces nothing.

modules/gitea/index.ts

@@ -49,6 +49,62 @@ async function pollRepos(client: GiteaClient): Promise<void> {
   primed = true;
 }
 
+// **A merge is announced whoever made it.** The merge tool below emits at the instant it acts; a
+// merge made in the forge's own pages or over its API would emit nothing, and the mesh would go on
+// believing every module current with its source (novox/hq 04-ISSUES/131). So merged pull requests
+// are watched the way repositories are: what the forge holds, asked for on a tick, announced once.
+// What has been announced is kept beside the module's state, so a restart does not announce the
+// whole history again — and the first tick on a machine with no record announces nothing, because
+// everything it sees then predates the watching.
+import { existsSync, mkdirSync, readFileSync, renameSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+const mergedRecord = process.env.MESH_GITEA_STATE_DIR ? join(process.env.MESH_GITEA_STATE_DIR, "merged-announced.json") : null;
+const announced = new Set<string>();
+let primedMerges = false;
+if (mergedRecord && existsSync(mergedRecord)) {
+  try {
+    for (const sha of JSON.parse(readFileSync(mergedRecord, "utf8")) as string[]) announced.add(sha);
+    primedMerges = true;
+  } catch {
+    // An unreadable record is treated as no record: prime again rather than re-announce history.
+  }
+}
+function keepAnnounced(): void {
+  if (!mergedRecord) return;
+  mkdirSync(join(mergedRecord, ".."), { recursive: true });
+  const tmp = mergedRecord + ".tmp";
+  writeFileSync(tmp, JSON.stringify([...announced].slice(-2000)));
+  renameSync(tmp, mergedRecord);
+}
+async function pollMerged(client: GiteaClient): Promise<void> {
+  const repos = await client.listRepos(1, 50);
+  let changed = false;
+  for (const repo of repos) {
+    const pulls = await client.listPullRequests(repo.owner, repo.name, { state: "closed", sort: "recentupdate", limit: "20" });
+    for (const pull of pulls) {
+      if (!pull.merged || !pull.merge_commit_sha || announced.has(pull.merge_commit_sha)) continue;
+      if (primedMerges) {
+        await emit("pull.merged", {
+          owner: repo.owner,
+          repo: repo.name,
+          number: pull.number,
+          title: pull.title,
+          head: pull.head,
+          base: pull.base,
+          merge_commit_sha: pull.merge_commit_sha,
+          merged_at: pull.merged_at,
+          clone_url: repo.clone_url,
+          html_url: pull.html_url,
+        });
+      }
+      announced.add(pull.merge_commit_sha);
+      changed = true;
+    }
+  }
+  if (!primedMerges || changed) keepAnnounced();
+  primedMerges = true;
+}
+
 if (gitea) {
   const client = gitea;
   // A poll that fails says so once, not once a minute: the same reason repeating (the forge not up
@@ -70,5 +126,6 @@ if (gitea) {
     run();
   };
   tick(() => pollRepos(client), 60_000);
-  console.log("[gitea] watching for new repositories");
+  tick(() => pollMerged(client), 30_000);
+  console.log("[gitea] watching for new repositories and merged pull requests");
 }