From 3b77dde666f291a153d576309a371f70d2adb79e Mon Sep 17 00:00:00 2001
From: jochen <jschoubben@gmail.com>
Date: Mon, 28 Sep 2026 09:17:38 +0200
Subject: [PATCH] A merge says which files it changed

Every module built from a repository was rebuilt for a change to any of them: one merge in this
repository meant twenty-six builds, which is what exhausted a public registry's pull limit. The
forge lists the files a merge changed and the event carries them, from the watcher and from the
merge tool alike; a merge that changed more files than were asked for says so, and the mesh then
treats the whole repository as changed rather than guessing.
---
 modules/gitea/client.ts      | 11 +++++++++++
 modules/gitea/index.ts       |  6 ++++++
 modules/gitea/tools/index.ts |  5 +++++
 3 files changed, 22 insertions(+)

diff --git a/modules/gitea/client.ts b/modules/gitea/client.ts
index 5a6e918..c8e5c28 100644
--- a/modules/gitea/client.ts
+++ b/modules/gitea/client.ts
@@ -229,6 +229,17 @@ export class GiteaClient {
     return GiteaClient.mapPull(await this.request<any>(`/repos/${owner}/${repo}/pulls/${index}`));
   }
 
+  /** The files a merged pull request changed, as paths from the repository's root.
+   *
+   *  `limit` is what is asked for, and a merge that changed more says so rather than being read
+   *  page by page: what the mesh does with a partial list is treat the whole repository as changed,
+   *  so more pages would buy nothing. */
+  async listPullFiles(owner: string, repo: string, index: number, limit = 100): Promise<{ paths: string[]; truncated: boolean }> {
+    const files = await this.request<any[]>(`/repos/${owner}/${repo}/pulls/${index}/files?limit=${limit}`);
+    const paths = (files ?? []).map((f) => String(f?.filename ?? "")).filter((p) => p !== "");
+    return { paths, truncated: paths.length >= limit };
+  }
+
   async createPullRequest(
     owner: string,
     repo: string,
diff --git a/modules/gitea/index.ts b/modules/gitea/index.ts
index 0e99f53..947086f 100644
--- a/modules/gitea/index.ts
+++ b/modules/gitea/index.ts
@@ -95,6 +95,10 @@ async function pollMerged(client: GiteaClient): Promise<void> {
       // at once.
       const fresh = !!pull.merged_at && !!since && pull.merged_at > since;
       if (primedMerges && fresh) {
+        // What it changed, asked for only now: a module is rebuilt because a file inside its own
+        // directory moved, and without this every module built from a repository is rebuilt for a
+        // change to any of them (novox/hq 04-ISSUES/131).
+        const changed = await client.listPullFiles(repo.owner, repo.name, pull.number);
         await emit("pull.merged", {
           owner: repo.owner,
           repo: repo.name,
@@ -106,6 +110,8 @@ async function pollMerged(client: GiteaClient): Promise<void> {
           merged_at: pull.merged_at,
           clone_url: repo.clone_url,
           html_url: pull.html_url,
+          paths: changed.paths,
+          paths_truncated: changed.truncated,
         });
         // Said, because a trigger that fires silently is indistinguishable from one that did not
         // fire (novox/hq 04-ISSUES/131) — this line is how an operator knows the mesh was told.
diff --git a/modules/gitea/tools/index.ts b/modules/gitea/tools/index.ts
index 103d4a9..fda1190 100644
--- a/modules/gitea/tools/index.ts
+++ b/modules/gitea/tools/index.ts
@@ -233,6 +233,9 @@ export function getGiteaTools(gitea: GiteaClient): ToolDefinition[] {
         await gitea.mergePullRequest(owner, repo, number, method, deleteBranch);
         // Read it again: the merge commit only exists now, and it is what a build is made from.
         const merged = await gitea.getPullRequest(owner, repo, number);
+        // And what it changed, so the mesh rebuilds the modules whose own files moved rather than
+        // every module built from the repository (novox/hq 04-ISSUES/131).
+        const changed = await gitea.listPullFiles(owner, repo, number);
         await emit("pull.merged", {
           owner,
           repo,
@@ -244,6 +247,8 @@ export function getGiteaTools(gitea: GiteaClient): ToolDefinition[] {
           merged_at: merged.merged_at,
           method,
           html_url: pull.html_url,
+          paths: changed.paths,
+          paths_truncated: changed.truncated,
         });
         return { merged: true, number, method, deleted_branch: deleteBranch };
       },
-- 
2.54.0