Put the merge check back to pending before a recheck asks it (hq issue 305)

A recheck asks of the head the forge already judged, and the forge keeps
the newest status of each context on it. Nobody reset mesh/merge-gate or
mesh/repo-check, so the old green stood and branch protection would merge
on it while the fresh check ran; rechecked heads did turn red.

mesh-delivery's recheck now asks the forge's holder to set the gate, and
the repository check when the head holds one, to pending ("checking
again: <why>") before it asks the controller; a forge that cannot be told
refuses the recheck whole. The gitea holder takes pending, and only
pending, on the merge check's statuses by hand: no verdict, so issue 293
still holds.

modules/gitea/delivery.ts

@@ -92,10 +92,15 @@ const mergeCheckContexts = new Set(["mesh/merge-gate", "mesh/repo-check"]);
  *  bounded description. */
 export function deliveryStatus(context: string, state: string, description: string, target?: string) {
   if (!/^mesh\/[a-z-]+$/.test(context)) throw new Error(`${context} is not a status of the mesh's own`);
-  // The merge check's statuses are its verdict's, set when the controller says it, and a branch may require
-  // them: never set by hand, so nothing passes — or blocks — a merge past the check (novox/hq issue 293).
-  if (mergeCheckContexts.has(context)) throw new Error(`${context} is the merge check's status, set by its verdict only`);
   if (!states.has(state)) throw new Error(`${state} is not a status the forge keeps`);
+  // The merge check's statuses are its verdict's, set when the controller says it, and a branch may require
+  // them: never set to a verdict by hand, so nothing passes — or fails — a merge past the check (novox/hq
+  // issue 293). Pending is no verdict: it is what this holder says on every new head until the verdict comes,
+  // and what a recheck of the same head says, so the old verdict does not let it merge while the fresh check
+  // runs.
+  if (mergeCheckContexts.has(context) && state !== "pending") {
+    throw new Error(`${context} is the merge check's status, set by its verdict only (pending, for a check asked again, is the one state it takes by hand)`);
+  }
   let d = String(description ?? "").replace(/\s+/g, " ").trim();
   if (d.length > 140) d = d.slice(0, 139) + "…";
   return { state: state as "pending" | "success" | "error" | "failure" | "warning", context, description: d,

modules/gitea/test/delivery.test.ts

@@ -55,5 +55,9 @@ test("one view per pull request, found by its marker; only the mesh's statuses",
   // The merge check's statuses are its verdict's alone: required by a branch, they are never set by hand.
   assert.throws(() => deliveryStatus("mesh/merge-gate", "success", "x"), /merge check's status/);
   assert.throws(() => deliveryStatus("mesh/repo-check", "warning", "x"), /merge check's status/);
+  assert.throws(() => deliveryStatus("mesh/merge-gate", "failure", "x"), /merge check's status/);
+  // Pending is no verdict: a recheck says it so the old verdict does not let the head merge meanwhile.
+  assert.equal(deliveryStatus("mesh/merge-gate", "pending", "checking again: main moved on").state, "pending");
+  assert.equal(deliveryStatus("mesh/repo-check", "pending", "checking again: main moved on").context, "mesh/repo-check");
   assert.equal(deliveryStatus("mesh/delivery", "success", "x", "javascript:alert(1)").target_url, undefined);
 });

modules/gitea/tools/index.ts

@@ -494,7 +494,7 @@ export function getGiteaTools(gitea: GiteaClient): ToolDefinition[] {
     },
     {
       name: "gitea_commit_status",
-      description: "Set one of the mesh's statuses on a commit (mesh/delivery, mesh/delivery-group): pending, success, error, failure or warning, a short description, and the page it links to.",
+      description: "Set one of the mesh's statuses on a commit (mesh/delivery, mesh/delivery-group): pending, success, error, failure or warning, a short description, and the page it links to. The merge check's statuses (mesh/merge-gate, mesh/repo-check) take pending only — a recheck putting them back until the fresh verdict sets them.",
       input: {
         owner: { type: "string", description: "the repository owner" },
         repo: { type: "string", description: "the repository name" },