fix(lx): count guest posts by author so a site cannot get stuck on guest slots

lib/lx/autoGuestPost.ts

@@ -68,10 +68,19 @@ export async function isGuestPostSlot(
   supabase: SupabaseClient<any>,
   authorSiteId: string,
 ): Promise<boolean> {
+  // A guest post is stored under the PARTNER's site_id, with the author in
+  // author_site_id. Counting by site_id alone missed every guest post this site
+  // wrote, so once its own count sat one short of a multiple of ten the slot
+  // stayed a guest slot for ever: pairux.com published nothing to its own blog
+  // from 2026-08-19 while writing the same guest post daily. Count what this
+  // site authored — its own posts plus the guest posts it wrote elsewhere —
+  // and not the guest posts partners wrote onto it.
   const { count, error } = await supabase
     .from("lx_article")
     .select("id", { count: "exact", head: true })
-    .eq("site_id", authorSiteId);
+    .or(
+      `and(site_id.eq.${authorSiteId},is_guest_post.eq.false),author_site_id.eq.${authorSiteId}`,
+    );
 
   // A failed count must not silently turn every slot into a guest post, nor
   // silently turn none of them into one. Falling back to "no" keeps the
@@ -114,10 +123,11 @@ export async function planGuestPost(
   // Who we have written for lately. One query for the whole cooldown rather
   // than one per candidate: the list is short and the cron is walking every
   // active site.
+  // By author_site_id, not site_id: the article lives under the partner.
   const { data: recent } = await supabase
     .from("lx_article")
     .select("target_site_id")
-    .eq("site_id", authorSiteId)
+    .eq("author_site_id", authorSiteId)
     .eq("is_guest_post", true)
     .gte("created_at", since);
 

tests/contract/auto-guest-post.test.ts

@@ -22,36 +22,43 @@ const matcher = vi.mocked(findGuestPostOpportunities);
  * getting one of those wrong is precisely the kind of mistake that returns
  * `undefined` and silently disables the feature rather than failing.
  */
-function stubSupabase(opts: {
-  articleCount?: number;
-  countError?: string;
-  recentGuestTargets?: string[];
-  existingRequests?: Array<{ target_site_id: string; topic: string }>;
-}) {
+function stubSupabase(
+  opts: {
+    articleCount?: number;
+    countError?: string;
+    recentGuestTargets?: string[];
+    existingRequests?: Array<{ target_site_id: string; topic: string }>;
+  },
+  filters: string[] = [],
+) {
   return {
     from(table: string) {
       if (table === "lx_article") {
         return {
           select(_cols: string, o?: { count?: string; head?: boolean }) {
             if (o?.head) {
               return {
-                eq: () =>
-                  Promise.resolve(
+                or: (f: string) => {
+                  filters.push(`or:${f}`);
+                  return Promise.resolve(
                     opts.countError
                       ? { count: null, error: { message: opts.countError } }
                       : { count: opts.articleCount ?? 0, error: null },
-                  ),
+                  );
+                },
               };
             }
             return {
-              eq: () => ({
-                eq: () => ({
-                  gte: () =>
-                    Promise.resolve({
+              eq: (col: string, val: unknown) => ({
+                eq: (col2: string, val2: unknown) => ({
+                  gte: () => {
+                    filters.push(`eq:${col}=${String(val)}`, `eq:${col2}=${String(val2)}`);
+                    return Promise.resolve({
                       data: (opts.recentGuestTargets ?? []).map((id) => ({
                         target_site_id: id,
                       })),
-                    }),
+                    });
+                  },
                 }),
               }),
             };
@@ -107,6 +114,16 @@ describe("guest post cadence", () => {
     );
     expect(slot).toBe(false);
   });
+
+  it("counts the guest posts this site wrote, which live under the partner", async () => {
+    // Counting by site_id alone never saw them, so a site one short of a
+    // multiple of ten was handed a guest slot on every tick, for ever.
+    const filters: string[] = [];
+    await isGuestPostSlot(stubSupabase({}, filters), "author");
+    expect(filters).toEqual([
+      "or:and(site_id.eq.author,is_guest_post.eq.false),author_site_id.eq.author",
+    ]);
+  });
 });
 
 describe("choosing a partner", () => {
@@ -142,6 +159,15 @@ describe("choosing a partner", () => {
     expect(plan?.targetSiteId).toBe("fresh");
   });
 
+  it("looks up the cooldown by author, not by the site the post lives on", async () => {
+    // The same mistake as the cadence count: by site_id the cooldown found
+    // nothing, and one partner got the same post seventeen days running.
+    matcher.mockResolvedValue([opportunity("partner", ["topic a"])]);
+    const filters: string[] = [];
+    await planGuestPost(stubSupabase({}, filters), "author");
+    expect(filters).toEqual(["eq:author_site_id=author", "eq:is_guest_post=true"]);
+  });
+
   it("does not commission a topic a human already requested", async () => {
     // The manual path and the cron share one ledger so they cannot
     // independently order the same article.