merge main: the tend surface for every tree, and the brief probe's own 200

Two incoming commits from the parallel tree-menu work:
  40e1d18  every tree is tended in the room's words — the panel is gone
  87d0649  asking whether a study exists is not an error — the brief probe
           gets its own 200

The second one fixes MY code: the study probe I added fired a GET per
imported tree at the brief route and read 404 as "no study", so every
no-study import logged a console 404 on every load. It now asks
/brief/exists, which answers 200 either way.

ONE CONFLICT, in src/ui/App.tsx, and it was structural rather than
semantic: I had DELETED the import-arrival effect (the "⚘ Plant it…" offer
the operator asked to be rid of) while they EDITED the study probe that sat
inside the same span. Resolved by keeping both intentions — their
/brief/exists probe stays, the arrival effect and its evaporate timer stay
gone. Verified after resolving: zero importPlantOffer/isFreshImportArrival
references remain, and the /api/process/:upid/brief/exists route their probe
calls really is there (app.ts:402).

tsc clean, 1347 pass / 0 fail, build green.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: RonTuretzky

src/server/app.test.ts

@@ -434,6 +434,13 @@ describe("POST /api/projects/import", () => {
     expect(built.previewUrl).toMatch(/^http:\/\/127\.0\.0\.1:\d+\//u);
   });
 
+  test("the brief EXISTENCE probe answers 200 either way — no console-404 per no-study import", async () => {
+    const { app } = await makeApp();
+    const response = await app.request("/api/process/upid-never-studied/brief/exists");
+    expect(response.status).toBe(200);
+    expect(((await response.json()) as { has: boolean }).has).toBe(false);
+  });
+
   test("A BARE REPO LINK IS STUDIED, NOT BUILT — and the brief route serves it", async () => {
     // The live miss this exists for: someone imported a repo, typed "just
     // study it first", and the room built it anyway because the description

src/server/app.ts

@@ -394,6 +394,14 @@ export function createProjectorApp(runtime: ProjectorRuntime, options: Projector
   // tree's "📖 About this project" card. 404 for trees that were never
   // studied (a build-intent import, a local concept, the room itself), which
   // is how the wall decides whether to offer the row at all.
+  // EXISTENCE PROBE — always 200. The wall asks this for EVERY import on
+  // every load to gate the "📖 About this project" row; answering the
+  // perfectly normal "no study" case with a 404 sprayed a console error per
+  // import (Chromium logs every 404 fetch) and tripped the console-error-free
+  // e2e on the seeded live path.
+  app.get("/api/process/:upid/brief/exists", (context) => {
+    return context.json({ has: runtime.projectBrief(context.req.param("upid")) !== null });
+  });
   app.get("/api/process/:upid/brief", (context) => {
     const brief = runtime.projectBrief(context.req.param("upid"));
     if (brief === null) {

src/ui/App.tsx

@@ -354,6 +354,38 @@ export function ProjectorApp({ initialSnapshot, urlSearch, initialOverlay, initi
     window.addEventListener("storage", onStorage);
     return () => window.removeEventListener("storage", onStorage);
   }, []);
+  // PROBE FOR STUDIES. The tree menu offers "📖 About this project" only when
+  // a study exists behind it — a row that opens an empty card is worse than
+  // no row. One HEAD-ish GET per imported tree, once, cached by upid.
+  useEffect(() => {
+    let cancelled = false;
+    for (const process of snapshot.processes) {
+      const kind = process.source?.kind;
+      if (kind !== "github-import" && kind !== "phone-import") {
+        continue;
+      }
+      if (process.upid in briefUpids) {
+        continue;
+      }
+      void (async () => {
+        let has = false;
+        try {
+          // The exists route answers 200 either way — probing the brief route
+          // itself meant a console 404 per no-study import on every load.
+          const response = await fetch(`/api/process/${encodeURIComponent(process.upid)}/brief/exists`);
+          has = response.ok && ((await response.json()) as { has?: unknown }).has === true;
+        } catch {
+          has = false; // server down / route absent: no row, no lie
+        }
+        if (!cancelled) {
+          setBriefUpids((current) => ({ ...current, [process.upid]: has }));
+        }
+      })();
+    }
+    return () => {
+      cancelled = true;
+    };
+  }, [snapshot.processes, briefUpids]);
 
   // ?zen=1 boots a dedicated display straight into the chrome-less scene.
   const [zenMode, setZenMode] = useState(urlConfig.zen);