fix: treat WHOIS empty-close as no_data and ETIMEDOUT as structured timeout

- A server that accepts the connection and closes it without sending data now rejects with `errorCode: "no_data"` and `stage: "read"` instead of resolving with an empty string
- OS-level `ETIMEDOUT` errors are mapped to the same `timeout` / `stage` shape as the library's own timer, with `stage` derived from whether the socket had connected yet
- `ECONNRESET` after data arrives is no longer marked `partial: true`; it was a complete reply and the reset just signalled the end of the stream
- `stage` on `LookupAttempt` is now documented as covering all WHOIS failures (not only timeout failures)

src/whois/client.timeout.test.ts

@@ -113,12 +113,38 @@ describe("whoisQuery timeouts", () => {
     ).rejects.toMatchObject({ code: "aborted" });
   });
 
-  it("keeps the data when a server resets the connection after replying", async () => {
+  it("keeps the data (not flagged partial) when a server resets after replying", async () => {
     const p = whoisQuery("whois.example", "example.test");
     await vi.advanceTimersByTimeAsync(0);
     socket.emit("connect");
     socket.emit("data", Buffer.from("answer"));
     socket.emit("error", Object.assign(new Error("reset"), { code: "ECONNRESET" }));
-    await expect(p).resolves.toMatchObject({ text: "answer", partial: true });
+    const res = await p;
+    expect(res.text).toBe("answer");
+    expect(res.partial).toBeUndefined();
+  });
+
+  it.each(["end", "close"])(
+    "rejects with no_data when the server sends nothing then %s",
+    async (evt) => {
+      const p = whoisQuery("whois.example", "example.test");
+      const assertion = expect(p).rejects.toMatchObject({ code: "no_data", stage: "read" });
+      await vi.advanceTimersByTimeAsync(0);
+      socket.emit("connect");
+      socket.emit(evt);
+      await assertion;
+    },
+  );
+
+  it.each([
+    [false, "connect"],
+    [true, "read"],
+  ])("gives an OS ETIMEDOUT (connected=%s) stage %s", async (connected, stage) => {
+    const p = whoisQuery("whois.example", "example.test");
+    const assertion = expect(p).rejects.toMatchObject({ code: "timeout", stage });
+    await vi.advanceTimersByTimeAsync(0);
+    if (connected) socket.emit("connect");
+    socket.emit("error", Object.assign(new Error("connect ETIMEDOUT"), { code: "ETIMEDOUT" }));
+    await assertion;
   });
 });

src/whois/client.ts

@@ -109,9 +109,18 @@ async function queryTcp(
     signal?.addEventListener("abort", onAbort, { once: true });
 
     socket.on("error", (err: NodeJS.ErrnoException) => {
-      // Servers that reset the connection after replying still gave us an answer
       if (err.code === "ECONNRESET" && received > 0) {
-        finish(() => resolve({ text: text(), partial: true }));
+        // The server replied and then reset. Nothing says the reply was cut short, so this is
+        // a normal result; `partial` is reserved for our own read timeout.
+        finish(() => resolve({ text: text() }));
+      } else if (err.code === "ETIMEDOUT") {
+        // OS-level timeout: keep the same shape as our own timer's errors
+        const stage = connected ? "read" : "connect";
+        finish(() =>
+          reject(
+            new RdapperError("timeout", `WHOIS ${stage} timeout (${host})`, { stage, cause: err }),
+          ),
+        );
       } else {
         finish(() => reject(err));
       }
@@ -121,12 +130,29 @@ async function queryTcp(
       chunks.push(buf);
       received += buf.length;
     });
-    socket.on("end", () => {
-      finish(() => resolve({ text: text() }));
-    });
+    // A connection that closes without sending anything (e.g. a throttled client being dropped)
+    // is a failure, not an empty successful answer.
+    const complete = () => {
+      if (received > 0) {
+        finish(() => resolve({ text: text() }));
+      } else {
+        finish(() =>
+          reject(
+            new RdapperError(
+              "no_data",
+              `WHOIS server closed the connection without a response (${host})`,
+              {
+                stage: "read",
+              },
+            ),
+          ),
+        );
+      }
+    };
+    socket.on("end", complete);
     // A close without a preceding end/error (half-open teardown) would otherwise wait out the timer
     socket.on("close", () => {
-      if (connected) finish(() => resolve({ text: text() }));
+      if (connected) complete();
       else {
         finish(() =>
           reject(new RdapperError("connect_failed", `WHOIS connection closed (${host})`)),