.gitea/workflows/build.yml

@@ -31,7 +31,29 @@ on:
     # job is ordinary commits.
     branches:
       - "**"
+    # Documentation-only changes cannot break a build, and this workflow is a
+    # full three-platform build (Windows included) behind a runner with
+    # capacity:1. Six of these fired for one afternoon of README/release-notes
+    # edits on 2026-09-09. Anything that feeds a build or a test is absent
+    # from this list on purpose -- release.yml and publish-release.sh only run
+    # on a `v*` tag, via release.yml's own trigger.
+    #
+    # Tradeoff: a docs-only push now shows NO status at all on the branch,
+    # rather than a green one. If a required-status check is ever added, these
+    # paths have to be reconsidered.
+    paths-ignore:
+      - "**.md"
+      - "LICENSE"
+      - "NOTICE"
+      - ".gitea/workflows/release.yml"
+      - ".gitea/scripts/publish-release.sh"
   pull_request:
+    paths-ignore:
+      - "**.md"
+      - "LICENSE"
+      - "NOTICE"
+      - ".gitea/workflows/release.yml"
+      - ".gitea/scripts/publish-release.sh"
 
 jobs:
   linux:

core/src/http_winhttp.cpp

@@ -19,8 +19,13 @@ You may obtain a copy of the License at
 #include <windows.h>
 #include <winhttp.h>
 
+#include <atomic>
+#include <chrono>
+#include <condition_variable>
 #include <cstddef>
+#include <mutex>
 #include <string>
+#include <thread>
 #include <vector>
 
 namespace stplugin {
@@ -72,6 +77,79 @@ private:
     HINTERNET h_ = nullptr;
 };
 
+/// Hard deadline for one WinHTTP exchange, enforced by cancelling it.
+///
+/// Neither receive timeout is a guaranteed deadline: Microsoft documents both
+/// as "checked only when data is received from the socket", so an expired
+/// timeout is not surfaced until the peer finally sends something. Measured on
+/// the Windows CI runner against a server that accepts and then stalls 5s: a
+/// 700ms budget returned after 1490, 1529, 2485, 3493 and 4506ms across five
+/// attempts -- always cancelled, never on time.
+///
+/// That overshoot matters because `fetchSlots` is called synchronously on the
+/// OBS UI thread behind the properties dialog's "Refresh camera list" button
+/// (obs-adapter/src/plugin-main.cpp), with a 5s budget. At the ratio above
+/// that is a frozen dialog for half a minute.
+///
+/// The documented way to force cancellation is to close the handle from
+/// another thread; the pending call then fails with
+/// ERROR_WINHTTP_OPERATION_CANCELLED. This owns the request handle so that
+/// exactly one of the two threads ever closes it: `handle_.exchange(nullptr)`
+/// hands the close to whichever gets there first.
+///
+/// Known, accepted race: the caller may load the handle and have the watchdog
+/// close it before the WinHttp* call reads it, in which case the call fails
+/// with ERROR_INVALID_HANDLE instead. Both outcomes are "the deadline
+/// expired", which is what the caller is told either way.
+class RequestDeadline {
+public:
+    RequestDeadline(HINTERNET request, DWORD after_ms) : handle_(request)
+    {
+        watchdog_ = std::thread([this, after_ms] {
+            std::unique_lock<std::mutex> lock(mutex_);
+            if (cv_.wait_for(lock, std::chrono::milliseconds(after_ms), [this] { return finished_; }))
+                return; // exchange finished inside the deadline
+            if (closeOnce())
+                expired_.store(true);
+        });
+    }
+
+    ~RequestDeadline()
+    {
+        {
+            std::lock_guard<std::mutex> lock(mutex_);
+            finished_ = true;
+        }
+        cv_.notify_all();
+        if (watchdog_.joinable())
+            watchdog_.join();
+        closeOnce(); // no-op if the watchdog got there first
+    }
+
+    RequestDeadline(const RequestDeadline &) = delete;
+    RequestDeadline &operator=(const RequestDeadline &) = delete;
+
+    HINTERNET get() const { return handle_.load(); }
+    bool expired() const { return expired_.load(); }
+
+private:
+    bool closeOnce()
+    {
+        HINTERNET h = handle_.exchange(nullptr);
+        if (!h)
+            return false;
+        WinHttpCloseHandle(h);
+        return true;
+    }
+
+    std::atomic<HINTERNET> handle_;
+    std::atomic<bool> expired_{false};
+    std::mutex mutex_;
+    std::condition_variable cv_;
+    bool finished_ = false;
+    std::thread watchdog_;
+};
+
 class WinHttpClient : public HttpClient {
 public:
     HttpResponse send(const HttpRequest &request) override
@@ -116,6 +194,39 @@ public:
         WinHttpSetTimeouts(session.get(), static_cast<int>(timeout), static_cast<int>(timeout),
                            static_cast<int>(timeout), static_cast<int>(timeout));
 
+        // WinHttpSetTimeouts' receive parameter maps to
+        // WINHTTP_OPTION_RECEIVE_TIMEOUT, which Microsoft documents as a
+        // PER-PACKET Winsock-layer read timeout ("applies to fetching each
+        // packet of data off the socket"), not a deadline on the response.
+        // The wait for the response HEADERS is a *separate* option,
+        // WINHTTP_OPTION_RECEIVE_RESPONSE_TIMEOUT ("to wait to receive all
+        // response headers to a request"), which WinHttpSetTimeouts does not
+        // touch and which defaults to 90 SECONDS. Without this call a server
+        // that accepts, reads the request and then stalls can hold this
+        // thread for a minute and a half regardless of request.timeout_ms --
+        // exactly the "blocking an OBS thread indefinitely" failure
+        // testPlatformBackendTimeout exists to prevent, and the likely
+        // mechanism behind that test's intermittent Windows failures.
+        //
+        // Caveat, also documented: this timeout "is checked only when data is
+        // received from the socket", so it bounds the wait but does not
+        // guarantee a hard deadline. A guaranteed deadline needs a watchdog
+        // thread calling WinHttpCloseHandle; not done here.
+        //
+        // Guarded because the constant postdates some Windows SDK headers; a
+        // toolchain without it keeps the previous (90s default) behaviour
+        // rather than failing to build.
+#ifdef WINHTTP_OPTION_RECEIVE_RESPONSE_TIMEOUT
+        DWORD response_timeout = timeout;
+        // Return value deliberately unchecked: a rejected option leaves the
+        // documented default in place, which is degraded but still correct
+        // behaviour, and there is no logging sink in this layer to report it
+        // to. The timeout probe in test_api_client.cpp is what would catch a
+        // regression here.
+        WinHttpSetOption(session.get(), WINHTTP_OPTION_RECEIVE_RESPONSE_TIMEOUT, &response_timeout,
+                         sizeof(response_timeout));
+#endif
+
         Handle connect(WinHttpConnect(session.get(), host, parts.nPort, 0));
         if (!connect) {
             response.network_error = lastErrorMessage("WinHttpConnect");
@@ -126,13 +237,36 @@ public:
         target += extra;
 
         const DWORD flags = (parts.nScheme == INTERNET_SCHEME_HTTPS) ? WINHTTP_FLAG_SECURE : 0u;
-        Handle req(WinHttpOpenRequest(connect.get(), widen(request.method).c_str(), target.c_str(), nullptr,
+        HINTERNET raw_req = WinHttpOpenRequest(connect.get(), widen(request.method).c_str(), target.c_str(),
-                                      WINHTTP_NO_REFERER, WINHTTP_DEFAULT_ACCEPT_TYPES, flags));
+                                               nullptr, WINHTTP_NO_REFERER, WINHTTP_DEFAULT_ACCEPT_TYPES,
-        if (!req) {
+                                               flags);
+        if (!raw_req) {
             response.network_error = lastErrorMessage("WinHttpOpenRequest");
             return response;
         }
 
+        // Ceiling at twice the caller's budget: each of the four
+        // WinHttpSetTimeouts phases (resolve, connect, send, receive) is
+        // allowed `timeout` on its own, so a slow-but-progressing exchange can
+        // legitimately exceed one budget, and this must not cancel those. The
+        // floor keeps a very small timeout_ms from producing a deadline the
+        // exchange cannot meet on a cold connection.
+        const DWORD deadline_ms = (timeout > 500u) ? (timeout * 2u) : 1000u;
+        RequestDeadline req(raw_req, deadline_ms);
+
+        // From here on, `req.get()` can be closed underneath us by the
+        // watchdog; every WinHttp* failure below is therefore checked against
+        // req.expired() before its GetLastError text is reported, so an
+        // expired deadline reads as a timeout rather than as
+        // "WinHttpReceiveResponse failed (GetLastError=12017)".
+        const auto fail = [&](const char *what) -> HttpResponse {
+            if (req.expired())
+                response.network_error = "timed out after " + std::to_string(deadline_ms) + " ms";
+            else
+                response.network_error = lastErrorMessage(what);
+            return response;
+        };
+
         std::wstring headers;
         if (!request.content_type.empty())
             headers = L"Content-Type: " + widen(request.content_type) + L"\r\n";
@@ -144,31 +278,23 @@ public:
                                               : const_cast<char *>(request.body.data());
         const DWORD body_len = static_cast<DWORD>(request.body.size());
 
-        if (!WinHttpSendRequest(req.get(), header_ptr, header_len, body_ptr, body_len, body_len, 0)) {
+        if (!WinHttpSendRequest(req.get(), header_ptr, header_len, body_ptr, body_len, body_len, 0))
-            response.network_error = lastErrorMessage("WinHttpSendRequest");
+            return fail("WinHttpSendRequest");
-            return response;
+        if (!WinHttpReceiveResponse(req.get(), nullptr))
-        }
+            return fail("WinHttpReceiveResponse");
-        if (!WinHttpReceiveResponse(req.get(), nullptr)) {
-            response.network_error = lastErrorMessage("WinHttpReceiveResponse");
-            return response;
-        }
 
         DWORD status = 0;
         DWORD status_size = sizeof(status);
         if (!WinHttpQueryHeaders(req.get(), WINHTTP_QUERY_STATUS_CODE | WINHTTP_QUERY_FLAG_NUMBER,
-                                 WINHTTP_HEADER_NAME_BY_INDEX, &status, &status_size, WINHTTP_NO_HEADER_INDEX)) {
+                                 WINHTTP_HEADER_NAME_BY_INDEX, &status, &status_size, WINHTTP_NO_HEADER_INDEX))
-            response.network_error = lastErrorMessage("WinHttpQueryHeaders");
+            return fail("WinHttpQueryHeaders");
-            return response;
-        }
         response.status = static_cast<long>(status);
 
         std::string body;
         for (;;) {
             DWORD available = 0;
-            if (!WinHttpQueryDataAvailable(req.get(), &available)) {
+            if (!WinHttpQueryDataAvailable(req.get(), &available))
-                response.network_error = lastErrorMessage("WinHttpQueryDataAvailable");
+                return fail("WinHttpQueryDataAvailable");
-                return response;
-            }
             if (available == 0)
                 break;
             if (body.size() + available > kMaxResponseBytes) {
@@ -177,10 +303,8 @@ public:
             }
             std::vector<char> chunk(available);
             DWORD read = 0;
-            if (!WinHttpReadData(req.get(), chunk.data(), available, &read)) {
+            if (!WinHttpReadData(req.get(), chunk.data(), available, &read))
-                response.network_error = lastErrorMessage("WinHttpReadData");
+                return fail("WinHttpReadData");
-                return response;
-            }
             if (read == 0)
                 break;
             body.append(chunk.data(), read);

core/tests/test_api_client.cpp

@@ -16,6 +16,7 @@ You may obtain a copy of the License at
 //      three runners rather than assumed to work.
 
 #include <chrono>
+#include <cstdio>
 #include <memory>
 #include <string>
 #include <thread>
@@ -422,22 +423,77 @@ void testPlatformBackendTimeout()
 {
     // A server that accepts and then stalls. The plugin must give up on its
     // own timeout rather than blocking an OBS thread indefinitely.
-    sttest::LoopbackServer server([](const std::string &) {
+    //
-        std::this_thread::sleep_for(std::chrono::seconds(5));
+    // INSTRUMENTED (2026-09-09) while chasing an intermittent Windows-only
-        return sttest::httpResponse(200, "OK", R"({"slots":[]})");
+    // failure: on roughly 2 of 6 CI runs both assertions below fail together,
-    });
+    // meaning the request waited out the full 5s stall and returned 200 --
-    ST_ASSERT(server.valid());
+    // the timeout did not fire at all. Same failure seen on 2026-09-07
+    // (job 5834) and 2026-09-09 (job 5911), on identical code that passed on
+    // other runs, so it is not a code change that caused it.
+    //
+    // The probe runs kProbes times and prints one line per attempt so a
+    // single CI run yields a failure RATE and the WinHTTP error code, rather
+    // than one bit. `ST_ASSERT` records and continues, so every attempt is
+    // reported even when one fails. Remove the loop and this comment once the
+    // mechanism is understood and fixed.
+    constexpr int kProbes = 5;
+    constexpr long long kStallMs = 5000;
+    constexpr long kTimeoutMs = 700;
 
-    std::shared_ptr<HttpClient> http(createPlatformHttpClient());
+    int timed_out = 0;
-    HttpRequest request;
+    for (int i = 0; i < kProbes; ++i) {
-    request.url = server.baseUrl() + "/api/obs/main-room/slots?key=k";
+        // A FRESH server per attempt, deliberately. `LoopbackServer` accepts
-    request.timeout_ms = 700;
+        // and handles one connection at a time on a single thread, so reusing
+        // one server across attempts would leave attempts 2..n sitting in the
+        // accept backlog -- a different scenario (never accepted) from the one
+        // that fails on Windows (accepted, request read, then stalled).
+        sttest::LoopbackServer server([kStallMs](const std::string &) {
+            std::this_thread::sleep_for(std::chrono::milliseconds(kStallMs));
+            return sttest::httpResponse(200, "OK", R"({"slots":[]})");
+        });
+        ST_ASSERT(server.valid());
 
-    const auto start = std::chrono::steady_clock::now();
+        std::shared_ptr<HttpClient> http(createPlatformHttpClient());
-    const HttpResponse response = http->send(request);
+        HttpRequest request;
-    const auto elapsed = std::chrono::steady_clock::now() - start;
+        request.url = server.baseUrl() + "/api/obs/main-room/slots?key=k";
-    ST_ASSERT(!response.ok());
+        request.timeout_ms = kTimeoutMs;
-    ST_ASSERT(std::chrono::duration_cast<std::chrono::milliseconds>(elapsed).count() < 4000);
+
+        const auto start = std::chrono::steady_clock::now();
+        const HttpResponse response = http->send(request);
+        const auto elapsed = std::chrono::steady_clock::now() - start;
+        const long long ms = std::chrono::duration_cast<std::chrono::milliseconds>(elapsed).count();
+
+        // 4000 was the old bound, chosen when nothing bounded the wait. The
+        // code now promises a hard ceiling of 2x the caller's budget
+        // (RequestDeadline in http_winhttp.cpp), so assert THAT -- 1400ms
+        // here, plus slack for a loaded runner. This is also the only signal
+        // that survives a green run: CTest prints nothing on success, so if
+        // WinHTTP's own erratic cancellation (measured at 1490-4506ms for
+        // this same 700ms budget) were doing the work instead of the
+        // watchdog, roughly half the attempts would land above this bound and
+        // say so, instead of quietly passing under a 4s ceiling.
+        constexpr long long kCeilingMs = 2500;
+        const bool gave_up = !response.ok() && ms < kCeilingMs;
+        if (gave_up)
+            ++timed_out;
+
+        // Always printed, pass or fail: elapsed time and the backend's own
+        // error string (which carries GetLastError on Windows) are the
+        // evidence. requests_seen separates "the client never reached the
+        // server" (0) from "the server read the request and the client then
+        // waited it out" (1).
+        std::fprintf(stderr,
+                     "  [timeout-probe %d/%d] elapsed=%lldms ok=%d status=%ld "
+                     "requests_seen=%d network_error='%s' -> %s\n",
+                     i + 1, kProbes, ms, response.ok() ? 1 : 0, response.status,
+                     server.requestCount(), response.network_error.c_str(),
+                     gave_up ? "gave up (expected)" : "WAITED OUT THE STALL");
+
+        ST_ASSERT(!response.ok());
+        ST_ASSERT(ms < kCeilingMs);
+    }
+    std::fprintf(stderr, "  [timeout-probe] %d/%d attempts honoured the %ldms timeout\n",
+                 timed_out, kProbes, kTimeoutMs);
 }
 
 } // namespace