diff --git a/reader/CMakeLists.txt b/reader/CMakeLists.txt
index fe0f0d7ec..1a07866cc 100644
--- a/reader/CMakeLists.txt
+++ b/reader/CMakeLists.txt
@@ -20,6 +20,10 @@ ADD_LIBRARY(JFJochReader STATIC
         SMV.h
         JFJochSMVReader.cpp
         JFJochSMVReader.h
+        XTC.cpp
+        XTC.h
+        JFJochXTCReader.cpp
+        JFJochXTCReader.h
         HDF5ImageLocator.cpp
         JFJochStartMessageReader.cpp
         JFJochStartMessageReader.h
diff --git a/reader/JFJochXTCReader.cpp b/reader/JFJochXTCReader.cpp
new file mode 100644
index 000000000..baea3d85d
--- /dev/null
+++ b/reader/JFJochXTCReader.cpp
@@ -0,0 +1,186 @@
+// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
+// SPDX-License-Identifier: GPL-3.0-only
+
+#include "JFJochXTCReader.h"
+
+#include <cmath>
+#include <filesystem>
+#include <fstream>
+
+#include <nlohmann/json.hpp>
+
+#include "../common/JFJochException.h"
+#include "../common/Logger.h"
+
+namespace {
+
+using Vec = std::array<double, 3>;
+
+double Dot(const Vec &a, const Vec &b) { return a[0] * b[0] + a[1] * b[1] + a[2] * b[2]; }
+
+Vec Cross(const Vec &a, const Vec &b) {
+    return {a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0]};
+}
+
+Vec ReadVec(const nlohmann::json &j) { return {j.at(0).get<double>(), j.at(1).get<double>(), j.at(2).get<double>()}; }
+
+// A DIALS laboratory vector in the internal frame. DIALS uses the imgCIF laboratory frame (z from
+// the sample to the source, y up), which differs from the internal one by a half turn about x.
+Coord DialsToInternal(const Vec &v) {
+    return {static_cast<float>(v[0]), static_cast<float>(-v[1]), static_cast<float>(-v[2])};
+}
+
+// The DIALS experiment list beside the streams, or in the directory above them.
+std::string FindExpt(const std::string &stream) {
+    const auto dir = std::filesystem::absolute(stream).parent_path();
+    for (const auto &d: {dir, dir.parent_path()}) {
+        std::error_code ec;
+        for (const auto &e: std::filesystem::directory_iterator(d, ec))
+            if (e.is_regular_file() && e.path().extension() == ".expt")
+                return e.path().string();
+    }
+    return {};
+}
+
+}  // namespace
+
+bool JFJochXTCReader::CanRead(const std::string &path) {
+    return xtc::CanRead(path);
+}
+
+void JFJochXTCReader::ReadGeometry(const std::string &expt) {
+    std::ifstream in(expt);
+    const auto j = nlohmann::json::parse(in);
+    const auto &beam = j.at("beam").at(0);
+    const auto &panels = j.at("detector").at(0).at("panels");
+    if (panels.size() != 1)
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
+                              expt + " describes a detector of " + std::to_string(panels.size())
+                              + " panels; only a single-panel detector is read from XTC");
+    const auto &panel = panels.at(0);
+
+    const double wavelength_A = beam.at("wavelength").get<double>();
+    // DIALS states the direction from the sample to the source; the beam travels the other way.
+    const Vec direction = ReadVec(beam.at("direction"));
+    const Vec b = {-direction[0], -direction[1], -direction[2]};
+    const Vec fast = ReadVec(panel.at("fast_axis")), slow = ReadVec(panel.at("slow_axis"));
+    const Vec origin = ReadVec(panel.at("origin"));   // mm, corner of the first pixel
+    const double pixel_mm = panel.at("pixel_size").at(0).get<double>();
+
+    // Where the beam meets the detector plane, in pixels along fast and slow, and how far along the
+    // detector normal the plane is.
+    const Vec normal = Cross(fast, slow);
+    const double t = Dot(origin, normal) / Dot(b, normal);
+    const Vec hit = {t * b[0] - origin[0], t * b[1] - origin[1], t * b[2] - origin[2]};
+    if (std::fabs(Dot(b, normal)) < 0.9999)
+        Logger("XTCReader").Warning("{}: the detector is tilted by {:.2f} deg against the beam; it is read "
+                                    "as square-on", expt, std::acos(std::fabs(Dot(b, normal))) * 180.0 / M_PI);
+
+    auto &experiment = dataset_->experiment;
+    const auto &f0 = frames_.front();
+    DetectorSetup detector = DetDECTRIS(f0.width, f0.height, "XTC camera", {});
+    detector.PixelSize_um(static_cast<float>(pixel_mm * 1000.0));
+    // A CCD: the phosphor converts at the surface, so there is no depth to correct parallax for.
+    detector.SensorThickness_um(0);
+    detector.SaturationLimit(65535);
+    detector.BitDepthImage(32);
+    const auto orientation = DetectorOrientation::Match(DialsToInternal(fast), DialsToInternal(slow));
+    if (!orientation.has_value())
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
+                              expt + ": the panel's fast and slow axes are not a square-on layout this reader supports");
+    detector.ImageOrientation(orientation.value());
+    detector.MinFrameTime(std::chrono::microseconds(0));
+    detector.MinCountTime(std::chrono::microseconds(0));
+    detector.ReadOutTime(std::chrono::nanoseconds(0));
+    experiment.Detector(detector);
+
+    experiment.BeamX_pxl(static_cast<float>(Dot(hit, fast) / pixel_mm));
+    experiment.BeamY_pxl(static_cast<float>(Dot(hit, slow) / pixel_mm));
+    experiment.DetectorDistance_mm(static_cast<float>(std::fabs(Dot(origin, normal))));
+    experiment.IncidentEnergy_keV(WVL_1A_IN_KEV / static_cast<float>(wavelength_A));
+
+    // The polarization degree is 2f - 1 of the fraction f DIALS states; positive where the plane
+    // contains the lab x axis (normal along y), as in the SMV reader.
+    if (beam.contains("polarization_fraction") && beam.contains("polarization_normal")) {
+        const Coord n = DialsToInternal(ReadVec(beam.at("polarization_normal")));
+        const float degree = 2.0f * beam.at("polarization_fraction").get<float>() - 1.0f;
+        experiment.PolarizationFactor(std::fabs(n.x) > std::fabs(n.y) ? -degree : degree);
+    }
+}
+
+void JFJochXTCReader::ReadFiles(const std::string &path) {
+    frames_.clear();
+    for (const auto &stream: xtc::CollectStreams(path)) {
+        auto f = xtc::IndexFrames(stream);
+        frames_.insert(frames_.end(), f.begin(), f.end());
+    }
+    if (frames_.empty())
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
+                              "No camera images found in the XTC of " + path);
+    for (const auto &f: frames_)
+        if (f.width != frames_.front().width || f.height != frames_.front().height)
+            throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
+                                  f.file + ": the images are not all the same size");
+
+    const std::string expt = FindExpt(frames_.front().file);
+    if (expt.empty())
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
+                              "XTC carries no detector geometry: put the DIALS experiment list (.expt) of "
+                              "the run beside the XTC files, or in the directory above them");
+    Logger("XTCReader").Info("{} images in XTC, geometry from {}", frames_.size(), expt);
+
+    dataset_ = std::make_shared<JFJochReaderDataset>();
+    dataset_->experiment = default_experiment;
+    ReadGeometry(expt);
+    dataset_->error_value = -1;
+    dataset_->experiment.ImagesPerTrigger(static_cast<int64_t>(frames_.size()));
+    dataset_->pixel_mask = std::make_shared<const PixelMask>(frames_.front().width, frames_.front().height);
+
+    SetStartMessage(dataset_);
+}
+
+uint64_t JFJochXTCReader::GetNumberOfImages() const {
+    return frames_.size();
+}
+
+void JFJochXTCReader::Close() {
+    frames_.clear();
+    dataset_.reset();
+}
+
+template <class Buffer>
+CompressedImage JFJochXTCReader::DecodeInto(int64_t image_number, Buffer &buffer,
+                                            std::vector<uint8_t> &scratch) const {
+    if (image_number < 0 || static_cast<size_t>(image_number) >= frames_.size())
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid, "Image number out of range");
+    const auto &f = frames_[image_number];
+    buffer.resize(static_cast<size_t>(f.width) * f.height * sizeof(int32_t));
+    xtc::ReadFrame(f, reinterpret_cast<int32_t *>(buffer.data()), scratch);
+    return CompressedImage(buffer.data(), buffer.size(), f.width, f.height,
+                           CompressedImageMode::Int32, CompressionAlgorithm::NO_COMPRESSION);
+}
+
+bool JFJochXTCReader::LoadImage_i(std::shared_ptr<JFJochReaderDataset> &dataset,
+                                  DataMessage &message,
+                                  std::vector<uint8_t> &buffer,
+                                  int64_t image_number,
+                                  bool update_dataset) {
+    (void) update_dataset;
+    if (!dataset || image_number < 0 || static_cast<size_t>(image_number) >= frames_.size())
+        return false;
+    std::vector<uint8_t> scratch;
+    message.image = DecodeInto(image_number, buffer, scratch);
+    message.number = image_number;
+    return true;
+}
+
+bool JFJochXTCReader::ReadRawImage(int64_t image_number, JFJochReaderRawImage &image) {
+    if (image_number < 0 || static_cast<size_t>(image_number) >= frames_.size())
+        return false;
+    image.image = DecodeInto(image_number, image.image_buffer, image.read_buffer);
+    return true;
+}
+
+std::vector<SpotToSave> JFJochXTCReader::ReadSpots(int64_t) const {
+    return {};   // raw XTC stores no analysis results
+}
diff --git a/reader/JFJochXTCReader.h b/reader/JFJochXTCReader.h
new file mode 100644
index 000000000..6b22eb4ef
--- /dev/null
+++ b/reader/JFJochXTCReader.h
@@ -0,0 +1,53 @@
+// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
+// SPDX-License-Identifier: GPL-3.0-only
+
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "JFJochReader.h"
+#include "XTC.h"
+
+// Reads serial-crystallography stills straight from LCLS-I XTC files: one camera image per event,
+// from a single-panel detector such as the Rayonix CCDs at MFX and XPP. A multi-panel detector
+// (CSPAD, ePix, JUNGFRAU at LCLS) is stored as raw per-module data with its own calibration, and is
+// not read here.
+//
+// XTC records the events and not the experiment: there is no distance, beam centre or wavelength
+// in it that this reader can use. Those come from a DIALS experiment list (.expt) beside the XTC
+// files, or in their parent directory - the geometry a deposition ships for cctbx.xfel, and what
+// cctbx.xfel itself reads them with. Without one the run is refused rather than guessed.
+//
+// The images are stills: no goniometer. Each is decoded on demand. The pixels are passed on as
+// stored - the CCD's constant offset of a few counts is left in, as it is in an SMV image, and the
+// pre-scan finds the defective pixels.
+class JFJochXTCReader : public JFJochReader {
+    std::vector<xtc::Frame> frames_;
+    std::shared_ptr<JFJochReaderDataset> dataset_;
+
+    bool LoadImage_i(std::shared_ptr<JFJochReaderDataset> &dataset,
+                     DataMessage &message,
+                     std::vector<uint8_t> &buffer,
+                     int64_t image_number,
+                     bool update_dataset) override;
+
+    template <class Buffer>
+    CompressedImage DecodeInto(int64_t image_number, Buffer &buffer, std::vector<uint8_t> &scratch) const;
+
+    void ReadGeometry(const std::string &expt);
+
+public:
+    ~JFJochXTCReader() override = default;
+
+    static bool CanRead(const std::string &path);
+
+    // path is one XTC stream, or a directory whose streams are all read.
+    void ReadFiles(const std::string &path);
+
+    [[nodiscard]] uint64_t GetNumberOfImages() const override;
+    void Close() override;
+
+    bool ReadRawImage(int64_t image_number, JFJochReaderRawImage &image) override;
+    [[nodiscard]] std::vector<SpotToSave> ReadSpots(int64_t image) const override;
+};
diff --git a/reader/XTC.cpp b/reader/XTC.cpp
new file mode 100644
index 000000000..03dd0de4c
--- /dev/null
+++ b/reader/XTC.cpp
@@ -0,0 +1,149 @@
+// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
+// SPDX-License-Identifier: GPL-3.0-only
+
+#include "XTC.h"
+
+#include <algorithm>
+#include <cstdio>
+#include <cstring>
+#include <filesystem>
+#include <memory>
+
+#include "../common/JFJochException.h"
+
+namespace {
+
+constexpr size_t DGRAM_HEADER = 40;   // clock time 8, timestamp 8, env 4, Xtc header 20
+constexpr size_t XTC_HEADER = 20;
+constexpr size_t FRAME_HEADER = 16;   // Camera::FrameV1: width, height, depth, offset
+constexpr uint32_t ID_XTC = 1;
+constexpr uint32_t ID_FRAME = 2;
+constexpr uint32_t TRANSITION_L1ACCEPT = 12;
+constexpr uint32_t TRANSITION_LAST = 12;
+
+struct FileCloser {
+    void operator()(FILE *f) const { if (f) fclose(f); }
+};
+using File = std::unique_ptr<FILE, FileCloser>;
+
+File Open(const std::string &path) {
+    File f(fopen(path.c_str(), "rb"));
+    if (!f)
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid, "Cannot open " + path);
+    return f;
+}
+
+uint32_t Word(const uint8_t *p, size_t i) {
+    uint32_t v;
+    memcpy(&v, p + 4 * i, 4);
+    return v;
+}
+
+// The transition a datagram header names, from the top bits of its timestamp's first word.
+uint32_t Transition(const uint8_t *dgram) {
+    return (Word(dgram, 2) >> 24) & 0xf;
+}
+
+// A first datagram is a Configure with a container as its outermost Xtc, whose extent covers at
+// least its own header.
+bool PlausibleFirstDatagram(const uint8_t *h) {
+    return Transition(h) <= TRANSITION_LAST && (Word(h, 8) & 0xffff) == ID_XTC && Word(h, 9) >= XTC_HEADER;
+}
+
+// Walks the Xtcs in [begin, end) of the file, looking for camera frames; the largest found is kept.
+void FindFrame(FILE *f, uint64_t begin, uint64_t end, xtc::Frame &best) {
+    uint64_t pos = begin;
+    while (pos + XTC_HEADER <= end) {
+        uint8_t h[XTC_HEADER];
+        if (fseeko(f, static_cast<off_t>(pos), SEEK_SET) != 0 || fread(h, 1, XTC_HEADER, f) != XTC_HEADER)
+            return;
+        const uint32_t type = Word(h, 3) & 0xffff;
+        const uint32_t extent = Word(h, 4);
+        if (extent < XTC_HEADER || pos + extent > end)
+            return;
+        if (type == ID_XTC)
+            FindFrame(f, pos + XTC_HEADER, pos + extent, best);
+        else if (type == ID_FRAME && extent >= XTC_HEADER + FRAME_HEADER) {
+            uint8_t fh[FRAME_HEADER];
+            if (fread(fh, 1, FRAME_HEADER, f) == FRAME_HEADER) {
+                const uint32_t width = Word(fh, 0), height = Word(fh, 1), depth = Word(fh, 2);
+                const uint64_t npixel = static_cast<uint64_t>(width) * height;
+                if (depth > 8 && depth <= 16 && XTC_HEADER + FRAME_HEADER + 2 * npixel <= extent
+                    && npixel > static_cast<uint64_t>(best.width) * best.height)
+                    best = {"", pos + XTC_HEADER + FRAME_HEADER, width, height};
+            }
+        }
+        pos += extent;
+    }
+}
+
+}  // namespace
+
+namespace xtc {
+
+bool CanRead(const std::string &path) {
+    std::error_code ec;
+    if (std::filesystem::is_directory(path, ec))
+        return !CollectStreams(path).empty();
+    if (!std::filesystem::is_regular_file(path, ec) || !path.ends_with(".xtc") || path.ends_with(".smd.xtc"))
+        return false;
+    File f(fopen(path.c_str(), "rb"));
+    uint8_t h[DGRAM_HEADER];
+    return f && fread(h, 1, DGRAM_HEADER, f.get()) == DGRAM_HEADER && PlausibleFirstDatagram(h);
+}
+
+std::vector<std::string> CollectStreams(const std::string &path) {
+    std::error_code ec;
+    if (!std::filesystem::is_directory(path, ec))
+        return {path};
+    std::vector<std::string> out;
+    for (const auto &e: std::filesystem::directory_iterator(path, ec)) {
+        const std::string p = e.path().string();
+        if (e.is_regular_file() && p.ends_with(".xtc") && !p.ends_with(".smd.xtc"))
+            out.push_back(p);
+    }
+    std::sort(out.begin(), out.end());
+    return out;
+}
+
+std::vector<Frame> IndexFrames(const std::string &file) {
+    File f = Open(file);
+    std::vector<Frame> out;
+    uint64_t pos = 0;
+    uint8_t h[DGRAM_HEADER];
+    while (fseeko(f.get(), static_cast<off_t>(pos), SEEK_SET) == 0
+           && fread(h, 1, DGRAM_HEADER, f.get()) == DGRAM_HEADER) {
+        const uint32_t extent = Word(h, 9);
+        if (extent < XTC_HEADER)
+            throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
+                                  file + ": a datagram's extent is shorter than its own header");
+        const uint64_t payload = pos + DGRAM_HEADER, end = pos + DGRAM_HEADER - XTC_HEADER + extent;
+        if (Transition(h) == TRANSITION_L1ACCEPT) {
+            Frame frame;
+            FindFrame(f.get(), payload, end, frame);
+            if (frame.width > 0) {
+                frame.file = file;
+                out.push_back(frame);
+            }
+        }
+        pos = end;
+    }
+    return out;
+}
+
+void ReadFrame(const Frame &frame, int32_t *out, std::vector<uint8_t> &scratch) {
+    const size_t npixel = static_cast<size_t>(frame.width) * frame.height;
+    scratch.resize(2 * npixel);
+    File f = Open(frame.file);
+    if (fseeko(f.get(), static_cast<off_t>(frame.offset), SEEK_SET) != 0
+        || fread(scratch.data(), 1, scratch.size(), f.get()) != scratch.size())
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
+                              frame.file + ": an image ends past the end of the file");
+    for (size_t i = 0; i < npixel; i++) {
+        uint16_t v;
+        memcpy(&v, scratch.data() + 2 * i, 2);
+        out[i] = v;
+    }
+}
+
+}  // namespace xtc
diff --git a/reader/XTC.h b/reader/XTC.h
new file mode 100644
index 000000000..8e2dcff6a
--- /dev/null
+++ b/reader/XTC.h
@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
+// SPDX-License-Identifier: GPL-3.0-only
+
+#pragma once
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+// The LCLS-I XTC container, as far as reading camera frames out of it needs: what the LCLS data
+// system (pdsdata) wrote at LCLS until 2023, and what serial-crystallography depositions from that
+// era (Rayonix at MFX and XPP) are archived as.
+//
+// A file is a sequence of datagrams. Each is a 40-byte header - the event's clock time and timestamp
+// (16 bytes, whose top bits name the transition: Configure, BeginRun, ..., L1Accept for an event),
+// an environment word, and the outermost Xtc header - followed by the Xtc's payload. An Xtc header is
+// five 32-bit words: damage, the source (two words), the type and version, and the extent, which
+// counts the header itself. A container (type Id_Xtc) holds further Xtcs one after another; anything
+// else is a leaf holding one data object. A camera image is a leaf of type Id_Frame (Camera::FrameV1):
+// width, height, bit depth and offset, 32 bits each, then the pixels row by row. Everything is
+// little-endian and uncompressed.
+//
+// A run is written as several streams (-s00, -s01, ...) by different recorders, each holding a
+// share of the events. Their order across streams is the event time, which this reader does not
+// reconstruct: stills are independent, so the streams are read one after another.
+namespace xtc {
+
+// One camera image: where its pixels start in which file.
+struct Frame {
+    std::string file;
+    uint64_t offset = 0;    // of the first pixel
+    uint32_t width = 0;
+    uint32_t height = 0;
+};
+
+// True if the path is an XTC file (or a directory holding one) - by its first datagram, not its name.
+bool CanRead(const std::string &path);
+
+// The event streams of the path: the file itself, or every XTC file in a directory, by name. The
+// "smalldata" copies (.smd.xtc) carry the events without their images and are left out.
+std::vector<std::string> CollectStreams(const std::string &path);
+
+// Every L1Accept of the file that holds a 16-bit camera image, in file order. Where an event holds
+// images from more than one camera, the largest is taken - the diffraction detector.
+std::vector<Frame> IndexFrames(const std::string &file);
+
+// Reads one image as 32-bit pixels into out (width*height values), through scratch.
+void ReadFrame(const Frame &frame, int32_t *out, std::vector<uint8_t> &scratch);
+
+}  // namespace xtc
diff --git a/rugnux/rugnux_cli.cpp b/rugnux/rugnux_cli.cpp
index 956ff62a8..09d2d711d 100644
--- a/rugnux/rugnux_cli.cpp
+++ b/rugnux/rugnux_cli.cpp
@@ -29,6 +29,7 @@
 #include "../reader/JFJochMarCCDReader.h"
 #include "../reader/JFJochSMVReader.h"
 #include "../reader/JFJochCrystFELReader.h"
+#include "../reader/JFJochXTCReader.h"
 #include "../reader/JFJochStartMessageReader.h"
 #include "BrokerFeed.h"
 #include "../writer/HDF5NXmx.h"
@@ -1730,6 +1731,7 @@ static int RunRugnux(int argc, char **argv, bool no_gpu) {
     SimulatedLive<JFJochMarCCDReader> marccd_reader;
     SimulatedLive<JFJochSMVReader> smv_reader;
     SimulatedLive<JFJochCrystFELReader> crystfel_reader;
+    SimulatedLive<JFJochXTCReader> xtc_reader;
     JFJochStartMessageReader live_reader;
     std::unique_ptr<BrokerFeed> broker_feed;
     JFJochReader *reader_ptr = nullptr;
@@ -1737,11 +1739,14 @@ static int RunRugnux(int argc, char **argv, bool no_gpu) {
     // first plausible member cannot be read throws here - and an input the program cannot read has to
     // come out as the message below, not as an unhandled exception with nothing printed at all.
     bool input_is_cbf = false, input_is_marccd = false, input_is_smv = false, input_is_crystfel = false;
+    bool input_is_xtc = false;
     try {
         input_is_crystfel = !crystfel_geometry.empty();
         input_is_cbf = !input_is_crystfel && JFJochCBFReader::CanRead(input_file);
         input_is_marccd = !input_is_cbf && JFJochMarCCDReader::CanRead(input_file);
         input_is_smv = !input_is_cbf && !input_is_marccd && JFJochSMVReader::CanRead(input_file);
+        input_is_xtc = !input_is_crystfel && !input_is_cbf && !input_is_marccd && !input_is_smv
+                       && JFJochXTCReader::CanRead(input_file);
         if (input_is_crystfel) {
             crystfel_reader.ReadFiles(input_file, crystfel_geometry);
             reader_ptr = &crystfel_reader;
@@ -1762,11 +1767,15 @@ static int RunRugnux(int argc, char **argv, bool no_gpu) {
             reader_ptr = &smv_reader;
             logger.Info("Read {} SMV images of the sweep containing {}",
                         smv_reader.GetNumberOfImages(), input_file);
+        } else if (input_is_xtc) {
+            xtc_reader.ReadFiles(input_file);
+            reader_ptr = &xtc_reader;
+            logger.Info("Read {} XTC still images from {}", xtc_reader.GetNumberOfImages(), input_file);
         } else if (std::filesystem::is_directory(input_file)) {
             // A directory is never an HDF5 master, so handing it to the HDF5 reader only buries the
             // real answer - that no one-file-per-image sweep was found in it - under a page of HDF5
             // stack output.
-            logger.Error("{} holds no CBF, marCCD or SMV sweep this program can read (a directory is "
+            logger.Error("{} holds no CBF, marCCD, SMV or XTC data this program can read (a directory is "
                          "read as the sweep of frames it holds)", input_file);
             exit(EXIT_FAILURE);
         } else if (!broker_url.empty() && !std::filesystem::exists(input_file)) {
@@ -1936,7 +1945,7 @@ static int RunRugnux(int argc, char **argv, bool no_gpu) {
                            "runs no space-group search. Use --mode mx, which makes the P1 merge the "
                            "ledger is folded from.");
         // Re-scaling reads reflections a previous run integrated, which only a _process.h5 holds.
-        if (input_is_cbf || input_is_marccd || input_is_smv || input_is_crystfel) {
+        if (input_is_cbf || input_is_marccd || input_is_smv || input_is_crystfel || input_is_xtc) {
             logger.Error("--mode scale needs the integrated reflections in a _process.h5; "
                          "a raw image sweep holds none. Run --mode mx on it first.");
             exit(EXIT_FAILURE);
@@ -3167,7 +3176,8 @@ static int RunRugnux(int argc, char **argv, bool no_gpu) {
     config.detect_beam_stop = detect_beam_stop;
     config.beam_center_check = beam_center_check;
     config.adaptive_integration_radius = adaptive_integration_radius;
-    config.counts_in_adu = input_is_smv || input_is_marccd || (input_is_crystfel && !crystfel_reader.CountsInPhotons());
+    config.counts_in_adu = input_is_smv || input_is_marccd || input_is_xtc
+                           || (input_is_crystfel && !crystfel_reader.CountsInPhotons());
     config.rotation_postrefine_geometry = rotation_postrefine_geometry;
     // Measure the spot budget from the data unless the user pinned it.
     config.measure_spot_budget = !max_spot_count_override.has_value();