feat(cli): add dev session watcher

Author: GaspardKirira

include/vix/cli/commands/run/dev/DevChangeClassifier.hpp

@@ -0,0 +1,57 @@
+/**
+ *
+ *  @file DevChangeClassifier.hpp
+ *  @author Gaspard Kirira
+ *
+ *  Copyright 2026, Gaspard Kirira.  All rights reserved.
+ *  https://github.com/vixcpp/vix
+ *  Use of this source code is governed by a MIT license
+ *  that can be found in the License file.
+ *
+ *  Vix.cpp
+ *
+ *  Dev mode file change classifier
+ *
+ */
+
+#ifndef VIX_CLI_COMMANDS_RUN_DEV_DEV_CHANGE_CLASSIFIER_HPP
+#define VIX_CLI_COMMANDS_RUN_DEV_DEV_CHANGE_CLASSIFIER_HPP
+
+#include <filesystem>
+#include <string>
+
+namespace vix::commands::RunCommand::dev
+{
+  namespace fs = std::filesystem;
+
+  enum class DevChangeKind
+  {
+    Ignore,
+    RebuildOnly,
+    ReconfigureAndRebuild
+  };
+
+  std::string to_string(DevChangeKind kind);
+
+  class DevChangeClassifier
+  {
+  public:
+    DevChangeClassifier() = default;
+
+    DevChangeKind classify(
+        const fs::path &projectDir,
+        const fs::path &changedPath) const;
+
+  private:
+    bool should_ignore_path(
+        const fs::path &projectDir,
+        const fs::path &changedPath) const;
+
+    bool is_source_file(const fs::path &path) const;
+    bool is_header_file(const fs::path &path) const;
+    bool is_config_file(const fs::path &path) const;
+  };
+
+} // namespace vix::commands::RunCommand::dev
+
+#endif // VIX_CLI_COMMANDS_RUN_DEV_DEV_CHANGE_CLASSIFIER_HPP

include/vix/cli/commands/run/dev/DevRebuilder.hpp

@@ -0,0 +1,77 @@
+/**
+ *
+ *  @file DevRebuilder.hpp
+ *  @author Gaspard Kirira
+ *
+ *  Copyright 2026, Gaspard Kirira.  All rights reserved.
+ *  https://github.com/vixcpp/vix
+ *  Use of this source code is governed by a MIT license
+ *  that can be found in the License file.
+ *
+ *  Vix.cpp
+ *
+ *  Dev mode project rebuilder
+ *
+ */
+
+#ifndef VIX_CLI_COMMANDS_RUN_DEV_DEV_REBUILDER_HPP
+#define VIX_CLI_COMMANDS_RUN_DEV_DEV_REBUILDER_HPP
+
+#include <filesystem>
+#include <string>
+
+#include <vix/cli/commands/run/RunDetail.hpp>
+
+namespace vix::commands::RunCommand::dev
+{
+  namespace fs = std::filesystem;
+  namespace detail = vix::commands::RunCommand::detail;
+
+  struct DevRebuilderOptions
+  {
+    fs::path projectDir;
+    fs::path buildDir;
+    std::string targetName;
+
+    detail::Options runOptions;
+
+    bool quiet{false};
+  };
+
+  struct DevRebuilderResult
+  {
+    bool ok{false};
+    bool configured{false};
+    bool built{false};
+
+    int exitCode{0};
+    std::string message;
+    std::string output;
+  };
+
+  class DevRebuilder
+  {
+  public:
+    explicit DevRebuilder(DevRebuilderOptions options);
+
+    const DevRebuilderOptions &options() const;
+
+    DevRebuilderResult ensure_configured() const;
+    DevRebuilderResult rebuild() const;
+    DevRebuilderResult reconfigure_and_rebuild() const;
+
+  private:
+    DevRebuilderOptions options_;
+
+    bool has_cmake_cache() const;
+
+    std::string configure_command() const;
+    std::string build_command() const;
+
+    DevRebuilderResult run_configure_command() const;
+    DevRebuilderResult run_build_command() const;
+  };
+
+} // namespace vix::commands::RunCommand::dev
+
+#endif // VIX_CLI_COMMANDS_RUN_DEV_DEV_REBUILDER_HPP

include/vix/cli/commands/run/dev/DevSession.hpp

@@ -0,0 +1,113 @@
+/**
+ *
+ *  @file DevSession.hpp
+ *  @author Gaspard Kirira
+ *
+ *  Copyright 2026, Gaspard Kirira.  All rights reserved.
+ *  https://github.com/vixcpp/vix
+ *  Use of this source code is governed by a MIT license
+ *  that can be found in the License file.
+ *
+ *  Vix.cpp
+ *
+ *  Dev mode session orchestrator
+ *
+ */
+
+#ifndef VIX_CLI_COMMANDS_RUN_DEV_DEV_SESSION_HPP
+#define VIX_CLI_COMMANDS_RUN_DEV_DEV_SESSION_HPP
+
+#include <chrono>
+#include <filesystem>
+#include <map>
+#include <string>
+#include <vector>
+
+#include <vix/cli/commands/run/RunDetail.hpp>
+#include <vix/cli/commands/run/dev/DevChangeClassifier.hpp>
+#include <vix/cli/commands/run/dev/DevRebuilder.hpp>
+
+namespace vix::commands::RunCommand::dev
+{
+  namespace fs = std::filesystem;
+  namespace detail = vix::commands::RunCommand::detail;
+
+  struct DevSessionOptions
+  {
+    fs::path projectDir;
+    fs::path buildDir;
+    std::string targetName;
+
+    detail::Options runOptions;
+
+    std::chrono::milliseconds pollInterval{300};
+    std::chrono::milliseconds debounceDelay{200};
+
+    bool quiet{false};
+  };
+
+  struct DevSessionResult
+  {
+    int exitCode{0};
+    std::string message;
+  };
+
+  struct DevFileSnapshot
+  {
+    std::map<std::string, fs::file_time_type> files;
+
+    bool empty() const;
+  };
+
+  struct DevDetectedChange
+  {
+    fs::path path;
+    DevChangeKind kind{DevChangeKind::Ignore};
+
+    bool valid() const;
+  };
+
+  class DevSession
+  {
+  public:
+    explicit DevSession(DevSessionOptions options);
+
+    const DevSessionOptions &options() const;
+
+    DevSessionResult run();
+
+  private:
+    DevSessionOptions options_;
+    DevChangeClassifier classifier_;
+    DevRebuilder rebuilder_;
+
+    DevFileSnapshot snapshot_project() const;
+
+    std::vector<DevDetectedChange> detect_changes(
+        const DevFileSnapshot &before,
+        const DevFileSnapshot &after) const;
+
+    DevChangeKind strongest_change_kind(
+        const std::vector<DevDetectedChange> &changes) const;
+
+    DevDetectedChange first_relevant_change(
+        const std::vector<DevDetectedChange> &changes) const;
+
+    DevDetectedChange wait_for_change(
+        DevFileSnapshot &snapshot) const;
+
+    int rebuild_for_change(DevChangeKind kind) const;
+
+    fs::path executable_path() const;
+
+#ifndef _WIN32
+    int run_child_once(const fs::path &exePath);
+    void stop_child(int pid) const;
+#endif
+
+    bool should_skip_directory(const fs::path &path) const;
+  };
+
+} // namespace vix::commands::RunCommand::dev
+
+#endif // VIX_CLI_COMMANDS_RUN_DEV_DEV_SESSION_HPP

src/commands/run/RunScript.cpp

@@ -22,6 +22,7 @@
 #include <vix/cli/errors/RawLogDetectors.hpp>
 #include <vix/cli/Style.hpp>
 #include <vix/utils/Env.hpp>
+#include <vix/cli/commands/run/dev/DevSession.hpp>
 
 #include <algorithm>
 #include <cerrno>
@@ -1575,6 +1576,22 @@ namespace vix::commands::RunCommand::detail
     const fs::path buildDir = projectDir / (devMode ? "build-ninja" : "build-dev");
     const std::string targetName = projectDir.filename().string();
 
+    if (devMode)
+    {
+      vix::commands::RunCommand::dev::DevSession session(
+          vix::commands::RunCommand::dev::DevSessionOptions{
+              projectDir,
+              buildDir,
+              targetName,
+              opt,
+              std::chrono::milliseconds(300),
+              std::chrono::milliseconds(200),
+              opt.quiet});
+
+      const auto result = session.run();
+      return result.exitCode;
+    }
+
     if (devMode)
     {
       info("Vix dev mode enabled.");