v0.3.7-pre.002

crates/ksp-app-backfill-desk/src/app_state.rs

@@ -0,0 +1,125 @@
+// file: crates/ksp-app-backfill-desk/src/app_state.rs
+// version: 1
+
+//! Shared backend state owned by the Backfill Desk Tauri application.
+
+/// Shared Backfill Desk application state managed by Tauri.
+pub(crate) struct AppState {
+    config_management: ksp_config_lib::ConfigManagement,
+    logging_runtime: std::sync::Mutex<LoggingRuntimeState>,
+    splash_settings: crate::SplashSettings,
+    splash_sequence_started: std::sync::atomic::AtomicBool,
+}
+
+impl crate::AppState {
+    /// Initializes the scaffold Config ownership, Logging runtime and splash settings.
+    pub(crate) fn initialize(arguments: &[std::ffi::OsString]) -> ksp_core_lib::Result<Self> {
+        let config_management = crate::config_management(arguments);
+        let config_management = match config_management {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let runtime_identity = crate::launch_identity();
+        let runtime_identity = match runtime_identity {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let logging_startup = crate::initialize_logging(&config_management, &runtime_identity);
+        let logging_startup = match logging_startup {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let splash_settings = crate::SplashSettings::load();
+        let splash_settings = match splash_settings {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => {
+                ksp_logging_lib::warn!(
+                    target: crate::TRACING_TARGET,
+                    domain = crate::TRACING_DOMAIN_WINDOWS,
+                    error_domain = error.code().domain(),
+                    error_code = error.code().code(),
+                    "managed splash timings are invalid; using transient in-memory defaults"
+                );
+                crate::SplashSettings::fallback()
+            },
+        };
+        ksp_logging_lib::debug!(
+            target: crate::TRACING_TARGET,
+            domain = crate::TRACING_DOMAIN_WINDOWS,
+            minimum_ms = splash_settings.minimum_ms(),
+            minimum_source = splash_settings.minimum_source(),
+            fade_in_ms = splash_settings.fade_in_ms(),
+            fade_in_source = splash_settings.fade_in_source(),
+            fade_out_ms = splash_settings.fade_out_ms(),
+            fade_out_source = splash_settings.fade_out_source(),
+            expected_backend_lifecycle_ms = splash_settings.expected_backend_lifecycle_ms(),
+            "resolved Backfill Desk splash timings"
+        );
+        return std::result::Result::Ok(Self {
+            config_management,
+            logging_runtime: std::sync::Mutex::new(LoggingRuntimeState {
+                guard: logging_startup.guard,
+                active_profile_id: logging_startup.active_profile_id,
+                fallback_active: logging_startup.fallback_active,
+                startup_diagnostic: logging_startup.startup_diagnostic,
+            }),
+            splash_settings,
+            splash_sequence_started: std::sync::atomic::AtomicBool::new(false),
+        });
+    }
+
+    /// Builds the safe scaffold status exposed by the Backfill Desk shell.
+    pub(crate) fn shell_status(&self) -> ksp_core_lib::Result<crate::ShellStatusDto> {
+        let document_count = self.config_management.engine().registry().descriptors().count();
+        let document_count = u32::try_from(document_count);
+        let document_count = match document_count {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => {
+                return std::result::Result::Err(
+                    ksp_core_lib::Error::new(crate::ERROR_CODE_APP_STATE_INVALID, "Config registry count cannot be represented by Backfill Desk")
+                        .with_source(error),
+                );
+            },
+        };
+        let runtime = self.logging_runtime.lock();
+        let runtime = match runtime {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(_) => {
+                return std::result::Result::Err(ksp_core_lib::Error::new(
+                    crate::ERROR_CODE_APP_STATE_LOCK_FAILED,
+                    "Backfill Desk Logging runtime state lock is poisoned",
+                ));
+            },
+        };
+        let _keep_guard_alive = &runtime.guard;
+        return std::result::Result::Ok(crate::ShellStatusDto {
+            active_logging_profile: runtime.active_profile_id.clone(),
+            application_version: env!("CARGO_PKG_VERSION").to_owned(),
+            config_document_count: document_count,
+            fallback_logging_active: runtime.fallback_active,
+            shell_phase: "pre.002-desktop-scaffold".to_owned(),
+            startup_diagnostic: runtime.startup_diagnostic.clone(),
+        });
+    }
+
+    /// Returns the resolved splash timings captured during application bootstrap.
+    #[must_use]
+    pub(crate) const fn splash_settings(&self) -> crate::SplashSettings {
+        return self.splash_settings;
+    }
+
+    /// Marks the one-shot splash lifecycle as started and reports whether this caller won the transition.
+    pub(crate) fn begin_splash_sequence(&self) -> bool {
+        return self
+            .splash_sequence_started
+            .compare_exchange(false, true, std::sync::atomic::Ordering::AcqRel, std::sync::atomic::Ordering::Acquire)
+            .is_ok();
+    }
+}
+
+struct LoggingRuntimeState {
+    guard: ksp_logging_lib::LoggingGuard,
+    active_profile_id: std::option::Option<String>,
+    fallback_active: bool,
+    startup_diagnostic: std::option::Option<crate::CommandErrorDto>,
+}

crates/ksp-app-backfill-desk/src/bootstrap.rs

@@ -0,0 +1,146 @@
+// file: crates/ksp-app-backfill-desk/src/bootstrap.rs
+// version: 1
+
+//! Config and Logging bootstrap for the Backfill Desk scaffold.
+
+/// Crate-internal Logging startup state shared by the application state.
+pub(crate) struct LoggingStartup {
+    /// Guard that keeps the installed Logging runtime alive.
+    pub(crate) guard: ksp_logging_lib::LoggingGuard,
+    /// Active managed profile when Config resolved one successfully.
+    pub(crate) active_profile_id: std::option::Option<String>,
+    /// Whether a transient in-memory fallback was installed.
+    pub(crate) fallback_active: bool,
+    /// Safe startup diagnostic retained for the shell.
+    pub(crate) startup_diagnostic: std::option::Option<crate::CommandErrorDto>,
+}
+
+enum LoggingStartupPlan {
+    Managed {
+        active_profile_id: String,
+        settings: ksp_logging_lib::LoggingSettings,
+    },
+    Fallback {
+        initial_error: ksp_core_lib::Error,
+        diagnostic: crate::CommandErrorDto,
+        settings: ksp_logging_lib::LoggingSettings,
+    },
+}
+
+/// Builds the Config management facade from the common KSP CLI bootstrap contract.
+pub(crate) fn config_management(arguments: &[std::ffi::OsString]) -> ksp_core_lib::Result<ksp_config_lib::ConfigManagement> {
+    let bootstrap = ksp_config_lib::ConfigBootstrapOptions::from_args(arguments);
+    let bootstrap = match bootstrap {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return std::result::Result::Err(error),
+    };
+    let registry = ksp_config_lib::ConfigFileRegistry::from_args(arguments);
+    let registry = match registry {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return std::result::Result::Err(error),
+    };
+    let engine = ksp_config_lib::ConfigDocumentEngine::new(bootstrap, registry);
+    return std::result::Result::Ok(ksp_config_lib::ConfigManagement::new(engine));
+}
+
+/// Initializes Logging from the standard managed Config document, with the common Desk fallback policy.
+pub(crate) fn initialize_logging(
+    management: &ksp_config_lib::ConfigManagement,
+    runtime_identity: &ksp_logging_lib::LoggingRuntimeIdentity,
+) -> ksp_core_lib::Result<crate::LoggingStartup> {
+    let plan = resolve_logging_startup(management);
+    return match plan {
+        LoggingStartupPlan::Managed { active_profile_id, settings } => {
+            let guard = ksp_logging_lib::initialize_with_identity(&settings, runtime_identity);
+            match guard {
+                std::result::Result::Ok(guard) => {
+                    ksp_logging_lib::info!(
+                        target: crate::TRACING_TARGET,
+                        domain = crate::TRACING_DOMAIN_BOOTSTRAP,
+                        active_profile = active_profile_id.as_str(),
+                        "initialized Backfill Desk logging from managed configuration"
+                    );
+                    std::result::Result::Ok(LoggingStartup {
+                        guard,
+                        active_profile_id: std::option::Option::Some(active_profile_id),
+                        fallback_active: false,
+                        startup_diagnostic: std::option::Option::None,
+                    })
+                },
+                std::result::Result::Err(error) => initialize_fallback_logging(error, runtime_identity),
+            }
+        },
+        LoggingStartupPlan::Fallback { initial_error, diagnostic, settings } => {
+            initialize_planned_fallback_logging(initial_error, diagnostic, settings, runtime_identity)
+        },
+    };
+}
+
+fn fallback_logging_settings() -> ksp_logging_lib::LoggingSettings {
+    return ksp_logging_lib::LoggingSettings::new(
+        ksp_logging_lib::LogFilterLevel::Info,
+        ksp_logging_lib::SpanEvents::Off,
+        std::option::Option::Some(ksp_logging_lib::ConsoleSettings::stderr()),
+        std::vec::Vec::new(),
+    );
+}
+
+fn resolve_logging_startup(management: &ksp_config_lib::ConfigManagement) -> LoggingStartupPlan {
+    let environment = ksp_config_lib::ConfigEnvironment::load();
+    let environment = match environment {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return fallback_startup_plan(error),
+    };
+    let resolved = management.engine().load_resolved_logging_config(std::option::Option::None, &environment);
+    let resolved = match resolved {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return fallback_startup_plan(error),
+    };
+    return LoggingStartupPlan::Managed { active_profile_id: resolved.profile_id().to_owned(), settings: resolved.into_settings() };
+}
+
+fn fallback_startup_plan(initial_error: ksp_core_lib::Error) -> LoggingStartupPlan {
+    let diagnostic = crate::CommandErrorDto::from_error(&initial_error);
+    return LoggingStartupPlan::Fallback { initial_error, diagnostic, settings: fallback_logging_settings() };
+}
+
+fn initialize_fallback_logging(
+    initial_error: ksp_core_lib::Error,
+    runtime_identity: &ksp_logging_lib::LoggingRuntimeIdentity,
+) -> ksp_core_lib::Result<crate::LoggingStartup> {
+    let diagnostic = crate::CommandErrorDto::from_error(&initial_error);
+    return initialize_planned_fallback_logging(initial_error, diagnostic, fallback_logging_settings(), runtime_identity);
+}
+
+fn initialize_planned_fallback_logging(
+    initial_error: ksp_core_lib::Error,
+    diagnostic: crate::CommandErrorDto,
+    settings: ksp_logging_lib::LoggingSettings,
+    runtime_identity: &ksp_logging_lib::LoggingRuntimeIdentity,
+) -> ksp_core_lib::Result<crate::LoggingStartup> {
+    let guard = ksp_logging_lib::initialize_with_identity(&settings, runtime_identity);
+    let guard = match guard {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(fallback_error) => {
+            return std::result::Result::Err(
+                ksp_core_lib::Error::new(crate::ERROR_CODE_LOGGING_BOOTSTRAP_FAILED, "Cannot initialize Backfill Desk fallback Logging runtime")
+                    .with_context("initial_error_domain", initial_error.code().domain())
+                    .with_context("initial_error_code", initial_error.code().code())
+                    .with_source(fallback_error),
+            );
+        },
+    };
+    ksp_logging_lib::warn!(
+        target: crate::TRACING_TARGET,
+        domain = crate::TRACING_DOMAIN_BOOTSTRAP,
+        error_domain = diagnostic.domain.as_str(),
+        error_code = diagnostic.code.as_str(),
+        "managed Logging configuration is unavailable; using transient in-memory fallback"
+    );
+    return std::result::Result::Ok(LoggingStartup {
+        guard,
+        active_profile_id: std::option::Option::None,
+        fallback_active: true,
+        startup_diagnostic: std::option::Option::Some(diagnostic),
+    });
+}

crates/ksp-app-backfill-desk/src/constants.rs

@@ -0,0 +1,21 @@
+// file: crates/ksp-app-backfill-desk/src/constants.rs
+// version: 1
+
+//! Application-owned tracing targets and domains.
+
+/// Structured domain used while bootstrapping Config and Logging.
+pub(crate) const TRACING_DOMAIN_BOOTSTRAP: &str = "backfill.bootstrap";
+/// Structured domain used by technical frontend events.
+pub(crate) const TRACING_DOMAIN_FRONTEND: &str = "frontend";
+/// Structured domain used by the Backfill Desk shell.
+pub(crate) const TRACING_DOMAIN_SHELL: &str = "backfill.shell";
+/// Structured domain used by Tauri window lifecycle operations.
+pub(crate) const TRACING_DOMAIN_WINDOWS: &str = "desktop.window";
+/// Owning target for backend events emitted by Backfill Desk.
+pub(crate) const TRACING_TARGET: &str = "ksp-app-backfill-desk";
+/// Owning target for generic frontend events emitted through the KSP bridge.
+pub(crate) const TRACING_TARGET_FRONTEND: &str = "ksp-app-backfill-desk.frontend";
+/// Owning target for main-window frontend events.
+pub(crate) const TRACING_TARGET_FRONTEND_MAIN: &str = "ksp-app-backfill-desk.frontend.main";
+/// Owning target for splash-window frontend events.
+pub(crate) const TRACING_TARGET_FRONTEND_SPLASH: &str = "ksp-app-backfill-desk.frontend.splash";

crates/ksp-app-backfill-desk/src/dto_common.rs

@@ -0,0 +1,54 @@
+// file: crates/ksp-app-backfill-desk/src/dto_common.rs
+// version: 1
+
+//! Common Tauri DTOs shared by the Backfill Desk shell.
+
+use ts_rs::TS; // rust-rules: trait-import
+
+/// Safe command error projection that never serializes arbitrary KSP error context or source values.
+#[derive(Clone, Debug, serde::Serialize, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export, export_to = "../frontend/ts/bindings/ksp_app_backfill_desk/dto_common/CommandErrorDto.ts")]
+pub(crate) struct CommandErrorDto {
+    /// Stable KSP error domain.
+    pub(crate) domain: String,
+    /// Stable KSP error code within the domain.
+    pub(crate) code: String,
+    /// Human-readable error message without arbitrary context fields.
+    pub(crate) message: String,
+}
+
+impl crate::CommandErrorDto {
+    /// Builds a bounded safe projection from a KSP error.
+    #[must_use]
+    pub(crate) fn from_error(error: &ksp_core_lib::Error) -> Self {
+        return Self {
+            domain: error.code().domain().to_owned(),
+            code: error.code().code().to_owned(),
+            message: error.message().to_owned(),
+        };
+    }
+}
+
+/// Safe scaffold/runtime snapshot exposed to the Backfill Desk shell.
+#[derive(Clone, Debug, serde::Serialize, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export, export_to = "../frontend/ts/bindings/ksp_app_backfill_desk/dto_common/ShellStatusDto.ts")]
+pub(crate) struct ShellStatusDto {
+    /// Active configured Logging profile, or `None` while transient fallback Logging is active.
+    pub(crate) active_logging_profile: std::option::Option<String>,
+    /// Cargo application version.
+    pub(crate) application_version: String,
+    /// Number of logical Config resources registered by the current runtime.
+    pub(crate) config_document_count: u32,
+    /// Whether Backfill Desk had to install its transient in-memory Logging fallback.
+    pub(crate) fallback_logging_active: bool,
+    /// Current implementation phase exposed by the shell.
+    pub(crate) shell_phase: String,
+    /// Safe startup diagnostic that caused fallback Logging, when applicable.
+    pub(crate) startup_diagnostic: std::option::Option<CommandErrorDto>,
+}
+
+#[cfg(test)]
+#[path = "../unit_tests/dto_common.rs"]
+mod tests;

crates/ksp-app-backfill-desk/src/errors.rs

@@ -0,0 +1,26 @@
+// file: crates/ksp-app-backfill-desk/src/errors.rs
+// version: 1
+
+//! Application-local error codes for Backfill Desk composition and desktop runtime surfaces.
+
+/// Shared Backfill Desk runtime state is internally inconsistent.
+pub(crate) const ERROR_CODE_APP_STATE_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "app_state_invalid");
+/// Shared Backfill Desk runtime state cannot be locked safely.
+pub(crate) const ERROR_CODE_APP_STATE_LOCK_FAILED: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "app_state_lock_failed");
+/// Frontend logging requested an unsupported level.
+pub(crate) const ERROR_CODE_FRONTEND_LOG_LEVEL_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "frontend_log_level_invalid");
+/// Frontend logging requested a target outside the application whitelist.
+pub(crate) const ERROR_CODE_FRONTEND_LOG_TARGET_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "frontend_log_target_invalid");
+/// Backfill Desk could not install the managed Logging runtime or its safe fallback.
+pub(crate) const ERROR_CODE_LOGGING_BOOTSTRAP_FAILED: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "logging_bootstrap_failed");
+/// Splash readiness was invoked from a window other than the splash window.
+pub(crate) const ERROR_CODE_SPLASH_ORIGIN_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "splash_origin_invalid");
+/// A KSP desk splash environment duration is malformed or exceeds its safety bound.
+pub(crate) const ERROR_CODE_SPLASH_SETTING_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "splash_setting_invalid");
+/// Tauri runtime assembly or execution failed.
+pub(crate) const ERROR_CODE_TAURI_RUNTIME_FAILED: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "tauri_runtime_failed");
+/// A required Tauri window is missing from the configured application runtime.
+pub(crate) const ERROR_CODE_TAURI_WINDOW_MISSING: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("backfill_desk", "tauri_window_missing");
+/// A Tauri window show/focus/destroy/event operation failed.
+pub(crate) const ERROR_CODE_TAURI_WINDOW_OPERATION_FAILED: ksp_core_lib::ErrorCode =
+    ksp_core_lib::ErrorCode::new("backfill_desk", "tauri_window_operation_failed");

crates/ksp-app-backfill-desk/src/frontend_logging.rs

@@ -0,0 +1,205 @@
+// file: crates/ksp-app-backfill-desk/src/frontend_logging.rs
+// version: 1
+
+//! KSP-owned bridge for technical log events emitted by Backfill Desk frontend scripts.
+
+use ts_rs::TS; // rust-rules: trait-import
+
+/// Log payload sent by Backfill Desk frontend scripts.
+#[derive(Clone, Debug, serde::Deserialize, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export, export_to = "../frontend/ts/bindings/ksp_app_backfill_desk/frontend_logging/FrontendLogPayloadDto.ts")]
+pub(crate) struct FrontendLogPayloadDto {
+    /// Lowercase KSP log level.
+    pub(crate) level: String,
+    /// Whitelisted logical frontend target identifier.
+    pub(crate) target_id: String,
+    /// Rendered technical frontend message.
+    pub(crate) message: String,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+enum FrontendLogLevel {
+    Trace,
+    Debug,
+    Info,
+    Warn,
+    Error,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+enum FrontendLogTarget {
+    Frontend,
+    Main,
+    Splash,
+}
+
+/// Emits one validated frontend event through the KSP Logging facade.
+pub(crate) fn emit_frontend_log_event(payload: FrontendLogPayloadDto) -> ksp_core_lib::Result<()> {
+    let level = parse_level(payload.level.as_str());
+    let level = match level {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return std::result::Result::Err(error),
+    };
+    let target = parse_target(payload.target_id.as_str());
+    let target = match target {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return std::result::Result::Err(error),
+    };
+    emit_validated_frontend_log(level, target, payload.message.as_str());
+    return std::result::Result::Ok(());
+}
+
+fn parse_level(level: &str) -> ksp_core_lib::Result<FrontendLogLevel> {
+    return match level.trim().to_ascii_lowercase().as_str() {
+        "trace" => std::result::Result::Ok(FrontendLogLevel::Trace),
+        "debug" => std::result::Result::Ok(FrontendLogLevel::Debug),
+        "info" => std::result::Result::Ok(FrontendLogLevel::Info),
+        "warn" => std::result::Result::Ok(FrontendLogLevel::Warn),
+        "error" => std::result::Result::Ok(FrontendLogLevel::Error),
+        _ => std::result::Result::Err(ksp_core_lib::Error::new(crate::ERROR_CODE_FRONTEND_LOG_LEVEL_INVALID, "Frontend log level is not supported")),
+    };
+}
+
+fn parse_target(target_id: &str) -> ksp_core_lib::Result<FrontendLogTarget> {
+    return match target_id.trim().to_ascii_lowercase().as_str() {
+        "frontend" => std::result::Result::Ok(FrontendLogTarget::Frontend),
+        "main" => std::result::Result::Ok(FrontendLogTarget::Main),
+        "splash" => std::result::Result::Ok(FrontendLogTarget::Splash),
+        _ => {
+            std::result::Result::Err(ksp_core_lib::Error::new(crate::ERROR_CODE_FRONTEND_LOG_TARGET_INVALID, "Frontend log target identifier is not supported"))
+        },
+    };
+}
+
+fn emit_validated_frontend_log(level: FrontendLogLevel, target: FrontendLogTarget, message: &str) {
+    return match target {
+        FrontendLogTarget::Frontend => emit_frontend_target(level, message),
+        FrontendLogTarget::Main => emit_main_target(level, message),
+        FrontendLogTarget::Splash => emit_splash_target(level, message),
+    };
+}
+
+fn emit_frontend_target(level: FrontendLogLevel, message: &str) {
+    return match level {
+        FrontendLogLevel::Trace => ksp_logging_lib::trace!(
+            target: crate::TRACING_TARGET_FRONTEND,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "frontend",
+            "{message}"
+        ),
+        FrontendLogLevel::Debug => ksp_logging_lib::debug!(
+            target: crate::TRACING_TARGET_FRONTEND,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "frontend",
+            "{message}"
+        ),
+        FrontendLogLevel::Info => ksp_logging_lib::info!(
+            target: crate::TRACING_TARGET_FRONTEND,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "frontend",
+            "{message}"
+        ),
+        FrontendLogLevel::Warn => ksp_logging_lib::warn!(
+            target: crate::TRACING_TARGET_FRONTEND,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "frontend",
+            "{message}"
+        ),
+        FrontendLogLevel::Error => ksp_logging_lib::error!(
+            target: crate::TRACING_TARGET_FRONTEND,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "frontend",
+            "{message}"
+        ),
+    };
+}
+
+fn emit_main_target(level: FrontendLogLevel, message: &str) {
+    return match level {
+        FrontendLogLevel::Trace => ksp_logging_lib::trace!(
+            target: crate::TRACING_TARGET_FRONTEND_MAIN,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "main",
+            "{message}"
+        ),
+        FrontendLogLevel::Debug => ksp_logging_lib::debug!(
+            target: crate::TRACING_TARGET_FRONTEND_MAIN,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "main",
+            "{message}"
+        ),
+        FrontendLogLevel::Info => ksp_logging_lib::info!(
+            target: crate::TRACING_TARGET_FRONTEND_MAIN,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "main",
+            "{message}"
+        ),
+        FrontendLogLevel::Warn => ksp_logging_lib::warn!(
+            target: crate::TRACING_TARGET_FRONTEND_MAIN,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "main",
+            "{message}"
+        ),
+        FrontendLogLevel::Error => ksp_logging_lib::error!(
+            target: crate::TRACING_TARGET_FRONTEND_MAIN,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "main",
+            "{message}"
+        ),
+    };
+}
+
+fn emit_splash_target(level: FrontendLogLevel, message: &str) {
+    return match level {
+        FrontendLogLevel::Trace => ksp_logging_lib::trace!(
+            target: crate::TRACING_TARGET_FRONTEND_SPLASH,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "splash",
+            "{message}"
+        ),
+        FrontendLogLevel::Debug => ksp_logging_lib::debug!(
+            target: crate::TRACING_TARGET_FRONTEND_SPLASH,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "splash",
+            "{message}"
+        ),
+        FrontendLogLevel::Info => ksp_logging_lib::info!(
+            target: crate::TRACING_TARGET_FRONTEND_SPLASH,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "splash",
+            "{message}"
+        ),
+        FrontendLogLevel::Warn => ksp_logging_lib::warn!(
+            target: crate::TRACING_TARGET_FRONTEND_SPLASH,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "splash",
+            "{message}"
+        ),
+        FrontendLogLevel::Error => ksp_logging_lib::error!(
+            target: crate::TRACING_TARGET_FRONTEND_SPLASH,
+            domain = crate::TRACING_DOMAIN_FRONTEND,
+            action = "frontend_log",
+            target_id = "splash",
+            "{message}"
+        ),
+    };
+}
+
+#[cfg(test)]
+#[path = "../unit_tests/frontend_logging.rs"]
+mod tests;

crates/ksp-app-backfill-desk/src/lib.rs

@@ -0,0 +1,90 @@
+// file: crates/ksp-app-backfill-desk/src/lib.rs
+// version: 1
+
+//! Tauri desktop application scaffold for controlling and inspecting KSP RAW backfill jobs.
+
+#![forbid(unsafe_code)]
+#![deny(unreachable_pub)]
+#![warn(missing_docs)]
+
+mod app_state;
+mod bootstrap;
+mod constants;
+mod dto_common;
+mod errors;
+mod frontend_logging;
+mod logging_runtime;
+mod splash;
+mod tauri;
+mod tw_main;
+mod tw_splash;
+
+/// Runs the KSP Backfill desktop application.
+pub use self::tauri::run;
+
+/// Shared Backfill Desk application state managed by Tauri.
+pub(crate) use self::app_state::AppState;
+/// Crate-internal Logging startup state shared by the application state.
+pub(crate) use self::bootstrap::LoggingStartup;
+/// Builds the Config management facade from the common KSP CLI bootstrap contract.
+pub(crate) use self::bootstrap::config_management;
+/// Initializes the scaffold Logging runtime from standard Config, with a bounded in-memory fallback.
+pub(crate) use self::bootstrap::initialize_logging;
+/// Structured domain used while bootstrapping Config and Logging.
+pub(crate) use self::constants::TRACING_DOMAIN_BOOTSTRAP;
+/// Structured domain used by technical frontend events.
+pub(crate) use self::constants::TRACING_DOMAIN_FRONTEND;
+/// Structured domain used by the Backfill Desk shell.
+pub(crate) use self::constants::TRACING_DOMAIN_SHELL;
+/// Structured domain used by Tauri window lifecycle operations.
+pub(crate) use self::constants::TRACING_DOMAIN_WINDOWS;
+/// Owning target for backend events emitted by Backfill Desk.
+pub(crate) use self::constants::TRACING_TARGET;
+/// Owning target for generic frontend events emitted through the KSP bridge.
+pub(crate) use self::constants::TRACING_TARGET_FRONTEND;
+/// Owning target for main-window frontend events.
+pub(crate) use self::constants::TRACING_TARGET_FRONTEND_MAIN;
+/// Owning target for splash-window frontend events.
+pub(crate) use self::constants::TRACING_TARGET_FRONTEND_SPLASH;
+/// Safe command error projection exposed to Tauri commands.
+pub(crate) use self::dto_common::CommandErrorDto;
+/// Safe scaffold/runtime snapshot exposed to the shell.
+pub(crate) use self::dto_common::ShellStatusDto;
+/// Shared Backfill Desk runtime state is internally inconsistent.
+pub(crate) use self::errors::ERROR_CODE_APP_STATE_INVALID;
+/// Shared Backfill Desk runtime state cannot be locked safely.
+pub(crate) use self::errors::ERROR_CODE_APP_STATE_LOCK_FAILED;
+/// Frontend logging requested an unsupported level.
+pub(crate) use self::errors::ERROR_CODE_FRONTEND_LOG_LEVEL_INVALID;
+/// Frontend logging requested a target outside the application whitelist.
+pub(crate) use self::errors::ERROR_CODE_FRONTEND_LOG_TARGET_INVALID;
+/// Backfill Desk could not install the managed Logging runtime or its safe fallback.
+pub(crate) use self::errors::ERROR_CODE_LOGGING_BOOTSTRAP_FAILED;
+/// Splash readiness was invoked from a window other than the splash window.
+pub(crate) use self::errors::ERROR_CODE_SPLASH_ORIGIN_INVALID;
+/// A KSP desk splash environment duration is malformed or exceeds its safety bound.
+pub(crate) use self::errors::ERROR_CODE_SPLASH_SETTING_INVALID;
+/// Tauri runtime assembly or execution failed.
+pub(crate) use self::errors::ERROR_CODE_TAURI_RUNTIME_FAILED;
+/// A required Tauri window is missing from the configured application runtime.
+pub(crate) use self::errors::ERROR_CODE_TAURI_WINDOW_MISSING;
+/// A Tauri window show/focus/destroy/event operation failed.
+pub(crate) use self::errors::ERROR_CODE_TAURI_WINDOW_OPERATION_FAILED;
+/// Log payload sent by Backfill Desk frontend scripts.
+pub(crate) use self::frontend_logging::FrontendLogPayloadDto;
+/// Emits one validated frontend event through the KSP Logging facade.
+pub(crate) use self::frontend_logging::emit_frontend_log_event;
+/// Creates the stable runtime identity for this Backfill Desk process launch.
+pub(crate) use self::logging_runtime::launch_identity;
+/// Command emitted by Rust to the splash frontend.
+pub(crate) use self::splash::SplashOrderDto;
+/// Runtime timings used by the common desk splash lifecycle.
+pub(crate) use self::splash::SplashSettings;
+/// Resolves the required main window or returns a typed error.
+pub(crate) use self::tw_main::require_main_window;
+/// Shows and focuses the main Backfill Desk window.
+pub(crate) use self::tw_main::show_main_window;
+/// Resolves the required splash window or returns a typed error.
+pub(crate) use self::tw_splash::require_splash_window;
+/// Starts the one-shot splash lifecycle after the splash frontend reports readiness.
+pub(crate) use self::tw_splash::splash_frontend_ready_service;

crates/ksp-app-backfill-desk/src/logging_runtime.rs

@@ -0,0 +1,10 @@
+// file: crates/ksp-app-backfill-desk/src/logging_runtime.rs
+// version: 1
+
+//! Backfill Desk Logging runtime identity helpers.
+
+/// Creates the stable runtime identity for this Backfill Desk process launch.
+pub(crate) fn launch_identity() -> ksp_core_lib::Result<ksp_logging_lib::LoggingRuntimeIdentity> {
+    let timestamp = format!("{}-p{}", chrono::Utc::now().format("%Y%m%d-%H%M%S%.3fZ"), std::process::id());
+    return ksp_logging_lib::LoggingRuntimeIdentity::new(crate::TRACING_TARGET, timestamp);
+}

crates/ksp-app-backfill-desk/src/main.rs

@@ -0,0 +1,58 @@
+// file: crates/ksp-app-backfill-desk/src/main.rs
+// version: 1
+
+//! Binary entry point for the KSP Backfill desktop application.
+
+#![forbid(unsafe_code)]
+#![deny(unreachable_pub)]
+#![warn(missing_docs)]
+#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
+
+use fs2::FileExt; // rust-rules: trait-import
+
+fn main() -> std::process::ExitCode {
+    let working_directory = configure_runtime_working_directory();
+    if let std::result::Result::Err(error) = working_directory {
+        eprintln!("cannot configure Backfill Desk runtime working directory: {error}");
+        return std::process::ExitCode::FAILURE;
+    }
+    let mut lock_path = std::env::temp_dir();
+    lock_path.push("com_sasedev_ksp_app_backfill_desk.lock");
+    let lock_file = match std::fs::OpenOptions::new().read(true).write(true).create(true).truncate(false).open(&lock_path) {
+        std::result::Result::Ok(file) => file,
+        std::result::Result::Err(error) => {
+            eprintln!("cannot create application lock '{}': {error}", lock_path.display());
+            return std::process::ExitCode::FAILURE;
+        },
+    };
+    if let std::result::Result::Err(error) = lock_file.try_lock_exclusive() {
+        if error.kind() == std::io::ErrorKind::WouldBlock {
+            eprintln!("another ksp-app-backfill-desk instance is already running");
+            return std::process::ExitCode::FAILURE;
+        }
+        eprintln!("cannot acquire application lock '{}': {error}", lock_path.display());
+        return std::process::ExitCode::FAILURE;
+    }
+    let _lock_file = lock_file;
+    let arguments = std::env::args_os().collect::<std::vec::Vec<std::ffi::OsString>>();
+    let run_result = ksp_app_backfill_desk_lib::run(arguments.as_slice());
+    return match run_result {
+        std::result::Result::Ok(()) => std::process::ExitCode::SUCCESS,
+        std::result::Result::Err(error) => {
+            eprintln!("application error: {error}");
+            std::process::ExitCode::FAILURE
+        },
+    };
+}
+
+fn configure_runtime_working_directory() -> std::io::Result<()> {
+    #[cfg(debug_assertions)]
+    {
+        let workspace_root = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("../..");
+        return std::env::set_current_dir(workspace_root);
+    }
+    #[cfg(not(debug_assertions))]
+    {
+        return std::result::Result::Ok(());
+    }
+}

crates/ksp-app-backfill-desk/src/splash.rs

@@ -0,0 +1,214 @@
+// file: crates/ksp-app-backfill-desk/src/splash.rs
+// version: 1
+
+//! Common splash settings and frontend event contracts for Backfill Desk.
+
+use ts_rs::TS; // rust-rules: trait-import
+
+const DEFAULT_SPLASH_FADE_IN_MS: u32 = 300;
+const DEFAULT_SPLASH_FADE_OUT_MS: u32 = 300;
+const DEFAULT_SPLASH_MINIMUM_MS: u64 = 1200;
+const ENV_SPLASH_FADE_IN_MS: &str = "KSP_DESK_SPLASH_FADE_IN_MS";
+const ENV_SPLASH_FADE_OUT_MS: &str = "KSP_DESK_SPLASH_FADE_OUT_MS";
+const ENV_SPLASH_MINIMUM_MS: &str = "KSP_DESK_SPLASH_MINIMUM_MS";
+const MAX_SPLASH_FADE_MS: u32 = 10_000;
+const MAX_SPLASH_MINIMUM_MS: u64 = 60_000;
+
+/// Runtime timings used by the common desk splash lifecycle.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub(crate) struct SplashSettings {
+    fade_in_ms: u32,
+    minimum_ms: u64,
+    fade_out_ms: u32,
+    fade_in_source: ksp_config_lib::ConfigEnvironmentSource,
+    minimum_source: ksp_config_lib::ConfigEnvironmentSource,
+    fade_out_source: ksp_config_lib::ConfigEnvironmentSource,
+}
+
+impl SplashSettings {
+    /// Resolves splash timings through the Config-owned environment snapshot.
+    pub(crate) fn load() -> ksp_core_lib::Result<Self> {
+        let environment = ksp_config_lib::ConfigEnvironment::load();
+        let environment = match environment {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let fade_in = environment.resolve_variable(ENV_SPLASH_FADE_IN_MS, std::option::Option::Some("300"));
+        let fade_in = match fade_in {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let minimum = environment.resolve_variable(ENV_SPLASH_MINIMUM_MS, std::option::Option::Some("1200"));
+        let minimum = match minimum {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let fade_out = environment.resolve_variable(ENV_SPLASH_FADE_OUT_MS, std::option::Option::Some("300"));
+        let fade_out = match fade_out {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let fade_in_ms = parse_u32_setting(ENV_SPLASH_FADE_IN_MS, fade_in.value(), MAX_SPLASH_FADE_MS);
+        let fade_in_ms = match fade_in_ms {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let minimum_ms = parse_u64_setting(ENV_SPLASH_MINIMUM_MS, minimum.value(), MAX_SPLASH_MINIMUM_MS);
+        let minimum_ms = match minimum_ms {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        let fade_out_ms = parse_u32_setting(ENV_SPLASH_FADE_OUT_MS, fade_out.value(), MAX_SPLASH_FADE_MS);
+        let fade_out_ms = match fade_out_ms {
+            std::result::Result::Ok(value) => value,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        return std::result::Result::Ok(Self {
+            fade_in_ms,
+            minimum_ms,
+            fade_out_ms,
+            fade_in_source: fade_in.source(),
+            minimum_source: minimum.source(),
+            fade_out_source: fade_out.source(),
+        });
+    }
+
+    /// Returns safe in-memory timings used when the managed environment cannot be resolved.
+    #[must_use]
+    pub(crate) const fn fallback() -> Self {
+        return Self {
+            fade_in_ms: DEFAULT_SPLASH_FADE_IN_MS,
+            minimum_ms: DEFAULT_SPLASH_MINIMUM_MS,
+            fade_out_ms: DEFAULT_SPLASH_FADE_OUT_MS,
+            fade_in_source: ksp_config_lib::ConfigEnvironmentSource::Fallback,
+            minimum_source: ksp_config_lib::ConfigEnvironmentSource::Fallback,
+            fade_out_source: ksp_config_lib::ConfigEnvironmentSource::Fallback,
+        };
+    }
+
+    /// Returns the configured fade-in duration.
+    #[must_use]
+    pub(crate) const fn fade_in_ms(self) -> u32 {
+        return self.fade_in_ms;
+    }
+
+    /// Returns the minimum fully-visible splash duration.
+    #[must_use]
+    pub(crate) const fn minimum_ms(self) -> u64 {
+        return self.minimum_ms;
+    }
+
+    /// Returns the configured fade-out duration.
+    #[must_use]
+    pub(crate) const fn fade_out_ms(self) -> u32 {
+        return self.fade_out_ms;
+    }
+
+    /// Returns the safe provenance code for the fade-in duration.
+    #[must_use]
+    pub(crate) const fn fade_in_source(self) -> &'static str {
+        return environment_source_code(self.fade_in_source);
+    }
+
+    /// Returns the safe provenance code for the minimum duration.
+    #[must_use]
+    pub(crate) const fn minimum_source(self) -> &'static str {
+        return environment_source_code(self.minimum_source);
+    }
+
+    /// Returns the safe provenance code for the fade-out duration.
+    #[must_use]
+    pub(crate) const fn fade_out_source(self) -> &'static str {
+        return environment_source_code(self.fade_out_source);
+    }
+
+    /// Returns the expected additive backend lifecycle from readiness through fade-out.
+    #[must_use]
+    pub(crate) fn expected_backend_lifecycle_ms(self) -> u64 {
+        return u64::from(self.fade_in_ms) + self.minimum_ms + u64::from(self.fade_out_ms);
+    }
+}
+
+/// Command emitted by Rust to the splash frontend.
+#[derive(Clone, Debug, serde::Serialize, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export, export_to = "../frontend/ts/bindings/ksp_app_backfill_desk/splash/SplashOrderDto.ts")]
+pub(crate) struct SplashOrderDto {
+    /// Splash action name.
+    pub(crate) action: String,
+    /// Optional status text.
+    pub(crate) message: std::option::Option<String>,
+    /// Optional message severity used by the bottom message feed.
+    pub(crate) status: std::option::Option<String>,
+    /// Optional animation duration in milliseconds.
+    pub(crate) duration_ms: std::option::Option<u32>,
+}
+
+impl SplashOrderDto {
+    /// Creates a new `SplashOrderDto` value.
+    #[must_use]
+    pub(crate) fn new(action: &str, message: std::option::Option<&str>, status: std::option::Option<&str>, duration_ms: std::option::Option<u32>) -> Self {
+        return Self {
+            action: action.to_owned(),
+            message: message.map(std::string::ToString::to_string),
+            status: status.map(std::string::ToString::to_string),
+            duration_ms,
+        };
+    }
+}
+
+const fn environment_source_code(source: ksp_config_lib::ConfigEnvironmentSource) -> &'static str {
+    return match source {
+        ksp_config_lib::ConfigEnvironmentSource::Process => "process",
+        ksp_config_lib::ConfigEnvironmentSource::DotEnv => "dotenv",
+        ksp_config_lib::ConfigEnvironmentSource::Fallback => "fallback",
+    };
+}
+
+fn parse_u64_setting(variable_name: &str, value: &str, maximum: u64) -> ksp_core_lib::Result<u64> {
+    let parsed = value.parse::<u64>();
+    let parsed = match parsed {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => {
+            return std::result::Result::Err(
+                ksp_core_lib::Error::new(crate::ERROR_CODE_SPLASH_SETTING_INVALID, "KSP desk splash duration is not a valid unsigned integer")
+                    .with_context("variable_name", variable_name)
+                    .with_source(error),
+            );
+        },
+    };
+    if parsed > maximum {
+        return std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_SPLASH_SETTING_INVALID, "KSP desk splash duration exceeds the allowed bound")
+                .with_context("variable_name", variable_name)
+                .with_context("maximum_ms", maximum.to_string()),
+        );
+    }
+    return std::result::Result::Ok(parsed);
+}
+
+fn parse_u32_setting(variable_name: &str, value: &str, maximum: u32) -> ksp_core_lib::Result<u32> {
+    let parsed = value.parse::<u32>();
+    let parsed = match parsed {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => {
+            return std::result::Result::Err(
+                ksp_core_lib::Error::new(crate::ERROR_CODE_SPLASH_SETTING_INVALID, "KSP desk splash duration is not a valid unsigned integer")
+                    .with_context("variable_name", variable_name)
+                    .with_source(error),
+            );
+        },
+    };
+    if parsed > maximum {
+        return std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_SPLASH_SETTING_INVALID, "KSP desk splash duration exceeds the allowed bound")
+                .with_context("variable_name", variable_name)
+                .with_context("maximum_ms", maximum.to_string()),
+        );
+    }
+    return std::result::Result::Ok(parsed);
+}
+
+#[cfg(test)]
+#[path = "../unit_tests/splash.rs"]
+mod tests;

crates/ksp-app-backfill-desk/src/tauri.rs

@@ -0,0 +1,99 @@
+// file: crates/ksp-app-backfill-desk/src/tauri.rs
+// version: 1
+
+//! Tauri runtime assembly for the KSP Backfill desktop application.
+
+/// Runs the Backfill desktop application.
+#[cfg_attr(mobile, tauri::mobile_entry_point)]
+pub fn run(arguments: &[std::ffi::OsString]) -> ksp_core_lib::Result<()> {
+    let app_state = crate::AppState::initialize(arguments);
+    let app_state = match app_state {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return std::result::Result::Err(error),
+    };
+    let mut builder = tauri::Builder::default();
+    builder = configure_state(builder, app_state);
+    builder = configure_plugins(builder);
+    builder = configure_commands(builder);
+    builder = configure_setup(builder);
+    let run_result = builder.run(tauri::generate_context!());
+    return match run_result {
+        std::result::Result::Ok(()) => std::result::Result::Ok(()),
+        std::result::Result::Err(error) => std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_TAURI_RUNTIME_FAILED, "Cannot run KSP Backfill Desk Tauri runtime")
+                .with_context("tauri_error", error.to_string()),
+        ),
+    };
+}
+
+fn configure_state(builder: tauri::Builder<tauri::Wry>, app_state: crate::AppState) -> tauri::Builder<tauri::Wry> {
+    return builder.manage(app_state);
+}
+
+fn configure_plugins(builder: tauri::Builder<tauri::Wry>) -> tauri::Builder<tauri::Wry> {
+    let tracing_plugin = tauri_plugin_tracing::Builder::new().build::<tauri::Wry>();
+    return builder.plugin(tracing_plugin);
+}
+
+#[allow(clippy::question_mark_used)] // Tauri generates the question-mark operator internally for async command dispatch.
+fn configure_commands(builder: tauri::Builder<tauri::Wry>) -> tauri::Builder<tauri::Wry> {
+    return builder.invoke_handler(tauri::generate_handler![emit_frontend_log, get_runtime_status, splash_frontend_ready]);
+}
+
+fn configure_setup(builder: tauri::Builder<tauri::Wry>) -> tauri::Builder<tauri::Wry> {
+    return builder.setup(|app| {
+        let splash = crate::require_splash_window(app);
+        if let std::result::Result::Err(error) = splash {
+            return std::result::Result::Err(std::boxed::Box::new(error));
+        }
+        let main = crate::require_main_window(app);
+        if let std::result::Result::Err(error) = main {
+            return std::result::Result::Err(std::boxed::Box::new(error));
+        }
+        ksp_logging_lib::debug!(target: crate::TRACING_TARGET, domain = crate::TRACING_DOMAIN_SHELL, "Backfill Desk Tauri shell setup completed");
+        return std::result::Result::Ok(());
+    });
+}
+
+fn project_command_error(command: &'static str, domain: &'static str, error: &ksp_core_lib::Error) -> crate::CommandErrorDto {
+    ksp_logging_lib::warn!(
+        target: crate::TRACING_TARGET,
+        domain = domain,
+        command = command,
+        error_domain = error.code().domain(),
+        error_code = error.code().code(),
+        "Backfill Desk Tauri command failed"
+    );
+    return crate::CommandErrorDto::from_error(error);
+}
+
+#[tauri::command]
+fn emit_frontend_log(payload: crate::FrontendLogPayloadDto) -> std::result::Result<(), crate::CommandErrorDto> {
+    let result = crate::emit_frontend_log_event(payload);
+    return match result {
+        std::result::Result::Ok(()) => std::result::Result::Ok(()),
+        std::result::Result::Err(error) => std::result::Result::Err(project_command_error("emit_frontend_log", crate::TRACING_DOMAIN_FRONTEND, &error)),
+    };
+}
+
+#[tauri::command]
+fn get_runtime_status(state: tauri::State<'_, crate::AppState>) -> std::result::Result<crate::ShellStatusDto, crate::CommandErrorDto> {
+    let result = state.shell_status();
+    return match result {
+        std::result::Result::Ok(value) => std::result::Result::Ok(value),
+        std::result::Result::Err(error) => std::result::Result::Err(project_command_error("get_runtime_status", crate::TRACING_DOMAIN_SHELL, &error)),
+    };
+}
+
+#[tauri::command]
+async fn splash_frontend_ready(
+    app: tauri::AppHandle,
+    webview_window: tauri::WebviewWindow,
+    state: tauri::State<'_, crate::AppState>,
+) -> std::result::Result<(), crate::CommandErrorDto> {
+    let result = crate::splash_frontend_ready_service(app, webview_window, &state).await;
+    return match result {
+        std::result::Result::Ok(()) => std::result::Result::Ok(()),
+        std::result::Result::Err(error) => std::result::Result::Err(project_command_error("splash_frontend_ready", crate::TRACING_DOMAIN_WINDOWS, &error)),
+    };
+}

crates/ksp-app-backfill-desk/src/tw_main.rs

@@ -0,0 +1,53 @@
+// file: crates/ksp-app-backfill-desk/src/tw_main.rs
+// version: 1
+
+//! Tauri-window helpers for the Backfill Desk main window.
+
+use tauri::Manager; // rust-rules: trait-import
+
+/// Crate-internal `WINDOW_LABEL_MAIN` constant.
+pub(crate) const WINDOW_LABEL_MAIN: &str = "main";
+
+/// Resolves the required main window or returns a typed error.
+pub(crate) fn require_main_window(manager: &impl Manager<tauri::Wry>) -> ksp_core_lib::Result<tauri::WebviewWindow> {
+    let window = manager.get_webview_window(WINDOW_LABEL_MAIN);
+    return match window {
+        std::option::Option::Some(value) => std::result::Result::Ok(value),
+        std::option::Option::None => std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_TAURI_WINDOW_MISSING, "Backfill Desk main window is missing")
+                .with_context("window_label", WINDOW_LABEL_MAIN),
+        ),
+    };
+}
+
+/// Shows main window.
+pub(crate) fn show_main_window(app: &tauri::AppHandle) -> ksp_core_lib::Result<()> {
+    let window = crate::require_main_window(app);
+    let window = match window {
+        std::result::Result::Ok(value) => value,
+        std::result::Result::Err(error) => return std::result::Result::Err(error),
+    };
+    let shown = window.show();
+    if let std::result::Result::Err(error) = shown {
+        return std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_TAURI_WINDOW_OPERATION_FAILED, "Cannot show Backfill Desk main window")
+                .with_context("window_label", WINDOW_LABEL_MAIN)
+                .with_source(error),
+        );
+    }
+    let focused = window.set_focus();
+    if let std::result::Result::Err(error) = focused {
+        return std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_TAURI_WINDOW_OPERATION_FAILED, "Cannot focus Backfill Desk main window")
+                .with_context("window_label", WINDOW_LABEL_MAIN)
+                .with_source(error),
+        );
+    }
+    ksp_logging_lib::debug!(
+        target: crate::TRACING_TARGET,
+        domain = crate::TRACING_DOMAIN_WINDOWS,
+        window_label = WINDOW_LABEL_MAIN,
+        "main window shown and focused"
+    );
+    return std::result::Result::Ok(());
+}

crates/ksp-app-backfill-desk/src/tw_splash.rs

@@ -0,0 +1,173 @@
+// file: crates/ksp-app-backfill-desk/src/tw_splash.rs
+// version: 1
+
+//! Tauri-window lifecycle for the Backfill Desk splash window.
+
+use tauri::Emitter; // rust-rules: trait-import
+use tauri::Manager; // rust-rules: trait-import
+
+/// Crate-internal splash window label.
+pub(crate) const WINDOW_LABEL_SPLASH: &str = "splash";
+
+const SPLASH_EVENT_NAME: &str = "ksp-splash-order";
+
+/// Resolves the required splash window or returns a typed error.
+pub(crate) fn require_splash_window(manager: &impl Manager<tauri::Wry>) -> ksp_core_lib::Result<tauri::WebviewWindow> {
+    let window = manager.get_webview_window(WINDOW_LABEL_SPLASH);
+    return match window {
+        std::option::Option::Some(value) => std::result::Result::Ok(value),
+        std::option::Option::None => std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_TAURI_WINDOW_MISSING, "Backfill Desk splash window is missing")
+                .with_context("window_label", WINDOW_LABEL_SPLASH),
+        ),
+    };
+}
+
+/// Starts the one-shot splash lifecycle after the splash frontend reports readiness.
+pub(crate) async fn splash_frontend_ready_service(
+    app: tauri::AppHandle,
+    invoking_window: tauri::WebviewWindow,
+    state: &crate::AppState,
+) -> ksp_core_lib::Result<()> {
+    if invoking_window.label() != WINDOW_LABEL_SPLASH {
+        return std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_SPLASH_ORIGIN_INVALID, "Splash readiness may only originate from the splash window")
+                .with_context("window_label", invoking_window.label()),
+        );
+    }
+    if !state.begin_splash_sequence() {
+        ksp_logging_lib::trace!(target: crate::TRACING_TARGET, domain = crate::TRACING_DOMAIN_WINDOWS, window_label = WINDOW_LABEL_SPLASH, "duplicate splash frontend readiness ignored");
+        return std::result::Result::Ok(());
+    }
+    let settings = state.splash_settings();
+    let lifecycle_started = std::time::Instant::now();
+    ksp_logging_lib::debug!(
+        target: crate::TRACING_TARGET,
+        domain = crate::TRACING_DOMAIN_WINDOWS,
+        window_label = WINDOW_LABEL_SPLASH,
+        fade_in_ms = settings.fade_in_ms(),
+        fade_in_source = settings.fade_in_source(),
+        minimum_ms = settings.minimum_ms(),
+        minimum_source = settings.minimum_source(),
+        fade_out_ms = settings.fade_out_ms(),
+        fade_out_source = settings.fade_out_source(),
+        expected_backend_lifecycle_ms = settings.expected_backend_lifecycle_ms(),
+        "splash frontend readiness accepted; starting splash to main lifecycle"
+    );
+    let emitted = emit_order(
+        &invoking_window,
+        crate::SplashOrderDto::new("fade_in", std::option::Option::None, std::option::Option::None, std::option::Option::Some(settings.fade_in_ms())),
+    );
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    let emitted = emit_message(&invoking_window, "Initialisation de Backfill Desk...", "info");
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    let emitted = emit_debug(&invoking_window, "Listener frontend prêt; fade-in piloté par Rust.");
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    sleep_and_log(&invoking_window, "fade-in", u64::from(settings.fade_in_ms()), lifecycle_started).await;
+    let emitted = emit_message(&invoking_window, "Configuration KSP chargée.", "success");
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    let emitted = emit_debug(&invoking_window, "Configuration et provenance des timings résolues via ksp-config-lib.");
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    let emitted = emit_message(&invoking_window, "Runtime Logging initialisé.", "success");
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    let emitted = emit_message(&invoking_window, "Scaffold desktop prêt.", "success");
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    sleep_and_log(&invoking_window, "minimum", settings.minimum_ms(), lifecycle_started).await;
+    let emitted = emit_message(&invoking_window, "Initialisation terminée.", "success");
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    let emitted = emit_order(
+        &invoking_window,
+        crate::SplashOrderDto::new("fade_out", std::option::Option::None, std::option::Option::None, std::option::Option::Some(settings.fade_out_ms())),
+    );
+    if let std::result::Result::Err(error) = emitted {
+        return std::result::Result::Err(error);
+    }
+    sleep_and_log(&invoking_window, "fade-out", u64::from(settings.fade_out_ms()), lifecycle_started).await;
+    let show_main = crate::show_main_window(&app);
+    if let std::result::Result::Err(error) = show_main {
+        return std::result::Result::Err(error);
+    }
+    let destroyed = invoking_window.destroy();
+    if let std::result::Result::Err(error) = destroyed {
+        return std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_TAURI_WINDOW_OPERATION_FAILED, "Cannot destroy Backfill Desk splash window")
+                .with_context("window_label", WINDOW_LABEL_SPLASH)
+                .with_source(error),
+        );
+    }
+    ksp_logging_lib::debug!(
+        target: crate::TRACING_TARGET,
+        domain = crate::TRACING_DOMAIN_WINDOWS,
+        window_label = WINDOW_LABEL_SPLASH,
+        expected_backend_lifecycle_ms = settings.expected_backend_lifecycle_ms(),
+        actual_backend_lifecycle_ms = lifecycle_started.elapsed().as_secs_f64() * 1000.0,
+        "splash window destroyed after main activation"
+    );
+    return std::result::Result::Ok(());
+}
+
+fn emit_message(window: &tauri::WebviewWindow, message: &str, status: &str) -> ksp_core_lib::Result<()> {
+    return emit_order(
+        window,
+        crate::SplashOrderDto::new("add_message", std::option::Option::Some(message), std::option::Option::Some(status), std::option::Option::None),
+    );
+}
+
+fn emit_debug(window: &tauri::WebviewWindow, message: &str) -> ksp_core_lib::Result<()> {
+    if !cfg!(debug_assertions) {
+        return std::result::Result::Ok(());
+    }
+    return emit_order(
+        window,
+        crate::SplashOrderDto::new("add_debug", std::option::Option::Some(message), std::option::Option::None, std::option::Option::None),
+    );
+}
+
+async fn sleep_and_log(window: &tauri::WebviewWindow, phase: &str, duration_ms: u64, lifecycle_started: std::time::Instant) {
+    let wait_started = std::time::Instant::now();
+    tokio::time::sleep(std::time::Duration::from_millis(duration_ms)).await;
+    ksp_logging_lib::debug!(
+        target: crate::TRACING_TARGET,
+        domain = crate::TRACING_DOMAIN_WINDOWS,
+        window_label = window.label(),
+        phase,
+        configured_wait_ms = duration_ms,
+        actual_wait_ms = wait_started.elapsed().as_secs_f64() * 1000.0,
+        lifecycle_elapsed_ms = lifecycle_started.elapsed().as_secs_f64() * 1000.0,
+        "splash lifecycle wait completed"
+    );
+    return;
+}
+
+fn emit_order(window: &tauri::WebviewWindow, order: crate::SplashOrderDto) -> ksp_core_lib::Result<()> {
+    let action = order.action.clone();
+    let emitted = window.emit(SPLASH_EVENT_NAME, order);
+    return match emitted {
+        std::result::Result::Ok(()) => {
+            ksp_logging_lib::trace!(target: crate::TRACING_TARGET, domain = crate::TRACING_DOMAIN_WINDOWS, window_label = WINDOW_LABEL_SPLASH, action = action.as_str(), "splash order emitted");
+            std::result::Result::Ok(())
+        },
+        std::result::Result::Err(error) => std::result::Result::Err(
+            ksp_core_lib::Error::new(crate::ERROR_CODE_TAURI_WINDOW_OPERATION_FAILED, "Cannot emit Backfill Desk splash order")
+                .with_context("window_label", WINDOW_LABEL_SPLASH)
+                .with_context("action", action)
+                .with_source(error),
+        ),
+    };
+}