feat(slash): fondation du système de commandes slash pour la CLI custom — #162 (QA verte)

Introduit le contrat unifié des commandes slash consommable par le frontend,
indépendant de la source (native, puis plugin plus tard) :

- domain: modèle pur SlashCommand / SlashCommandSource / SlashCommandAvailability,
  métadonnées UI (nom, description, disponibilité, confirmation requise) et
  validation des noms/préfixes.
- application: registry + list/filter par préfixe + plan d'exécution natif ;
  commandes natives /help et /clean (/clean = nettoyage de la vue de session
  courante ; pas de /reset distinct tant qu'aucune utilité produit ne le justifie).
- backend + app-tauri: exposition du contrat via DTO/transport + tests DTO.

Source neutre : les commandes contribuées par plugins (#165) transiteront par
le même registry sans changer le contrat frontend.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/app-tauri/src/chat.rs

@@ -93,6 +93,16 @@ impl ChatBridge {
         self.inner.scrollback(session)
     }
 
+    /// Clears only the retained conversation scrollback for a live session,
+    /// keeping any currently attached channel in place.
+    ///
+    /// Returns the number of chunks removed. This powers `/clean`: the frontend
+    /// clears its mounted view from the command response, and future re-attaches
+    /// no longer replay the old conversation.
+    pub fn clear_scrollback(&self, session: &SessionId) -> usize {
+        self.inner.clear_scrollback(session)
+    }
+
     /// Removes a session's transport state **and** its retained scrollback
     /// unconditionally (chat cell explicitly closed). Twin of
     /// [`PtyBridge::unregister`](crate::pty::PtyBridge::unregister).

crates/app-tauri/src/commands.rs

@@ -15,21 +15,23 @@ use application::{
     AppError, AssignSkillToAgentInput, AttachLiveAgentInput, ChangeAgentProfileInput,
     CloseProjectInput, CreateAgentInput, CreateLayoutInput, CreateMemoryInput, CreateSkillInput,
     DeleteAgentInput, DeleteEmbedderProfileInput, DeleteLayoutInput, DeleteMemoryInput,
-    DeleteSkillInput, DeleteTemplateInput, DetectAgentDriftInput, GetMemoryInput,
-    GetProjectSystemPermissionsInput, GetProjectWorkStateInput, GitBranchesInput, GitCheckoutInput,
-    GitCommitInput, GitGraphInput, GitInitInput, GitLogInput, GitStagePathInput, GitStatusInput,
-    InspectConversationInput, LaunchAgentInput, ListAgentsInput, ListDevicesInput,
-    ListLayoutsInput, ListMemoriesInput, ListResumableAgentsInput, ListSkillsInput, LiveSessions,
-    LoadLayoutInput, McpRuntime, MutateLayoutInput, OpenPluginLayoutWindowInput, OpenProjectInput,
-    ReadAgentContextInput, ReadConversationPageInput, ReadMcpToolPermissionsInput,
-    ReadMemoryIndexInput, ReadProjectContextInput, RecallMemoryInput, ReconcileLayoutsInput,
-    ReconcileLiveStateInput, RenameDeviceInput, RenameLayoutInput, ResolveAgentPermissionsInput,
+    DeleteSkillInput, DeleteTemplateInput, DetectAgentDriftInput, ExecuteSlashCommandInput,
+    GetMemoryInput, GetProjectSystemPermissionsInput, GetProjectWorkStateInput, GitBranchesInput,
+    GitCheckoutInput, GitCommitInput, GitGraphInput, GitInitInput, GitLogInput, GitStagePathInput,
+    GitStatusInput, InspectConversationInput, LaunchAgentInput, ListAgentsInput, ListDevicesInput,
+    ListLayoutsInput, ListMemoriesInput, ListResumableAgentsInput, ListSkillsInput,
+    ListSlashCommandsInput, LiveSessions, LoadLayoutInput, McpRuntime, MutateLayoutInput,
+    OpenPluginLayoutWindowInput, OpenProjectInput, ReadAgentContextInput,
+    ReadConversationPageInput, ReadMcpToolPermissionsInput, ReadMemoryIndexInput,
+    ReadProjectContextInput, RecallMemoryInput, ReconcileLayoutsInput, ReconcileLiveStateInput,
+    RenameDeviceInput, RenameLayoutInput, ResolveAgentPermissionsInput,
     ResolveAgentSystemPermissionsInput, ResolveMemoryLinksInput, RevokeDeviceInput,
-    RotateConversationLogInput, SetActiveLayoutInput, SnapshotRunningAgentsInput,
-    StopLiveAgentInput, SyncAgentWithTemplateInput, UnassignSkillFromAgentInput,
-    UpdateAgentContextInput, UpdateAgentEffortInput, UpdateAgentMcpToolPermissionsInput,
-    UpdateAgentPermissionsInput, UpdateAgentSystemPermissionsInput, UpdateMemoryInput,
-    UpdateProjectContextInput, UpdateProjectMcpToolPermissionsInput, UpdateProjectPermissionsInput,
+    RotateConversationLogInput, SetActiveLayoutInput, SlashCommandEffect,
+    SnapshotRunningAgentsInput, StopLiveAgentInput, SyncAgentWithTemplateInput,
+    UnassignSkillFromAgentInput, UpdateAgentContextInput, UpdateAgentEffortInput,
+    UpdateAgentMcpToolPermissionsInput, UpdateAgentPermissionsInput,
+    UpdateAgentSystemPermissionsInput, UpdateMemoryInput, UpdateProjectContextInput,
+    UpdateProjectMcpToolPermissionsInput, UpdateProjectPermissionsInput,
     UpdateProjectSystemPermissionsInput, UpdateSkillInput,
 };
 use backend::stream::OutputSink;
@@ -51,7 +53,8 @@ use crate::dto::{
     CreateProjectRequestDto, CreateSkillRequestDto, CreateTemplateRequestDto,
     DeleteLayoutRequestDto, DeleteLayoutResultDto, DeliveredDelegationRequestDto,
     DetectProfilesRequestDto, DetectProfilesResponseDto, EmbedderEnginesDto, EmbedderProfileDto,
-    EmbedderProfileListDto, ErrorDto, FirstRunStateDto, FrontAttachedRequestDto, GitBranchesDto,
+    EmbedderProfileListDto, ErrorDto, ExecuteSlashCommandRequestDto,
+    ExecuteSlashCommandResponseDto, FirstRunStateDto, FrontAttachedRequestDto, GitBranchesDto,
     GitCheckoutRequestDto, GitCommitDto, GitCommitListDto, GitCommitRequestDto, GitStageRequestDto,
     GitStatusListDto, GraphCommitListDto, HealthRequestDto, HealthResponseDto,
     ImportChatAttachmentsRequestDto, ImportChatAttachmentsResponseDto,
@@ -68,12 +71,12 @@ use crate::dto::{
     ResolvedAgentSystemPermissionsDto, ResumableAgentListDto, SaveEmbedderProfileRequestDto,
     SaveModelServerRequestDto, SaveOpenCodeProviderProfileRequestDto, SaveProfileRequestDto,
     SetActiveLayoutRequestDto, SetActiveLayoutResultDto, SkillDto, SkillListDto,
-    StopLiveAgentRequestDto, StopLiveAgentResponseDto, SyncAgentWithTemplateRequestDto,
-    SyncResultDto, TemplateDto, TemplateListDto, TerminalClosedDto, TerminalSessionDto,
-    TurnPageDto, UnassignSkillRequestDto, UpdateAgentContextRequestDto,
-    UpdateAgentEffortRequestDto, UpdateAgentMcpToolPermissionsRequestDto,
-    UpdateAgentPermissionsRequestDto, UpdateAgentSystemPermissionsRequestDto,
-    UpdateMemoryRequestDto, UpdateProjectContextRequestDto,
+    SlashCommandEffectDto, SlashCommandListDto, StopLiveAgentRequestDto, StopLiveAgentResponseDto,
+    SyncAgentWithTemplateRequestDto, SyncResultDto, TemplateDto, TemplateListDto,
+    TerminalClosedDto, TerminalSessionDto, TurnPageDto, UnassignSkillRequestDto,
+    UpdateAgentContextRequestDto, UpdateAgentEffortRequestDto,
+    UpdateAgentMcpToolPermissionsRequestDto, UpdateAgentPermissionsRequestDto,
+    UpdateAgentSystemPermissionsRequestDto, UpdateMemoryRequestDto, UpdateProjectContextRequestDto,
     UpdateProjectMcpToolPermissionsRequestDto, UpdateProjectPermissionsRequestDto,
     UpdateProjectSystemPermissionsRequestDto, UpdateSkillRequestDto, UpdateTemplateRequestDto,
     WriteTerminalRequestDto,
@@ -105,6 +108,69 @@ pub fn health(
         .map_err(ErrorDto::from)
 }
 
+/// `list_slash_commands` — list/filter the unified slash-command registry.
+#[tauri::command]
+pub fn list_slash_commands(
+    request: Option<crate::dto::ListSlashCommandsRequestDto>,
+    state: State<'_, AppState>,
+) -> SlashCommandListDto {
+    let request = request.unwrap_or_default();
+    state
+        .list_slash_commands
+        .execute(ListSlashCommandsInput {
+            prefix: request.prefix,
+        })
+        .into()
+}
+
+/// `execute_slash_command` — execute a selected slash command.
+///
+/// # Errors
+/// Returns an [`ErrorDto`] (`INVALID` for unavailable commands/missing context,
+/// `NOT_FOUND` for unknown commands or closed sessions).
+#[tauri::command]
+pub fn execute_slash_command(
+    request: ExecuteSlashCommandRequestDto,
+    state: State<'_, AppState>,
+) -> Result<ExecuteSlashCommandResponseDto, ErrorDto> {
+    let session_id = request
+        .session_id
+        .as_deref()
+        .map(parse_session_id)
+        .transpose()?;
+    let output = state
+        .execute_slash_command
+        .execute(ExecuteSlashCommandInput {
+            name: request.name,
+            session_id,
+        })
+        .map_err(ErrorDto::from)?;
+
+    let effect = match output.effect {
+        SlashCommandEffect::Help { commands } => SlashCommandEffectDto::Help { commands },
+        SlashCommandEffect::CleanConversation { session_id } => {
+            if state.structured_sessions.session(&session_id).is_none() {
+                return Err(ErrorDto::from(AppError::NotFound(format!(
+                    "structured session {session_id}"
+                ))));
+            }
+            let cleared_chunks = state.chat_bridge.clear_scrollback(&session_id);
+            SlashCommandEffectDto::CleanConversation {
+                session_id: session_id.to_string(),
+                cleared_chunks,
+            }
+        }
+        SlashCommandEffect::ProfileSwitch { session_id } => SlashCommandEffectDto::ProfileSwitch {
+            session_id: session_id.to_string(),
+        },
+    };
+
+    Ok(ExecuteSlashCommandResponseDto {
+        command: output.command,
+        effect,
+    })
+}
+
 /// `get_server_exposure_settings` — read persisted embedded-server exposure settings.
 ///
 /// # Errors

crates/app-tauri/src/lib.rs

@@ -248,6 +248,8 @@ pub fn run() {
         })
         .invoke_handler(tauri::generate_handler![
             commands::health,
+            commands::list_slash_commands,
+            commands::execute_slash_command,
             commands::create_project,
             commands::open_project,
             commands::close_project,

crates/app-tauri/tests/dto.rs

@@ -3,13 +3,19 @@
 //! its tagged, camelCase JSON shape.
 
 use app_tauri_lib::dto::{
-    parse_node_id, parse_session_id, ErrorDto, HealthRequestDto, HealthResponseDto, LayoutDto,
+    parse_node_id, parse_session_id, ErrorDto, ExecuteSlashCommandRequestDto,
+    ExecuteSlashCommandResponseDto, HealthRequestDto, HealthResponseDto, LayoutDto,
     LayoutOperationDto, OpenTerminalRequestDto, ReattachResultDto, ResizeTerminalRequestDto,
-    TerminalClosedDto, WriteTerminalRequestDto,
+    SlashCommandEffectDto, SlashCommandListDto, TerminalClosedDto, WriteTerminalRequestDto,
 };
 use app_tauri_lib::events::{DomainEventDto, DOMAIN_EVENT};
-use application::{CloseTerminalOutput, LayoutOperation, LoadLayoutOutput, OpenTerminalInput};
-use domain::{Direction, LayoutNode, LayoutTree, LeafCell, NodeId, PreferredView};
+use application::{
+    CloseTerminalOutput, ExecuteSlashCommandOutput, LayoutOperation, ListSlashCommandsOutput,
+    LoadLayoutOutput, OpenTerminalInput, SlashCommandEffect,
+};
+use domain::{
+    native_slash_commands, Direction, LayoutNode, LayoutTree, LeafCell, NodeId, PreferredView,
+};
 
 use application::{AppError, HealthInput};
 use domain::events::DomainEvent;
@@ -52,6 +58,73 @@ fn health_request_deserialises_camel_case_and_defaults() {
     assert_eq!(HealthInput::from(empty).note, None);
 }
 
+#[test]
+fn slash_command_list_dto_serialises_unified_metadata() {
+    let dto = SlashCommandListDto::from(ListSlashCommandsOutput {
+        commands: native_slash_commands(),
+    });
+    let v = serde_json::to_value(&dto).unwrap();
+
+    assert_eq!(v["commands"][0]["name"], "/help");
+    assert_eq!(v["commands"][0]["source"], "native");
+    assert_eq!(v["commands"][0]["native"], "help");
+    assert_eq!(
+        v["commands"][0]["availability"],
+        json!({ "status": "available" })
+    );
+    assert_eq!(v["commands"][1]["name"], "/clean");
+    assert!(v["commands"][2]["requiresConfirmation"].as_bool().unwrap());
+    assert_eq!(v["commands"][2]["availability"]["status"], "unavailable");
+    assert!(v.get("requires_confirmation").is_none());
+}
+
+#[test]
+fn slash_command_execute_request_deserialises_camelcase_session() {
+    let session_id = Uuid::from_u128(123).to_string();
+    let dto: ExecuteSlashCommandRequestDto =
+        serde_json::from_value(json!({ "name": "clean", "sessionId": session_id })).unwrap();
+
+    assert_eq!(dto.name, "clean");
+    assert_eq!(dto.session_id.as_deref(), Some(session_id.as_str()));
+}
+
+#[test]
+fn slash_command_execute_response_serialises_effect_shape() {
+    let session_id = SessionId::from_uuid(Uuid::from_u128(456));
+    let command = native_slash_commands()
+        .into_iter()
+        .find(|command| command.name == "/clean")
+        .unwrap();
+    let dto = ExecuteSlashCommandResponseDto::from(ExecuteSlashCommandOutput {
+        command,
+        effect: SlashCommandEffect::CleanConversation { session_id },
+    });
+    let v = serde_json::to_value(&dto).unwrap();
+
+    assert_eq!(v["command"]["name"], "/clean");
+    assert_eq!(
+        v["effect"],
+        json!({
+            "kind": "cleanConversation",
+            "sessionId": session_id.to_string(),
+            "clearedChunks": 0
+        })
+    );
+    assert!(v["effect"].get("cleared_chunks").is_none());
+}
+
+#[test]
+fn slash_command_help_effect_carries_command_metadata() {
+    let dto = SlashCommandEffectDto::Help {
+        commands: native_slash_commands(),
+    };
+    let v = serde_json::to_value(&dto).unwrap();
+
+    assert_eq!(v["kind"], "help");
+    assert_eq!(v["commands"][0]["name"], "/help");
+    assert_eq!(v["commands"][1]["name"], "/clean");
+}
+
 #[test]
 fn error_dto_carries_stable_code_and_message() {
     let dto = ErrorDto::from(AppError::NotFound("project".into()));

crates/application/src/lib.rs

@@ -32,6 +32,7 @@ pub mod plugin;
 pub mod project;
 pub mod remote;
 pub mod skill;
+pub mod slash_command;
 pub mod sprints;
 pub mod system_permissions;
 pub mod template;
@@ -194,6 +195,10 @@ pub use skill::{
     ResolveAgentCapabilitiesInput, UnassignSkillFromAgent, UnassignSkillFromAgentInput,
     UpdateSkill, UpdateSkillInput, UpdateSkillOutput,
 };
+pub use slash_command::{
+    ExecuteSlashCommand, ExecuteSlashCommandInput, ExecuteSlashCommandOutput, ListSlashCommands,
+    ListSlashCommandsInput, ListSlashCommandsOutput, SlashCommandEffect, SlashCommandRegistry,
+};
 pub use sprints::{
     normalized_reorder, AssignTicketToSprint, AssignTicketToSprintInput,
     AssignTicketToSprintOutput, CreateSprint, CreateSprintInput, CreateSprintOutput, DeleteSprint,

crates/application/src/slash_command.rs

@@ -0,0 +1,256 @@
+//! Slash-command registry and native execution planning.
+//!
+//! The registry is transport-neutral and can later receive plugin-provided
+//! commands without changing the frontend-facing list/filter contract.
+
+use domain::{
+    filter_slash_commands, native_slash_commands, NativeSlashCommand, SessionId, SlashCommand,
+    SlashCommandAvailability,
+};
+
+use crate::AppError;
+
+/// Lists slash commands.
+#[derive(Debug, Clone, Default)]
+pub struct ListSlashCommandsInput {
+    /// Optional typed prefix, with or without the leading `/`.
+    pub prefix: Option<String>,
+}
+
+/// Slash-command list output.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ListSlashCommandsOutput {
+    /// Filtered commands in deterministic UI order.
+    pub commands: Vec<SlashCommand>,
+}
+
+/// Executes a native slash command.
+#[derive(Debug, Clone)]
+pub struct ExecuteSlashCommandInput {
+    /// Command name, with or without the leading `/`.
+    pub name: String,
+    /// Current structured chat session, required by conversation-local commands.
+    pub session_id: Option<SessionId>,
+}
+
+/// Execution output: application decides intent; adapters perform transport-only
+/// side effects when needed.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ExecuteSlashCommandOutput {
+    /// Canonical command name.
+    pub command: SlashCommand,
+    /// Planned effect.
+    pub effect: SlashCommandEffect,
+}
+
+/// Native command effects understood by driving adapters and the UI.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum SlashCommandEffect {
+    /// Return the unified command list.
+    Help {
+        /// Commands to display.
+        commands: Vec<SlashCommand>,
+    },
+    /// Clear one live structured conversation.
+    CleanConversation {
+        /// Session whose retained conversation view must be cleared.
+        session_id: SessionId,
+    },
+    /// Placeholder for ticket #164.
+    ProfileSwitch {
+        /// Session whose agent/profile flow is targeted.
+        session_id: SessionId,
+    },
+}
+
+/// In-memory slash-command registry.
+#[derive(Debug, Clone, Default)]
+pub struct SlashCommandRegistry {
+    plugin_commands: Vec<SlashCommand>,
+}
+
+impl SlashCommandRegistry {
+    /// Creates an empty registry with IdeA native commands.
+    #[must_use]
+    pub const fn new() -> Self {
+        Self {
+            plugin_commands: Vec::new(),
+        }
+    }
+
+    /// Returns all commands from all sources in deterministic order.
+    #[must_use]
+    pub fn all(&self) -> Vec<SlashCommand> {
+        let mut commands = native_slash_commands();
+        commands.extend(self.plugin_commands.clone());
+        commands
+    }
+
+    /// Returns commands filtered by prefix.
+    #[must_use]
+    pub fn list(&self, input: ListSlashCommandsInput) -> ListSlashCommandsOutput {
+        ListSlashCommandsOutput {
+            commands: filter_slash_commands(self.all(), input.prefix.as_deref()),
+        }
+    }
+
+    /// Plans execution for a command.
+    ///
+    /// # Errors
+    /// Returns [`AppError::NotFound`] for an unknown command, [`AppError::Invalid`]
+    /// for unavailable commands or missing command-local context.
+    pub fn execute(
+        &self,
+        input: ExecuteSlashCommandInput,
+    ) -> Result<ExecuteSlashCommandOutput, AppError> {
+        let name = normalize_command_name(&input.name)?;
+        let command = self
+            .all()
+            .into_iter()
+            .find(|command| command.name == name)
+            .ok_or_else(|| AppError::NotFound(format!("slash command {name}")))?;
+        if let SlashCommandAvailability::Unavailable { reason } = &command.availability {
+            return Err(AppError::Invalid(format!(
+                "slash command {name} unavailable: {reason}"
+            )));
+        }
+
+        let Some(native) = command.native else {
+            return Err(AppError::Invalid(format!(
+                "slash command {name} has no executable adapter"
+            )));
+        };
+        let effect = match native {
+            NativeSlashCommand::Help => SlashCommandEffect::Help {
+                commands: self.all(),
+            },
+            NativeSlashCommand::Clean => SlashCommandEffect::CleanConversation {
+                session_id: input.session_id.ok_or_else(|| {
+                    AppError::Invalid("/clean requires a current session id".to_owned())
+                })?,
+            },
+            NativeSlashCommand::Profile => SlashCommandEffect::ProfileSwitch {
+                session_id: input.session_id.ok_or_else(|| {
+                    AppError::Invalid("/profile requires a current session id".to_owned())
+                })?,
+            },
+        };
+
+        Ok(ExecuteSlashCommandOutput { command, effect })
+    }
+}
+
+fn normalize_command_name(name: &str) -> Result<String, AppError> {
+    let trimmed = name.trim();
+    if trimmed.is_empty() {
+        return Err(AppError::Invalid("slash command name is empty".to_owned()));
+    }
+    Ok(if trimmed.starts_with('/') {
+        trimmed.to_owned()
+    } else {
+        format!("/{trimmed}")
+    })
+}
+
+/// Use case wrapper for list/filter.
+#[derive(Debug, Clone, Default)]
+pub struct ListSlashCommands {
+    registry: SlashCommandRegistry,
+}
+
+impl ListSlashCommands {
+    /// Builds the use case.
+    #[must_use]
+    pub const fn new(registry: SlashCommandRegistry) -> Self {
+        Self { registry }
+    }
+
+    /// Executes the use case.
+    #[must_use]
+    pub fn execute(&self, input: ListSlashCommandsInput) -> ListSlashCommandsOutput {
+        self.registry.list(input)
+    }
+}
+
+/// Use case wrapper for execution planning.
+#[derive(Debug, Clone, Default)]
+pub struct ExecuteSlashCommand {
+    registry: SlashCommandRegistry,
+}
+
+impl ExecuteSlashCommand {
+    /// Builds the use case.
+    #[must_use]
+    pub const fn new(registry: SlashCommandRegistry) -> Self {
+        Self { registry }
+    }
+
+    /// Executes the use case.
+    pub fn execute(
+        &self,
+        input: ExecuteSlashCommandInput,
+    ) -> Result<ExecuteSlashCommandOutput, AppError> {
+        self.registry.execute(input)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use uuid::Uuid;
+
+    fn session() -> SessionId {
+        SessionId::from_uuid(Uuid::from_u128(42))
+    }
+
+    #[test]
+    fn list_filters_native_commands_by_prefix() {
+        let out =
+            ListSlashCommands::new(SlashCommandRegistry::new()).execute(ListSlashCommandsInput {
+                prefix: Some("he".to_owned()),
+            });
+        assert_eq!(out.commands.len(), 1);
+        assert_eq!(out.commands[0].name, "/help");
+    }
+
+    #[test]
+    fn help_returns_unified_command_list() {
+        let out = ExecuteSlashCommand::new(SlashCommandRegistry::new())
+            .execute(ExecuteSlashCommandInput {
+                name: "help".to_owned(),
+                session_id: None,
+            })
+            .unwrap();
+        assert_eq!(out.command.name, "/help");
+        let SlashCommandEffect::Help { commands } = out.effect else {
+            panic!("help effect expected");
+        };
+        assert!(commands.iter().any(|command| command.name == "/clean"));
+    }
+
+    #[test]
+    fn clean_requires_and_returns_current_session() {
+        let sid = session();
+        let out = ExecuteSlashCommand::new(SlashCommandRegistry::new())
+            .execute(ExecuteSlashCommandInput {
+                name: "/clean".to_owned(),
+                session_id: Some(sid),
+            })
+            .unwrap();
+        assert_eq!(
+            out.effect,
+            SlashCommandEffect::CleanConversation { session_id: sid }
+        );
+    }
+
+    #[test]
+    fn profile_is_known_but_not_executable_yet() {
+        let err = ExecuteSlashCommand::new(SlashCommandRegistry::new())
+            .execute(ExecuteSlashCommandInput {
+                name: "/profile".to_owned(),
+                session_id: Some(session()),
+            })
+            .unwrap_err();
+        assert!(matches!(err, AppError::Invalid(message) if message.contains("unavailable")));
+    }
+}

crates/backend/src/dto.rs

@@ -13,14 +13,15 @@ use application::{
     AgentBackgroundTaskState, AgentTicketState, AppError, AppExitWorkGuardDetail,
     AppExitWorkGuardState, AttachLiveAgentOutput, BackgroundTaskKindLabel,
     ConversationPreviewStatus, ConversationTurnWorkPreview, ConversationWorkSummary,
-    CreateProjectInput, CreateProjectOutput, GitGraphOutput, HealthInput, HealthReport, LayoutKind,
-    ListProjectsOutput, LiveSessionKind, LiveSessionSnapshot, OpenProjectOutput, ProjectWorkState,
+    CreateProjectInput, CreateProjectOutput, ExecuteSlashCommandOutput, GitGraphOutput,
+    HealthInput, HealthReport, LayoutKind, ListProjectsOutput, ListSlashCommandsOutput,
+    LiveSessionKind, LiveSessionSnapshot, OpenProjectOutput, ProjectWorkState, SlashCommandEffect,
     StopLiveAgentOutput, TicketWorkSource, TicketWorkStatus, TurnPage, TurnSource, TurnView,
 };
 use domain::ports::{ReplyProgress, ReplyProgressKind, ReplyProgressSource, ReplyProgressStage};
 use domain::{
     AgentBusyState, PageCursor, PageDirection, Project, ProjectId, ProjectSystemPermissions,
-    ResolvedAgentSystemPermissions, SystemPermissionSet, TurnRole,
+    ResolvedAgentSystemPermissions, SlashCommand, SystemPermissionSet, TurnRole,
 };
 
 pub use crate::ticket_dto::*;
@@ -764,6 +765,106 @@ impl From<HealthReport> for HealthResponseDto {
     }
 }
 
+/// Request DTO for slash-command list/filter.
+#[derive(Debug, Clone, Default, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ListSlashCommandsRequestDto {
+    /// Optional typed prefix, with or without the leading `/`.
+    #[serde(default)]
+    pub prefix: Option<String>,
+}
+
+/// UI-facing slash-command metadata DTO.
+pub type SlashCommandDto = SlashCommand;
+
+/// Slash-command list response DTO.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SlashCommandListDto {
+    /// Commands in deterministic UI order.
+    pub commands: Vec<SlashCommandDto>,
+}
+
+impl From<ListSlashCommandsOutput> for SlashCommandListDto {
+    fn from(value: ListSlashCommandsOutput) -> Self {
+        Self {
+            commands: value.commands,
+        }
+    }
+}
+
+/// Request DTO for slash-command execution.
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ExecuteSlashCommandRequestDto {
+    /// Command name, with or without the leading `/`.
+    pub name: String,
+    /// Current structured chat session id, required by `/clean` and future
+    /// conversation-local commands.
+    #[serde(default)]
+    pub session_id: Option<String>,
+}
+
+/// Slash-command execution response DTO.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ExecuteSlashCommandResponseDto {
+    /// Executed command metadata.
+    pub command: SlashCommandDto,
+    /// Effect handled by the UI/adapter.
+    pub effect: SlashCommandEffectDto,
+}
+
+impl From<ExecuteSlashCommandOutput> for ExecuteSlashCommandResponseDto {
+    fn from(value: ExecuteSlashCommandOutput) -> Self {
+        Self {
+            command: value.command,
+            effect: value.effect.into(),
+        }
+    }
+}
+
+/// Slash-command execution effect DTO.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase", tag = "kind")]
+pub enum SlashCommandEffectDto {
+    /// Display command help.
+    Help {
+        /// Commands to display.
+        commands: Vec<SlashCommandDto>,
+    },
+    /// The current conversation was cleared.
+    CleanConversation {
+        /// Session id that was cleared.
+        #[serde(rename = "sessionId")]
+        session_id: String,
+        /// Number of retained chunks removed by the backend bridge.
+        #[serde(rename = "clearedChunks")]
+        cleared_chunks: usize,
+    },
+    /// Placeholder for ticket #164.
+    ProfileSwitch {
+        /// Session id targeted by the profile flow.
+        #[serde(rename = "sessionId")]
+        session_id: String,
+    },
+}
+
+impl From<SlashCommandEffect> for SlashCommandEffectDto {
+    fn from(value: SlashCommandEffect) -> Self {
+        match value {
+            SlashCommandEffect::Help { commands } => Self::Help { commands },
+            SlashCommandEffect::CleanConversation { session_id } => Self::CleanConversation {
+                session_id: session_id.to_string(),
+                cleared_chunks: 0,
+            },
+            SlashCommandEffect::ProfileSwitch { session_id } => Self::ProfileSwitch {
+                session_id: session_id.to_string(),
+            },
+        }
+    }
+}
+
 /// Error DTO returned to the frontend in the `Err` arm of every command.
 ///
 /// `code` is a stable machine-readable string (see [`AppError::code`]); the

crates/backend/src/lib.rs

@@ -23,18 +23,19 @@ use application::{
     CreateSprint, CreateTemplate, DeleteAgent, DeleteEmbedderProfile, DeleteIssue, DeleteLayout,
     DeleteMemory, DeleteModelArtifact, DeleteModelServer, DeleteProfile, DeleteSkill, DeleteSprint,
     DeleteTemplate, DescribeEmbedderEngines, DetectAgentDrift, DetectProfiles,
-    DismissEmbedderSuggestion, EnsureLocalModelServer, FirstRunState, GetAppExitWorkGuardState,
-    GetLiveStateLean, GetMemory, GetProjectPermissions, GetProjectSystemPermissions,
-    GetProjectWorkState, GitBranches, GitCheckout, GitCommit, GitGraph, GitInit, GitLog, GitStage,
-    GitStatus, GitUnstage, HarvestMemoryFromTurn, HealthUseCase, ImportChatAttachments,
-    InspectConversation, InstallPluginFromArchive, InstallPluginFromDirectory,
-    JsonPluginManifestValidator, LaunchAgent, LaunchAgentInput, LinkIssues, ListAgents,
-    ListAgentsInput, ListClaudeModels, ListCodexModels, ListDevices, ListEmbedderProfiles,
-    ListIssues, ListLayouts, ListMemories, ListModelServers, ListOpenCodeProviders,
-    ListPluginRuntimeContributions, ListPlugins, ListProfiles, ListProjects, ListResumableAgents,
-    ListSkills, ListSprints, ListTemplates, LiveAgentRegistry, LiveSessions, LiveStateLeanProvider,
-    LiveStateProvider, LiveStateReadProvider, LoadLayout, MarkIssueAttachmentSummarized,
-    McpRuntime, McpToolPermissionCatalogue, MoveTabToNewWindow, MutateLayout, OnnxModelView,
+    DismissEmbedderSuggestion, EnsureLocalModelServer, ExecuteSlashCommand, FirstRunState,
+    GetAppExitWorkGuardState, GetLiveStateLean, GetMemory, GetProjectPermissions,
+    GetProjectSystemPermissions, GetProjectWorkState, GitBranches, GitCheckout, GitCommit,
+    GitGraph, GitInit, GitLog, GitStage, GitStatus, GitUnstage, HarvestMemoryFromTurn,
+    HealthUseCase, ImportChatAttachments, InspectConversation, InstallPluginFromArchive,
+    InstallPluginFromDirectory, JsonPluginManifestValidator, LaunchAgent, LaunchAgentInput,
+    LinkIssues, ListAgents, ListAgentsInput, ListClaudeModels, ListCodexModels, ListDevices,
+    ListEmbedderProfiles, ListIssues, ListLayouts, ListMemories, ListModelServers,
+    ListOpenCodeProviders, ListPluginRuntimeContributions, ListPlugins, ListProfiles, ListProjects,
+    ListResumableAgents, ListSkills, ListSlashCommands, ListSprints, ListTemplates,
+    LiveAgentRegistry, LiveSessions, LiveStateLeanProvider, LiveStateProvider,
+    LiveStateReadProvider, LoadLayout, MarkIssueAttachmentSummarized, McpRuntime,
+    McpToolPermissionCatalogue, MoveTabToNewWindow, MutateLayout, OnnxModelView,
     OpenPluginLayoutWindow, OpenProject, OpenTerminal, OpenTicketAssistant, OrchestratorService,
     PairAttemptLimiter, PairDevice, PermissionProjectorRegistry, PluginCommandTasks,
     PluginConfigDocuments, PluginEventSubscriptions, PluginStorageAccess,
@@ -48,15 +49,15 @@ use application::{
     ResolveMemoryLinks, RestoreOpenWindows, RetryBackgroundTask, ReviewPluginPackage,
     RevokeAllDevices, RevokeDevice, RotateConversationLog, SaveEmbedderProfile, SaveModelServer,
     SaveOpenCodeProviderProfile, SaveProfile, SessionLimitService, SetActiveLayout,
-    SetPluginEnabled, SnapshotOpenWindows, SnapshotRunningAgents, SpawnBackgroundCommand,
-    StopLiveAgent, StructuredRoutingMode, StructuredSessions, SuggestedThisSession,
-    SyncAgentWithTemplate, TerminalSessions, TouchDevice, UnassignSkillFromAgent,
-    UnassignTicketFromSprint, UninstallPlugin, UnlinkIssues, UpdateAgentContext, UpdateAgentEffort,
-    UpdateAgentMcpToolPermissions, UpdateAgentPermissions, UpdateAgentSystemPermissions,
-    UpdateIssue, UpdateIssueCarnet, UpdateLiveState, UpdateMemory, UpdateProjectContext,
-    UpdateProjectMcpToolPermissions, UpdateProjectPermissions, UpdateProjectSystemPermissions,
-    UpdateSkill, UpdateTemplate, WakeSessionProvider, WriteMemory, WriteToTerminal,
-    AGENT_MEMORY_RECALL_BUDGET,
+    SetPluginEnabled, SlashCommandRegistry, SnapshotOpenWindows, SnapshotRunningAgents,
+    SpawnBackgroundCommand, StopLiveAgent, StructuredRoutingMode, StructuredSessions,
+    SuggestedThisSession, SyncAgentWithTemplate, TerminalSessions, TouchDevice,
+    UnassignSkillFromAgent, UnassignTicketFromSprint, UninstallPlugin, UnlinkIssues,
+    UpdateAgentContext, UpdateAgentEffort, UpdateAgentMcpToolPermissions, UpdateAgentPermissions,
+    UpdateAgentSystemPermissions, UpdateIssue, UpdateIssueCarnet, UpdateLiveState, UpdateMemory,
+    UpdateProjectContext, UpdateProjectMcpToolPermissions, UpdateProjectPermissions,
+    UpdateProjectSystemPermissions, UpdateSkill, UpdateTemplate, WakeSessionProvider, WriteMemory,
+    WriteToTerminal, AGENT_MEMORY_RECALL_BUDGET,
 };
 use async_trait::async_trait;
 use domain::ports::{
@@ -877,6 +878,10 @@ impl AgentResumer for AppAgentResumer {
 pub struct BackendCore {
     /// Trivial health use case validating the end-to-end wiring.
     pub health: Arc<HealthUseCase>,
+    /// List/filter the unified slash-command registry.
+    pub list_slash_commands: Arc<ListSlashCommands>,
+    /// Plan execution of a slash command.
+    pub execute_slash_command: Arc<ExecuteSlashCommand>,
     /// Pair a persistent device session.
     pub pair_device: Arc<PairDevice>,
     /// Limits failed pairing attempts.
@@ -1448,6 +1453,9 @@ impl BackendCore {
             Arc::clone(&ids) as Arc<dyn IdGenerator>,
             Arc::clone(&events_port),
         ));
+        let slash_command_registry = SlashCommandRegistry::new();
+        let list_slash_commands = Arc::new(ListSlashCommands::new(slash_command_registry.clone()));
+        let execute_slash_command = Arc::new(ExecuteSlashCommand::new(slash_command_registry));
         let pair_device = Arc::new(PairDevice::new(
             Arc::clone(&device_session_port),
             Arc::clone(&ids) as Arc<dyn IdGenerator>,
@@ -2924,6 +2932,8 @@ impl BackendCore {
 
         Self {
             health,
+            list_slash_commands,
+            execute_slash_command,
             pair_device,
             pair_attempt_limiter: Arc::clone(&pair_attempt_limiter_port),
             authenticate_session,

crates/backend/src/stream.rs

@@ -156,6 +156,20 @@ where
             .unwrap_or_default()
     }
 
+    pub fn clear_scrollback(&self, key: &K) -> usize {
+        self.entries
+            .lock()
+            .ok()
+            .and_then(|mut m| {
+                m.get_mut(key).map(|entry| {
+                    let cleared = entry.scrollback.len();
+                    entry.scrollback.clear();
+                    cleared
+                })
+            })
+            .unwrap_or_default()
+    }
+
     pub fn unregister(&self, key: &K) {
         if let Ok(mut map) = self.entries.lock() {
             map.remove(key);

crates/domain/src/lib.rs

@@ -65,6 +65,7 @@ pub mod remote;
 pub mod sandbox;
 pub mod session_limit;
 pub mod skill;
+pub mod slash_command;
 pub mod sprint;
 pub mod system_permissions;
 pub mod template;
@@ -108,6 +109,11 @@ pub use chat_attachment::{
 
 pub use skill::{Skill, SkillKind, SkillRef, SkillScope};
 
+pub use slash_command::{
+    filter_slash_commands, native_slash_commands, NativeSlashCommand, SlashCommand,
+    SlashCommandAvailability, SlashCommandSource,
+};
+
 pub use template::{AgentTemplate, TemplateVersion};
 
 pub use profile::{

crates/domain/src/slash_command.rs

@@ -0,0 +1,201 @@
+//! Slash-command model for the custom structured CLI surface.
+//!
+//! This module is intentionally pure: it declares the stable command metadata and
+//! validates names/prefixes, but it does not execute side effects.
+
+use serde::{Deserialize, Serialize};
+
+use crate::error::DomainError;
+
+/// A slash-command source. Native commands are built into IdeA; plugin commands
+/// will be contributed through the same registry contract later.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum SlashCommandSource {
+    /// Built into IdeA.
+    Native,
+    /// Contributed by a plugin.
+    Plugin {
+        /// Opaque plugin id.
+        plugin_id: String,
+    },
+}
+
+/// Whether a command can currently be executed.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase", tag = "status")]
+pub enum SlashCommandAvailability {
+    /// The command can be executed now.
+    Available,
+    /// The command is known but cannot be executed in the current product state.
+    Unavailable {
+        /// Human-readable reason.
+        reason: String,
+    },
+}
+
+impl SlashCommandAvailability {
+    /// Returns whether this availability allows execution.
+    #[must_use]
+    pub const fn is_available(&self) -> bool {
+        matches!(self, Self::Available)
+    }
+}
+
+/// Built-in command behaviour known to IdeA.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum NativeSlashCommand {
+    /// Lists commands and help text.
+    Help,
+    /// Clears the current structured conversation view.
+    Clean,
+    /// Opens the profile switch flow. Implemented by ticket #164.
+    Profile,
+}
+
+/// UI-facing slash-command metadata.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SlashCommand {
+    /// Canonical slash name, including the leading `/`.
+    pub name: String,
+    /// Short UI label/description.
+    pub short_description: String,
+    /// Whether the UI must ask for confirmation before execution.
+    pub requires_confirmation: bool,
+    /// Current command availability.
+    pub availability: SlashCommandAvailability,
+    /// Unified native/plugin source.
+    pub source: SlashCommandSource,
+    /// Built-in command discriminator when `source == native`.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub native: Option<NativeSlashCommand>,
+}
+
+impl SlashCommand {
+    /// Builds validated command metadata.
+    ///
+    /// # Errors
+    /// Returns [`DomainError::EmptyField`] for an empty/blank name or description,
+    /// and [`DomainError::Invariant`] when the name does not start with `/`.
+    pub fn new(
+        name: impl Into<String>,
+        short_description: impl Into<String>,
+        requires_confirmation: bool,
+        availability: SlashCommandAvailability,
+        source: SlashCommandSource,
+        native: Option<NativeSlashCommand>,
+    ) -> Result<Self, DomainError> {
+        let name = name.into();
+        let short_description = short_description.into();
+        crate::validation::non_empty(&name, "slash_command.name")?;
+        crate::validation::non_empty(&short_description, "slash_command.short_description")?;
+        if !name.starts_with('/') {
+            return Err(DomainError::Invariant(
+                "slash command name must start with '/'".to_owned(),
+            ));
+        }
+        Ok(Self {
+            name,
+            short_description,
+            requires_confirmation,
+            availability,
+            source,
+            native,
+        })
+    }
+}
+
+/// Returns the native IdeA slash commands in deterministic UI order.
+#[must_use]
+pub fn native_slash_commands() -> Vec<SlashCommand> {
+    vec![
+        SlashCommand::new(
+            "/help",
+            "Afficher les commandes disponibles",
+            false,
+            SlashCommandAvailability::Available,
+            SlashCommandSource::Native,
+            Some(NativeSlashCommand::Help),
+        )
+        .expect("valid native slash command"),
+        SlashCommand::new(
+            "/clean",
+            "Nettoyer la conversation courante",
+            false,
+            SlashCommandAvailability::Available,
+            SlashCommandSource::Native,
+            Some(NativeSlashCommand::Clean),
+        )
+        .expect("valid native slash command"),
+        SlashCommand::new(
+            "/profile",
+            "Changer le profil de l'agent",
+            true,
+            SlashCommandAvailability::Unavailable {
+                reason: "La selection de profil est livree par le ticket #164".to_owned(),
+            },
+            SlashCommandSource::Native,
+            Some(NativeSlashCommand::Profile),
+        )
+        .expect("valid native slash command"),
+    ]
+}
+
+/// Filters commands by a user-entered slash prefix.
+///
+/// Blank prefixes return every command. Prefixes without a leading `/` are
+/// interpreted as if the slash was present, matching composer input.
+#[must_use]
+pub fn filter_slash_commands(
+    commands: impl IntoIterator<Item = SlashCommand>,
+    prefix: Option<&str>,
+) -> Vec<SlashCommand> {
+    let prefix = prefix.map(str::trim).filter(|p| !p.is_empty()).map(|p| {
+        if p.starts_with('/') {
+            p.to_owned()
+        } else {
+            format!("/{p}")
+        }
+    });
+    commands
+        .into_iter()
+        .filter(|command| {
+            prefix
+                .as_ref()
+                .is_none_or(|prefix| command.name.starts_with(prefix))
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn native_registry_exposes_help_clean_and_profile_placeholder() {
+        let commands = native_slash_commands();
+        let names = commands.iter().map(|c| c.name.as_str()).collect::<Vec<_>>();
+        assert_eq!(names, vec!["/help", "/clean", "/profile"]);
+        assert!(commands[0].availability.is_available());
+        assert!(commands[1].availability.is_available());
+        assert!(!commands[2].availability.is_available());
+        assert!(commands[2].requires_confirmation);
+    }
+
+    #[test]
+    fn prefix_filter_accepts_with_or_without_leading_slash() {
+        let names = filter_slash_commands(native_slash_commands(), Some("cl"))
+            .into_iter()
+            .map(|c| c.name)
+            .collect::<Vec<_>>();
+        assert_eq!(names, vec!["/clean"]);
+
+        let names = filter_slash_commands(native_slash_commands(), Some("/pro"))
+            .into_iter()
+            .map(|c| c.name)
+            .collect::<Vec<_>>();
+        assert_eq!(names, vec!["/profile"]);
+    }
+}