diff --git a/crates/application/src/slash_command.rs b/crates/application/src/slash_command.rs
index 41f1c909..90e5cd5d 100644
--- a/crates/application/src/slash_command.rs
+++ b/crates/application/src/slash_command.rs
@@ -386,6 +386,37 @@ mod tests {
         assert_eq!(arguments, vec![serde_json::json!({ "selection": "abc" })]);
     }
 
+    #[test]
+    fn native_command_names_are_routed_before_plugin_commands() {
+        let colliding_plugin = plugin_slash_command(
+            "dev.acme.plugin",
+            "dev.acme.plugin.clean",
+            "/clean",
+            "Plugin clean",
+            false,
+            SlashCommandAvailability::Available,
+        )
+        .unwrap();
+        let sid = session();
+
+        let out = ExecuteSlashCommand::new(SlashCommandRegistry::new())
+            .execute_with_plugins(
+                ExecuteSlashCommandInput {
+                    name: "/clean".to_owned(),
+                    session_id: Some(sid),
+                    arguments: Vec::new(),
+                },
+                vec![colliding_plugin],
+            )
+            .unwrap();
+
+        assert_eq!(out.command.source, SlashCommandSource::Native);
+        assert_eq!(
+            out.effect,
+            SlashCommandEffect::CleanConversation { session_id: sid }
+        );
+    }
+
     #[test]
     fn runtime_catalog_plugin_slash_commands_feed_unified_registry() {
         let catalog = PluginRuntimeCatalog {
diff --git a/frontend/src/features/agents/CustomAgentChatView.test.tsx b/frontend/src/features/agents/CustomAgentChatView.test.tsx
index 8b9ba2ee..3061c125 100644
--- a/frontend/src/features/agents/CustomAgentChatView.test.tsx
+++ b/frontend/src/features/agents/CustomAgentChatView.test.tsx
@@ -972,6 +972,169 @@ describe("CustomAgentChatView", () => {
     expect(composer.value).toBe("");
   });
 
+  it("executes /clean as a native conversation clear effect", async () => {
+    const agent = {
+      launchAgentChat: vi.fn(),
+      reattachAgentChat: vi.fn(async (sessionId: string) => ({
+        sessionId,
+        scrollback: [{ kind: "userPrompt", text: "old conversation" }],
+      })),
+      sendAgentChat: vi.fn(async () => {}),
+      executeSlashCommand: vi.fn(async () => ({
+        command: {
+          name: "/clean",
+          shortDescription: "Nettoyer la conversation courante",
+          requiresConfirmation: false,
+          availability: { status: "available" as const },
+          source: "native" as const,
+          native: "clean" as const,
+        },
+        effect: {
+          kind: "cleanConversation" as const,
+          sessionId: "chat-session-1",
+          clearedChunks: 1,
+        },
+      })),
+      cancelAgentChat: vi.fn(async () => {}),
+      closeAgentChat: vi.fn(async () => {}),
+    };
+
+    render(
+      <DIProvider
+        gateways={{
+          agent,
+          system: { pickFile: vi.fn(async () => null) },
+        } as unknown as Gateways}
+      >
+        <CustomAgentChatView
+          projectId="project-1"
+          agentId="agent-1"
+          agentName="Worker"
+          profile={profile}
+          cwd="/repo"
+          nodeId="node-1"
+          sessionId="chat-session-1"
+          conversationId="conversation-1"
+          onSessionId={vi.fn()}
+          onConversationId={vi.fn()}
+        />
+      </DIProvider>,
+    );
+
+    expect(await screen.findByText("old conversation")).toBeTruthy();
+
+    const composer = screen.getByLabelText(/message CLI custom/) as HTMLTextAreaElement;
+    fireEvent.change(composer, { target: { value: "/clean" } });
+    fireEvent.keyDown(composer, { key: "Enter" });
+
+    await waitFor(() =>
+      expect(agent.executeSlashCommand).toHaveBeenCalledWith("/clean", {
+        sessionId: "chat-session-1",
+      }),
+    );
+    await waitFor(() => expect(screen.queryByText("old conversation")).toBeNull());
+    expect(screen.queryByRole("alert")).toBeNull();
+    expect(agent.sendAgentChat).not.toHaveBeenCalled();
+    expect(composer.value).toBe("");
+  });
+
+  it("executes /help as a native help effect", async () => {
+    const agent = {
+      launchAgentChat: vi.fn(),
+      reattachAgentChat: vi.fn(async (sessionId: string) => ({
+        sessionId,
+        scrollback: [],
+      })),
+      sendAgentChat: vi.fn(async () => {}),
+      executeSlashCommand: vi.fn(async () => ({
+        command: {
+          name: "/help",
+          shortDescription: "Afficher les commandes disponibles",
+          requiresConfirmation: false,
+          availability: { status: "available" as const },
+          source: "native" as const,
+          native: "help" as const,
+        },
+        effect: {
+          kind: "help" as const,
+          commands: [
+            {
+              name: "/help",
+              shortDescription: "Afficher les commandes disponibles",
+              requiresConfirmation: false,
+              availability: { status: "available" as const },
+              source: "native" as const,
+              native: "help" as const,
+            },
+            {
+              name: "/clean",
+              shortDescription: "Nettoyer la conversation courante",
+              requiresConfirmation: false,
+              availability: { status: "available" as const },
+              source: "native" as const,
+              native: "clean" as const,
+            },
+            {
+              name: "/profile",
+              shortDescription: "Changer le profil de l'agent",
+              requiresConfirmation: true,
+              availability: { status: "available" as const },
+              source: "native" as const,
+              native: "profile" as const,
+            },
+          ],
+        },
+      })),
+      cancelAgentChat: vi.fn(async () => {}),
+      closeAgentChat: vi.fn(async () => {}),
+    };
+
+    render(
+      <DIProvider
+        gateways={{
+          agent,
+          system: { pickFile: vi.fn(async () => null) },
+        } as unknown as Gateways}
+      >
+        <CustomAgentChatView
+          projectId="project-1"
+          agentId="agent-1"
+          agentName="Worker"
+          profile={profile}
+          cwd="/repo"
+          nodeId="node-1"
+          sessionId="chat-session-1"
+          conversationId="conversation-1"
+          onSessionId={vi.fn()}
+          onConversationId={vi.fn()}
+        />
+      </DIProvider>,
+    );
+
+    await waitFor(() =>
+      expect(agent.reattachAgentChat).toHaveBeenCalledWith(
+        "chat-session-1",
+        expect.any(Function),
+      ),
+    );
+
+    const composer = screen.getByLabelText(/message CLI custom/) as HTMLTextAreaElement;
+    fireEvent.change(composer, { target: { value: "/help" } });
+    fireEvent.keyDown(composer, { key: "Enter" });
+
+    await waitFor(() =>
+      expect(agent.executeSlashCommand).toHaveBeenCalledWith("/help", {
+        sessionId: "chat-session-1",
+      }),
+    );
+    expect(
+      await screen.findByText(/\/clean - Nettoyer la conversation courante/),
+    ).toBeTruthy();
+    expect(screen.queryByRole("alert")).toBeNull();
+    expect(agent.sendAgentChat).not.toHaveBeenCalled();
+    expect(composer.value).toBe("");
+  });
+
   it("shows feedback when a plugin slash-command callback cannot be dispatched", async () => {
     const registry = new PluginRuntimeRegistry();
     const agent = {
diff --git a/frontend/src/features/agents/CustomAgentChatView.tsx b/frontend/src/features/agents/CustomAgentChatView.tsx
index 797abc13..ec51113e 100644
--- a/frontend/src/features/agents/CustomAgentChatView.tsx
+++ b/frontend/src/features/agents/CustomAgentChatView.tsx
@@ -401,6 +401,12 @@ function isSlashCommandAvailable(command: SlashCommand): boolean {
   return command.availability.status === "available";
 }
 
+function formatSlashCommandHelp(commands: SlashCommand[]): string {
+  return commands
+    .map((command) => `${command.name} - ${command.shortDescription}`)
+    .join("\n");
+}
+
 function foldChunk(turns: ChatTurn[], raw: unknown): ChatTurn[] {
   if (!isReplyRecord(raw)) {
     return [...turns, { role: "unknown", text: unknownChunkLabel(raw) }];
@@ -792,42 +798,23 @@ export function CustomAgentChatView({
     [supported, draft, attachments.length, busy, opening],
   );
 
-  async function openProfileCommandFlow() {
-    if (!agent.executeSlashCommand) {
-      setError("Commande /profile indisponible dans ce runtime.");
-      return;
-    }
-    setError(null);
-    try {
-      const sid =
-        currentSession ??
-        (await recoverStructuredSession({
-          applyScrollback: false,
-          retryAttachNotFound: true,
-        }));
-      const result = await agent.executeSlashCommand("/profile", { sessionId: sid });
-      if (result.effect.kind !== "profileSwitch") {
-        throw new Error("La commande /profile n'a pas renvoyé le flow profil.");
-      }
-      const availableProfiles = (await profileGateway.listProfiles()).filter(
-        (candidate) => Boolean(candidate.structuredAdapter),
-      );
-      if (availableProfiles.length === 0) {
-        throw new Error("Aucun profil compatible avec la CLI custom n'est configuré.");
-      }
-      setDraft("");
-      setProfileDialog({
-        profiles: availableProfiles,
-        selectedProfileId:
-          availableProfiles.find((candidate) => candidate.id !== profile.id)?.id ??
-          availableProfiles[0].id,
-        confirmedReset: false,
-        busy: false,
-        error: null,
-      });
-    } catch (e) {
-      setError(describe(e));
+  async function openProfileDialog() {
+    const availableProfiles = (await profileGateway.listProfiles()).filter((candidate) =>
+      Boolean(candidate.structuredAdapter),
+    );
+    if (availableProfiles.length === 0) {
+      throw new Error("Aucun profil compatible avec la CLI custom n'est configuré.");
     }
+    setDraft("");
+    setProfileDialog({
+      profiles: availableProfiles,
+      selectedProfileId:
+        availableProfiles.find((candidate) => candidate.id !== profile.id)?.id ??
+        availableProfiles[0].id,
+      confirmedReset: false,
+      busy: false,
+      error: null,
+    });
   }
 
   async function confirmProfileCommandChange() {
@@ -904,22 +891,38 @@ export function CustomAgentChatView({
         }));
       const result = await agent.executeSlashCommand(invocation.name, {
         sessionId: sid,
-        arguments: invocation.arguments,
+        ...(invocation.arguments.length > 0
+          ? { arguments: invocation.arguments }
+          : {}),
       });
-      if (result.effect.kind !== "pluginCallback") {
-        throw new Error(
-          `La commande ${invocation.name} n'a pas renvoyé d'effet pluginCallback.`,
-        );
+      if (result.effect.kind === "help") {
+        const helpText = formatSlashCommandHelp(result.effect.commands);
+        setTurns((prev) => [
+          ...prev,
+          { role: "agent", text: helpText },
+        ]);
+        return;
+      }
+      if (result.effect.kind === "cleanConversation") {
+        setTurns([]);
+        return;
+      }
+      if (result.effect.kind === "profileSwitch") {
+        await openProfileDialog();
+        return;
+      }
+      if (result.effect.kind === "pluginCallback") {
+        await pluginRuntime.registry.runCommandStrict(
+          result.effect.pluginId,
+          result.effect.commandId,
+          ...result.effect.arguments,
+        );
+        setTurns((prev) => [
+          ...prev,
+          { role: "tool", label: `Commande plugin ${result.command.name} exécutée.` },
+        ]);
+        return;
       }
-      await pluginRuntime.registry.runCommandStrict(
-        result.effect.pluginId,
-        result.effect.commandId,
-        ...result.effect.arguments,
-      );
-      setTurns((prev) => [
-        ...prev,
-        { role: "tool", label: `Commande plugin ${result.command.name} exécutée.` },
-      ]);
     } catch (e) {
       const message = `Commande ${invocation.name} échouée: ${describe(e)}`;
       setError(message);
@@ -971,10 +974,6 @@ export function CustomAgentChatView({
   async function send() {
     const text = draft.trim();
     if (!canSend || !agent.sendAgentChat) return;
-    if (text === "/profile") {
-      await openProfileCommandFlow();
-      return;
-    }
     const slashInvocation = slashCommandInvocation(text);
     if (slashInvocation) {
       await executeSlashCommand(slashInvocation);