diff --git a/frontend/src/api/client.ts b/frontend/src/api/client.ts
index ea59138..297f47f 100644
--- a/frontend/src/api/client.ts
+++ b/frontend/src/api/client.ts
@@ -51,27 +51,39 @@ export interface GitCommit {
   files_changed: number;
 }
 
-export async function getGitLog(): Promise<GitCommit[]> {
+const projQuery = (project?: string | null) =>
+  project ? `&project=${encodeURIComponent(project)}` : "";
+
+export async function getGitLog(project?: string | null): Promise<GitCommit[]> {
   try {
-    const res = await fetch("/api/git/log");
+    const res = await fetch(`/api/git/log?limit=40${projQuery(project)}`);
     return (await res.json()).commits;
   } catch {
     return [];
   }
 }
 
-export async function getGitDiff(hash?: string): Promise<string> {
-  const url = hash ? `/api/git/diff?hash=${encodeURIComponent(hash)}` : "/api/git/diff";
-  const res = await fetch(url);
+export async function getGitDiff(
+  hash?: string,
+  project?: string | null
+): Promise<string> {
+  const params = new URLSearchParams();
+  if (hash) params.set("hash", hash);
+  if (project) params.set("project", project);
+  const qs = params.toString();
+  const res = await fetch(`/api/git/diff${qs ? `?${qs}` : ""}`);
   if (!res.ok) return "";
   return (await res.json()).diff;
 }
 
-export async function revertCommit(hash: string): Promise<{ message: string }> {
+export async function revertCommit(
+  hash: string,
+  project?: string | null
+): Promise<{ message: string }> {
   const res = await fetch("/api/git/revert", {
     method: "POST",
     headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ hash }),
+    body: JSON.stringify({ hash, project: project ?? null }),
   });
   if (!res.ok) throw await apiError(res, "revert impossible");
   return res.json();
@@ -214,6 +226,7 @@ export interface Session {
   id: string;
   title: string;
   model?: string;
+  project?: string | null;
   created_at: number;
   updated_at: number;
   message_count?: number;
@@ -400,29 +413,39 @@ export interface FileNode {
   children?: FileNode[];
 }
 
-export async function listFiles(): Promise<FileNode[]> {
-  const res = await fetch("/api/files");
+export async function listFiles(project?: string | null): Promise<FileNode[]> {
+  const query = project ? `?project=${encodeURIComponent(project)}` : "";
+  const res = await fetch(`/api/files${query}`);
   return (await res.json()).tree;
 }
 
-export async function fileContent(path: string): Promise<string> {
-  const res = await fetch(`/api/files/content?path=${encodeURIComponent(path)}`);
+export async function fileContent(
+  path: string,
+  project?: string | null
+): Promise<string> {
+  const res = await fetch(
+    `/api/files/content?path=${encodeURIComponent(path)}${projQuery(project)}`
+  );
   if (!res.ok) return "";
   return (await res.json()).content;
 }
 
-export async function deleteFile(path: string): Promise<void> {
-  const res = await fetch(`/api/files?path=${encodeURIComponent(path)}`, {
-    method: "DELETE",
-  });
+export async function deleteFile(
+  path: string,
+  project?: string | null
+): Promise<void> {
+  const res = await fetch(
+    `/api/files?path=${encodeURIComponent(path)}${projQuery(project)}`,
+    { method: "DELETE" }
+  );
   if (!res.ok) {
     throw await apiError(res, `suppression impossible (${res.status})`);
   }
 }
 
-export function downloadFile(path: string): void {
+export function downloadFile(path: string, project?: string | null): void {
   const link = document.createElement("a");
-  link.href = `/api/files/download?path=${encodeURIComponent(path)}`;
+  link.href = `/api/files/download?path=${encodeURIComponent(path)}${projQuery(project)}`;
   link.download = path.split(/[\\/]/).pop() ?? "fichier";
   document.body.appendChild(link);
   link.click();
@@ -473,15 +496,51 @@ export async function listSessions(): Promise<Session[]> {
   return (await res.json()).sessions;
 }
 
-export async function createSession(model?: string): Promise<Session> {
+export async function createSession(
+  model?: string,
+  project?: string | null
+): Promise<Session> {
   const res = await fetch("/api/sessions", {
     method: "POST",
     headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ title: "Nouvelle session", model }),
+    body: JSON.stringify({
+      title: "Nouvelle session",
+      model,
+      project: project ?? null,
+    }),
   });
   return res.json();
 }
 
+export async function listProjects(): Promise<{
+  projects: { name: string; files: number }[];
+  root_files: number;
+}> {
+  const res = await fetch("/api/projects");
+  return res.json();
+}
+
+export async function createProject(name: string): Promise<void> {
+  const res = await fetch("/api/projects", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ name }),
+  });
+  if (!res.ok) throw await apiError(res, "création du projet impossible");
+}
+
+export async function setSessionProject(
+  id: string,
+  project: string | null
+): Promise<void> {
+  const res = await fetch(`/api/sessions/${id}`, {
+    method: "PATCH",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ project: project ?? "" }),
+  });
+  if (!res.ok) throw await apiError(res, "changement de projet impossible");
+}
+
 export async function getSession(
   id: string
 ): Promise<{ session: Session; messages: Message[] }> {
diff --git a/frontend/src/panels/ActivityViews.tsx b/frontend/src/panels/ActivityViews.tsx
index 665a19c..f6861e1 100644
--- a/frontend/src/panels/ActivityViews.tsx
+++ b/frontend/src/panels/ActivityViews.tsx
@@ -61,7 +61,7 @@ export function FilesView() {
 }
 
 function WorkspaceTree({ nodes, depth }: { nodes: FileNode[]; depth: number }) {
-  const { openPreview, previewPath, removeFile } = useStore();
+  const { openPreview, previewPath, removeFile, currentProject } = useStore();
   const confirmDelete = (node: FileNode) => {
     const msg =
       node.type === "dir"
@@ -93,7 +93,7 @@ function WorkspaceTree({ nodes, depth }: { nodes: FileNode[]; depth: number }) {
             </button>
             {node.type === "file" && (
               <button
-                onClick={() => downloadFile(node.path)}
+                onClick={() => downloadFile(node.path, currentProject())}
                 className="flex items-center gap-1 border-2 border-line bg-base px-2 py-1 text-[11px] text-accent"
                 title={`Télécharger ${node.name}`}
               >
diff --git a/frontend/src/panels/LeftPanel.tsx b/frontend/src/panels/LeftPanel.tsx
index ab2bca5..36cff1b 100644
--- a/frontend/src/panels/LeftPanel.tsx
+++ b/frontend/src/panels/LeftPanel.tsx
@@ -117,7 +117,7 @@ export function LeftPanel() {
 }
 
 function FileTree({ nodes, depth }: { nodes: FileNode[]; depth: number }) {
-  const { openPreview, previewPath, removeFile } = useStore();
+  const { openPreview, previewPath, removeFile, currentProject } = useStore();
   const confirmDelete = (n: FileNode) => {
     const msg =
       n.type === "dir"
@@ -156,7 +156,7 @@ function FileTree({ nodes, depth }: { nodes: FileNode[]; depth: number }) {
                 <button
                   onClick={(event) => {
                     event.stopPropagation();
-                    downloadFile(n.path);
+                    downloadFile(n.path, currentProject());
                   }}
                   className="hidden flex-none text-muted-2 hover:text-accent group-hover:block"
                   title={`Télécharger ${n.name}`}
diff --git a/frontend/src/panels/PreviewPanel.tsx b/frontend/src/panels/PreviewPanel.tsx
index 56c504e..0c79334 100644
--- a/frontend/src/panels/PreviewPanel.tsx
+++ b/frontend/src/panels/PreviewPanel.tsx
@@ -98,7 +98,7 @@ export function PreviewPanel() {
         {previewPath && (
           <>
             <button
-              onClick={() => downloadFile(previewPath)}
+              onClick={() => downloadFile(previewPath, useStore.getState().currentProject())}
               className="flex h-8 items-center gap-1.5 border-[3px] border-line bg-card px-2.5 text-[12px] text-accent"
               title={`Télécharger ${previewPath}`}
             >
@@ -202,21 +202,24 @@ export function PreviewPanel() {
 /** Onglet Git : historique des commits, diff colorisé, retour arrière. */
 function GitPanel() {
   const refreshFiles = useStore((s) => s.refreshFiles);
+  const currentProject = useStore((s) => s.currentProject);
+  const project = currentProject();
   const [commits, setCommits] = useState<GitCommit[]>([]);
   const [selected, setSelected] = useState<string | null>(null);
   const [diff, setDiff] = useState("");
   const [busy, setBusy] = useState<string | null>(null);
   const [error, setError] = useState<string | null>(null);
 
-  const load = () => getGitLog().then(setCommits).catch(() => {});
+  const load = () => getGitLog(project).then(setCommits).catch(() => {});
   useEffect(() => {
     load();
-  }, []);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [project]);
 
   const openDiff = async (hash: string) => {
     setSelected(hash);
     setDiff("Chargement…");
-    setDiff((await getGitDiff(hash)) || "(diff vide)");
+    setDiff((await getGitDiff(hash, project)) || "(diff vide)");
   };
 
   const doRevert = async (hash: string) => {
@@ -225,7 +228,7 @@ function GitPanel() {
     setBusy(hash);
     setError(null);
     try {
-      await revertCommit(hash);
+      await revertCommit(hash, project);
       await load();
       await refreshFiles();
       if (selected === hash) setSelected(null);
diff --git a/frontend/src/store/useStore.ts b/frontend/src/store/useStore.ts
index d6618f9..2b79ae5 100644
--- a/frontend/src/store/useStore.ts
+++ b/frontend/src/store/useStore.ts
@@ -4,6 +4,8 @@ import {
   deleteFile,
   deleteSession,
   getConfig,
+  listProjects,
+  setSessionProject,
   getModels,
   getSession,
   getStatus,
@@ -77,6 +79,11 @@ interface LokiState {
   removeSession: (id: string) => Promise<void>;
   renameSession: (id: string, title: string) => Promise<void>;
   removeFile: (path: string) => Promise<void>;
+
+  projects: { name: string; files: number }[];
+  refreshProjects: () => Promise<void>;
+  currentProject: () => string | null;
+  setProject: (name: string | null) => Promise<void>;
   sendMessage: (content: string) => Promise<void>;
   stopStreaming: () => void;
 
@@ -110,6 +117,7 @@ export const useStore = create<LokiState>((set, get) => ({
   fileTree: [],
   previewPath: null,
   previewContent: "",
+  projects: [],
   config: null,
   availableTools: [],
   pendingShell: null,
@@ -156,7 +164,7 @@ export const useStore = create<LokiState>((set, get) => ({
   },
 
   openPreview: async (path) => {
-    const content = await fileContent(path);
+    const content = await fileContent(path, get().currentProject());
     set({ previewPath: path, previewContent: content });
   },
 
@@ -197,12 +205,39 @@ export const useStore = create<LokiState>((set, get) => ({
 
   refreshFiles: async () => {
     try {
-      set({ fileTree: await listFiles() });
+      set({ fileTree: await listFiles(get().currentProject()) });
     } catch {
       /* workspace indisponible */
     }
   },
 
+  refreshProjects: async () => {
+    try {
+      const { projects } = await listProjects();
+      set({ projects });
+    } catch {
+      /* backend indisponible */
+    }
+  },
+
+  currentProject: () => {
+    const s = get().sessions.find((x) => x.id === get().currentSessionId);
+    return s?.project ?? null;
+  },
+
+  setProject: async (name) => {
+    const sid = get().currentSessionId;
+    if (!sid) {
+      const s = await createSession(get().selectedModel || undefined, name);
+      set({ currentSessionId: s.id, messages: [] });
+    } else {
+      await setSessionProject(sid, name);
+    }
+    await get().refreshSessions();
+    set({ previewPath: null, previewContent: "" });
+    await get().refreshFiles();
+  },
+
   refreshStatus: async () => {
     try {
       const status = await getStatus();
@@ -250,7 +285,10 @@ export const useStore = create<LokiState>((set, get) => ({
   },
 
   newSession: async () => {
-    const s = await createSession(get().selectedModel || undefined);
+    // La nouvelle session hérite du projet de la session courante.
+    const s = await createSession(
+      get().selectedModel || undefined, get().currentProject()
+    );
     const streaming = get().streaming;
     set({
       currentSessionId: s.id,
@@ -272,6 +310,8 @@ export const useStore = create<LokiState>((set, get) => ({
         ? {}
         : { streamContent: "", streamStatus: "", streamNotice: null }),
     });
+    // L'arborescence suit le projet de la session ouverte.
+    await get().refreshFiles();
   },
 
   removeSession: async (id) => {
@@ -290,7 +330,7 @@ export const useStore = create<LokiState>((set, get) => ({
   },
 
   removeFile: async (path) => {
-    await deleteFile(path);
+    await deleteFile(path, get().currentProject());
     // Ferme l'aperçu si le fichier supprimé (ou son dossier) y est affiché.
     const preview = get().previewPath;
     if (preview && (preview === path || preview.startsWith(path + "/"))) {