diff --git a/artifacts/api-server/src/routes/timesheets.ts b/artifacts/api-server/src/routes/timesheets.ts
index 66a0d79..6911577 100644
--- a/artifacts/api-server/src/routes/timesheets.ts
+++ b/artifacts/api-server/src/routes/timesheets.ts
@@ -290,7 +290,7 @@ router.put("/timesheets/:timesheetId/entries", async (req, res): Promise<void> =
       } else {
         const [updated] = await db
           .update(timeEntriesTable)
-          .set({ hours: entry.hours })
+          .set({ hours: entry.hours, description: entry.description ?? null })
           .where(eq(timeEntriesTable.id, existing[0].id))
           .returning();
         results.push(updated);
@@ -302,6 +302,7 @@ router.put("/timesheets/:timesheetId/entries", async (req, res): Promise<void> =
           timesheetLineId: entry.timesheetLineId,
           date: dateStr,
           hours: entry.hours,
+          description: entry.description ?? null,
         })
         .returning();
       results.push(created);
diff --git a/artifacts/cra-app/public/opengraph.jpg b/artifacts/cra-app/public/opengraph.jpg
index 4f199d5..6aba47d 100644
Binary files a/artifacts/cra-app/public/opengraph.jpg and b/artifacts/cra-app/public/opengraph.jpg differ
diff --git a/artifacts/cra-app/src/pages/timesheet-detail.tsx b/artifacts/cra-app/src/pages/timesheet-detail.tsx
index 956b0cc..756e9cc 100644
--- a/artifacts/cra-app/src/pages/timesheet-detail.tsx
+++ b/artifacts/cra-app/src/pages/timesheet-detail.tsx
@@ -17,7 +17,8 @@ import {
   Plus, 
   Trash2, 
   CheckCircle,
-  AlertCircle
+  AlertCircle,
+  MessageSquare
 } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { Badge } from "@/components/ui/badge";
@@ -39,6 +40,7 @@ type LocalEntry = {
   timesheetLineId: number;
   date: string;
   hours: number;
+  description?: string | null;
 };
 
 export default function TimesheetDetailPage() {
@@ -59,6 +61,7 @@ export default function TimesheetDetailPage() {
   const upsertEntries = useUpsertTimeEntries();
 
   const [localEntries, setLocalEntries] = useState<Record<string, number>>({});
+  const [localDescriptions, setLocalDescriptions] = useState<Record<string, string>>({});
   const [isAddingLine, setIsAddingLine] = useState(false);
   const [hasUnsavedChanges, setHasUnsavedChanges] = useState(false);
   const dirtyKeysRef = useRef<Set<string>>(new Set());
@@ -68,15 +71,20 @@ export default function TimesheetDetailPage() {
   useEffect(() => {
     if (timesheet?.lines) {
       const initial: Record<string, number> = {};
+      const initialDesc: Record<string, string> = {};
       timesheet.lines.forEach(line => {
         line.entries?.forEach(entry => {
           const dateStr = typeof entry.date === "string" && entry.date.length > 10
             ? entry.date.slice(0, 10)
             : entry.date;
           initial[`${line.id}-${dateStr}`] = entry.hours;
+          if (entry.description) {
+            initialDesc[`${line.id}-${dateStr}`] = entry.description;
+          }
         });
       });
       setLocalEntries(initial);
+      setLocalDescriptions(initialDesc);
       setHasUnsavedChanges(false);
       dirtyKeysRef.current.clear();
     }
@@ -109,10 +117,13 @@ export default function TimesheetDetailPage() {
   const saveTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
   const localEntriesRef = useRef(localEntries);
   localEntriesRef.current = localEntries;
+  const localDescriptionsRef = useRef(localDescriptions);
+  localDescriptionsRef.current = localDescriptions;
 
   const doSave = useCallback(() => {
     if (!timesheetId) return;
     const entries = localEntriesRef.current;
+    const descriptions = localDescriptionsRef.current;
 
     const entriesToSave: LocalEntry[] = [];
     const dirty = dirtyKeysRef.current;
@@ -123,7 +134,8 @@ export default function TimesheetDetailPage() {
         entriesToSave.push({
           timesheetLineId: parseInt(lineIdStr),
           date: fullDate,
-          hours
+          hours,
+          description: descriptions[key] || null
         });
       }
     });
@@ -157,6 +169,16 @@ export default function TimesheetDetailPage() {
     saveTimerRef.current = setTimeout(() => doSave(), 800);
   };
 
+  const handleSetDescription = (lineId: number, dateStr: string, desc: string) => {
+    const key = `${lineId}-${dateStr}`;
+    setLocalDescriptions(prev => ({ ...prev, [key]: desc }));
+    setHasUnsavedChanges(true);
+    dirtyKeysRef.current.add(key);
+
+    if (saveTimerRef.current) clearTimeout(saveTimerRef.current);
+    saveTimerRef.current = setTimeout(() => doSave(), 800);
+  };
+
   useEffect(() => {
     return () => {
       if (saveTimerRef.current) clearTimeout(saveTimerRef.current);
@@ -185,13 +207,14 @@ export default function TimesheetDetailPage() {
 
     if (hasUnsavedChanges) {
       const entries = localEntriesRef.current;
+      const descriptions = localDescriptionsRef.current;
       const dirty = dirtyKeysRef.current;
       const entriesToSave: LocalEntry[] = [];
       Object.entries(entries).forEach(([key, hours]) => {
         const lineIdStr = key.split("-")[0];
         const fullDate = key.substring(lineIdStr.length + 1);
         if (hours > 0 || dirty.has(key)) {
-          entriesToSave.push({ timesheetLineId: parseInt(lineIdStr), date: fullDate, hours });
+          entriesToSave.push({ timesheetLineId: parseInt(lineIdStr), date: fullDate, hours, description: descriptions[key] || null });
         }
       });
       setSaveStatus("saving");
@@ -416,10 +439,14 @@ export default function TimesheetDetailPage() {
                     {daysArray.map(day => {
                       const key = `${line.id}-${day.dateStr}`;
                       const val = localEntries[key] || 0;
+                      const desc = localDescriptions[key] || "";
                       
                       const cellContent = (
-                        <div className="flex items-center justify-center h-9 w-full text-xs">
+                        <div className="relative flex items-center justify-center h-9 w-full text-xs">
                           {val === 0 ? "" : val}
+                          {desc && (
+                            <span className="absolute top-0.5 right-0.5 h-1.5 w-1.5 rounded-full bg-amber-400" />
+                          )}
                         </div>
                       );
 
@@ -432,13 +459,14 @@ export default function TimesheetDetailPage() {
                             isEditable ? "cursor-pointer hover:bg-primary/10" : "",
                             val > 0 ? "bg-primary/5 text-primary font-semibold" : ""
                           )}
+                          title={desc || undefined}
                         >
                           {isEditable ? (
                             <Popover>
                               <PopoverTrigger asChild>
                                 {cellContent}
                               </PopoverTrigger>
-                              <PopoverContent className="w-auto p-1.5" side="bottom" align="center">
+                              <PopoverContent className="w-56 p-2 space-y-2" side="bottom" align="center">
                                 <div className="grid grid-cols-5 gap-1">
                                   {HOUR_OPTIONS.map(h => (
                                     <button
@@ -457,6 +485,17 @@ export default function TimesheetDetailPage() {
                                     </button>
                                   ))}
                                 </div>
+                                <div className="flex items-center gap-1.5 pt-1 border-t">
+                                  <MessageSquare className="h-3 w-3 text-muted-foreground shrink-0" />
+                                  <input
+                                    type="text"
+                                    placeholder="Note (optionnel)"
+                                    value={desc}
+                                    onChange={(e) => handleSetDescription(line.id, day.dateStr, e.target.value)}
+                                    onClick={(e) => e.stopPropagation()}
+                                    className="w-full text-xs bg-transparent border-none outline-none placeholder:text-muted-foreground/50"
+                                  />
+                                </div>
                               </PopoverContent>
                             </Popover>
                           ) : cellContent}
diff --git a/lib/api-client-react/src/generated/api.schemas.ts b/lib/api-client-react/src/generated/api.schemas.ts
index 61e6d43..d2cdbb3 100644
--- a/lib/api-client-react/src/generated/api.schemas.ts
+++ b/lib/api-client-react/src/generated/api.schemas.ts
@@ -100,6 +100,7 @@ export interface TimeEntry {
   timesheetLineId: number;
   date: string;
   hours: number;
+  description?: string | null;
 }
 
 export interface TimesheetLineWithEntries {
@@ -149,6 +150,7 @@ export type UpsertTimeEntriesBodyEntriesItem = {
   timesheetLineId: number;
   date: string;
   hours: number;
+  description?: string | null;
 };
 
 export interface UpsertTimeEntriesBody {
diff --git a/lib/api-spec/openapi.yaml b/lib/api-spec/openapi.yaml
index 50552dd..aea180a 100644
--- a/lib/api-spec/openapi.yaml
+++ b/lib/api-spec/openapi.yaml
@@ -636,6 +636,9 @@ components:
           format: date
         hours:
           type: number
+        description:
+          type: string
+          nullable: true
       required:
         - id
         - timesheetLineId
@@ -657,6 +660,9 @@ components:
                 format: date
               hours:
                 type: number
+              description:
+                type: string
+                nullable: true
             required:
               - timesheetLineId
               - date
diff --git a/lib/api-zod/src/generated/api.ts b/lib/api-zod/src/generated/api.ts
index 130721a..70cbdbf 100644
--- a/lib/api-zod/src/generated/api.ts
+++ b/lib/api-zod/src/generated/api.ts
@@ -154,6 +154,7 @@ export const GetTimesheetResponse = zod.object({
           timesheetLineId: zod.number(),
           date: zod.coerce.date(),
           hours: zod.number(),
+          description: zod.string().nullish(),
         }),
       ),
     }),
@@ -243,6 +244,7 @@ export const UpsertTimeEntriesBody = zod.object({
       timesheetLineId: zod.number(),
       date: zod.coerce.date(),
       hours: zod.number(),
+      description: zod.string().nullish(),
     }),
   ),
 });
@@ -252,6 +254,7 @@ export const UpsertTimeEntriesResponseItem = zod.object({
   timesheetLineId: zod.number(),
   date: zod.coerce.date(),
   hours: zod.number(),
+  description: zod.string().nullish(),
 });
 export const UpsertTimeEntriesResponse = zod.array(
   UpsertTimeEntriesResponseItem,
diff --git a/lib/api-zod/src/generated/types/timeEntry.ts b/lib/api-zod/src/generated/types/timeEntry.ts
index aab8a5e..82cb77d 100644
--- a/lib/api-zod/src/generated/types/timeEntry.ts
+++ b/lib/api-zod/src/generated/types/timeEntry.ts
@@ -11,4 +11,5 @@ export interface TimeEntry {
   timesheetLineId: number;
   date: Date;
   hours: number;
+  description?: string | null;
 }
diff --git a/lib/api-zod/src/generated/types/upsertTimeEntriesBodyEntriesItem.ts b/lib/api-zod/src/generated/types/upsertTimeEntriesBodyEntriesItem.ts
index 55f7072..7114cac 100644
--- a/lib/api-zod/src/generated/types/upsertTimeEntriesBodyEntriesItem.ts
+++ b/lib/api-zod/src/generated/types/upsertTimeEntriesBodyEntriesItem.ts
@@ -10,4 +10,5 @@ export type UpsertTimeEntriesBodyEntriesItem = {
   timesheetLineId: number;
   date: Date;
   hours: number;
+  description?: string | null;
 };
diff --git a/lib/api-zod/src/index.ts b/lib/api-zod/src/index.ts
index 47a637d..ac442e7 100644
--- a/lib/api-zod/src/index.ts
+++ b/lib/api-zod/src/index.ts
@@ -1 +1,2 @@
 export * from "./generated/api";
+export * from "./generated/types";
diff --git a/replit.md b/replit.md
index 6b729a2..20d6c39 100644
--- a/replit.md
+++ b/replit.md
@@ -23,7 +23,7 @@ A French timesheet management application (CRA - Compte Rendu d'Activité) built
 
 - **Dashboard**: Overview with monthly hours chart, project breakdown, active project count, timesheet status
 - **Timesheet Management**: Create, view, edit monthly timesheets (CRA)
-- **CRA Grid**: Interactive calendar grid where rows = projects, columns = days of month. Click cells to cycle 0 → 0.5 → 1 hours. Weekend distinction, row/column totals
+- **CRA Grid**: Interactive calendar grid where rows = projects, columns = days of month. Click cells to open popover with hour options [0, 0.5, 1, 2, 3, 4, 5, 6, 7, 7.7]. Includes optional description per cell (amber dot indicator). Auto-save with debounce. Weekend distinction, row/column totals
 - **Project Management**: CRUD for projects with code, name, client, category
 - **Timesheet Workflow**: Draft → Submitted → Validated status flow
 
@@ -32,7 +32,7 @@ A French timesheet management application (CRA - Compte Rendu d'Activité) built
 - `projects` — Project definitions (code, name, client, category)
 - `timesheets` — Monthly timesheet headers (year, month, status, collaborator)
 - `timesheet_lines` — Project assignments within a timesheet
-- `time_entries` — Daily hour entries per line (date, hours)
+- `time_entries` — Daily hour entries per line (date, hours, description)
 
 ## Key Commands