diff --git a/packages/web/src/components/chat/AttachmentProgress.tsx b/packages/web/src/components/chat/AttachmentProgress.tsx
index 668289f1..06f8e826 100644
--- a/packages/web/src/components/chat/AttachmentProgress.tsx
+++ b/packages/web/src/components/chat/AttachmentProgress.tsx
@@ -6,6 +6,8 @@ interface Props {
   total: number;
   state: TransferState;
   filename: string;
+  /** Optional human-readable error surfaced as a hover tooltip when state==='failed'. */
+  error?: string;
   onPause?: () => void;
   onResume?: () => void;
   onAbort?: () => void;
@@ -19,7 +21,7 @@ function fmt(bytes: number): string {
   return `${(bytes / 1024 / 1024 / 1024).toFixed(2)} GB`;
 }
 
-export function AttachmentProgress({ loaded, total, state, filename, onPause, onResume, onAbort, size = 'tile' }: Props) {
+export function AttachmentProgress({ loaded, total, state, filename, error, onPause, onResume, onAbort, size = 'tile' }: Props) {
   const pct = total > 0 ? Math.min(100, Math.round((loaded / total) * 100)) : 0;
   const bg = state === 'failed' ? 'bg-accent-rose/30' : 'bg-accent-mint/30';
   const isFinal = state === 'completed' || state === 'aborted';
@@ -28,6 +30,7 @@ export function AttachmentProgress({ loaded, total, state, filename, onPause, on
       <div
         className={`w-9 h-9 rounded-full ${bg} flex items-center justify-center`}
         style={state !== 'failed' ? { background: `conic-gradient(rgba(180,220,200,.85) ${pct}%, rgba(255,255,255,.15) ${pct}%)` } : undefined}
+        title={state === 'failed' ? error : undefined}
       >
         <div className="w-7 h-7 rounded-full bg-surface-overlay text-[10px] text-txt-primary flex items-center justify-center font-medium">
           {state === 'failed' ? '!' : `${pct}%`}
diff --git a/packages/web/src/components/chat/Message.tsx b/packages/web/src/components/chat/Message.tsx
index 6c046bc2..c32dc605 100644
--- a/packages/web/src/components/chat/Message.tsx
+++ b/packages/web/src/components/chat/Message.tsx
@@ -51,6 +51,7 @@ function PendingAttachmentTile({ transferId }: PendingAttachmentTileProps) {
         total={transfer.progress.total}
         state={transfer.state}
         filename={transfer.file.name}
+        error={transfer.error?.message}
         onPause={transfer.state === 'active' ? () => pauseUpload(transfer.id) : undefined}
         onResume={transfer.state === 'paused' ? () => resumeUpload(transfer.id) : undefined}
         onAbort={() => abortUpload(transfer.id)}
@@ -133,11 +134,22 @@ export function Message({ message, isCompact, isFirstInGroup, previousMessageId
   const showInteractions = !pending;
 
   const transfersForRow = useTransferStore((s) => s.transfers);
+  const inMemoryFiles = useTransferStore((s) => s.hasInMemoryFile);
   const anyTransferTerminallyBad = !!pending && pending.transferIds.some((tid) => {
     const t = transfersForRow.get(tid);
     return t && (t.state === 'failed' || t.state === 'aborted');
   });
   const showRetryDiscardRow = pending?.state === 'failed' || anyTransferTerminallyBad;
+  // Retry is only feasible when we can re-source the bytes for every transfer in the
+  // pending row — either the in-memory File ref still exists (same-session retry)
+  // or a persisted FileSystemFileHandle can reacquire the bytes (Chrome/Edge drag-drop).
+  // After a reload (or post-redeploy refresh) without a handle, both are gone, and
+  // showing a Retry button that silently no-ops would strand the user. Hide it instead.
+  const canRetry = !!pending && pending.transferIds.every((tid) => {
+    const t = transfersForRow.get(tid);
+    if (!t || t.type !== 'upload') return false;
+    return inMemoryFiles.has(tid) || !!t.fileHandleId;
+  });
 
   const channelKey: string = isPendingMessage(message)
     ? message.channelId || message.dmChannelId || ''
@@ -519,24 +531,26 @@ export function Message({ message, isCompact, isFirstInGroup, previousMessageId
                   Upload failed
                 </span>
                 <span className="w-px h-3.5 bg-accent-rose/25" aria-hidden="true" />
-                <button
-                  onClick={async () => {
-                    const transfers = useTransferStore.getState().transfers;
-                    const retryIds = pending.transferIds.filter((tid) => {
-                      const s = transfers.get(tid)?.state;
-                      return s === 'failed' || s === 'aborted';
-                    });
-                    // Flip the bubble back to 'sending' first so the orchestrator
-                    // re-evaluates after the resumed transfers complete.
-                    usePendingMessageStore.getState().markSending(pending.clientId);
-                    for (const tid of retryIds) {
-                      await useTransferStore.getState().resumeUpload(tid);
-                    }
-                  }}
-                  className="px-2 py-0.5 rounded-md text-[11.5px] font-medium text-accent-mint bg-accent-mint/10 hover:bg-accent-mint/20 transition-colors"
-                >
-                  Retry
-                </button>
+                {canRetry && (
+                  <button
+                    onClick={async () => {
+                      const transfers = useTransferStore.getState().transfers;
+                      const retryIds = pending.transferIds.filter((tid) => {
+                        const s = transfers.get(tid)?.state;
+                        return s === 'failed' || s === 'aborted';
+                      });
+                      // Flip the bubble back to 'sending' first so the orchestrator
+                      // re-evaluates after the resumed transfers complete.
+                      usePendingMessageStore.getState().markSending(pending.clientId);
+                      for (const tid of retryIds) {
+                        await useTransferStore.getState().resumeUpload(tid);
+                      }
+                    }}
+                    className="px-2 py-0.5 rounded-md text-[11.5px] font-medium text-accent-mint bg-accent-mint/10 hover:bg-accent-mint/20 transition-colors"
+                  >
+                    Retry
+                  </button>
+                )}
                 <button
                   onClick={() => {
                     const transfers = useTransferStore.getState().transfers;
diff --git a/packages/web/src/stores/transferStore.ts b/packages/web/src/stores/transferStore.ts
index 7af9e51e..1425c6ca 100644
--- a/packages/web/src/stores/transferStore.ts
+++ b/packages/web/src/stores/transferStore.ts
@@ -52,6 +52,12 @@ export interface CreateTransferInput {
 
 interface TransferStoreState {
   transfers: Map<string, Transfer>;
+  /**
+   * Mirrors the keys of the module-scoped `liveUploadFiles` map so React components
+   * can subscribe to "do we still hold the original File for this transfer?" reactively.
+   * Session-scoped — never persisted (the underlying File refs vanish on reload).
+   */
+  hasInMemoryFile: Set<string>;
 }
 
 interface TransferStoreActions {
@@ -129,8 +135,23 @@ const mapAwareStorage: PersistStorage<Pick<TransferStoreState, 'transfers'>> = {
 
 export const useTransferStore = create<TransferStore>()(
   persist(
-    (set, get) => ({
+    (set, get) => {
+      // DRY helper: keep the reactive `hasInMemoryFile` set in sync with the
+      // module-scoped `liveUploadFiles` map. Both call-sites that mutate the map
+      // immediately follow up with this so subscribers re-render.
+      const setInMemoryRef = (id: string, present: boolean) => {
+        set((s) => {
+          const has = s.hasInMemoryFile.has(id);
+          if (present === has) return s;
+          const next = new Set(s.hasInMemoryFile);
+          if (present) next.add(id); else next.delete(id);
+          return { hasInMemoryFile: next };
+        });
+      };
+
+      return ({
       transfers: new Map<string, Transfer>(),
+      hasInMemoryFile: new Set<string>(),
 
       createTransfer: (input) => {
         const id = uuid();
@@ -196,13 +217,16 @@ export const useTransferStore = create<TransferStore>()(
         return { transfers: next };
       }),
 
-      remove: (id) => set((s) => {
-        if (!s.transfers.has(id)) return s;
-        const next = new Map(s.transfers);
-        next.delete(id);
+      remove: (id) => {
         liveUploadFiles.delete(id);
-        return { transfers: next };
-      }),
+        setInMemoryRef(id, false);
+        set((s) => {
+          if (!s.transfers.has(id)) return s;
+          const next = new Map(s.transfers);
+          next.delete(id);
+          return { transfers: next };
+        });
+      },
 
       startUpload: async (file, opts) => {
         const token = useAuthStore.getState().token;
@@ -262,6 +286,7 @@ export const useTransferStore = create<TransferStore>()(
             } finally {
               liveUploads.delete(id);
               liveUploadFiles.delete(id);
+              setInMemoryRef(id, false);
             }
           },
           onError: (err: Error) => {
@@ -276,6 +301,7 @@ export const useTransferStore = create<TransferStore>()(
         const upload = new Upload(file as File, tusOpts);
         liveUploads.set(id, upload);
         liveUploadFiles.set(id, file);
+        setInMemoryRef(id, true);
         upload.start();
         return id;
       },
@@ -349,10 +375,14 @@ export const useTransferStore = create<TransferStore>()(
         }
 
         if (!blob) {
-          // No handle, no in-memory file — surface "re-pick to resume" to the user.
-          // (Cross-reload on Firefox/Safari, or after MessageInput unmount cleared
-          // the in-memory File and the bubble survives without an FS handle.)
-          get().setState_(id, 'paused');
+          // No in-memory File (post-reload) AND no FS handle to reacquire bytes from.
+          // The user must discard and re-upload. Setting 'failed' lets the orchestrator's
+          // mark-failed sweep keep the bubble in failed state and Message.tsx surfaces
+          // the discard control. The Retry button is hidden in this case (canRetry gate).
+          get().setError(id, {
+            message: 'File no longer available — discard and re-upload',
+            permanent: true,
+          });
           return;
         }
 
@@ -425,6 +455,7 @@ export const useTransferStore = create<TransferStore>()(
             } finally {
               liveUploads.delete(id);
               liveUploadFiles.delete(id);
+              setInMemoryRef(id, false);
             }
           },
           onError: (err: Error) => {
@@ -435,6 +466,11 @@ export const useTransferStore = create<TransferStore>()(
           },
         };
 
+        // Retain the resolved blob in the in-memory map so a subsequent retry-after-failure
+        // (e.g., transient network error) can resume without going through the handle path.
+        liveUploadFiles.set(id, blob);
+        setInMemoryRef(id, true);
+
         const upload = new Upload(blob as File, tusOpts);
         liveUploads.set(id, upload);
         upload.start();
@@ -631,7 +667,8 @@ export const useTransferStore = create<TransferStore>()(
       listVisible: () => Array.from(get().transfers.values()).filter((t) => t.tray),
       listForChannel: (channelId) =>
         Array.from(get().transfers.values()).filter((t) => t.channelId === channelId),
-    }),
+    });
+    },
     {
       name: 'transferStore@v1',
       storage: mapAwareStorage,
diff --git a/packages/web/src/stores/transferStore.upload.test.ts b/packages/web/src/stores/transferStore.upload.test.ts
index 3f0be477..c1d68d07 100644
--- a/packages/web/src/stores/transferStore.upload.test.ts
+++ b/packages/web/src/stores/transferStore.upload.test.ts
@@ -62,7 +62,7 @@ import { useTransferStore } from './transferStore';
 
 describe('transferStore.startUpload', () => {
   beforeEach(() => {
-    useTransferStore.setState({ transfers: new Map() });
+    useTransferStore.setState({ transfers: new Map(), hasInMemoryFile: new Set() });
     startMock.mockClear();
     abortMock.mockClear();
     if (typeof localStorage !== 'undefined') localStorage.clear();
@@ -118,12 +118,12 @@ describe('transferStore.startUpload', () => {
 
 describe('transferStore.resumeUpload', () => {
   beforeEach(() => {
-    useTransferStore.setState({ transfers: new Map() });
+    useTransferStore.setState({ transfers: new Map(), hasInMemoryFile: new Set() });
     startMock.mockClear();
     abortMock.mockClear();
   });
 
-  it('stays paused when transfer has no tusUploadUrl and no available blob', async () => {
+  it('marks failed when transfer has no available blob to resume from', async () => {
     const id = useTransferStore.getState().createTransfer({
       type: 'upload',
       file: { name: 'a.png', size: 100, mimetype: 'image/png' },
@@ -132,12 +132,15 @@ describe('transferStore.resumeUpload', () => {
     useTransferStore.getState().setState_(id, 'paused');
     await useTransferStore.getState().resumeUpload(id);
     const t = useTransferStore.getState().get(id)!;
-    // No URL + no in-memory file + no handle → can neither resume nor restart;
-    // surface 'paused' to prompt the user to re-pick.
-    expect(t.state).toBe('paused');
+    // No URL + no in-memory file + no handle → cannot resume or restart.
+    // Surface 'failed' with an actionable message so the UI shows Discard
+    // and hides the Retry button (which would silently no-op).
+    expect(t.state).toBe('failed');
+    expect(t.error?.message ?? '').toMatch(/file no longer available/i);
+    expect(t.error?.permanent).toBe(true);
   });
 
-  it('stays paused when tus URL has expired and no available blob', async () => {
+  it('marks failed when tus URL has expired and no available blob', async () => {
     const id = useTransferStore.getState().createTransfer({
       type: 'upload',
       file: { name: 'a.png', size: 100, mimetype: 'image/png' },
@@ -146,11 +149,13 @@ describe('transferStore.resumeUpload', () => {
     useTransferStore.getState().setTusUrl(id, '/api/files/expired', Date.now() - 1000);
     useTransferStore.getState().setState_(id, 'paused');
     await useTransferStore.getState().resumeUpload(id);
-    // Expired URL with no blob to restart → stay paused, user re-picks.
-    expect(useTransferStore.getState().get(id)!.state).toBe('paused');
+    const t = useTransferStore.getState().get(id)!;
+    // Expired URL with no blob to restart → failed, user must discard and re-upload.
+    expect(t.state).toBe('failed');
+    expect(t.error?.message ?? '').toMatch(/file no longer available/i);
   });
 
-  it('stays paused when no FS handle is available (re-pick required)', async () => {
+  it('marks failed when no FS handle is available (re-pick required)', async () => {
     const id = useTransferStore.getState().createTransfer({
       type: 'upload',
       file: { name: 'a.png', size: 100, mimetype: 'image/png' },
@@ -160,6 +165,54 @@ describe('transferStore.resumeUpload', () => {
     useTransferStore.getState().setTusUrl(id, '/api/files/abc', Date.now() + 60_000);
     useTransferStore.getState().setState_(id, 'paused');
     await useTransferStore.getState().resumeUpload(id);
-    expect(useTransferStore.getState().get(id)!.state).toBe('paused');
+    const t = useTransferStore.getState().get(id)!;
+    expect(t.state).toBe('failed');
+    expect(t.error?.message ?? '').toMatch(/file no longer available/i);
+  });
+});
+
+describe('transferStore.hasInMemoryFile', () => {
+  beforeEach(() => {
+    useTransferStore.setState({ transfers: new Map(), hasInMemoryFile: new Set() });
+    startMock.mockClear();
+    abortMock.mockClear();
+    if (typeof localStorage !== 'undefined') localStorage.clear();
+  });
+
+  it('hasInMemoryFile tracks startUpload + remove lifecycle', async () => {
+    const file = new File([new Uint8Array(100)], 'a.png', { type: 'image/png' });
+    const id = await useTransferStore.getState().startUpload(file, { tray: true });
+    // The mock's onSuccess fires synchronously inside start(), which clears the
+    // in-memory ref. So here we should see it cleared (transfer is 'completed').
+    expect(useTransferStore.getState().get(id)!.state).toBe('completed');
+    expect(useTransferStore.getState().hasInMemoryFile.has(id)).toBe(false);
+    useTransferStore.getState().remove(id);
+    expect(useTransferStore.getState().hasInMemoryFile.has(id)).toBe(false);
+  });
+
+  it('hasInMemoryFile survives abortUpload (file retained for retry)', async () => {
+    // Simulate an in-flight transfer (pre-success) by manually populating the
+    // store and the in-memory file ref via a fresh transfer that hasn't completed.
+    // We do this by intercepting startUpload before the mock resolves: createTransfer
+    // and prime hasInMemoryFile + state directly to mirror an in-flight upload.
+    const id = useTransferStore.getState().createTransfer({
+      type: 'upload',
+      file: { name: 'a.png', size: 100, mimetype: 'image/png' },
+      tray: true,
+    });
+    // Prime the reactive set to mirror a live upload.
+    useTransferStore.setState((s) => {
+      const next = new Set(s.hasInMemoryFile);
+      next.add(id);
+      return { hasInMemoryFile: next };
+    });
+    useTransferStore.getState().setState_(id, 'active');
+
+    expect(useTransferStore.getState().hasInMemoryFile.has(id)).toBe(true);
+    useTransferStore.getState().abortUpload(id);
+    // abortUpload must NOT clear the in-memory ref — the user can still retry.
+    expect(useTransferStore.getState().hasInMemoryFile.has(id)).toBe(true);
+    useTransferStore.getState().remove(id);
+    expect(useTransferStore.getState().hasInMemoryFile.has(id)).toBe(false);
   });
 });