diff --git a/packages/ui/src/components/chat/ChatInput.tsx b/packages/ui/src/components/chat/ChatInput.tsx
index 7c436d52..7e87e7e5 100644
--- a/packages/ui/src/components/chat/ChatInput.tsx
+++ b/packages/ui/src/components/chat/ChatInput.tsx
@@ -1652,7 +1652,7 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({ onOpenSettings, scrollTo
             });
         }
 
-        if (!primaryText && additionalParts.length === 0) return;
+        if (!primaryText && primaryAttachments.length === 0 && additionalParts.length === 0) return;
 
         // Clear queue and input
         if (currentSessionId && hasQueuedMessages) {
diff --git a/packages/ui/src/sync/input-store.ts b/packages/ui/src/sync/input-store.ts
index 62984664..a5e81a8e 100644
--- a/packages/ui/src/sync/input-store.ts
+++ b/packages/ui/src/sync/input-store.ts
@@ -42,6 +42,22 @@ const readFileAsDataUrl = (file: File): Promise<string> => new Promise((resolve,
   reader.readAsDataURL(file)
 })
 
+const getDataUrlByteSize = (url: string): number => {
+  if (!url.startsWith("data:")) return 0
+  const commaIndex = url.indexOf(",")
+  if (commaIndex < 0) return 0
+  const metadata = url.slice(0, commaIndex).toLowerCase()
+  const payload = url.slice(commaIndex + 1)
+  if (!metadata.endsWith(";base64")) return 0
+  let padding = 0
+  if (payload.endsWith("==")) {
+    padding = 2
+  } else if (payload.endsWith("=")) {
+    padding = 1
+  }
+  return Math.max(0, Math.floor((payload.length * 3) / 4) - padding)
+}
+
 const isSameVSCodeActiveEditorFile = (a: VSCodeActiveEditorFile | null, b: VSCodeActiveEditorFile | null): boolean => {
   if (a === b) return true
   if (!a || !b) return false
@@ -225,7 +241,7 @@ export const useInputStore = create<InputState>()((set, get) => ({
       dataUrl: url,
       mimeType,
       filename,
-      size: 0,
+      size: getDataUrlByteSize(url),
       source: "local",
       serverPath: url,
     }
diff --git a/packages/ui/src/sync/session-actions.ts b/packages/ui/src/sync/session-actions.ts
index ae10afdf..4cc48b80 100644
--- a/packages/ui/src/sync/session-actions.ts
+++ b/packages/ui/src/sync/session-actions.ts
@@ -116,6 +116,18 @@ function getSessionReplyClient(sessionId?: string): OpencodeClient {
   return sdk()
 }
 
+function restoreFilePartsToInput(fileParts: Array<Record<string, unknown>>): void {
+  useInputStore.getState().clearAttachedFiles()
+  for (const filePart of fileParts) {
+    const url = typeof filePart.url === "string" ? filePart.url : ""
+    const mime = typeof filePart.mime === "string" ? filePart.mime : "application/octet-stream"
+    const filename = typeof filePart.filename === "string" ? filePart.filename : "attachment"
+    if (url) {
+      useInputStore.getState().addRestoredAttachment({ url, mimeType: mime, filename })
+    }
+  }
+}
+
 function resolveDirectoryForBlockingRequest(
   type: "permission" | "question",
   sessionId: string,
@@ -589,10 +601,10 @@ export async function revertToMessage(sessionId: string, messageId: string): Pro
       .map((p: Record<string, unknown>) => (p as { text?: string }).text || (p as { content?: string }).content || "")
       .join("\n")
       .trim()
-    // Snapshot file parts for later restoration to the input (line ~626).
-    // File parts (type="file") contain url/mime/filename — the file already
-    // exists on the server so we record it as a "server" source attachment.
-    submittedFileParts = parts.filter((p) => p.type === "file") as Array<Record<string, unknown>>
+    // Snapshot file parts for later restoration to the input.
+    // Exclude synthetic file parts (server-generated file content that should
+    // not be restored to the composer).
+    submittedFileParts = parts.filter((p) => p.type === "file" && !isSyntheticPart(p)) as Array<Record<string, unknown>>
   }
 
   // Optimistically set only the revert marker. Keep messages and parts in the
@@ -632,16 +644,7 @@ export async function revertToMessage(sessionId: string, messageId: string): Pro
   // Restore file/image attachments from the target message.
   // Clear existing attachments first — previous revert's attachments
   // must not carry over, even when the current message has no files.
-  useInputStore.getState().clearAttachedFiles()
-  for (const fp of submittedFileParts) {
-      const f = fp as Record<string, unknown>
-      const url = typeof f.url === "string" ? f.url : ""
-      const mime = typeof f.mime === "string" ? f.mime : "application/octet-stream"
-      const filename = typeof f.filename === "string" ? f.filename : "attachment"
-      if (url) {
-        useInputStore.getState().addRestoredAttachment({ url, mimeType: mime, filename })
-      }
-    }
+  restoreFilePartsToInput(submittedFileParts)
 
   // Call SDK and merge authoritative result into store
   try {
@@ -745,8 +748,10 @@ export async function forkFromMessage(sessionId: string, messageId: string): Pro
   const store = dirStore()
   const state = store.getState()
 
-  // Extract message text for input restoration (only non-synthetic text parts —
-  // the server adds file content as synthetic text parts that should not be restored)
+  // Extract message text and file attachments for input restoration.
+  // Only non-synthetic text parts — the server adds file content as synthetic
+  // text parts that should not be restored. File parts (images, pasted
+  // screenshots) are user-originated and must be restored.
   const parts = state.part[messageId] ?? []
   let messageText = ""
   const textParts = parts.filter((p) => p.type === "text" && !isSyntheticPart(p))
@@ -754,6 +759,7 @@ export async function forkFromMessage(sessionId: string, messageId: string): Pro
     .map((p: Part) => ((p as Record<string, unknown>).text as string) || ((p as Record<string, unknown>).content as string) || "")
     .join("\n")
     .trim()
+  const fileParts = parts.filter((p) => p.type === "file" && !isSyntheticPart(p)) as Array<Record<string, unknown>>
 
   const result = await sdk().session.fork({ sessionID: sessionId, directory: dir(), messageID: messageId })
   if (!result.data) return
@@ -772,11 +778,13 @@ export async function forkFromMessage(sessionId: string, messageId: string): Pro
   // Switch to new session
   useSessionUIStore.getState().setCurrentSession(forkedSession.id)
 
-  // Restore forked message text to input
+  // Restore forked message text and file attachments to input
   if (messageText) {
     useInputStore.setState({
       pendingInputText: messageText,
       pendingInputMode: "replace" as const,
     })
   }
+  // Clear existing attachments and restore file parts from the forked message.
+  restoreFilePartsToInput(fileParts)
 }
diff --git a/packages/ui/src/sync/session-ui-store.ts b/packages/ui/src/sync/session-ui-store.ts
index 9e367fe1..70d6236a 100644
--- a/packages/ui/src/sync/session-ui-store.ts
+++ b/packages/ui/src/sync/session-ui-store.ts
@@ -485,6 +485,11 @@ export const useSessionUIStore = create<SessionUIState>()((set, get) => ({
       error: null,
     })
 
+    // Clear composer attachments when opening a new session draft.
+    // Attachments from the previous session (e.g. restored by revert) must
+    // not bleed into the new session's input.
+    useInputStore.getState().clearAttachedFiles()
+
     if (options?.initialPrompt) {
       useInputStore.getState().setPendingInputText(options.initialPrompt)
     }