fix(chat): restore file attachments when reverting or forking messages (#1288)

* chore: add .worktrees/ to gitignore for worktree workflow

* fix(chat): restore file attachments when reverting or forking messages

* fix(chat): address review findings in attachment restoration

- Move filePartsToAttachments helper below all imports into its own
  'Attachment helpers' section (was incorrectly placed between imports)
- Compute size from base64 data URL for pasted screenshots instead of
  hardcoding 0; file:// URLs keep size 0 which formatFileSize suppresses
  gracefully
- Capture prevAttachedFiles before optimistic mutation and restore on
  SDK revert failure
- Always use source: 'local' for restored attachments so they are
  visible and removable in the composer regardless of URL scheme

* fix(chat): resolve merge conflicts and restore attachments in fork

- Merge upstream main which already added attachment restoration to
  revertToMessage via addRestoredAttachment
- Add !isSyntheticPart filter to revertToMessage file part collection
  (upstream was missing this)
- Add attachment restoration to forkFromMessage (was not fixed upstream)
- Use upstream's addRestoredAttachment approach for consistency

* fix(chat): clear restored attachments when opening new session draft

Reverted-message attachments (and any other pending attachments in the
global input store) were carrying over to the new session input because
openNewSessionDraft did not clear attachedFiles.

Clear attachedFiles in openNewSessionDraft, which is the navigation-away
event for new sessions (it already sets currentSessionId: null). This
matches the semantics of starting a fresh conversation.

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

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) {

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,
     }

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)
 }

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)
     }