feat(tools): generate_document tool emitting real .docx (#4847 Problem 3)

Cargo.toml

@@ -268,6 +268,13 @@ pdf-extract = "0.10"
 # stack) now lives in the tinychannels crate; the `whatsapp-web` feature forwards
 # to `tinychannels/whatsapp-web`.
 ppt-rs = "0.2.14"
+# Native-Rust `.docx` writer for the `generate_document` tool (GH #4847).
+# Pure Rust (no subprocess / managed runtime), MIT-licensed, actively
+# maintained (2.8M downloads, last release 0.4.20 — Apr 2026). Mirrors the
+# `ppt-rs` presentation engine: synthesise bytes in-process, hand them to
+# the byte-agnostic artifact pipeline. `default-features` keeps the crate's
+# image support (unused here, but avoids a bespoke feature list drifting).
+docx-rs = "0.4.20"
 
 [target.'cfg(windows)'.dependencies]
 # Windows: tokio-tungstenite uses native-tls (schannel) so wss://

app/src/components/chat/ArtifactCard.tsx

@@ -7,6 +7,7 @@ import {
   saveArtifactViaDialog,
 } from '../../services/artifactDownloadService';
 import type { ArtifactSnapshot } from '../../store/chatRuntimeSlice';
+import { extensionFor } from './artifactExtension';
 
 /**
  * Inline chat card surfacing a single agent-generated artifact (#2779).
@@ -33,30 +34,6 @@ export interface ArtifactCardProps {
   onRetry?: (artifactId: string) => void;
 }
 
-/**
- * Extension hint for the Tauri download command. Falls back to a
- * lowercased kind slug when the title doesn't carry an explicit
- * extension (defensive — `create_artifact` sanitises the title +
- * extension separately, but a malformed title shouldn't crash the
- * card).
- */
-function extensionFor(kind: ArtifactSnapshot['kind'], title: string): string {
-  const dot = title.lastIndexOf('.');
-  if (dot > 0 && dot < title.length - 1) {
-    return title.slice(dot + 1).toLowerCase();
-  }
-  switch (kind) {
-    case 'presentation':
-      return 'pptx';
-    case 'document':
-      return 'pdf';
-    case 'image':
-      return 'png';
-    default:
-      return 'bin';
-  }
-}
-
 function KindIcon({ kind }: { kind: ArtifactSnapshot['kind'] }) {
   const stroke = 'currentColor';
   switch (kind) {

app/src/components/chat/ChatFilesPanel.tsx

@@ -15,6 +15,7 @@ import {
 } from '../../store/chatRuntimeSlice';
 import { useAppDispatch } from '../../store/hooks';
 import Button from '../ui/Button';
+import { extensionFor } from './artifactExtension';
 
 /**
  * Popover panel listing every `ready` artifact for a thread (#3024).
@@ -76,23 +77,6 @@ function localizeErrorCode(
   }
 }
 
-function extensionFor(kind: ArtifactSnapshot['kind'], title: string): string {
-  const dot = title.lastIndexOf('.');
-  if (dot > 0 && dot < title.length - 1) {
-    return title.slice(dot + 1).toLowerCase();
-  }
-  switch (kind) {
-    case 'presentation':
-      return 'pptx';
-    case 'document':
-      return 'pdf';
-    case 'image':
-      return 'png';
-    default:
-      return 'bin';
-  }
-}
-
 function KindIcon({ kind }: { kind: ArtifactSnapshot['kind'] }) {
   const stroke = 'currentColor';
   switch (kind) {

app/src/components/chat/__tests__/ArtifactCard.test.tsx

@@ -130,7 +130,7 @@ describe('ArtifactCard', () => {
   });
 
   it.each([
-    ['document' as const, 'pdf'],
+    ['document' as const, 'docx'],
     ['image' as const, 'png'],
     ['other' as const, 'bin'],
     ['presentation' as const, 'pptx'],