Hover-edit a previous prompt into the composer without forking

ARCHITECTURE.md

@@ -77,6 +77,17 @@ tenant and writes settings rows — no deploy, no host, no anchor instance
 one publish onto the workbench's live stream, so the conversation takes
 messages whether or not any agent process is running.
 
+**Editing an own prompt.** Edit is a composer replace, not a timeline
+mutation and not a thread fork. The timeline offers Edit only on the
+signed-in reader's own prompts that have text
+(`packages/chat-ui/src/timeline.tsx`). Choosing it copies that message's
+text into the composer through `ComposerHandle.setText`
+(`packages/chat-ui/src/composer.tsx`). `setText` replaces the draft and
+clears leftover composer-private state (slash, mention, pending invites,
+attachments, in-flight attachment reads). Sending is the ordinary post
+onto the timeline already in view (root or an open thread). It does not
+PATCH the origin message and it does not call `forkThread`.
+
 A workbench's address is derived, not resolved. Asking an invited agent
 for a turn is a separate act over Interchange mail; the agent replies by
 emitting `connector.reply` events on its own stream, and a reply bridge

DESIGN.md

@@ -277,6 +277,18 @@ short tags or a card, and mirroring them to the right would land next to
 the composer and break the one consistent place a reader looks for
 approvals and tool activity.
 
+## Message actions
+
+A message's compact action cluster — add reaction, reply in thread (or
+Fork inside a thread), Edit on own prompts, and ellipsis — reveals on
+pointer hover or keyboard focus-within. It is not hover-only and not a
+persistent inline row of links. The ellipsis button and a right-click on
+the message open the same menu; Edit appears there too when the row is
+the signed-in reader's own prompt with text.
+
+Edit copies the prompt into the composer. It is not an in-place rewrite
+of the bubble.
+
 ## Connect cards
 
 In-thread cards flip in place: disconnected → connected → next step. The

IMPLEMENTATION.md

@@ -41,6 +41,12 @@ core, reusable components live there; only workbench-specific composition
 is pinned to a specific upstream commit rather than a floating version
 range.
 
+`@corbits/chat-ui` owns the conversation surface. The composer's host
+seam is `ComposerHandle`: `insertText` splices at the caret (Mention);
+`setText` replaces the whole draft (Edit a previous prompt) and is the
+layer that clears leftover slash, mention, invite, and attachment state
+so a replaced draft cannot send under the old picker's rules.
+
 ## Vendored `@intx/*`
 
 Interchange capabilities are consumed as published `@intx/*` npm packages

PRODUCT.md

@@ -115,6 +115,14 @@ does not wake an agent. Generic `connections/pending` still wakes the
 asking agent. Neither path posts the connected notice as the connecting
 person.
 
+## Reusing an own prompt
+
+A person can **Edit** their own previous prompt. Edit copies that text
+into the composer, replacing any leftover draft — slash command, mention,
+invite, and attachments. Sending posts a new message on the same
+timeline: it does not rewrite the original, and it does not fork a
+thread. Other people's prompts have no Edit.
+
 ## Plugins and Skills
 
 A **Skill** is a named, reusable capability — instructions an agent can

packages/chat-ui/src/chat-workspace.tsx

@@ -60,7 +60,12 @@ import { displayWorkbenchTitle } from "./workbench-display-title";
 import { useStreamingReply, typingAgentNames } from "./streaming-reply";
 import { useTurnActivity, TurnActivityStrip } from "./turn-activity";
 import type { StreamingReplyState } from "./streaming-reply";
-import { AgentBadge, WorkbenchTimeline, messageDomId } from "./timeline";
+import {
+  AgentBadge,
+  WorkbenchTimeline,
+  messageDomId,
+  messageText,
+} from "./timeline";
 import { NoUsableModelBanner } from "./no-usable-model-banner";
 import { ResumeFailedBanner } from "./resume-failed-banner";
 import type {
@@ -1541,6 +1546,14 @@ function ChatWorkspaceInner({
                     onOpenThread={
                       inThreadView ? forkMessage : openThreadForMessage
                     }
+                    onEditMessage={(messageId) => {
+                      if (messagesState.kind !== "ready") return;
+                      const item = messagesState.items.find(
+                        (message) => message.id === messageId,
+                      );
+                      if (item === undefined) return;
+                      composerRef.current?.setText(messageText(item));
+                    }}
                     {...(onOpenProfile !== undefined ? { onOpenProfile } : {})}
                     {...(onOpenArtifact !== undefined
                       ? { onOpenArtifact }

packages/chat-ui/src/composer.tsx

@@ -60,10 +60,11 @@ export type ComposerSendPayload = {
 };
 
 /** Imperative seam a host can grab a ref to, so content from outside the
- * composer's own tree — the profile card's Mention action (CL-5914) — can
- * land in the active draft at the caret. */
+ * composer's own tree — the profile card's Mention action (CL-5914) or
+ * hover-edit of a previous prompt — can land in the active draft. */
 export type ComposerHandle = {
   readonly insertText: (text: string) => void;
+  readonly setText: (text: string) => void;
 };
 
 /** Splice `insertion` in at `caret`, pure and independent of any DOM state
@@ -367,6 +368,7 @@ export const Composer = forwardRef<
   const [focused, setFocused] = useState(false);
   const textareaRef = useRef<HTMLTextAreaElement>(null);
   const fileInputRef = useRef<HTMLInputElement>(null);
+  const attachGenerationRef = useRef(0);
 
   /** Auto-grow: the textarea reports its own content height, so the
    * measurement resets to the CSS-declared min-height before reading
@@ -380,6 +382,21 @@ export const Composer = forwardRef<
     textarea.style.height = `${textarea.scrollHeight}px`;
   }, [value]);
 
+  function syncComposerSuggestState(text: string, caret: number) {
+    setHelpOpen(false);
+    const openSlash = activeSlashQuery(text, caret);
+    if (openSlash !== null) {
+      setSlash(openSlash);
+      setSlashHighlight(0);
+      setMention(null);
+      return;
+    }
+    setSlash(null);
+    const openMention = activeMentionQuery(text, caret);
+    setMention(openMention);
+    setHighlight(0);
+  }
+
   useImperativeHandle(
     ref,
     () => ({
@@ -393,6 +410,22 @@ export const Composer = forwardRef<
           textarea?.setSelectionRange(result.caret, result.caret);
         });
       },
+      setText: (text: string) => {
+        attachGenerationRef.current += 1;
+        setValue(text);
+        setMention(null);
+        setSlash(null);
+        setHelpOpen(false);
+        setPendingInvites([]);
+        setAttachments([]);
+        setErrorMessage(null);
+        setPreparing(false);
+        requestAnimationFrame(() => {
+          const textarea = textareaRef.current;
+          textarea?.focus();
+          textarea?.setSelectionRange(text.length, text.length);
+        });
+      },
     }),
     [value],
   );
@@ -413,21 +446,6 @@ export const Composer = forwardRef<
     sending,
   });
 
-  function syncComposerSuggestState(text: string, caret: number) {
-    setHelpOpen(false);
-    const openSlash = activeSlashQuery(text, caret);
-    if (openSlash !== null) {
-      setSlash(openSlash);
-      setSlashHighlight(0);
-      setMention(null);
-      return;
-    }
-    setSlash(null);
-    const openMention = activeMentionQuery(text, caret);
-    setMention(openMention);
-    setHighlight(0);
-  }
-
   /**
    * Fires the send and tracks its flight for the button's spinner —
    * nothing here decides what the timeline shows on success or failure.
@@ -537,6 +555,7 @@ export const Composer = forwardRef<
     if (!canAttachComposer({ sending, preparing })) return;
 
     const files = Array.from(fileList);
+    const generation = attachGenerationRef.current;
     const validation = validateAttachmentPick(
       attachments.length,
       attachmentBytesOnComposer(attachments),
@@ -563,11 +582,15 @@ export const Composer = forwardRef<
         });
       }
       // All-or-nothing: only commit once every file in the pick has read.
+      if (attachGenerationRef.current !== generation) return;
       setAttachments((previous) => [...previous, ...next]);
     } catch {
+      if (attachGenerationRef.current !== generation) return;
       setErrorMessage(CHAT_STRINGS.composerAttachmentReadError);
     } finally {
-      setPreparing(false);
+      if (attachGenerationRef.current === generation) {
+        setPreparing(false);
+      }
       resetFileInput();
     }
   }

packages/chat-ui/src/strings.ts

@@ -132,6 +132,7 @@ export const CHAT_STRINGS = {
   forkThreadAction: "Fork",
   forkThreadError: "Couldn't fork that message into a thread — try again.",
   replyInThreadAction: "Reply in thread",
+  editMessageAction: "Edit",
   messageActionsMenuLabel: "Message actions",
   copyTextAction: "Copy text",
   copyTextCopiedToast: "Copied",

packages/chat-ui/src/styles.css

@@ -3105,9 +3105,11 @@
 /* Mock's hover toolbar: the compact trailing-edge cluster (add-reaction,
    reply-in-thread, ellipsis) that replaces the old persistent inline
    "Reply in thread" link and the standalone add-reaction trigger. Floats
-   over the message's top-right corner, fading in on hover/focus-within
-   like `.chat-pin-toggle` above, plus `data-open` so it stays put while its
-   own picker or menu is open even if focus moves into a portaled menu.
+   over the inboard (trailing) corner — top-right on others' left-aligned
+   rows, top-left on own right-aligned rows so Edit does not sit on the
+   prompt — fading in on hover/focus-within like `.chat-pin-toggle` above,
+   plus `data-open` so it stays put while its own picker or menu is open
+   even if focus moves into a portaled menu.
    Positioned relative to `.chat-message-row` (CL-6376) — the wrapper
    around this one message's own content, siblings-with but excluding its
    optional `.chat-day-divider` — rather than `.chat-message-group` as a
@@ -3162,6 +3164,13 @@
   transition: opacity 120ms var(--chat-ease);
 }
 
+/* Own (right-aligned) rows: inboard edge is the left of the row, matching
+   how `[data-own="true"] .chat-artifact-chip` already mirrors. */
+.chat-message-group[data-own="true"] .chat-hover-toolbar {
+  right: auto;
+  left: 0.4rem;
+}
+
 .chat-message-group:hover .chat-hover-toolbar,
 .chat-message-group:focus-within .chat-hover-toolbar,
 .chat-hover-toolbar[data-open="true"] {
@@ -3171,6 +3180,7 @@
 
 .chat-hover-toolbar .chat-reaction-add,
 .chat-hover-reply,
+.chat-hover-edit,
 .chat-hover-ellipsis {
   position: relative;
   display: inline-flex;
@@ -3191,6 +3201,7 @@
 
 .chat-hover-toolbar .chat-reaction-add::after,
 .chat-hover-reply::after,
+.chat-hover-edit::after,
 .chat-hover-ellipsis::after {
   content: "";
   position: absolute;
@@ -3199,13 +3210,15 @@
 
 .chat-hover-toolbar .chat-reaction-add svg,
 .chat-hover-reply svg,
+.chat-hover-edit svg,
 .chat-hover-ellipsis svg {
   width: 0.9rem;
   height: 0.9rem;
 }
 
 .chat-hover-toolbar .chat-reaction-add:hover,
 .chat-hover-reply:hover,
+.chat-hover-edit:hover,
 .chat-hover-ellipsis:hover,
 .chat-hover-toolbar .chat-reaction-add[aria-expanded="true"],
 .chat-hover-ellipsis[aria-expanded="true"] {