# Conversation branching or forking is supported

- **Pattern:** `ab-000337` (`ai-ux-patterns.feedback-control.conversation-branching`)
- **Severity:** high
- **Lifecycle:** active
- **Last modified:** 2026-04-18
- **Canonical URL:** https://auditbuffet.com/patterns/ab-000337
- **License:** CC-BY-4.0 — attribute to AuditBuffet Pattern Catalog (https://auditbuffet.com/patterns/ab-000337)

## Why it matters

When a conversation takes a wrong turn twenty messages deep — a bad file upload, a misread instruction, a hallucination that the model now treats as ground truth — users need a way to rewind and try a different path without losing the useful context that came before. A strictly linear conversation forces "delete the last ten messages or start a new chat" as the only exits, both of which throw away work. Branching preserves that work.

## Severity rationale

High because linear-only conversations force users to discard useful context whenever a thread derails.

## Remediation

Start with edit-and-regenerate as the minimum viable branch. When a user edits a prior message, truncate state to that point and call `reload()` to regenerate from the edited turn. Full tree branching requires a `parent_message_id` column on the messages table and a tree-rendering sidebar; ship the minimum first. Implement in `src/components/chat/message-actions.tsx`.

```tsx
setMessages(messages.slice(0, editIndex).concat({ ...messages[editIndex], content: newContent }))
reload()
```

## Detection

- **ID:** `conversation-branching`
- **Severity:** `high`
- **What to look for:** Count all conversation state management patterns in the data model. Enumerate whether the data model supports branching: check for `parentMessageId` fields, version history on messages, tree-structured state, or edit-and-regenerate handlers. Look for "fork from here", "branch", or "continue from this point" actions on individual messages. At least 1 branching mechanism must exist.
- **Pass criteria:** Users can either (a) branch a conversation from a specific message, creating a parallel thread, or (b) edit a prior user message to create a new continuation (which is a minimal branching implementation). At least 1 branching mechanism must be implemented. Report the count on pass: "Found X branching mechanisms."
- **Fail criteria:** Conversations are entirely linear — no forking, no edit-and-regenerate. Users can only append new messages.
- **Skip (N/A) when:** Same as `regeneration-button`.
- **Detail on fail:** `"Conversation is strictly linear — message state is a flat array with no parentMessageId, no forking UI, and no edit-and-regenerate capability"`.
- **Remediation:** Full branching is complex. Start with edit-and-regenerate as a minimum viable branching pattern.

  For edit-and-regenerate (minimal branching):

  ```tsx
  const handleEditAndRegenerate = (messageIndex: number, newContent: string) => {
    // Keep all messages up to and including the edited user message
    const truncated = [
      ...messages.slice(0, messageIndex),
      { ...messages[messageIndex], content: newContent }
    ]
    setMessages(truncated)
    // Trigger regeneration from this point
    reload()
  }
  ```

  For full branching, consider a `parentId` field on messages and a tree-rendering component. This is a larger feature — the Vercel AI SDK `useChat` hook supports `experimental_resume` for multi-turn management.

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Taxons: user-experience

HTML version: https://auditbuffet.com/patterns/ab-000337