fix(client-core): keep image prompts in place after conversation reseed

packages/client/core/src/conversation-store.ts

@@ -2,7 +2,7 @@ import type { AgentEvent, SessionId } from '@linkcode/schema';
 import type { Unsubscribe } from '@linkcode/transport';
 import { noop } from 'foxact/noop';
 import type { LinkCodeClient, SequencedAgentEvent } from './client';
-import type { Conversation, ConversationSeed } from './conversation';
+import type { Conversation, ConversationBuilder, ConversationSeed } from './conversation';
 import { createConversationBuilder } from './conversation';
 
 /** A `useSyncExternalStore`-shaped incremental projection of one session's conversation.
@@ -29,52 +29,80 @@ const EMPTY_CONVERSATION: Conversation = {
   pendingQuestionIds: [],
 };
 
-/**
- * Whether the seed's transcript snapshot can be assumed to contain this event — the only license
- * the `uptoSeq` cut has to drop it as "already in the snapshot". Providers flush transcripts by
- * whole item, so coverage is checked per provider identity, or by counted value for user prompts
- * whose host and provider ids cannot converge. A chunk of a message the snapshot never saw (the
- * in-flight reply — claude-code writes the row only when the message completes) must survive a
- * mid-turn reseed, or the streamed text vanishes at a chunk boundary (CODE-272). Everything
- * outside the switch (interactive requests and resolutions, status, stop, errors, usage …) is
- * ephemeral: it never appears in `history.read`, so cutting it would erase it outright — a pending
- * permission-request would vanish and strand the turn (CODE-35).
- */
-function coveredBySeed(
+type UserMessageEvent = Extract<AgentEvent, { type: 'user-message' }>;
+interface SeedUserMessageQueue {
+  messages: UserMessageEvent[];
+  nextIndex: number;
+}
+
+function takeSeedUserMessage(
+  messagesByContent: Map<string, SeedUserMessageQueue>,
+  content: UserMessageEvent['content'],
+): UserMessageEvent | undefined {
+  const key = JSON.stringify(content);
+  const queue = messagesByContent.get(key);
+  if (!queue) return undefined;
+  const message = queue.messages[queue.nextIndex];
+  queue.nextIndex += 1;
+  if (queue.nextIndex === queue.messages.length) messagesByContent.delete(key);
+  return message;
+}
+
+/** Fold a pre-cut event only when the transcript snapshot does not already cover it. */
+function foldPreCutEvent(
+  builder: ConversationBuilder,
   event: AgentEvent,
+  receivedAt: number | undefined,
   seedMessageIds: ReadonlySet<string>,
   seedToolIds: ReadonlySet<string>,
-  seedUserMessageCounts: Map<string, number>,
-): boolean {
+  seedUserMessages: Map<string, SeedUserMessageQueue>,
+): void {
   switch (event.type) {
     case 'agent-message':
     case 'agent-message-chunk':
     case 'agent-thought':
-    case 'agent-thought-chunk':
-      return seedMessageIds.has(event.messageId);
+    case 'agent-thought-chunk': {
+      if (!seedMessageIds.has(event.messageId)) builder.advance(event, receivedAt);
+      break;
+    }
     case 'user-message': {
-      // Host and provider ids cannot converge, so consume one matching seed row by value. Counting
-      // preserves repeated prompts while an unflushed queued prompt remains visible past the cut.
-      const key = JSON.stringify(event.content);
-      const remaining = seedUserMessageCounts.get(key) ?? 0;
-      if (remaining === 0) return false;
-      if (remaining === 1) seedUserMessageCounts.delete(key);
-      else seedUserMessageCounts.set(key, remaining - 1);
-      return true;
+      // Host and provider ids cannot converge, so consume matching seed rows by value. Some
+      // histories omit images; use the full live echo to enrich that seed row in place.
+      if (takeSeedUserMessage(seedUserMessages, event.content)) break;
+      if (event.content.some((block) => block.type === 'image')) {
+        const seedMessage = takeSeedUserMessage(
+          seedUserMessages,
+          event.content.filter((block) => block.type !== 'image'),
+        );
+        if (seedMessage) {
+          builder.advance({
+            ...event,
+            messageId: seedMessage.messageId,
+            branchCursor: seedMessage.branchCursor,
+          });
+          break;
+        }
+      }
+      builder.advance(event, receivedAt);
+      break;
+    }
+    case 'tool-call': {
+      if (!seedToolIds.has(event.toolCall.toolCallId)) builder.advance(event, receivedAt);
+      break;
+    }
+    case 'tool-call-content-chunk': {
+      if (!seedToolIds.has(event.toolCallId)) builder.advance(event, receivedAt);
+      break;
     }
-    case 'tool-call':
-      return seedToolIds.has(event.toolCall.toolCallId);
-    case 'tool-call-content-chunk':
-      return seedToolIds.has(event.toolCallId);
     default:
-      return false;
+      builder.advance(event, receivedAt);
   }
 }
 
 /**
  * Project a session's conversation from a transcript seed plus the live event buffer: the seed
  * folds once, then `getSnapshot` lazily advances by unconsumed events, skipping events inside the
- * `uptoSeq` cut that the snapshot verifiably covers (see {@link coveredBySeed}). The sync is idempotent and monotone with a stable snapshot identity
+ * `uptoSeq` cut that the snapshot verifiably covers (see {@link foldPreCutEvent}). The sync is idempotent and monotone with a stable snapshot identity
  * between events — the `useSyncExternalStore` getSnapshot contract. A store is bound to one
  * (session, seed) pair; create a fresh one when either changes.
  */
@@ -92,7 +120,7 @@ export function createConversationStore(
   // Identities the snapshot actually holds, for the per-event coverage check of the cut.
   const seedMessageIds = new Set<string>();
   const seedToolIds = new Set<string>();
-  const seedUserMessageCounts = new Map<string, number>();
+  const seedUserMessages = new Map<string, SeedUserMessageQueue>();
   if (seed) {
     for (const { event } of seed.events) {
       switch (event.type) {
@@ -104,7 +132,9 @@ export function createConversationStore(
           break;
         case 'user-message': {
           const key = JSON.stringify(event.content);
-          seedUserMessageCounts.set(key, (seedUserMessageCounts.get(key) ?? 0) + 1);
+          const queue = seedUserMessages.get(key);
+          if (queue) queue.messages.push(event);
+          else seedUserMessages.set(key, { messages: [event], nextIndex: 0 });
           break;
         }
         case 'tool-call':
@@ -131,11 +161,10 @@ export function createConversationStore(
     const events = client.eventsSnapshot(sessionId);
     for (let i = firstIndexAfter(events, consumedSeq); i < events.length; i += 1) {
       const { event, seq, receivedAt } = events[i];
-      if (
-        seq > uptoSeq ||
-        !coveredBySeed(event, seedMessageIds, seedToolIds, seedUserMessageCounts)
-      ) {
+      if (seq > uptoSeq) {
         builder.advance(event, receivedAt);
+      } else {
+        foldPreCutEvent(builder, event, receivedAt, seedMessageIds, seedToolIds, seedUserMessages);
       }
     }
     // Snap to the counter even when the buffer lags it (cleared by a stop): those events are

packages/client/core/tests/integration/conversation-store.test.ts

@@ -73,6 +73,54 @@ describe('createConversationStore', () => {
     close();
   });
 
+  it('enriches a lossy seeded prompt with its live image instead of appending a duplicate', async () => {
+    const { client, send, close } = await harness();
+    const livePrompt: AgentEvent = {
+      type: 'user-message',
+      messageId: 'host-prompt' as MessageId,
+      content: [
+        { type: 'text', text: 'describe this image' },
+        { type: 'image', data: 'cG5n', mimeType: 'image/png' },
+      ],
+      branchCursor: 'live-cursor',
+    };
+    const reply: AgentEvent = {
+      type: 'agent-message',
+      messageId: 'reply' as MessageId,
+      content: [{ type: 'text', text: 'It is a test image.' }],
+    };
+    send(livePrompt);
+    send(reply);
+    await tick();
+
+    const store = createConversationStore(client, sessionId, {
+      events: [
+        // Some provider histories retain the prompt text but omit its image blocks.
+        {
+          event: {
+            type: 'user-message',
+            messageId: 'provider-prompt' as MessageId,
+            content: [{ type: 'text', text: 'describe this image' }],
+            branchCursor: 'provider-cursor',
+          },
+        },
+        { event: reply },
+      ],
+      uptoSeq: 2,
+    });
+
+    const messages = store.getSnapshot().items.filter((item) => item.kind === 'message');
+    expect(messages).toHaveLength(2);
+    expect(messages[0]).toMatchObject({
+      id: 'provider-prompt',
+      role: 'user',
+      blocks: livePrompt.content,
+      branchCursor: 'provider-cursor',
+    });
+    expect(messages[1]).toMatchObject({ id: 'reply', role: 'assistant' });
+    close();
+  });
+
   it('consumes only one matching seed row for repeated prompt content', async () => {
     const { client, send, close } = await harness();
     send(userText('repeat', 'host-1'));