diff --git a/src/workspaces/officerdev/src/apps/ChatHistory/ChatDetailPanel.tsx b/src/workspaces/officerdev/src/apps/ChatHistory/ChatDetailPanel.tsx
index 791257fc..105a447b 100644
--- a/src/workspaces/officerdev/src/apps/ChatHistory/ChatDetailPanel.tsx
+++ b/src/workspaces/officerdev/src/apps/ChatHistory/ChatDetailPanel.tsx
@@ -123,6 +123,15 @@ function DetailBar({ sessionTitle, cwd, partCount, isConnected, isGenerating, on
 }
 
 type NewChatProps = {
+  /**
+   * The harness that owns this conversation, as `harness/model` — e.g. `opencode/big-pickle`.
+   *
+   * Load-bearing on resume, not cosmetic. The server routes by model: anything starting `claude-code`
+   * goes to the Claude sidecar, everything else to OpenCode. Send nothing and it falls back to the
+   * user's default, which is how a `ses_…` id ended up being handed to `claude --resume` — a
+   * wrong-harness dispatch rather than a degradation.
+   */
+  model?: string | null;
   resumeSummary?: string;
   resumeSessionId?: string;
   initialMessages?: ChatMessage[];
@@ -191,7 +200,10 @@ function NewChat(props: NewChatProps) {
       <EmbeddableChat
         chat={chat}
         sessionId={undefined}
-        initialModel={locationState?.model ?? undefined}
+        // The session's own model wins. `locationState.model` is declared on ChatLocationState and
+        // written by nothing, so it was the only source and always undefined on resume; it stays as a
+        // fallback for a future caller that navigates with one deliberately.
+        initialModel={props.model ?? locationState?.model ?? undefined}
         initialMessage={initialMessage}
         defaultInput={locationState?.prefillInput ?? ''}
         cwd={cwd}
@@ -241,6 +253,7 @@ export const ChatDetailPanel = () => {
       initialMessages={selected.initialMessages}
       total={selected.total}
       initialOffset={selected.initialOffset}
+      model={selected.model}
       sessionCwd={selected.cwd}
       sessionTitle={title}
       partCount={selected.partCount}