fix(electrobun): preserve conversation history when resuming session (don't clearSession on resume)

ui-electrobun/src/mainview/agent-store.svelte.ts

@@ -546,9 +546,6 @@ async function _startAgentInner(
   prompt: string,
   options: StartOptions,
 ): Promise<{ ok: boolean; error?: string }> {
-  // If there's an existing done/error session for this project, clear it first
-  clearSession(projectId);
-
   // Check for pending resume (user selected a session in the picker)
   const pending = pendingResumes.get(projectId);
   if (pending) {
@@ -559,6 +556,13 @@ async function _startAgentInner(
     }
   }
 
+  const isResume = options.resumeMode === 'continue' || options.resumeMode === 'resume';
+
+  // If resuming, keep existing session messages; if new, clear old session
+  if (!isResume) {
+    clearSession(projectId);
+  }
+
   const sessionId = `${projectId}-${Date.now()}`;
 
   // Read settings defaults if not explicitly provided (Fix #5)
@@ -587,25 +591,38 @@ async function _startAgentInner(
     }
   } catch { /* use provided or defaults */ }
 
-  // Create reactive session state
+  // Create reactive session state — carry forward messages if resuming
+  const existingSessionId = projectSessionMap.get(projectId);
+  const existingMessages = (isResume && existingSessionId && sessions[existingSessionId])
+    ? [...sessions[existingSessionId].messages]
+    : [];
+
+  // Add the new user prompt to messages
+  const newUserMsg = {
+    id: `${sessionId}-user-0`,
+    seqId: nextSeqId(sessionId),
+    role: 'user' as const,
+    content: prompt,
+    timestamp: Date.now(),
+  };
+
   sessions[sessionId] = {
     sessionId,
     projectId,
     provider,
     status: 'running',
-    messages: [{
-      id: `${sessionId}-user-0`,
-      seqId: nextSeqId(sessionId),
-      role: 'user',
-      content: prompt,
-      timestamp: Date.now(),
-    }],
+    messages: [...existingMessages, newUserMsg],
     costUsd: 0,
     inputTokens: 0,
     outputTokens: 0,
     model: defaultModel ?? 'claude-opus-4-5',
   };
 
+  // Clean up the old session entry if resuming (we moved messages to the new one)
+  if (isResume && existingSessionId && existingSessionId !== sessionId) {
+    delete sessions[existingSessionId];
+  }
+
   projectSessionMap.set(projectId, sessionId);
   bump(); // Force re-render — new session created
   resetStallTimer(sessionId, projectId);