diff --git a/src/parser.ts b/src/parser.ts
index fa6a345..97469d2 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -121,6 +121,30 @@ function parseApiCall(entry: JournalEntry): ParsedApiCall | null {
   }
 }
 
+function dedupeStreamingMessageIds(entries: JournalEntry[]): JournalEntry[] {
+  const firstIdxById = new Map<string, number>()
+  const lastIdxById = new Map<string, number>()
+  for (let i = 0; i < entries.length; i++) {
+    const id = getMessageId(entries[i]!)
+    if (!id) continue
+    if (!firstIdxById.has(id)) firstIdxById.set(id, i)
+    lastIdxById.set(id, i)
+  }
+  if (lastIdxById.size === 0) return entries
+  const result: JournalEntry[] = []
+  for (let i = 0; i < entries.length; i++) {
+    const id = getMessageId(entries[i]!)
+    if (id && lastIdxById.get(id) !== i) continue
+    if (id && firstIdxById.get(id) !== i) {
+      const firstTs = entries[firstIdxById.get(id)!]!.timestamp
+      result.push({ ...entries[i]!, timestamp: firstTs ?? entries[i]!.timestamp })
+      continue
+    }
+    result.push(entries[i]!)
+  }
+  return result
+}
+
 function groupIntoTurns(entries: JournalEntry[], seenMsgIds: Set<string>): ParsedTurn[] {
   const turns: ParsedTurn[] = []
   let currentUserMessage = ''
@@ -291,7 +315,8 @@ async function parseSessionFile(
   if (entries.length === 0) return null
 
   const sessionId = basename(filePath, '.jsonl')
-  let turns = groupIntoTurns(entries, seenMsgIds)
+  const dedupedEntries = dedupeStreamingMessageIds(entries)
+  let turns = groupIntoTurns(dedupedEntries, seenMsgIds)
   if (dateRange) {
     // Bucket a turn by the timestamp of its first assistant call (when the cost was
     // actually incurred). Filtering entries directly produced orphan assistant calls