fix(query): dedupe expanded search tail

Avoid appending search hits that were already included as context when max message expansion limits only expand the first hits.

apps/cli/src/query/commands-messages.test.ts

@@ -2,6 +2,7 @@ import { describe, it } from 'node:test'
 import assert from 'node:assert/strict'
 
 import {
+  appendUniqueTailMessages,
   assertContextAnchorsPresent,
   capExpandedSearchMessages,
   parseContextIds,
@@ -27,6 +28,24 @@ describe('capExpandedSearchMessages', () => {
   })
 })
 
+describe('appendUniqueTailMessages', () => {
+  it('does not append tail hits already included by expanded context', () => {
+    const expanded: MessageLike[] = [
+      { id: 10, senderName: 'Alice', content: 'alpha hit', timestamp: 1710000000 },
+      { id: 11, senderName: 'Bob', content: 'beta hit as context', timestamp: 1710000001 },
+    ]
+    const tail: MessageLike[] = [
+      { id: 11, senderName: 'Bob', content: 'beta hit as context', timestamp: 1710000001 },
+      { id: 12, senderName: 'Carol', content: 'tail hit', timestamp: 1710000002 },
+    ]
+
+    assert.deepEqual(
+      appendUniqueTailMessages(expanded, tail).map((message) => message.id),
+      [10, 11, 12]
+    )
+  })
+})
+
 describe('parseContextIds', () => {
   it('rejects blank id tokens instead of converting them to 0', () => {
     assert.throws(() => parseContextIds('1021,'), /Invalid --id value/)

apps/cli/src/query/commands-messages.ts

@@ -64,6 +64,11 @@ export function capExpandedSearchMessages(
   return capped.sort((a, b) => messages.indexOf(a) - messages.indexOf(b))
 }
 
+export function appendUniqueTailMessages(expanded: MessageLike[], tail: MessageLike[]): MessageLike[] {
+  const expandedIds = new Set(expanded.map((message) => message.id))
+  return [...expanded, ...tail.filter((message) => !expandedIds.has(message.id))]
+}
+
 export function parseContextIds(value: string): number[] {
   const tokens = value.split(',').map((token) => token.trim())
   const ids = tokens.map((token) => (token.length > 0 ? Number(token) : Number.NaN))
@@ -281,7 +286,7 @@ export function registerMessageCommands(program: Command): void {
             )
             const keptHits = new Set(expandableHits.map((m) => m.id))
             const tail = hits.filter((m) => !keptHits.has(m.id))
-            pipelineMessages = [...expanded, ...tail]
+            pipelineMessages = appendUniqueTailMessages(expanded, tail)
             if (pipelineMessages.length > maxMessages) {
               pipelineMessages = capExpandedSearchMessages(pipelineMessages, hitIds, maxMessages)
               warnings.push(`response capped at ${maxMessages} messages`)