perf(chat): avoid repeated skill catalog scans while building the picker (#31936)

* perf(chat): remove repeated scans and array copies from the skill picker

* perf(chat): keep picker grouping within the module line limit

---------

Co-authored-by: OrcaWin <293788423+OrcaWin@users.noreply.github.com>

src/renderer/src/components/native-chat/native-chat-composer-state.test.ts

@@ -456,6 +456,19 @@ describe('native skill and command picker', () => {
     expect(items[1]).toMatchObject({ kind: 'skill', description: null, sources: [] })
   })
 
+  it('keeps the first reported description for duplicate unlocated skill names', () => {
+    const items = buildNativeChatPickerItems([], [], '', '/', [
+      { name: 'missing' },
+      { name: 'missing', description: 'Later description' },
+      { name: 'present', description: 'First description' },
+      { name: 'present', description: 'Later description' }
+    ])
+    expect(items).toMatchObject([
+      { name: 'missing', description: null },
+      { name: 'present', description: 'First description' }
+    ])
+  })
+
   it('keeps the disk scan only when a session report is absent', () => {
     const items = buildNativeChatPickerItems(
       [],

src/shared/native-chat-picker-items.ts

@@ -156,7 +156,9 @@ function mergeNativeChatSkills(
     if (!safeName) {
       continue
     }
-    byName.set(safeName, [...(byName.get(safeName) ?? []), { ...skill, name: safeName }])
+    const namedSkills = byName.get(safeName) ?? []
+    namedSkills.push({ ...skill, name: safeName })
+    byName.set(safeName, namedSkills)
   }
   const discovered = new Map(
     [...byName.entries()].map(([name, namedSkills]) => [
@@ -172,8 +174,12 @@ function mergeNativeChatSkills(
   // A reported skill with its file is its own row: two skills may share a name, and the pick
   // tells the agent which file it means.
   const nameCounts = new Map<string, number>()
+  const firstReportedByName = new Map<string, NativeChatSessionSkill>()
   for (const skill of sessionSkills ?? []) {
     nameCounts.set(skill.name, (nameCounts.get(skill.name) ?? 0) + 1)
+    if (!firstReportedByName.has(skill.name)) {
+      firstReportedByName.set(skill.name, skill)
+    }
   }
   const located = (sessionSkills ?? []).flatMap((skill) =>
     skill.path && isTokenSafe(skill.name)
@@ -202,7 +208,7 @@ function mergeNativeChatSkills(
     ...located,
     ...[...new Set(names)].map((name) => {
       const skill = discovered.get(name) ?? pickerSkill(name, [], skillSigil)
-      const reported = sessionSkills?.find((entry) => entry.name === name)?.description
+      const reported = firstReportedByName.get(name)?.description
       return skill.description === null && reported
         ? { ...skill, description: sanitizePickerText(reported, 240) }
         : skill