From 662ebcbbd11527c10a49acab407bacebe622cfa4 Mon Sep 17 00:00:00 2001
From: Neil <4138956+nwparker@users.noreply.github.com>
Date: Sat, 30 May 2026 10:26:37 -0700
Subject: [PATCH] perf: handle large ssh config alias lists (#3792)

---
 src/main/ssh/ssh-config-parser.test.ts | 35 ++++++++++++++++++++++++++
 src/main/ssh/ssh-config-parser.ts      | 14 ++++++++---
 2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/src/main/ssh/ssh-config-parser.test.ts b/src/main/ssh/ssh-config-parser.test.ts
index 2b5cf6af34a..541742df8c0 100644
--- a/src/main/ssh/ssh-config-parser.test.ts
+++ b/src/main/ssh/ssh-config-parser.test.ts
@@ -6,6 +6,16 @@ vi.mock('os', () => ({
   homedir: () => '/home/testuser'
 }))
 
+const LARGE_HOST_ALIAS_COUNT = 150_000
+
+function buildHostAliases(count: number): string {
+  const aliases: string[] = []
+  for (let index = 0; index < count; index += 1) {
+    aliases.push(`generated-${index}`)
+  }
+  return aliases.join(' ')
+}
+
 describe('parseSshConfig', () => {
   it('parses a basic host block', () => {
     const config = `
@@ -172,6 +182,31 @@ Host staging stage *.example.com
     ])
   })
 
+  it('parses large concrete alias lists on one Host line', () => {
+    const config = [
+      `Host ${buildHostAliases(LARGE_HOST_ALIAS_COUNT)}`,
+      '  HostName generated.example.com',
+      'Host after',
+      '  HostName after.example.com'
+    ].join('\n')
+
+    const hosts = parseSshConfig(config)
+
+    expect(hosts).toHaveLength(LARGE_HOST_ALIAS_COUNT + 1)
+    expect(hosts[0]).toEqual({
+      host: 'generated-0',
+      hostname: 'generated.example.com'
+    })
+    expect(hosts[LARGE_HOST_ALIAS_COUNT - 1]).toEqual({
+      host: `generated-${LARGE_HOST_ALIAS_COUNT - 1}`,
+      hostname: 'generated.example.com'
+    })
+    expect(hosts.at(-1)).toEqual({
+      host: 'after',
+      hostname: 'after.example.com'
+    })
+  })
+
   it('applies identity agent settings to every concrete alias on a multi-pattern Host line', () => {
     const config = `
 Host staging stage
diff --git a/src/main/ssh/ssh-config-parser.ts b/src/main/ssh/ssh-config-parser.ts
index 70b0cacdbe0..391bf0cf20d 100644
--- a/src/main/ssh/ssh-config-parser.ts
+++ b/src/main/ssh/ssh-config-parser.ts
@@ -44,7 +44,7 @@ export function parseSshConfig(content: string): SshConfigHost[] {
 
     if (key === 'host') {
       if (current.length > 0) {
-        hosts.push(...current)
+        appendHosts(hosts, current)
       }
 
       const patterns = splitHostPatterns(value)
@@ -62,7 +62,7 @@ export function parseSshConfig(content: string): SshConfigHost[] {
 
     if (key === 'match') {
       if (current.length > 0) {
-        hosts.push(...current)
+        appendHosts(hosts, current)
       }
       current = []
       continue
@@ -122,11 +122,19 @@ export function parseSshConfig(content: string): SshConfigHost[] {
   }
 
   if (current.length > 0) {
-    hosts.push(...current)
+    appendHosts(hosts, current)
   }
   return hosts
 }
 
+function appendHosts(target: SshConfigHost[], entries: SshConfigHost[]): void {
+  // Why: generated SSH configs can put many concrete aliases on one Host line;
+  // spreading that block into push can exceed JavaScript's argument limit.
+  for (const entry of entries) {
+    target.push(entry)
+  }
+}
+
 function splitHostPatterns(input: string): string[] {
   const patterns: string[] = []
   let current = ''