perf(relay): stop the port scan walking all of procfs after every socket has an owner

src/relay/port-scan-handler.test.ts

@@ -119,6 +119,31 @@ function mockLinuxProcScan({
   })
 }
 
+describe('PortScanHandler Linux walk bounds', () => {
+  it('stops walking procfs once every listening socket has an owner', async () => {
+    // Why: this scan repeats for the life of the session, and its unit cost was O(all host
+    // processes x all fds) regardless of how few sockets it was resolving. On a busy remote the
+    // process count only climbs, so the scan got permanently more expensive -- the shape behind
+    // "SSH degrades the longer Orca stays open". One listener means one readlink, not 100,000.
+    mockLinuxProcScan({ pidCount: 1_000, fdCount: 100 })
+
+    await capturePortDetectHandler()({}, requestContext())
+
+    expect(readlinkMock).toHaveBeenCalledTimes(1)
+  })
+
+  it('still walks the whole table when a socket has no reachable owner', async () => {
+    // The inverse: an unattributable inode (another user's process) must not make the scan give up
+    // early on sockets it could still attribute.
+    mockLinuxProcScan({ pidCount: 3, fdCount: 2 })
+    readlinkMock.mockImplementation(() => Promise.resolve('socket:[99999]'))
+
+    await capturePortDetectHandler()({}, requestContext())
+
+    expect(readlinkMock).toHaveBeenCalledTimes(6)
+  })
+})
+
 describe('PortScanHandler Linux cancellation', () => {
   it('does not touch procfs for an already-cancelled request', async () => {
     const controller = new AbortController()

src/relay/port-scan-handler.ts

@@ -161,6 +161,13 @@ export class PortScanHandler {
 
     for (const pidStr of pids) {
       signal?.throwIfAborted()
+      // Why: every remaining pid costs a readdir plus one readlink per fd, and this scan repeats for
+      // the life of the session. Without this the walk was O(all host processes x all fds) even once
+      // every listener was already attributed, so its cost grew with the remote's process count and
+      // never came back down — the shape behind "SSH gets slower the longer Orca stays open".
+      if (result.size === inodes.size) {
+        return result
+      }
       const fdDir = `/proc/${pidStr}/fd`
       let fds: string[]
       try {
@@ -192,6 +199,9 @@ export class PortScanHandler {
         const inode = Number.parseInt(match[1], 10)
         if (inodes.has(inode)) {
           result.set(inode, pid)
+          if (result.size === inodes.size) {
+            return result
+          }
         }
       }
     }