diff --git a/cmuxTests/CLICodexHookTimeoutRegressionTestSupport.swift b/cmuxTests/CLICodexHookTimeoutRegressionTestSupport.swift
index e244962d3fc8..cf43af0877f2 100644
--- a/cmuxTests/CLICodexHookTimeoutRegressionTestSupport.swift
+++ b/cmuxTests/CLICodexHookTimeoutRegressionTestSupport.swift
@@ -266,7 +266,18 @@ func waitForFile(_ url: URL, containing expected: String, timeout: TimeInterval)
     return false
 }
 
-func waitForCondition(timeout: TimeInterval, pollInterval: TimeInterval = 0.02, _ condition: () -> Bool) -> Bool {
+/// Polls `condition` while blocking the calling thread with `Thread.sleep`.
+///
+/// Use it only for conditions a background thread satisfies, such as a socket
+/// accumulator or a file a child process writes. It runs no run loop, so on the
+/// main thread it starves main-queue and main-actor work and the condition can
+/// never become true. Main-thread waits belong in the per-file XCTWaiter
+/// helpers, which pump the main queue between polls.
+func waitForConditionBlocking(
+    timeout: TimeInterval,
+    pollInterval: TimeInterval = 0.02,
+    _ condition: () -> Bool
+) -> Bool {
     let deadline = Date().addingTimeInterval(timeout)
     while Date() < deadline {
         if condition() {
diff --git a/cmuxTests/CLICodexHookTimeoutRegressionTests.swift b/cmuxTests/CLICodexHookTimeoutRegressionTests.swift
index 1f0fb823ac9c..7b8393b78da6 100644
--- a/cmuxTests/CLICodexHookTimeoutRegressionTests.swift
+++ b/cmuxTests/CLICodexHookTimeoutRegressionTests.swift
@@ -257,7 +257,7 @@ struct CLICodexHookTimeoutRegressionTests {
         )
         #expect(oldPrompt.status == 0, Comment(rawValue: oldPrompt.stderr))
         #expect(oldPrompt.stdout == "{}\n")
-        #expect(waitForCondition(timeout: 2) {
+        #expect(waitForConditionBlocking(timeout: 2) {
             commands.snapshot().contains { $0.hasPrefix("set_status codex Running ") }
         })
 
@@ -270,7 +270,7 @@ struct CLICodexHookTimeoutRegressionTests {
         )
         #expect(currentPrompt.status == 0, Comment(rawValue: currentPrompt.stderr))
         #expect(currentPrompt.stdout == "{}\n")
-        #expect(waitForCondition(timeout: 2) {
+        #expect(waitForConditionBlocking(timeout: 2) {
             let snapshot = commands.snapshot()
             return snapshot.contains { $0.hasPrefix("clear_notifications ") }
                 && snapshot.contains { $0.hasPrefix("set_status codex Running ") }
@@ -286,7 +286,7 @@ struct CLICodexHookTimeoutRegressionTests {
         )
         #expect(staleStop.status == 0, Comment(rawValue: staleStop.stderr))
         #expect(staleStop.stdout == "{}\n")
-        #expect(waitForCondition(timeout: 2) {
+        #expect(waitForConditionBlocking(timeout: 2) {
             commands.snapshot().count > staleStopStart
         })