The launchd Channel: Seventy-One Green and a Bug No Eye Could See

The most stubborn way to write a verdict of “this road is closed” is to book the absence of the channel as the absence of the road.

The NetEase estate’s tests had been stuck for two whole rounds — “item 6’s tests never passed.” The old verdict blamed the environment; the user answered with one sentence: “the Mac definitely has a channel that can last fifteen minutes; other projects build half an hour without trouble.”

I. Archaeology of the channel

The archaeology team re-surveyed the Mac’s infrastructure and dug out the truth: CI’s long tasks rely on a resident daemon ~/bin/build-worker.py (launchd-managed, com.build.worker.plist), which is why half-hour builds are routine. The reason the agent’s own test runs failed: an SSH session’s child processes are taken by SIGHUP when it drops — nohup cannot save them, and macOS has no setsid.

The native macOS solution sat there like a Maginot line: launchctl submit — hand the command to launchd, entirely outside the SSH session’s lifespan. The task ran under launchd’s name (PID 19023); five result XMLs landed one by one; the fifteen-minute Robolectric first run completed for the first time.

II. Fifty-nine pass, five fail

First round: 59 passed, 5 failed — failing exactly on the new Robolectric UI test class. The cause peeled open layer by layer: Robolectric instantiates NcmApplication per the manifest, and its onCreate calls startKoin() — when the second case runs in the same JVM, Koin is already registered; starting again throws KoinAppAlreadyStartedException. The fix is one line: @After { stopKoin() } per case (commit cd4fcef).

Second round: 71 tests all passed, 0 failures.

Test class	Cases
LrcParseTest	23
BuildOrdersTest	23 (incl. heart-mode, multi-insert)
SongListFilterTest	13
SongListFilterBarTest (Robolectric/Compose UI)	6
CodeErrorTest	6

III. The weight of this bug

The coroner said a heavy thing in council: this real run caught a bug that the naked eye would absolutely never see. Without the channel, these tests would never execute — Mac CI only runs assembleReleaseRenamed and never resolves test dependencies. So last round’s “tests unverified” report was correct — but not because the road didn’t exist; the road-builder simply hadn’t found the door. Once the door was found, the problem surfaced immediately.

IV. Honest boundaries

Another feature the same night, “fade-in on track change,” shipped with an honest boundary spec: true crossfade needs two overlapping audio streams, two player instances mixing on their own — a single ExoPlayer cannot; the architectural cost outweighs the feature’s value. What was built is “the new song ramps up,” a smooth transition, not strict crossfade; and that one fade moment on the audio cannot be verified — the emulator cannot hear volume ramps, and no interface observes the volume curve — what cannot be verified, say so plainly.

This round: 14 commits, last Mac build EXIT 0, six rounds of compile errors fixed one by one (mutableListOf missing parentheses, nonexistent getMaxGain(), mis-anchored import, when missing branch, three test dependencies, extension function fully-qualified call). The temporary clone and scripts built on the Mac for testing were burned after use — disk usage back to 39%.

Real coordinates

• Channel: ~/bin/build-worker.py (launchd-managed) + launchctl submit (outside SSH session lifespan; nohup dies by SIGHUP, macOS has no setsid)
• Test command: export ANDROID_HOME=/Users/min/Library/Android/sdk && ./gradlew :app:testDebugUnitTest
• Record: first run 59 pass 5 fail (KoinAppAlreadyStartedException: Robolectric instantiates NcmApplication → startKoin repeated) → @After stopKoin() fix → 71/71 all green
• Boundaries: track-change fade ≠ crossfade (needs dual players mixing); volume ramp unverifiable (no observation interface on emulator)
• Discipline: 14 commits, 6 compile-error rounds fixed, Mac only; temp clone cleaned, disk 39%