# R12 recapture — background service interruption with an observed fifth fetch waiter

PR [#26601](https://git.cafe/pingdotgg/t3code/pull/26601). Evidence only; no tracked source changes, pushes, PR comments, or PR body edits. Server-only runtime proof; screenshots, viewport, and theme are N/A. No browser or app server was started.

## Method and steps

1. Used the same byte-identical scratch driver on the pinned merge-base and head, on machine `fs-40`. Each invocation creates five fresh synthetic committed repositories and local bare origins in its own timestamped run directory. Native `GitVcsDriver.layer`, `NodeServices.layer`, and `ServerConfig.layerTest` are used.
2. Each origin uses the unchanged Python upload-pack transport fixture: install a SIGTERM-ignore handler, emit READY over Unix-socket IPC, then naturally complete after 8,000 ms. The driver calls `statusDetailsRemote(cwd, { refreshUpstream: true })` for five different repository keys. It awaits READY for each of the first four before requesting the fifth. The production fetch safety timeout remains 300,000 ms; no timeout, teardown setting, or fixture duration was tuned.
3. Passively observe the real four-permit semaphore: a runtime wrapper around its prototype `withPermits` returns the original effect unchanged and attaches observers to that instance’s existing native waiter Set. Each observer first delegates the original Set.add/delete, then records the state. Construction, permit accounting, acquisition, release, cancellation, Effect scheduling, native process spawning, signals, and time are unchanged. This is observation instrumentation, not a replacement semaphore, fake platform, process handle, or clock. Tracked source and installed library files are untouched.
4. Await the actual native wait-queue insertion event for `capture.R12.caller4`, identified through the current fiber’s inherited span chain. The queue event occurs inside `effect/Semaphore.waitForPermits` after its `free < n` check and native `self.waiters.add(observer)`. It records `permits=4, taken=4, free=0, waiters=1` and the span chain `GitVcsDriver.fetchRemoteForStatus.wait → refreshStatusRemoteCacheEntry → refreshStatusUpstreamIfStale → statusDetailsRemote → capture.R12.caller4`. Thus the fifth fetch has passed repository preflight and Cache.get, forked its service-owned writer, and is actually waiting to acquire the four-fetch slot. No sleep or polling is used as queue evidence.
5. Run an independent real pooled `rev-parse HEAD` probe; it succeeds while the four-fetch semaphore remains saturated. Interrupt caller 0 only, await its interrupted Exit, then verify all four fetch helpers remain live, no helper has received TERM, and the fifth waiter remains registered.
6. Close the owning service scope. Observe the fifth waiter removed while all four permits are still taken, then four serial native process-group SIGTERM/SIGKILL pairs. Await Scope.close, interrupt any remaining caller fibers, and record four fetch spawns total, zero fifth fetch spawns or READY events, no natural-completion markers, zero live helpers, and zero remaining fetch waiters through RUN_COMPLETE.
7. Run a post-capture /proc check over every recorded PID and fixture process group. Both runs have 50 recorded PIDs, zero live recorded PIDs, zero live group members, and no remaining lock files. Delete the two temporary untracked test files by literal path; both git status outputs are empty. Remove the capturer-created merge-base worktree. The lead’s head worktree and scratch root are preserved.

## Observed monotonic sequence (before the comparison table)

All `ms` values are monotonically measured from each invocation’s own `process.hrtime.bigint()` origin. Fixture `mono_ns` values are its `time.monotonic_ns()`. Numbers below are exact raw events, not reconstructed delays. The driver measures closeMs from immediately before SERVICE_CLOSE_REQUEST logging through completion of Scope.close, so log overhead is included.

### Before: [30eb7e7bb1](https://git.cafe/pingdotgg/t3code/commit/30eb7e7bb1ef103fdd6f54081b6a4acf66b3ee4c)

Full SHA: `30eb7e7bb1ef103fdd6f54081b6a4acf66b3ee4c`. Wall origin: `2026-10-28T20:04:51.726Z`. Run: `2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture`.

```jsonl
{"sha":"30eb7e7bb1ef103fdd6f54081b6a4acf66b3ee4c","wallOrigin":"2026-10-28T20:04:51.726Z","os":"Linux","kernel":"6.1.102","node":"v26.13.0","git":"git version 2.43.0","cpus":4,"platformNodeShared":"4.0.5","driverHash":"c0371bd935db8fce6da4b0961271b5000df4e885989b86d35a0f83ea773b3e20","helperHash":"f7f10c819bdb0bbb8a004b05d04b205406b9b64b11e0e9fbfc128f8a39454cf9","group":"R12-recapture","root":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture","inputProtocol":"native GitVcsDriver.layer + NodeServices.layer + ServerConfig.layerTest; passive native spawn/signal observer; passive native semaphore waiters Set.add/delete observer delegates unchanged; traced caller identity; real git aliases/hooks/local upload-pack; READY IPC; no fake spawner/clock/platform","ms":15.077,"kind":"ENVIRONMENT"}
{"service":"R12","id":23,"pid":316681,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.0","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.0/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":540.213,"kind":"SPAWNED"}
{"label":"R12.0","pid":316683,"ppid":316682,"pgid":316681,"mono_ns":38712465557877,"duration_ms":8000,"mode":"transport","source":"fixture","ms":573.781,"kind":"READY"}
{"service":"R12","id":47,"pid":316689,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.1","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.1/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":616.949,"kind":"SPAWNED"}
{"label":"R12.1","pid":316691,"ppid":316690,"pgid":316689,"mono_ns":38712542703499,"duration_ms":8000,"mode":"transport","source":"fixture","ms":650.443,"kind":"READY"}
{"service":"R12","id":71,"pid":316697,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.2","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.2/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":697.391,"kind":"SPAWNED"}
{"label":"R12.2","pid":316699,"ppid":316698,"pgid":316697,"mono_ns":38712621519134,"duration_ms":8000,"mode":"transport","source":"fixture","ms":729.275,"kind":"READY"}
{"service":"R12","id":95,"pid":316705,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.3","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.3/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":771.963,"kind":"SPAWNED"}
{"label":"R12.3","pid":316707,"ppid":316706,"pgid":316705,"mono_ns":38712698634469,"duration_ms":8000,"mode":"transport","source":"fixture","ms":806.461,"kind":"READY"}
{"label":"R12","count":4,"fifthReady":0,"ms":807.273,"kind":"FOUR_FETCHES_READY"}
{"label":"R12.caller4","ms":807.904,"kind":"REQUEST"}
{"fiberId":199,"spans":["GitVcsDriver.fetchRemoteForStatus.wait","refreshStatusRemoteCacheEntry","refreshStatusUpstreamIfStale","statusDetailsRemote","capture.R12.caller4"],"permits":4,"taken":4,"free":0,"waiters":1,"observer":"native Set.add already completed inside effect/Semaphore.waitForPermits","ms":847.629,"kind":"FETCH_SLOT_QUEUE_INSERT"}
{"label":"R12.4","queueEventMs":847.629,"fiberId":199,"spans":["GitVcsDriver.fetchRemoteForStatus.wait","refreshStatusRemoteCacheEntry","refreshStatusUpstreamIfStale","statusDetailsRemote","capture.R12.caller4"],"permits":4,"taken":4,"free":0,"waiters":1,"fifthPreflight":[{"ms":815.94,"args":["rev-parse","--abbrev-ref","--symbolic-full-name","@{upstream}"]},{"ms":823.229,"args":["remote"]},{"ms":830.789,"args":["rev-parse","--git-common-dir"]},{"ms":843.422,"args":["rev-parse","--show-toplevel"]},{"ms":845.091,"args":["symbolic-ref","--quiet","--short","HEAD"]}],"fifthFetchSpawns":0,"ms":848.184,"kind":"FIFTH_FETCH_OBSERVED_QUEUED"}
{"label":"R12.independent","ms":850.069,"kind":"REQUEST"}
{"label":"R12.independent","elapsedMs":7.874,"result":[{"exitCode":0,"stdout":"f55955920bcd200b63666c2cee708f432f2d79f8\n","stderr":"","stdoutTruncated":false,"stderrTruncated":false}],"ms":857.968,"kind":"RETURN"}
{"label":"R12.independent","count":1,"ms":858.236,"kind":"PROBES"}
{"label":"R12.caller0","ms":858.322,"kind":"CALLER_INTERRUPT_REQUEST"}
{"label":"R12.caller0","elapsedMs":0.937,"exit":"Failure(Cause([Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1)]))","ms":859.589,"kind":"CALLER_INTERRUPT_COMPLETE"}
{"label":"R12","pids":[316683,316691,316699,316707],"live":[316683,316691,316699,316707],"liveCount":4,"markers":[],"markerCount":0,"ms":860.294,"kind":"SNAPSHOT"}
{"label":"R12","queuedFetchWaiters":1,"liveHelpers":4,"ms":861.322,"kind":"SERVICE_CLOSE_REQUEST"}
{"fiberId":199,"spans":["GitVcsDriver.fetchRemoteForStatus.wait","refreshStatusRemoteCacheEntry","refreshStatusUpstreamIfStale","statusDetailsRemote","capture.R12.caller4"],"permits":4,"taken":4,"free":0,"waiters":0,"observer":"native Set.delete already completed","ms":861.863,"kind":"FETCH_SLOT_QUEUE_REMOVE"}
{"pid":-316705,"signal":"SIGTERM","ms":876.35,"kind":"SIGNAL"}
{"label":"R12.3","pid":316707,"ppid":316706,"pgid":316705,"mono_ns":38712769248853,"policy":"ignore","source":"fixture","ms":882.857,"kind":"TERM"}
{"label":"R12.caller4","elapsedMs":101.487,"result":{"isRepo":true,"defaultBranch":null,"isDefaultBranch":true,"branch":"main","upstreamRef":"origin/main","hasUpstream":true,"aheadCount":0,"behindCount":0,"aheadOfDefaultCount":0},"ms":909.423,"kind":"RETURN"}
{"pid":-316705,"signal":"SIGKILL","ms":1883.455,"kind":"SIGNAL"}
{"service":"R12","id":95,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.3","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.3/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":1126.68,"ms":1894.638,"kind":"FINALIZED"}
{"pid":-316697,"signal":"SIGTERM","ms":1899.84,"kind":"SIGNAL"}
{"label":"R12.2","pid":316699,"ppid":316698,"pgid":316697,"mono_ns":38713792794308,"policy":"ignore","source":"fixture","ms":1908.242,"kind":"TERM"}
{"pid":-316697,"signal":"SIGKILL","ms":2900.229,"kind":"SIGNAL"}
{"service":"R12","id":71,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.2","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.2/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":2218.357,"ms":2911.737,"kind":"FINALIZED"}
{"pid":-316689,"signal":"SIGTERM","ms":2914.842,"kind":"SIGNAL"}
{"label":"R12.1","pid":316691,"ppid":316690,"pgid":316689,"mono_ns":38714807700560,"policy":"ignore","source":"fixture","ms":2920.135,"kind":"TERM"}
{"pid":-316689,"signal":"SIGKILL","ms":3916.899,"kind":"SIGNAL"}
{"service":"R12","id":47,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.1","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.1/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":3314.863,"ms":3927.764,"kind":"FINALIZED"}
{"pid":-316681,"signal":"SIGTERM","ms":3932.363,"kind":"SIGNAL"}
{"label":"R12.0","pid":316683,"ppid":316682,"pgid":316681,"mono_ns":38715825245835,"policy":"ignore","source":"fixture","ms":3938.331,"kind":"TERM"}
{"pid":-316681,"signal":"SIGKILL","ms":4936.107,"kind":"SIGNAL"}
{"service":"R12","id":23,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.0","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-51.717Z-30eb7e7bb1-R12-recapture/R12.0/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":4411.267,"ms":4947.511,"kind":"FINALIZED"}
{"label":"R12","closeMs":4087.134,"remainingFetchWaiters":0,"ms":4948.479,"kind":"SERVICE_CLOSE_COMPLETE"}
{"label":"R12","pids":[316683,316691,316699,316707],"live":[],"liveCount":0,"markers":[],"markerCount":0,"ms":4949.075,"kind":"SNAPSHOT"}
{"rows":1,"ms":4951.65,"kind":"RUN_COMPLETE"}
```

### After: [3c6d27fa7c](https://git.cafe/pingdotgg/t3code/commit/3c6d27fa7c98ab98a23463891452f761aedbdea8)

Full SHA: `3c6d27fa7c98ab98a23463891452f761aedbdea8`. Wall origin: `2026-10-28T20:04:26.054Z`. Run: `2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture`.

```jsonl
{"sha":"3c6d27fa7c98ab98a23463891452f761aedbdea8","wallOrigin":"2026-10-28T20:04:26.054Z","os":"Linux","kernel":"6.1.102","node":"v26.13.0","git":"git version 2.43.0","cpus":4,"platformNodeShared":"4.0.5","driverHash":"c0371bd935db8fce6da4b0961271b5000df4e885989b86d35a0f83ea773b3e20","helperHash":"f7f10c819bdb0bbb8a004b05d04b205406b9b64b11e0e9fbfc128f8a39454cf9","group":"R12-recapture","root":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture","inputProtocol":"native GitVcsDriver.layer + NodeServices.layer + ServerConfig.layerTest; passive native spawn/signal observer; passive native semaphore waiters Set.add/delete observer delegates unchanged; traced caller identity; real git aliases/hooks/local upload-pack; READY IPC; no fake spawner/clock/platform","ms":18.165,"kind":"ENVIRONMENT"}
{"service":"R12","id":23,"pid":316204,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.0","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.0/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":541.712,"kind":"SPAWNED"}
{"label":"R12.0","pid":316206,"ppid":316205,"pgid":316204,"mono_ns":38686800286765,"duration_ms":8000,"mode":"transport","source":"fixture","ms":582.371,"kind":"READY"}
{"service":"R12","id":47,"pid":316212,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.1","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.1/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":626.824,"kind":"SPAWNED"}
{"label":"R12.1","pid":316214,"ppid":316213,"pgid":316212,"mono_ns":38686881587615,"duration_ms":8000,"mode":"transport","source":"fixture","ms":663.073,"kind":"READY"}
{"service":"R12","id":71,"pid":316220,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.2","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.2/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":707.217,"kind":"SPAWNED"}
{"label":"R12.2","pid":316222,"ppid":316221,"pgid":316220,"mono_ns":38686962138937,"duration_ms":8000,"mode":"transport","source":"fixture","ms":743.6,"kind":"READY"}
{"service":"R12","id":95,"pid":316228,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.3","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.3/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"ms":786.841,"kind":"SPAWNED"}
{"label":"R12.3","pid":316230,"ppid":316229,"pgid":316228,"mono_ns":38687039005645,"duration_ms":8000,"mode":"transport","source":"fixture","ms":820.442,"kind":"READY"}
{"label":"R12","count":4,"fifthReady":0,"ms":821.352,"kind":"FOUR_FETCHES_READY"}
{"label":"R12.caller4","ms":821.813,"kind":"REQUEST"}
{"fiberId":199,"spans":["GitVcsDriver.fetchRemoteForStatus.wait","refreshStatusRemoteCacheEntry","refreshStatusUpstreamIfStale","statusDetailsRemote","capture.R12.caller4"],"permits":4,"taken":4,"free":0,"waiters":1,"observer":"native Set.add already completed inside effect/Semaphore.waitForPermits","ms":859.565,"kind":"FETCH_SLOT_QUEUE_INSERT"}
{"label":"R12.4","queueEventMs":859.565,"fiberId":199,"spans":["GitVcsDriver.fetchRemoteForStatus.wait","refreshStatusRemoteCacheEntry","refreshStatusUpstreamIfStale","statusDetailsRemote","capture.R12.caller4"],"permits":4,"taken":4,"free":0,"waiters":1,"fifthPreflight":[{"ms":829.777,"args":["rev-parse","--abbrev-ref","--symbolic-full-name","@{upstream}"]},{"ms":837.299,"args":["remote"]},{"ms":844.769,"args":["rev-parse","--git-common-dir"]},{"ms":856.345,"args":["rev-parse","--show-toplevel"]},{"ms":857.692,"args":["symbolic-ref","--quiet","--short","HEAD"]}],"fifthFetchSpawns":0,"ms":860.028,"kind":"FIFTH_FETCH_OBSERVED_QUEUED"}
{"label":"R12.independent","ms":861.868,"kind":"REQUEST"}
{"label":"R12.independent","elapsedMs":7.214,"result":[{"exitCode":0,"stdout":"f55955920bcd200b63666c2cee708f432f2d79f8\n","stderr":"","stdoutTruncated":false,"stderrTruncated":false}],"ms":869.112,"kind":"RETURN"}
{"label":"R12.independent","count":1,"ms":869.351,"kind":"PROBES"}
{"label":"R12.caller0","ms":869.431,"kind":"CALLER_INTERRUPT_REQUEST"}
{"label":"R12.caller0","elapsedMs":0.893,"exit":"Failure(Cause([Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1),Interrupt(1)]))","ms":870.502,"kind":"CALLER_INTERRUPT_COMPLETE"}
{"label":"R12","pids":[316206,316214,316222,316230],"live":[316206,316214,316222,316230],"liveCount":4,"markers":[],"markerCount":0,"ms":871.072,"kind":"SNAPSHOT"}
{"label":"R12","queuedFetchWaiters":1,"liveHelpers":4,"ms":871.764,"kind":"SERVICE_CLOSE_REQUEST"}
{"fiberId":199,"spans":["GitVcsDriver.fetchRemoteForStatus.wait","refreshStatusRemoteCacheEntry","refreshStatusUpstreamIfStale","statusDetailsRemote","capture.R12.caller4"],"permits":4,"taken":4,"free":0,"waiters":0,"observer":"native Set.delete already completed","ms":872.109,"kind":"FETCH_SLOT_QUEUE_REMOVE"}
{"pid":-316228,"signal":"SIGTERM","ms":885.732,"kind":"SIGNAL"}
{"label":"R12.3","pid":316230,"ppid":316229,"pgid":316228,"mono_ns":38687104870115,"policy":"ignore","source":"fixture","ms":890.731,"kind":"TERM"}
{"label":"R12.caller4","elapsedMs":90.18,"result":{"isRepo":true,"defaultBranch":null,"isDefaultBranch":true,"branch":"main","upstreamRef":"origin/main","hasUpstream":true,"aheadCount":0,"behindCount":0,"aheadOfDefaultCount":0},"ms":912.002,"kind":"RETURN"}
{"pid":-316228,"signal":"SIGKILL","ms":1890.634,"kind":"SIGNAL"}
{"service":"R12","id":95,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.3","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.3/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":1117.562,"ms":1900.98,"kind":"FINALIZED"}
{"pid":-316220,"signal":"SIGTERM","ms":1904.572,"kind":"SIGNAL"}
{"label":"R12.2","pid":316222,"ppid":316221,"pgid":316220,"mono_ns":38688123775352,"policy":"ignore","source":"fixture","ms":1909.447,"kind":"TERM"}
{"pid":-316220,"signal":"SIGKILL","ms":2913.524,"kind":"SIGNAL"}
{"service":"R12","id":71,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.2","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.2/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":2220.936,"ms":2923.969,"kind":"FINALIZED"}
{"pid":-316212,"signal":"SIGTERM","ms":2927.01,"kind":"SIGNAL"}
{"label":"R12.1","pid":316214,"ppid":316213,"pgid":316212,"mono_ns":38689146147135,"policy":"ignore","source":"fixture","ms":2932.325,"kind":"TERM"}
{"pid":-316212,"signal":"SIGKILL","ms":3930.118,"kind":"SIGNAL"}
{"service":"R12","id":47,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.1","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.1/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":3318.369,"ms":3941.251,"kind":"FINALIZED"}
{"pid":-316204,"signal":"SIGTERM","ms":3944.699,"kind":"SIGNAL"}
{"label":"R12.0","pid":316206,"ppid":316205,"pgid":316204,"mono_ns":38690163863932,"policy":"ignore","source":"fixture","ms":3949.768,"kind":"TERM"}
{"pid":-316204,"signal":"SIGKILL","ms":4944.389,"kind":"SIGNAL"}
{"service":"R12","id":23,"cwd":"/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.0","args":["--git-dir","/tmp/lead-26601-r1/capture-r12/2026-10-28T20-04-26.043Z-3c6d27fa7c-R12-recapture/R12.0/.git","fetch","--quiet","--no-tags","--no-auto-gc","--","origin"],"elapsedMs":4418.04,"ms":4954.676,"kind":"FINALIZED"}
{"label":"R12","closeMs":4083.752,"remainingFetchWaiters":0,"ms":4955.542,"kind":"SERVICE_CLOSE_COMPLETE"}
{"label":"R12","pids":[316206,316214,316222,316230],"live":[],"liveCount":0,"markers":[],"markerCount":0,"ms":4956.088,"kind":"SNAPSHOT"}
{"rows":1,"ms":4957.917,"kind":"RUN_COMPLETE"}
```

## Before | After

| Observation | Before [30eb7e7bb1](https://git.cafe/pingdotgg/t3code/commit/30eb7e7bb1ef103fdd6f54081b6a4acf66b3ee4c) | After [3c6d27fa7c](https://git.cafe/pingdotgg/t3code/commit/3c6d27fa7c98ab98a23463891452f761aedbdea8) |
|---|---:|---:|
| Full SHA | `30eb7e7bb1ef103fdd6f54081b6a4acf66b3ee4c` | `3c6d27fa7c98ab98a23463891452f761aedbdea8` |
| Fifth native queue insertion (ms) | 847.629 | 859.565 |
| Queue state before caller interrupt / service close | 4 taken, 0 free, 1 waiter | 4 taken, 0 free, 1 waiter |
| Independent pooled probe | 1/1 succeeds | 1/1 succeeds |
| Caller-only interrupt (ms) | 0.937 | 0.893 |
| Live helpers after caller interrupt → after service close | 4 → 0 | 4 → 0 |
| Active fetch groups receiving TERM then KILL | 4 | 4 |
| Measured owning-service close (ms) | **4087.134** | **4083.752** |
| Fetch spawns total / fifth fetch spawns / fifth READY | 4 / 0 / 0 | 4 / 0 / 0 |
| Remaining queue waiters / natural markers / live recorded PIDs | 0 / 0 / 0 | 0 / 0 / 0 |
| Focused capture invocation | 1 passed | 1 passed |

**Verdict:** parity verified, including cancellation of an already queued fifth fetch. The original proposed 1,000–2,500 ms aggregate close target remains missed on both revisions. The measured ~4.1 s total is the pre-existing serial teardown behavior: each active fetch receives its own ~1 s TERM-to-KILL grace, and teardown proceeds serially. This recapture does not claim a speed improvement or a repaired aggregate shutdown bound.

## Environment, reproduction, and artifacts

Machine `fs-40`; Linux 6.1.102; Node v26.13.0; Git 2.43.0; installed `effect`, `@effect/platform-node`, and `@effect/platform-node-shared` 4.0.5; 4 available CPUs. Native Linux/POSIX evidence only; no Windows or macOS runtime claim. Both runs used GIT_CONFIG_GLOBAL=/dev/null.

From each revision’s `apps/server`, after copying the identical driver to `src/vcs/scratch26601.capture.test.ts`:

```sh
GIT_CONFIG_GLOBAL=/dev/null vp test run src/vcs/scratch26601.capture.test.ts
```

[Raw logs and synthetic run directories](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/0bf3587433cfa330/R12-raw-logs.tar.gz) include both complete events.jsonl streams, environment.json, results.json, invocation logs, clean status files, process-group verification, base install log, and the failed observer-bootstrap attempt (no Git fixture started in that failed attempt).

[Identical R12 driver](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/6c88202b53025fc4/driver-r12.test.ts)
```text
c0371bd935db8fce6da4b0961271b5000df4e885989b86d35a0f83ea773b3e20
```

[Unchanged Python fixture](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/e621eb15938e9b28/fixture26601.py)
```text
f7f10c819bdb0bbb8a004b05d04b205406b9b64b11e0e9fbfc128f8a39454cf9
```

Changes from the earlier R12 driver are limited to isolating this row, adding inherited caller span labels and the passive native queue insertion/removal observer, awaiting the actual fifth queue event before caller interruption, and asserting the requested observable outcomes. All other matrix rows and production code are untouched. Both runs report driver hash `c0371bd935db8fce6da4b0961271b5000df4e885989b86d35a0f83ea773b3e20`.

FRICTION:
- tool | Vitest could not spy on the immutable ESM `Semaphore.make` export (`Cannot redefine property: make`), before any fixture Git command started | observe the native semaphore instance’s waiters via its writable prototype method; return the original effect unchanged.

VERDICT: R12 queue-entry and cancellation evidence captured; parity verified; pre-existing aggregate shutdown target miss retained.