[only21mil]

Problem

On Linux the server caches whether it can run agents in systemd scopes. A probe timeout after 5 seconds counted as "no user manager". If the user manager is slow at the first agent launch, the server logs Agent scopes are off: no systemd user manager and never checks again.

From then until a restart, every agent runs outside the agents slice. The memory limits that keep the server, sshd and tailscaled alive do not apply to it, and an out-of-memory kill is no longer reported as one, because that report reads the scope. If only the OOMPolicy probe times out, scopes stay on but without OOMPolicy=stop, also until restart.

Change

A probe that timed out or failed to start now fails detection instead of returning "off".

• A timeout on the OOMPolicy probe fails detection too, so the next launch asks again.
• Detection is cached with Effect.cachedWithTTL, with a TTL chosen by the result: forever on success, zero on failure. A launch that hears a failure runs unscoped and logs Agent scopes are off until systemd answers. The next launch probes again.
• Launches sharing one failed probe hear it at different times. Because the cache expires failures itself, a late one cannot clear a detection that has since succeeded.
• A detection that succeeded, including a "no" answer, stays cached for the server's life. A host with no user manager gets an immediate error from systemd-run, so it is not probed on every launch.
• Concurrent launches still share one probe run.
• A retry runs stopLeftoverAgents again. That is safe: no agent from this server is in its slice yet, because none was scoped.

While the user manager stays silent, each launch waits about 10 seconds, two 5 second timeouts, before it runs unscoped. On main the first launch waits about 15 seconds; later launches run unscoped until restart.

The test fake gains a stalled option that makes every systemctl and systemd-run call time out. The option is set before the scope service is built, so it also covers a detection that runs at startup. The test starts two launches on one stalled probe. The first clears the stall and launches again before the second hears the old failure. It expects the first agent's second launch to get the agents slice and a later launch to keep it.

Size: agentScope.ts +20/−4, agentScope.test.ts +75/−26 (+53/−4 ignoring the fake's re-indent).

Scope and approval

No issue covers this. It is a small fix to a clear bug in the detection #17662 added: one timeout should not turn scopes off until restart.

Rebased on current main; its scope options, Delegate=yes and slice limits are kept.

Open PRs that touch the same lines:

• fix(server): agents launch without a scope when systemd can no longer create one #26388 by @juliusmarminge moves the same probe, so whichever lands second needs a small rebase.
• fix(server): keep owned ACP work in agent resource scopes #21767 by @marinushv touches the test fake.

Verification

• vp test run src/process/agentScope.test.ts: 15 passed.
• The test fails against main's agentScope.ts and passes on the branch. On main the first agent's second launch gets no scope: expected '' to be 'app-t3code-agents-<hash>.slice'.
• vp run check:changed against main: format, lint, knip, typecheck and tests pass.

Real binaries, Linux, systemd 259, run on this branch before the rebase, which did not change the detection logic. An uncommitted test ran ProcessRunner with real systemctl and systemd-run against a silent user bus socket, then removed it. On main, the first timeout turned scopes off for every later launch. On the branch, each launch probed again while the bus was silent, and the "no user manager" answer was cached after launch 3. Called directly, both binaries hang on the silent bus and exit 1 at once with no bus. No real user manager was involved.

Nothing on screen changes. Scopes change the server's agent command line.

Not checked:

• A real user manager stalled under load. I did not stall the session manager on a shared machine, so the timeout case uses a silent socket and the unit test.
• A launch that gets a scope after a real manager recovers. The unit test covers that step with a fake runner.
• A timeout on only the OOMPolicy probe. No test covers it; the probe fails detection the same way.
• A merge with fix(server): reap recorded Linux Claude survivors before recovery #22834, which no longer merges cleanly with main.
• systemd versions before 253, and distributions other than Fedora.

Prior PRs

None for this bug. #17662 by @t3dotgg added agent scopes and the cached detection this PR changes.

Generated with Claude Opus 5.5 and GPT-6.1 Sol in T3 Code Nightly

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• apps/server/src/process/agentScope.test.ts
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Walkthrough

Systemd detection now distinguishes runner failures from nonzero exits. It caches successful detections indefinitely and retries failed evaluations. Tests cover stalled probes and concurrent launches.

Changes: Systemd detection and recovery

Layer / File(s)	Summary
Probe and cache behavior apps/server/src/process/agentScope.ts	The probe uses runOrFail and checks the process exit code. Successful detections are cached indefinitely; failures are logged, return undefined, and are not cached.
Stall and concurrent recovery tests apps/server/src/process/agentScope.test.ts	The fake runner can stall and fail with ProcessTimeoutError. A concurrent-launch test checks the resulting slices after recovery and confirms that a later launch does not stop the recovered slice.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Possibly related PRs

• pingdotgg/t3code#23913 — This PR changes shared systemd scope options and startup probes. This change modifies failure handling for the same probes.
• pingdotgg/t3code#21700 — This PR changes systemd scope probing and launch options. This change modifies failure handling for that detection path.
• pingdotgg/t3code#26388 — This PR reruns systemd scope probes before launches. This change also covers failed detection probes.

Suggested labels: bugfix

Suggested reviewers: maria-rcks, t3dotgg

Merge Risk: Minimal · previous review 164e0

No merge-blocking risk remains from the identified concurrency issue.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title names the main change: a failed systemd probe timeout now triggers a retry of agent scopes instead of caching an "off" result. It matches the summary, the objectives, and the description. It…
Description check		The description follows the template. It has Problem, Change, Scope and approval, and Verification sections, plus a note on the agent model. The Problem section gives the bug, the reproduction environ…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title names the main change: a failed systemd probe timeout now triggers a retry of agent scopes instead of caching an "off" result. It matches the summary, the objectives, and the description. It uses the conventional commit format and is 70 characters long, so it is concise.

Full details: Description check

Explanation

The description follows the template. It has Problem, Change, Scope and approval, and Verification sections, plus a note on the agent model. The Problem section gives the bug, the reproduction environment, and the expected behavior. The Change section explains the fix and why the cache uses per-result TTLs. The Scope section names the bug and the related open PRs and links the prior PR #17662. The Verification section lists the focused test, the failing-then-passing result, the real-binary comparison, and the unchecked items. The description does not link a triaged issue or a maintainer approval comment. It says no issue covers the change and gives a justification for a small fix to a clear bug, which the template allows. The Verification section also lists what was not checked. The description also gives a Claude and GPT model attribution at the end, so the agent note is present. Minor gap: the Change section does not state the agent model and harness in the expected place. Overall the description is mostly complete.

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[macroscopeapp]

Approvability

Verdict: Approved at 73fa090

Macroscope's review found this PR approvable — This is a focused Linux server bug fix that retries agent-scope detection after transient systemd probe failures while preserving cached valid results. The added regression test covers recovery, and the change introduces no schema, deployment, security, billing, or static-analysis configuration impact.

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Actionable comments posted: 1

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Inline comments:
Review comments at @apps/server/src/process/agentScope.ts:
- Line 219: Update the `detectSystemd` cache to keep successful detections
indefinitely and expire failed detections immediately, then remove the
per-caller `redetectSystemd` invalidation from the `systemd` failure handler.
Add a concurrent recovery test verifying that an older failure cannot invalidate
a newer successful detection.

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[maria-rcks]

Note

Written by gpt-6.1-sol on behalf of Maria

Verified in a real dev environment

verified unchanged head 57b1b7543aec0069f7e515221cb19a0bd840cf7a on this linux vm with systemd 255.4, real codex gpt-6.1-sol turns through the dev web client, repo playwright, and /usr/bin/google-chrome. projects and threads were created through the client against a real git repository. no mocked provider or systemd commands.

• reproduced on github/main (955e2bfbb5) in a separate worktree after vp i. a dev-server-only user-bus connection accepted connections without answering, causing real systemctl/systemd-run timeouts. after restoring access to the real manager, a codex turn completed but inherited the dev server's cgroup instead of receiving a scope owned by that server.
• stopped main before starting this head, installed dependencies, and repeated the bus timeout. the pr logged Agent scopes are off until systemd answers; a real codex turn still completed while the bus was stalled.
• restored the real bus without restarting the t3 server. codex shares its app-server across threads, so another thread alone does not launch a new process. adding a second codex instance through provider settings and selecting it in the composer exercised a fresh launch. detection recovered, and the real provider process entered this server's owned slice.
• stopped a running shell tool with the client's stop button. the shared codex scope survived. sending a follow-up resumed the thread, read the repository file, and returned RESUMED_SCOPE_OK from the same recovered scope.
• blacksmith: vp test run apps/server/src/process/agentScope.test.ts, all 15 tests passed, including concurrent recovery. the head's 29 reported ci checks are successful. no source changes or pushes were needed.

short runtime transcript (cgroup suffixes shown):

main, after bus recovery:
  Agent scopes are off: no systemd user manager
  server pid 35149 and codex pid 38130: same inherited scope
  .../app-t3code-agents-a29d81d75689.slice/t3code-codex-e9639fb2.scope

pr, same server pid 39851 throughout timeout and recovery:
  05:30:28 Agent scopes are off until systemd answers
  ProcessTimeoutError: /usr/bin/systemd-run, timeoutMs: 5000
  05:34:53 Agent scopes are on, oomPolicy: true

systemctl --user show t3code-codex-ecbcb95c.scope:
  ActiveState=active
  Slice=app-t3code-agents-5c7566105688.slice
  Delegate=yes
  OOMPolicy=continue

codex pid 45861 and resumed tool:
  .../app-t3code-agents-5c7566105688.slice/t3code-codex-ecbcb95c.scope
  scope verification workspace
  RESUMED_SCOPE_OK

OOMPolicy=continue is intentional for the shared codex app-server; the detection probe confirmed support for OOMPolicy=stop. the agents slice retained its memory limits.

Not verified

• a manager stalled by actual host load: the timeout was induced at the dev server's bus connection, then restored to the real manager.
• the timeout on only the OOMPolicy probe, executable-start failure, older systemd fallback, and real OOM termination were not separately exercised in the app.
• the concurrent late-failure ordering was covered by the existing focused test, not forced through simultaneous real provider launches.
• native desktop/mobile clients, other providers, remote/relay/tunnel connections, and macos/windows were not exercised on this linux vm.