[only21mil]

Problem

On Linux the server caches whether it can run agents in systemd scopes. A probe that timed out (5 s) counted as "no user manager", so one slow answer turned scopes off until restart: agents ran outside the agents slice and its memory limits. If only the OOMPolicy probe timed out, scopes stayed on without OOMPolicy=stop until restart.

Change

A timed-out probe now fails detection. Detection is cached with Effect.cachedWithTTL: forever on success (a real "no" included), zero on failure, so a late caller of an old failed probe cannot clear a newer success. A launch that hears a failure runs unscoped and logs Agent scopes are off until systemd answers; the next launch probes again. A probe systemd answered with an error still decides, so older managers keep the fallback.

Scope

Bug fix: one probe timeout turns off agent memory limits until restart. No issue covers this. It is a small fix to a clear bug in the detection #17662 added.

Verification

To see it on Linux (server only): 1. hold the probe carrying OOMPolicy=stop in a PATH-local systemd-run and start the server; 2. open two terminals; 3. release the probe and open two more.

Setup: an AI agent ran a real T3 server per commit in a throwaway Ubuntu 24.04 VM (systemd 255), fresh home, terminals over the WebSocket API, each shell's scope read back. Steps: the three above. Unedited excerpts:

0fbe8a2e44 (main):

[05:29:16.214] INFO (#38): Agent scopes are on {
  oomPolicy: false
[driver +23.4s] launch 4: systemctl --user show t3code-terminal-96a91ee0.scope: OOMPolicy=continue Slice=app-t3code-agents.slice Delegate=yes ActiveState=active

290261c8ec (this branch):

[driver +20.1s] launch 1: no agent scope (shell shares the server's cgroup)
[05:29:39.514] WARN (#30): Agent scopes are off until systemd answers {
    _tag: 'ProcessTimeoutError',
[05:29:55.841] INFO (#1254): Agent scopes are on
    oomPolicy: true
[driver +29.2s] launch 3: systemctl --user show t3code-terminal-0a734480.scope: OOMPolicy=stop Slice=app-t3code-agents.slice Delegate=yes ActiveState=active

Re-checked 2026-11-15 UTC on 290261c8ec (4a7be022c3 plus a merge of main 0fbe8a2e44).

Links: the two commits above, the regression test in agentScope.test.ts, #17662, #30581, #36327.

Not shown:

• A real user manager stalled under host load (the stall is held at systemd-run).
• A real out-of-memory kill.
• Older systemd (249, 252) and other distributions on these commits.
• The late-failure case in a real server (reachable by reading only).
• A probe that cannot start: since fix(server): a hung network mount no longer freezes the server when it spawns a process #36327 a systemd-run with a bad interpreter exits 127 through env, which reads as an answer on both commits (details).

Both probes held, bad interpreter, merge and open PRs on the same lines

No screen changes: scopes change only how the server launches agents.

Unedited excerpts from the run transcripts (harness lines and the server log). In the stall runs the PATH-local systemd-run execs the real one once released.

Both probes held from server start, released before launch 3:

0fbe8a2e44 (main):

[05:30:17.421] INFO (#38): Agent scopes are off: no systemd user manager
[driver +24.8s] launch 4: no agent scope (shell shares the server's cgroup)

290261c8ec (this branch):

[05:30:41.048] WARN (#30): Agent scopes are off until systemd answers {
    _tag: 'ProcessTimeoutError',
[05:30:56.859] INFO (#1246): Agent scopes are on
    oomPolicy: true
[driver +28.6s] launch 3: systemctl --user show t3code-terminal-13bc0420.scope: OOMPolicy=stop Slice=app-t3code-agents.slice Delegate=yes ActiveState=active

On 290261c8ec a timed-out OOMPolicy probe fails detection before the second probe runs.

systemd-run on PATH with a bad interpreter line, fixed before launch 3:

0fbe8a2e44 (main):

[05:31:08.508] INFO (#38): Agent scopes are off: no systemd user manager
[driver +14.1s] launch 4: no agent scope (shell shares the server's cgroup)

290261c8ec (this branch):

[05:31:24.683] INFO (#38): Agent scopes are off: no systemd user manager
[driver +13.3s] launch 4: no agent scope (shell shares the server's cgroup)

By reading, a missing or non-executable systemd-run is never probed; main and the branch both run unscoped with no log.

290261c8ec merges main 0fbe8a2e44 into 4a7be022c3, a maintainer's merge of main 20ee041354 that stays below it. The conflict was only in agentScope.test.ts, with #30581's memory test and its failing verbs in the fake runner; both sides are kept. Against main, agentScope.ts differs only by this PR's change, the same changed lines as against 20ee041354; #30581's applyMemoryLimits sits in the detection result this PR caches on success.

vp test run src/process/agentScope.test.ts on 290261c8ec: 17 passed, 10 runs in a row, #30581's "follows a live memory change at the next launch" included. The late-failure test fails with main 0fbe8a2e44's agentScope.ts (a 120 s timeout: main caches the startup timeout as "no scopes", so the stalled probe the test waits on never runs again) and, 10 of 10, with this PR's late-failure guard reverted (a stop of the agents slice appears). Typecheck of apps/server and vp run check:changed 0fbe8a2e44 pass.

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.

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

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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 · up to 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…
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.
Description check		The description follows the template's main sections. Problem, Change, Scope, and Verification are all filled in with specific content. The Problem section explains the cached timeout behavior and its…

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's main sections. Problem, Change, Scope, and Verification are all filled in with specific content. The Problem section explains the cached timeout behavior and its effect on agent memory limits. The Change section explains the TTL cache and the failure handling. The Scope section calls this a bug fix and links related issues (#17662, #30581, #36327). The Verification section gives real Linux runs, commit references, test results, and a list of untested areas. The template also asks for the model and harness used. The author lists "Claude Opus 5.5 and GPT-6.1 Sol" at the end, so that item is covered. The Scope section also says "No issue covers this", which meets the template's requirement to say why no issue is needed for a small fix. The description is long and includes a collapsed details block, but it is complete enough to review. The title is not part of this check's input, so the conventional-commit title rule cannot be assessed here.

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Files selected for processing: 2

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

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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.

[only21mil]

Note

🤖 Opus 5.5 replying on behalf of Victor.

@maria-rcks thanks for testing this; we ran all three through a real T3 server opening terminals against a real systemd user manager, on main and on 57b1b7543a. With only the OOMPolicy probe stalled, main kept every later scope without OOMPolicy=stop after systemd recovered, while this branch ran the stalled launches unscoped and turned on with oomPolicy: true on the next launch. An executable systemd-run that cannot start turned scopes off for good on main, while this branch retried and scoped the next launch once it could start; a missing or non-executable systemd-run never reaches the probe, so both behave the same there. On a real systemd 249 VM the probe gets Unknown assignment: OOMPolicy=stop and both fall back at once to scopes without OOMPolicy, and since systemd 252 already accepts OOMPolicy on scopes, that fallback covers 251 and older.

[only21mil]

Note

🤖 Opus 5.5 replying on behalf of Victor.

I merged main to clear a new conflict with #22834 in the agent scope tests. Main now detects systemd at startup, so one of my tests needed its set-up changed; that is a separate test-only commit, and the fix itself is unchanged.

[juliusmarminge]

Evidence

Started each real server with transient systemd probe stalls, removed the fault, confirmed a direct OOMPolicy=stop probe succeeded, then opened a web terminal and inspected its own scope without restarting the server. Same synthetic data, Chromium viewport 1280×800 and light theme on both sides. Both scenarios:prove comparisons exited 0.

Variant	Before	After
A: only OOMPolicy probe stalls	20ee041354: remains OOMPolicy=continue. Recording	4a7be022c3: recovers OOMPolicy=stop. Recording
B: both probes stall	20ee041354: remains unscoped. Recording	4a7be022c3: recovers OOMPolicy=stop in app-t3code-agents.slice. Recording

Single-test scenario · Startup fault driver patch. Neither file was committed.

Not shown:

• Definitive unsupported results and executable spawn failures were not exercised; this environment supports scopes and OOMPolicy, and the captures cover transient probe timeouts.

[github-actions]

This PR conflicts with main. Rebase it or merge main into it. If it still conflicts after 7 days with no activity, it will be closed automatically.

See the conflict window.

[only21mil]

Note

🤖 Opus 5.5 replying on behalf of Victor.

The maintainers' pipeline evidence run on 4a7be022c3 does not cover the new head 290261c8ec. I merged main to clear the conflict with #30581 in the agent scope tests, and the fix is unchanged.