Trial P-51 (fail): with the subprocess scrub on, the pinned CLI's sandbox lets every write outside the work directory land by don-petry · Pull Request #316 · combsmith/software-factory

don-petry · 2026-10-22T13:23:25Z

Closes #312. The open design question it leaves, Intents that need a tool, is #314.

Trial P-51: fail

Question. On a GitHub-hosted Linux runner, does the pinned model CLI's sandbox let a tool's write outside its work directory land, and is it the subprocess scrub or the order of the Tasks that decides?

Pass condition, written at 2026-10-22T12:12:39Z, before anything ran, and held at the top of tools/trial_p51_sandbox_writes.sh: in every configuration a Run can be given (the scrub unset, 0 or 1), in both orders, at the pinned version before and after:

the CLI exited 0 and its answer is no error;
the tool's result went back and is not an error;
the probe ran;
none of the four writes outside the work directory landed.

How it ran. As P-50 did: in the canary, a workflow with no secret, only contents: read on its job, and ubuntu-24.04 with kernel.apparmor_restrict_unprivileged_userns=0 (P-50 showed the tool does not run without it). The CLI was at 2.1.306, and its API was P-50's stub on 127.0.0.1, with a dummy key and no model. There were three configurations: CLAUDE_CODE_SUBPROCESS_ENV_SCRUB unset, 0 and 1, with nothing else changed between them. Each Task had its own work and configuration directories, and the three ran in one order, then in reverse. The probe tried four writes outside its work directory:

a file in the home directory;
a dotfile there;
a file in /tmp;
a file in the work directory's parent, which was under the runner's own temporary directory, not /tmp.

It also wrote one file inside the work directory, as a control.

The fixture holds the trial's run, 39781351303, and the run before it, 39778822341, which showed the same in every configuration.

What it showed, in both orders:

Scrub	home	dotfile	`/tmp`	parent
unset (`GITHUB_ACTIONS` set, the runner's other variables removed)	refused	refused	refused	refused
`0`	refused	refused	refused	refused
`1`	landed	landed	landed	landed

In every Task, the tool ran in a PID namespace of its own, its result went back with no error, and the control write landed.

So on Linux at 2.1.306, the scrub that takes the credential's listed name out of a tool's environment also opens the sandbox to writes outside the work directory. The ruling is on #194: no step sets the scrub unless it also passes --tools "", and no step holding the model credential has any tool. Intents that need a tool are #314.

What this changes

tools/trial_p51_sandbox_writes.sh, byte for byte as the canary ran it. With it come its stand-in tests (SandboxWritesTrial, run against P-50's real stub), six mutants, and a test that reads the fixture's analysis again from the job's log.
trials/P-51.json.
Design §4.9: the sentence on writes, and "until P-26, P-50 and P-51 pass". §6: a new P-51 row. §6.1: P-51 is listed beside P-26 and P-50.
trials/AGENTS.md: P-51's rules.

The script fixes the faults P-50's had, listed on #312: it reads the stub's port through a pipe, gives each Task its own configuration directory, and checks that the tool's result is not an error. The walk faults do not apply, since P-51 does not walk processes.

Canary

The branch trial/p-51 is deleted after this PR opens. Its runs stay in the canary, and their logs hold no secret: the key is a dummy, and the printed records are booleans, counts and exit codes. Every file the probe wrote outside its work directory was removed by the script in the same job. No token was minted, and nothing else was made.

Gates

PATH=/usr/bin:/bin SIM_SEEDS=40 make verify: 1013 tests, OK, at c0958c1, before main merged in (the merge brought only Kernel: a Run that ran and left no outcome is an attempt; one cancelled, or never started, is none (#286) #302's and Facts port: the snapshot's diff and files read by one compare pinned to the head commit (#284) #303's changes, which touch none of this)
Claude review with a security pass: no blockers or majors. Its minors on cleanup and wording are fixed, which needed one more canary run, and the result was the same. The suggestion to require the control write in a future pass condition is noted for whoever runs this again.
P-51's six mutants, applied by hand: all killed.
Muse: not run (Maintainer, 2026-10-20: Kernel/hook only).

🤖 Generated with Claude Code

Summary by CodeRabbit

Documentation
- Clarified the documented sandbox trial results across three subprocess-scrub configurations, including which attempted writes were blocked and when external writes occurred.
- Updated the trial order and runbook guidance to include the new sandbox-write trial.
Tests
- Added validation for trial results, configuration isolation, and cleanup of files created outside the trial work directory.

…ool its parent environment too The pinned CLI ran against a stub of the Messages API on the runner, with a dummy key and no secret, in the canary. As the runner stands the probe never ran; with unprivileged user namespaces allowed it ran in a PID namespace of its own, the CLI out of sight, and still held the parent marker in its own environment and in each process above it. The scrub took out the listed name alone. The fixture keeps both attempts of the same commit; the script, stub and stand-in tests come with it. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

P-26 landed beside P-50 in tools/mutants.py and tests/test_tools.py; both are kept. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…is reversed once, and the fixture is the final run The probe walked from its own shell, so the first process it read was itself; it now starts at its parent, keeps each environment apart and says why it stopped. Each Task has a configuration directory of its own, a third run puts the scrubbed Task first, and the stub logs whether a tool result says it is an error. The fixture is rebuilt from the run at 0b1c47b alone, the rows say only what it shows, and the test reads the analysis again from the log. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…alone, and no workflow here runs it The Maintainer's ruling on issue 287, as decision 0044's Boundaries row: tools/trial_p50_stub.py may import http.server and nothing that reaches out, its server binds 127.0.0.1 written as it is, it calls no create_connection, and no workflow of this repo names it. Each limit has counter-examples and a mutant; two network mutants follow the line they break. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…xample that names its rule The re-review got round the list of what was refused in a dozen ways: a subclass, a server held under another name, socketserver beneath it, the server module's own socket, getattr, a module named by a string, a subprocess. The stub may now import four modules by their own names, name nothing else of http, os and sys, make its server one way on 127.0.0.1, and touch no socket. Each counter-example names the rule that must catch it; nine mutants. The rows say the one process above the tool held the marker, and that this repo's tests run the stub too. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…TS.md keeps its lines short Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

P-47's design row and batch entry landed where P-50's did; both are kept. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…set aside by name, and the fixture is the run that ran it SonarCloud found three path traversals in the stub's arguments and one clear-text HTTP server. The stub now logs to one fixed name where it is started and prints its port, which the script reads through a pipe; P-50 ran again in the canary with it (run 39776840915, the same in every configuration), and the fixture is that run. python:S5332 is set aside in sonar-project.properties for the stub alone, by ruling: it serves on 127.0.0.1 only. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…y name the allowlist holds CodeRabbit's finding: ().__class__.__base__.__subclasses__() or a function's __globals__ reaches the socket classes past an allowlist of names. The stub's check now refuses any attribute that starts and ends with two underscores; two counter-examples and a mutant. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…dbox lets every write outside the work directory land In the canary, with user namespaces allowed and the CLI's API P-50's stub, no secret: the scrub unset, 0 and 1, each Task its own configuration directory, in both orders. At 1 the writes to the home directory, a dotfile, /tmp and the work directory's parent all landed; unset or 0, all four were refused. The script fixes the faults P-50's had, listed on #312; its stand-in tests and five mutants come with it. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…get before its trap, and runs apart from /tmp The review's fixes, with P-51 run once more in the canary (39781351303, the same in every configuration) and the fixture rebuilt from it: the trap's kill cannot stop the cleanup, a target already there is refused and left as found, OUT is made after the checks, and the scratch directory is under the runner's temporary directory. A Task whose answer is an error has a case and a mutant; nothing is left in /tmp. The rows say each of the four writes tried, and that the unset configuration had the runner's other variables removed. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

P-50's last fix, the stub's check refusing __special__ attributes. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

P-50 landed on main as #313; P-51's lines are kept beside it. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

chatgpt-codex-connector · 2026-10-22T13:23:35Z

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tests/test_tools.py

📝 Walkthrough

Adds the P-51 Linux sandbox-write trial. It tests four external write locations under three subprocess scrub settings, records per-configuration results, and documents the findings and trial gate.

Changes: P-51 sandbox-write trial

Layer / File(s)	Summary
Run P-51 configurations `tools/trial_p51_sandbox_writes.sh`	The script starts the local stub and runs the pinned CLI in fresh work and configuration directories for each scrub setting. It attempts four external writes and one control write.
Record and validate trial outcomes `tools/trial_p51_sandbox_writes.sh`, `tests/test_tools.py`, `tools/mutants.py`	The script records CLI, stub, probe, and write results and evaluates pass conditions. Tests cover configuration order, write outcomes, cleanup, isolation, and invalid inputs. Mutants target the trial’s pass criteria.
Document findings and trial conditions `docs/architecture/software-factory-design.md`, `trials/AGENTS.md`	The design documentation records the observed write results and adds P-51 to the trial order. Trial guidance describes its run conditions and pass criteria.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Other

Sequence Diagram(s)

sequenceDiagram
  participant TrialScript
  participant PinnedCLI
  participant P50Stub
  participant WriteProbe
  TrialScript->>P50Stub: start local stub
  TrialScript->>PinnedCLI: run task with selected scrub setting
  PinnedCLI->>P50Stub: request streamed tool call
  PinnedCLI->>WriteProbe: attempt external writes and control write
  PinnedCLI->>P50Stub: submit tool result
  TrialScript->>TrialScript: record CLI, stub, and write outcomes

Possibly related issues

combsmith/software-factory#287 — The trial reports how the subprocess scrub setting relates to writes outside the work directory.
combsmith/software-factory#314 — The trial supplies evidence on the scrub and sandbox-write conflict described by this issue.
combsmith/software-factory#194 — The design update retains the gate that withholds shell and network tools until P-26, P-50, and P-51 pass.

Merge Risk: 🔵 Low · up to d2616

Concurrent trial runs can intermittently fail the test despite cleaning up correctly. Scope the leak assertion to each run’s recorded targets; the remaining merge risk is bounded.

Pre-merge checks: 3 · 2

Failed checks: 2 warnings

Check name	Status	Explanation	Resolution
Linked Issues check		Issue `#312` requires both Task orders and scrub settings unset, 0, and 1. The script and reported fixture cover those cases, record four write targets, update the design, and define the pre-run pass co…	Add write probes for the CLI configuration directory and a path under the runner workspace. Record each probe exit code and external post-run presence result. Run both orders with all three scrub settings, then update the fixture and design…
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 15 functions across 3 files. (2 skipped: 2…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 3 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly identifies the P-51 trial and states its main finding: writes outside the work directory landed when the subprocess scrub was enabled.
Out of Scope Changes check		The changed script, trial rules, design entries, stand-in tests, fixture-analysis test, and P-51 mutants all support the `#312` trial, its recorded result, or its regression checks. The available change…

Full details: Out of Scope Changes check

Explanation

The changed script, trial rules, design entries, stand-in tests, fixture-analysis test, and P-51 mutants all support the #312 trial, its recorded result, or its regression checks. The available change summary shows no unrelated change.

Full details: Linked Issues check

Explanation

Issue #312 requires both Task orders and scrub settings unset, 0, and 1. The script and reported fixture cover those cases, record four write targets, update the design, and define the pre-run pass condition. The script does not test the CLI configuration directory or a path under the runner workspace, although #312 explicitly requires both targets. The reported parent path is under the runner temporary directory, not the runner workspace.

Resolution

Add write probes for the CLI configuration directory and a path under the runner workspace. Record each probe exit code and external post-run presence result. Run both orders with all three scrub settings, then update the fixture and design results.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 15 functions across 3 files. (2 skipped: 2 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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Inline comments:
Review comments at @tests/test_tools.py:
- Line 4803: Update the P-51 test’s `/tmp` leak check so it checks only targets
recorded by that test’s configurations, rather than comparing shared `/tmp`
snapshots. Append each configuration’s targets to the test’s recorded-targets
file, then retain the stand-in folder through the concurrent test results and
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docs/architecture/software-factory-design.md
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…t of /tmp that other runs share CodeRabbit's finding: the mutation check runs copies of the suite at once, so a file another run left in /tmp could fail this test, or hide a leak. The stand-in CLI records each target the probe was given, and the test checks those, twelve to a run, and nothing else. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

sonarqubecloud · 2026-10-22T13:44:16Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

don-petry and others added 13 commits October 21, 2026 22:24

Merge origin/main into trials/p-50-linux-sandbox

ed9942a

P-26 landed beside P-50 in tools/mutants.py and tests/test_tools.py; both are kept. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Decision 0044's new row names issue 287 by its title, and trials/AGEN…

e2d4daa

…TS.md keeps its lines short Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Merge origin/main into trials/p-50-linux-sandbox

901a30e

P-47's design row and batch entry landed where P-50's did; both are kept. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Merge trials/p-50-linux-sandbox into trials/p-51-sandbox-writes

c0958c1

P-50's last fix, the stub's check refusing __special__ attributes. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Merge origin/main into trials/p-51-sandbox-writes

d261665

P-50 landed on main as #313; P-51's lines are kept beside it. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

don-petry requested a review from a team as a code owner October 22, 2026 13:23

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don-petry added this pull request to the merge queue Oct 22, 2026

Merged via the queue into main with commit 7573702 Oct 22, 2026
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don-petry deleted the trials/p-51-sandbox-writes branch October 22, 2026 14:27

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Trial P-51 (fail): with the subprocess scrub on, the pinned CLI's sandbox lets every write outside the work directory land - #316

Trial P-51 (fail): with the subprocess scrub on, the pinned CLI's sandbox lets every write outside the work directory land#316
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Trial P-51: fail

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