[kixelated]

Problem

Bun 1.4.2 marks quest gate's own piped stdout or stderr O_NONBLOCK. That flag lives on the open file description its command inherits, so the command starts with non-blocking stdio. uv then panics on the first EAGAIN and aborts with no message (astral-sh/uv#22170). Bun 1.4.4 clears the flag before spawning (oven-sh/bun#43868).

A consumer whose flake makes quest's nixpkgs follow its own, newer nixpkgs already gets 1.4.4. A quest built from this flake's own lock still uses 1.4.2.

Change

• package.json: packageManager is now bun@1.4.4. CI's setup-bun steps read it through bun-version-file. There is no engines field, and bun.lock doesn't record the Bun version.
• flake.nix: adds a nixpkgs-bun input and an overlay that takes only bun from it. The packages, the dev shell, quest-pinned and the bun-version check all pick it up. It's locked to nixpkgs-unstable 9d3b8db, which ships Bun 1.4.4.
• test/gate.test.ts: adds a Linux-only regression test. It runs the real CLI's quest gate with stdout and stderr piped, and checks that the gated command's fds 1 and 2 don't have O_NONBLOCK, by reading /proc/self/fdinfo.

Choices made without asking

• Bun only, not a nixpkgs bump. Current nixpkgs (d3b13ad), and also 58deea6 from moq-dev/quest#502, still ship Bun 1.4.2. The rev that ships 1.4.4 also moves opencode from 2.1.1 to 2.2.5. The opencode-client check would then need @opencode/client bumped too, which is the runner's sandboxed opencode path and outside this fix. The flake comment says to drop nixpkgs-bun once nixpkgs reaches 1.4.4. Dependabot's nix group keeps both inputs moving until then, and bun-version still fails if they drift from packageManager.
• A test rather than only a manual repro. The flags are read directly and nothing depends on timing, so the test doesn't flake. It skips off Linux, which has no /proc/self/fdinfo.

Validation

• New test on this branch's Bun 1.4.4: passes. On Bun 1.4.2 (PATH=<bun-1.4.2>/bin:$PATH bun run test test/gate.test.ts -t "piped output blocks"): fails with expected 2048 to be +0, which is O_NONBLOCK on fd 1.
• Manual repro: spawn bun src/cli/bin.ts gate -- grep -h ^flags: /proc/self/fdinfo/1 /proc/self/fdinfo/2 with stdout and stderr piped. I ran it from both Node and Bun parents, with and without QUEST_GATE_ADMITTED.
  • Bun 1.4.2: 04002 / 02 in every case.
  • Bun 1.4.4: 02 / 02 in every case.
• just check: pass. just test: pass (29 files; 1089 passed, 5 skipped; shell hook, install and installer suites passed).
• nix flake check: all checks passed, including bun-version, opencode-client, package and quest-tree.
• nix build .#default: the bundle's shebang is …-bun-1.4.4/bin/bun --no-env-file. nixpkgs-bun gives Bun 1.4.4 on all three flake systems.
• Conflicts: none with moq-dev/quest#500 (not touched), moq-dev/quest#502 or moq-dev/quest#499. I checked each with git merge-tree.

Downstream runner

A self-hosted land runner that builds quest from its own pinned rev of this flake still runs quest on Bun 1.4.2. I checked that read-only, from the shebang of its installed bundle. This PR doesn't reach it until that pin is bumped past this change, which is the runner owner's job. I didn't change the runner.

Suggested follow-ups

• Bump the downstream runner's quest pin once this lands.
• Remove nixpkgs-bun with the next nixpkgs bump that brings Bun 1.4.4 and its matching opencode/@opencode/client update.

Models

Size: S
Implementer: Claude Code, claude-opus-5-5, high effort

Review

Rewritten by quest review after each round.

• Reviewer: Codex, gpt-6.1-sol, medium effort
• Session: 01a1b372-5dc8-7443-80d3-56bae0a47e0a, round 1
• Head: d30c729
• Base: origin/main at a3789c7
• Score: 10/10, The specified diff consistently pins Bun 1.4.4 and its regression scenario passes directly, with no actionable defects found; full checks were blocked by the read-only environment.
• Findings: none

Addressed the online review: removed private-repository links and host-specific details from this description.

🤖 Generated with Claude Code

(Written by Opus 5.5 with high)

[pullfrog]

  ^{｜ Review this ➔}

[kixelated]

Automated review by review (OpenAI)

Reviewed head d30c729 against base a3789c7.

[P2] Remove private-repository references from the public PR description.
Location: PR description, Problem, Change, Land runner, and Suggested follow-ups sections. The description includes private-repository links and host-specific operational details. assets/CONTEXT.md explicitly prohibits private-repository links in public repositories and requires justifying the work on its own merits. Remove those references and operational details, retaining the generic blocking-stdio reproduction, public upstream links, version rationale, and validation. Keep any deployment coordination in its appropriate private destination.

No actionable implementation defect found in the four-file diff. The Bun overlay feeds the package builds, development shell, and version check; the locked upstream package declares Bun 1.4.4 for all three flake systems. The public Bun fix in oven-sh/bun#43868 is included in bun-v1.4.4, and the new test exercises inherited stdout/stderr flags through the real CLI.

Static review only through the GitHub connector. I did not execute code, tests, builds, or Nix evaluation, and have not independently reproduced the reported validation results.

(Written by review (OpenAI))

[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

The flake now uses a separate nixpkgs input for Bun and continues to use the existing nixpkgs input for other packages. The package manager version in package.json is updated to Bun 1.4.4. A Linux-only test checks that a gated command with piped output exits successfully and that stdout and stderr do not have the O_NONBLOCK flag.

Merge Risk: Minimal · up to d30c7

The Nix workflows select Bun 1.4.4. No merge-blocking risk was identified; the separate runner still needs its planned update.

Pre-merge checks: 5

Check name	Status	Explanation
Title check		The title identifies the Bun 1.4.4 update and its blocking stdio objective.
Docstring Coverage		No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…
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 matches the Bun version update, Nix overlay, and Linux regression test.

Full details: Docstring Coverage

Explanation

No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 0 functions across 1 files. (2 skipped: 2 unsupported.)

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Reviewing files that changed from the base of the PR and between a3789c7 and d30c729.

Files ignored due to path filters: 1

• flake.lock is excluded by !**/*.lock

Files selected for processing: 3

• flake.nix
• package.json
• test/gate.test.ts

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