fix(test): keep fixture stubs ahead of the host PATH

[toasterbook88]

Keep fixture stubs ahead of the host PATH (Hardware Validation is red on main)

Three test fixtures added in #489 replace their child-process PATH with
stubdir:/usr/bin:/bin. The scripts under test call real tools (awk for
the nvidia-smi bundle parse and the classifier/observation checks), and on
profile-based Linux runners those tools live only in the system profile —
not under /usr/bin//bin. Result: the last Hardware Validation pushes
are red with sh: line 1: awk: command not found while the same tests
pass on conventional hosts and locally (run/job refs: 37250216353,
37250828528, jobs 111576154161, 111577904135). Full root-cause comment is
on the source PR (#489).

Change

• cmd/axis/model_mlx_test.go and cmd/axis/model_observation_test.go keep
  the stub directory first and append the inherited PATH after it, built
  with a single sep := string(os.PathListSeparator); HOME= handling is
  unchanged. Fixture stubs keep shadowing real binaries.
• internal/facts/remote_bundle_gpu_test.go replaces the manual
  append(os.Environ(), "PATH=…") with the package's existing
  withSandboxedPATH(dir) helper, which already orders stubs first and
  appends profile fallbacks. No new PATH implementation is introduced.

Validation run

• go vet ./cmd/axis ./internal/facts clean.
• Focused suites green:
  go test ./cmd/axis -run 'TestShellStopMLX|TestLlamaServerSample' and
  go test ./internal/facts -run 'TestRemoteBundleKeeps|TestResidentModels'.
• A batched TestModelEvict* run (TestModelEvictDefaultsToLiveSnapshot,
  TestModelEvictLiveFalseUsesDaemonCache, TestModelEvictByGPUIndex,
  TestModelResumeByReceiptID,
  TestModelResumeUnitNameUsesSnapshotSupervisorAndPort) first hit
  event-flush 5-second timeouts during a heavy-load window (workstation
  load average 116–160). A later batch re-run of the same five tests
  passed on this tree, and the same batched set passed on a pristine
  main-tip tree. No controlled load A/B was performed, so the timeouts
  are load-correlated with causality unproven; no test code was changed.
• No workflow file is touched: the workflow's Install runner dependencies
  step already places the profile directory on PATH, and the hermetic-test
  harness leaves PATH to the caller.
• This branch needs one Hardware Validation run on itself to confirm the
  self-hosted lane goes green with the fixture fix in place; local focused
  runs alone do not satisfy that.

Notes

• Test-only change; no product code touched (3 files, +14/−3).
• Merging this before the next release tag keeps the hardware lane quiet.

[toasterbook88]

AXIS Grok gate

Verdict: PASS-WITH-RISK
PR: #493 fix(test): keep fixture stubs ahead of the host PATH
Head: e1f74d4
URL: #493
Event: COMMENT only. No APPROVE.

Files (3, +14/−3, test-only):

• cmd/axis/model_mlx_test.go
• cmd/axis/model_observation_test.go
• internal/facts/remote_bundle_gpu_test.go

Invariant hits: none on the product plane. No fact-plane write, no confirm/dispatch lock, no cache badge change, no secret_read / ssh_bypass / fleet_exec / spawn_subagent / self-authorize / unattended config write. Advisory self-model unchanged. Charter hops still 0.

What the diff does: the three #489 fixtures stopped replacing PATH with stubdir:/usr/bin:/bin. cmd/axis now sets PATH to stubdir + os.PathListSeparator + os.Getenv("PATH") (HOME= unchanged in the observation helper). facts reuses withSandboxedPATH, which already puts the stub dir first, then inherited PATH, then /run/current-system/sw/bin:/usr/bin:/bin, and appends that PATH last so Go's last-duplicate-wins replaces the host PATH entry. Stubs still shadow same-named binaries.

CI at review (2026-10-05T19:47Z): Test & Build queued (run 37365694832), govulncheck queued (run 37365694620), Analyze (actions) queued (run 37365692278), auto-merge skipped. Combined status success is only Devin Review skipped (trial expired). Hardware Validation is not on this head: .github/workflows/hardware-validation.yml is workflow_dispatch + cron only, no pull_request trigger. The cited red runs (37250216353, 37250828528) are not re-run by this PR.

Residuals:

• The lane this claims to fix cannot go green on the PR itself. Confirm with a workflow_dispatch of Hardware Validation on this SHA, or accept that the next main push is the receipt.
• cmd/axis helpers inherit PATH but do not append the Nix profile fallback that withSandboxedPATH adds. They work only if the runner job PATH already contains awk. Empty or Ubuntu-shaped PATH still misses it.
• Inheriting the host PATH is less hermetic: unstubbed names resolve to host binaries. Named stubs stay first, so that is the intended tradeoff, not a product change.
• Author is cranium-agent (agent@local). Diff matches the stated root cause; local focused runs in the body are not a Hardware Validation receipt. Evict timeout note is load-correlated and not a code change.

Operator action: do not treat this as a merge receipt for the red hardware lane. Wait for Test & Build, or dispatch Hardware Validation on e1f74d4. No APPROVE from this gate.

[Copilot]

Note

Copilot was unable to run its full agentic suite in this review.

Copilot review overview

Review effort: Lite
Findings: 2 · 1

Open (3)

• Same issue as in runSampleShell: relying solely on the inherited PATH removes the previous… · New
• This change drops the previous explicit /usr/bin:/bin fallback and relies entirely on the parent… · New
• PATH-construction logic is now duplicated across multiple Axis tests (and differs from… · New

What changed in this PR

Adjusts test command environments to use a more robust PATH setup so fixtures (stubs) remain first while still working on profile-based runners (e.g., NixOS).

Changes:

• Switched one GPU bundle test to a shared sandboxed PATH helper.
• Updated Axis CLI tests to prepend fixture dirs while inheriting the host PATH for utilities like awk/base64.

File	Description
internal/​facts/​remote_bundle_gpu_test.go	Replaces hand-built PATH env with package helper for consistent sandbox behavior across runners.
cmd/​axis/​model_observation_test.go	Updates shell runner PATH to include inherited host PATH while keeping fixture stubs first.
cmd/​axis/​model_mlx_test.go	Same PATH inheritance approach for mlx test harness, keeping stubs first.

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