brew: escalate writes to the prefix owner so the agent converges deps itself - #171
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… itself Homebrew assumes exactly one non-root owner of exactly one prefix, so on cooperative shared machines (plans#26) the sandboxed agent user cannot install formulae — the machine-level root cause of the plans#36 leg-2 googletest incident (brew wwise-cli EPERM). Rejected alternatives: per-user prefix (no bottles off the default prefix on Apple Silicon → source builds), host-level provisioning (a human in the loop for every new formula), group-writable prefix (fragments brew's single-owner ownership metadata). Precedent: snappy's build image already routes brew through a dedicated linuxbrew user — same pattern, designated owner. - BrewIntegration prepends sudo -n -u <prefix-owner> to brew writes (tap, install) when the prefix is not writable by the current user. The owner is stat'd at runtime — never hardcoded — and a writable prefix short-circuits to plain brew: single-user machines unchanged. A sudo -n refusal names the missing edge and its remediation. - AgentBootstrap's sudoers drop-in gains the brew edge: the agent may run exactly brew as the prefix owner, NOPASSWD. Stat'd at bootstrap, re-converged by re-running register, omitted when the host has no brew or the agent owns the prefix itself. Co-authored-by: Cursor <cursoragent@cursor.com>
Codecov Report✅ All modified and coverable lines are covered by tests. 📢 Thoughts on this report? Let us know! |
srb tc rejects splatting a dynamically-sized array into system() (error 7019); route the escalation argv through T.unsafe like run_brew_install already does. Cover the changed lines codecov flagged: URL-less tap registration (with and without escalation, asserting the remediation hint only appears when escalated) and brew --prefix discovery (memoized success and ENOENT-absent brew). Co-authored-by: Cursor <cursoragent@cursor.com>
JPDuchesne
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Sep 16, 2026
Agent-isolation and emulated-Mac fixes: install-deps failure isolation with typed errors (#170), brew escalation to the prefix owner + AgentBootstrap sudoers edge (#171), BuildKit secret files in a verified per-uid dir under the data root — colima-visible and substitution-proof (#173), build-watcher guest-load liveness signal + 15m stall window (#174), sigpending ulimit for Rosetta signal-queue aborts (#175), and brew trust before tap in docker-install-build-deps (tap-rot fix).
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Stacked on #170.
Homebrew assumes exactly one non-root owner of exactly one prefix, so on cooperative shared machines (d3mlabs/plans#26) the sandboxed agent user cannot install formulae — the machine-level root cause of the plans#36 leg-2 googletest incident (
brew wwise-cliEPERM abortinginstall-deps).Rejected alternatives: per-user prefix (no bottles off the default prefix on Apple Silicon → source builds), host-level provisioning (human in the loop for every new formula), group-writable prefix (fragments brew's single-owner ownership metadata; unsupported by brew). Precedent: snappy's build image already routes brew through a dedicated
linuxbrewuser because brew refuses root — same pattern, designated owner.BrewIntegrationprependssudo -n -u <prefix-owner>to brew writes (tap,install) when the prefix is not writable by the current user. Owner stat'd at runtime, never hardcoded; a writable prefix short-circuits to plainbrew(single-user machines unchanged).sudo -nrefusal surfaces "rundev runner registerto re-converge" instead of a cryptic brew failure; escalated tap failures hint at local-tap path readability.AgentBootstrap#sudoers_contentgains the brew edge: agent may run exactly the brew binary as the prefix owner, NOPASSWD. Prefix/owner stat'd at bootstrap time; re-running register re-converges; omitted when the host has no brew or the agent already owns the prefix.Test-first: all 7 new tests written and confirmed failing before the implementation. Full suite green except the 4 pre-existing
BuildContainerTestfailures (also fail on cleanmainon this machine).End-to-end verification on this machine (after merge): re-run
dev runner register, thendev install-depsasai-agentin the snappy workspace — the previously failingwwise-cliinstall should succeed unattended.Made with Cursor