[OriginWeave] Canonicalize sandbox-enabled MV3 browser workflow and thin caller #1792

Owner-path defect

OriginWeave's governed-browser source and repository contracts now require real pinned Chromium execution with sandboxing enabled, but the current repository-local workflow authority is inconsistent with that contract and product PRs are not authorized to repair .github/** themselves.

Fresh exact evidence:

• OriginWeave protected main: c789b802fc98a8d7fd8c09d9327f36828054d2a1.
• OriginWeave Refresh governance audit after clearfolio rollout #43 exact head: e5db34c57d7b1de61d613a196117ca2cce296bec, Draft, reconstructed non-destructively so its .github/workflows/mv3-compatibility.yml is byte-for-byte protected-main rather than a leaf-owned workflow mutation.
• tests/test_mv3_compatibility_contract.py::test_workflow_installs_chromium_sandbox_helper requires the pinned Chrome for Testing helper to be root-owned, mode 4755, and exposed through CHROME_DEVEL_SANDBOX.
• Protected-main/current-#43 .github/workflows/mv3-compatibility.yml downloads/extracts Chrome for Testing 150.0.7871.129 and chmods only chrome/chromedriver; it does not install/configure chrome_sandbox and does not export CHROME_DEVEL_SANDBOX.
• The product runner intentionally no longer passes --no-sandbox.
• Formal OriginWeave reviews: Refresh governance audit after clearfolio rollout #43 5100544074; ⚡ Bolt: [performance improvement] PR 리뷰 스케줄러 동기 호출 병목 개선 #70 5100592088; Repair fragile OpenCode approval reasons from evidence #245 5100581535. OriginWeave issue Fix Strix protobuf dependency lock #212 is the leaf-side dependency ledger.
• Current Refresh governance audit after clearfolio rollout #43 MV3 run 33740544442, job 100601170874, and ⚡ Bolt: [performance improvement] PR 리뷰 스케줄러 동기 호출 병목 개선 #70 MV3 run 33738452556, job 100594512852, remain queued with steps=[], runner_id=0, no assigned runner/group. Runner acquisition is tracked separately by ops: diagnose and bound organization GitHub Actions queue starvation #712/Actions queue saturation: 120 open PRs + self-amplifying scheduler block all org merges (pg-erd-cloud: 0 merges since 2026-08-20) #1531; do not conflate capacity with the workflow-source defect.

Historical exact-head #43 evidence proved the pinned archive contains a usable chrome_sandbox and that root:root + mode 4755 + CHROME_DEVEL_SANDBOX completed repeated real Chromium MV3 passes. That predecessor execution is technical feasibility evidence only; it is not current-head GREEN or current workflow authorization.

Chromium's current Ubuntu developer-build guidance warns that --no-sandbox disables critical security features and should never be used for open-web browsing. Chromium's SUID sandbox guidance shows the raw-build helper shape (chown root:root, chmod 4755, CHROME_DEVEL_SANDBOX), while current Ubuntu 23.10+ guidance also permits a narrowly reviewed AppArmor/user-namespace configuration. Therefore the central design may use the setuid helper or a demonstrably equivalent sandbox-capable mechanism, but it must not weaken sandboxing.

Required central architecture

Create or extend a canonical reusable workflow in ContextualWisdomLab/.github for OriginWeave's pinned Chromium/MV3 evidence, with an exact-SHA thin caller in OriginWeave. Do not copy product-domain browser policy into .github; central ownership is limited to trusted workflow/toolchain/evidence mechanics.

The reusable workflow should own at minimum:

1. immutable Chrome for Testing / ChromeDriver identity and checksum verification;
2. a sandbox-capable Ubuntu execution setup that preserves Chromium sandboxing without --no-sandbox or global disabling of Ubuntu's user-namespace security;
3. least-privilege permissions, no provider/model credentials, bounded network behavior, deterministic artifact retention, and exact caller-head binding;
4. execution of OriginWeave-owned runner entry points rather than copying browser-domain logic into the central repository;
5. typed distinction between runner unavailable, browser startup/sandbox failure, product-contract failure, cancellation, and successful current-head evidence;
6. immutable action pins and workflow-contract tests protecting the helper/setup and caller SHA;
7. enough inputs to support the existing downloads/compatibility Agent Task lane and the Repair fragile OpenCode approval reasons from evidence #245 Web Audio privacy evidence without creating independent workflow authorities for each product feature.

RED acceptance

On the current protected-main workflow shape, a deterministic contract must demonstrate that sandbox-preserving OriginWeave browser execution requires setup not supplied by the workflow. A queued/unassigned job is incomplete evidence and does not substitute for this source-level RED.

Also retain a fixture proving that --no-sandbox, empty/disabled sandbox configuration, missing helper/AppArmor allowance, wrong Chrome/ChromeDriver identity, or an unverified caller revision cannot become successful browser-security evidence.

GREEN acceptance

• The central reusable workflow is protected-main integrated through normal review/check policy.
• OriginWeave consumes it through a thin exact-SHA caller with no duplicated provider/model/browser-policy authority.
• Refresh governance audit after clearfolio rollout #43 and ⚡ Bolt: [performance improvement] PR 리뷰 스케줄러 동기 호출 병목 개선 #70 non-destructively adopt the canonical caller and execute real pinned Chromium with sandboxing enabled on their unchanged product heads or reviewed successors.
• Refresh governance audit after clearfolio rollout #43 downloads evidence still proves repeated initial+restart behavior and cleanup; ⚡ Bolt: [performance improvement] PR 리뷰 스케줄러 동기 호출 병목 개선 #70 still proves semantic observation → native input/click → post-condition → exact echo/URL invariant → cleanup rather than command ACK alone.
• Repair fragile OpenCode approval reasons from evidence #245's Web Audio product delta is preserved and its evidence is integrated through the same governed workflow owner or a justified reusable sub-lane; its current leaf workflow mutation is not treated as permanent authority.
• Repository contracts, current-head CI/coverage/rustdoc where applicable, SAST/Security, artifact/provenance evidence and live governance gates are terminal and exact-head bound.

Non-goals

• Restoring --no-sandbox.
• Globally disabling Ubuntu AppArmor user-namespace restrictions.
• Moving OriginWeave browser policy/domain truth into .github.
• Treating runner queue starvation as workflow GREEN.
• Self-approval, bypass, force-push, gate weakening, or predecessor-check reuse.

Coordinate with .github#712 / .github#1531 for runner/queue control and OriginWeave#212 for leaf adoption. Keep those causal classes separate.