ci(qa): serialise runs sharing the integration test project

[ajimae]

Why

Every Qa run points at one commercetools project, and the integration suites seed and clear fixtures in it. Nothing serialised those runs.

This was latent while cleanup was broken. Once #63 made teardown reliable, one run's clear step began reliably wiping fixtures another run was mid-way through asserting on — the inverse of the old duplicate-key failures.

Observed directly on main when the #63 and #64 merges landed 41 seconds apart:

Run	Trigger	Result
36021926028	#63 merge	all jobs green
36022011913	#64 merge	3 failed / 808 passed

● Resource Deleter › should delete resource › carts deleted
    // Check that resource exists
    expect(payload.body.results.length).toBeGreaterThanOrEqual(1);
    Expected: >= 1
    Received:    0

The fixture was seeded, then deleted by the other run before the assertion.

The change

concurrency:
  group: qa-integration
  cancel-in-progress: false

Two deliberate choices:

• Constant group, not keyed on github.ref. The usual ${{ github.workflow }}-${{ github.ref }} only dedupes within a branch. The contended resource here is the shared project, not the branch, so runs must serialise across all branches and PRs.
• cancel-in-progress: false. Cancelling is the default reflex, but a run killed mid-suite skips teardown and leaks fixtures into the project — exactly the failure this is meant to prevent.

max-parallel: 1 is already set on the regression matrix, so intra-run serialisation was never the gap. Cross-run was.

Trade-off worth knowing

Qa runs now queue globally instead of running in parallel, so concurrent PRs will wait on each other. With one shared project that is unavoidable without provisioning per-run projects.

Also note GitHub keeps only one pending run per concurrency group — if three runs queue, the middle one is cancelled. That is a real rough edge. It is much better than the current state, and #63's clear-before-seed means a cancelled run no longer poisons the project permanently, but it is not free. The durable fix is a dedicated project per run.

Verification

Workflow YAML parses; concurrency resolves to {"group":"qa-integration","cancel-in-progress":false} and all five jobs are intact.

Concurrency behaviour cannot be exercised from a single PR run — it only shows up when runs overlap.

🤖 Generated with Claude Code

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