ADR-005: CI variable surface

docs/decisions/adr-005-ci-variable-surface.md

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+# ADR-005: CI variable surface
+
+**Date:** 2026-08-18
+**Status:** Accepted
+**Review-order:** 5 of 10 (references ADR-001)
+
+**Context:** ddev-module-developer reads `SKIP_*` and `_*_ALLOW_FAILURE` from
+`.gitlab-ci.yml`. ddev-drupal-code-quality does not. The merge proposal
+originally gated this on a project-type mode; ADR-001 replaces mode gating with
+presence detection.
+
+## Decision
+
+Adopt `SKIP_*` and `_*_ALLOW_FAILURE` wholesale. Per-tool variables take
+precedence over `_ALL_VALIDATE_ALLOW_FAILURE`.
+
+Variables are honoured when the project's `.gitlab-ci.yml` contains Drupal
+template variables (presence-detected). When no `.gitlab-ci.yml` exists or it
+has no Drupal template references, the variables are ignored.
+
+## Rationale
+
+For contrib projects these are the sanctioned control surface.
+ddev-module-developer's implementation already handles per-tool precedence over
+the blanket allow-failure flag correctly; we adopt that behavior as-is.
+
+Presence detection replaces mode gating because a site project's
+`.gitlab-ci.yml` may exist for an entirely unrelated deploy pipeline with no
+Drupal template anywhere in it. Silently honouring `SKIP_PHPCS` from a file the
+team does not think of as controlling local checks would mean checks quietly
+disabled. Checking for Drupal template variable patterns avoids this false
+positive.
+
+## Consequences
+
+- Projects with a Drupal-template `.gitlab-ci.yml` get CI variable support
+  automatically. No opt-in needed.
+- Site projects with non-Drupal CI pipelines are unaffected.
+- The detection heuristic (what counts as "Drupal template variables present")
+  must be defined precisely during implementation. False negatives are safer than
+  false positives: failing to read a variable means tools run unconditionally,
+  which is the 1.x behavior.