feat(harnesses): shared-variables/v1 context + workflow-script/v1 composite (WF-COMP-31, WV-19) (03878b12-86b5-4b88-86d5-7182ae1c471f)

harnesses/contexts/shared-variables/v1/harness.yaml

@@ -0,0 +1,20 @@
+kind: context
+name: shared-variables
+version: 1
+description: "Workflow variables filesystem contract — /variables/ layout, key naming, helpers and CLI for CP-held step inputs/outputs (spec/workflow-variables.md WV-19; injected per-task via HD-14 extra_layers)"
+requires: []
+provides: [shared-variables]
+
+# WV-20: both env vars are set by THIS harness layer (not the entrypoint, not
+# the container backend). WORKFLOW_VARIABLES_ROOT is static; WORKFLOW_VARIABLES_SELF
+# is templated by the composer at harness-composition time on the dispatcher,
+# substituting the node's resolved step_path (the SAME value WV-15 derives at mint
+# time). A task with no shared-variables/v1 layer (unstamped) has neither env var
+# set, and /variables does not exist for it at all.
+env:
+  WORKFLOW_VARIABLES_ROOT: /variables
+  WORKFLOW_VARIABLES_SELF: "{{ step_path }}"
+
+context_files:
+  - source: ./CLAUDE.md
+    target: /opt/harness/context/shared-variables/CLAUDE.md