fix: inherit the foreach parent's env scope in body steps - #3657

Inherit the parent step's env scope in foreach body steps

Fixes #3327

Problem

A foreach body step does not see environment values visible to the foreach step itself: output variables published by its predecessors (output: NAME) and the step's own env:. Only DAG-level env and params are visible in the body.

contextWithItemScope stores the parent's env (including its scope) in the context via WithEnv, but body steps build their env through newEnv, which reads rCtx.EnvScope from the DAG context. That scope is still the DAG-level one, so the parent's step env and predecessor output variables are dropped. The foreach payload itself is carried separately and is unaffected.

Change

contextWithItemScope now also copies the parent step's scope into the DAG context before the body runner starts. Body steps therefore resolve the same env and output variables as the parent, while the DAG-level scope is still inherited through the scope chain.

The foreach entry itself is deliberately not copied into the DAG context scope: it is already provided through WithEnv, and exposing it there would resolve bare $foreach references in body text, which spec 003 requires to be preserved (covered by the existing TestForeachUnbracedBody).

The PR has two commits: the first adds the regression test (fails on main), the second contains the fix.

Tests

• New TestForeachRuntimeBodyInheritsParentEnvAndPredecessorOutputs: a predecessor publishes GREETING, the foreach step declares REGION, and a body step references both. On main the body leaves ${GREETING}|${env.REGION} unresolved; with the fix it resolves to hello|eu.
• go test ./internal/runtime/ -run TestForeach and go test ./internal/runtime/builtin/foreach/ pass, including TestForeachUnbracedBody and the structured item-scope cases.
• gofmt and go vet clean on the changed packages.

Summary by cubic

Fixes foreach body steps not seeing environment values available to the foreach step itself, such as its env: and predecessors' output: variables (#3327). Body steps now resolve the same env and output variables as the parent step, without Dagu-set per-step values, trace context, or leakage into child runs.

• Carries the foreach step's env and output entries to body steps via Env, leaving the DAG context scope untouched.
• Leaves out Dagu-set per-step values and trace context so each body step keeps its own; a child run started from a body step does not inherit the foreach step's values.
• Leaves the foreach entry out so bare $foreach references in body text stay unresolved as the spec requires (covered by TestForeachUnbracedBody).
• Documents the behavior in Spec 018, noting that passing these values to a child run requires pass_env.
• Adds tests for parent env and predecessor output inheritance (fails on main), trace context isolation, and child run env.

^{Written for commit 3f3e440. Summary will update on new commits.}

Summary by CodeRabbit

• Bug Fixes
  • Corrected environment handling in foreach workflows so body steps can access environment values configured on the foreach step alongside outputs from predecessor steps. Foreach item data remains available within the body. This helps ensure body steps receive the expected context when running with inherited settings and dependencies.