fix: Missing job-index and job-total attributes in strategy context

[majiayu000]

Summary

This PR fixes #5976

Changes

• Added MatrixIndex and MatrixCount fields to RunContext struct to track the current matrix job index (0-based) and total number of matrix jobs
• Updated newRunContext function signature to accept and initialize these new fields
• Added job-index and job-total attributes to the strategy context in both NewExpressionEvaluatorWithEnv and newStepExpressionEvaluator functions
• These values are now accessible via strategy.job-index and strategy.job-total expressions in workflows, matching GitHub Actions behavior

The implementation follows GitHub Actions specification where:

• job-index: 0-based index of the current job in the matrix (e.g., 0, 1, 2, 3 for 4 jobs)
• job-total: Total number of jobs in the matrix

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Generated with Claude Code

[ChristopherHX]

Thank you for taking a look,

You missed updating composite action runcontext creation

act/pkg/runner/action_composite.go

Lines 47 to 82 in b2aee4b

	func newCompositeRunContext(ctx context.Context, parent *RunContext, step actionStep, actionPath string) *RunContext {
	env := evaluateCompositeInputAndEnv(ctx, parent, step)
	// run with the global config but without secrets
	configCopy := *(parent.Config)
	configCopy.Secrets = nil
	// create a run context for the composite action to run in
	compositerc := &RunContext{
	Name: parent.Name,
	JobName: parent.JobName,
	Run: &model.Run{
	JobID: parent.Run.JobID,
	Workflow: &model.Workflow{
	Name: parent.Run.Workflow.Name,
	Jobs: map[string]*model.Job{
	parent.Run.JobID: {},
	},
	},
	},
	Config: &configCopy,
	StepResults: map[string]*model.StepResult{},
	JobContainer: parent.JobContainer,
	ActionPath: actionPath,
	Env: env,
	GlobalEnv: parent.GlobalEnv,
	Masks: parent.Masks,
	ExtraPath: parent.ExtraPath,
	Parent: parent,
	EventJSON: parent.EventJSON,
	nodeToolFullPath: parent.nodeToolFullPath,
	}
	compositerc.ExprEval = compositerc.NewExpressionEvaluator(ctx)
	return compositerc
	}

We also need tests for both workflow and composite action, so we can ensure this will continue to work in the future.

Tests can be workflows in pkg/runner/testdata//push.yml

use "act -W /push.yml" in pkg/runner/testdata/ to run them manually. I can help adding entries to runner_test.go

---

I would suggest to try writing test workflows yourself, without the help from AI tooling to learn more about act itself.

[majiayu000]

@ChristopherHX Thanks for your review. Added the requested integration tests:

• workflow: pkg/runner/testdata/strategy-job-index/push.yml
• composite action: pkg/runner/testdata/strategy-job-index-composite/{push.yml,composite_action/action.yml}
• wired into pkg/runner/runner_test.go