diff --git a/modules/actions/jobparser/interpeter.go b/modules/actions/jobparser/interpeter.go
index 76a3b06d9c4..90201ac2a1f 100644
--- a/modules/actions/jobparser/interpeter.go
+++ b/modules/actions/jobparser/interpeter.go
@@ -34,7 +34,11 @@ func NewInterpeter(
 		JobID: jobID,
 	}
 
-	// Add the current job to the workflow so run.Job() doesn't return nil
+	// run.Workflow is allocated above and never shared: each call to NewInterpeter
+	// creates its own *model.Run. Writing job into the fresh Jobs map here is
+	// therefore safe even when NewInterpeter is called concurrently for different
+	// matrix combinations of the same job. The job pointer itself is only read
+	// (for Strategy and Needs()), never written through.
 	run.Workflow.Jobs[jobID] = job
 
 	for id, result := range results {
diff --git a/services/actions/job_emitter.go b/services/actions/job_emitter.go
index 6c2b7e27c9a..ad592c11937 100644
--- a/services/actions/job_emitter.go
+++ b/services/actions/job_emitter.go
@@ -412,7 +412,7 @@ func (r *jobStatusResolver) resolve(ctx context.Context) map[int64]actions_model
 		// more to do here — just move to the next job.
 		if len(newMatrixJobs) > 0 {
 			resolveMetrics.matrixReevaluated++
-			log.Info("Matrix re-evaluation succeeded for job %d (JobID: %s): created %d new jobs (duration: %dms)",
+			log.Debug("Matrix re-evaluation succeeded for job %d (JobID: %s): created %d new jobs (duration: %dms)",
 				id, actionRunJob.JobID, len(newMatrixJobs), duration)
 			continue
 		}
diff --git a/services/actions/matrix.go b/services/actions/matrix.go
index cdba5f83752..cc2fe3f9f6e 100644
--- a/services/actions/matrix.go
+++ b/services/actions/matrix.go
@@ -344,7 +344,7 @@ func ReEvaluateMatrixForJobWithNeeds(ctx context.Context, job *actions_model.Act
 		return nil, nil
 	}
 
-	log.Info("Matrix re-evaluation complete for job %d (JobID: %s): created %d new jobs",
+	log.Debug("Matrix re-evaluation complete for job %d (JobID: %s): created %d new jobs",
 		job.ID, job.JobID, len(newJobs))
 
 	return newJobs, nil
diff --git a/services/actions/matrix_test.go b/services/actions/matrix_test.go
index 5d8c9a7fc29..1eb48a331d1 100644
--- a/services/actions/matrix_test.go
+++ b/services/actions/matrix_test.go
@@ -6,7 +6,11 @@ package actions
 import (
 	"testing"
 
+	actions_model "code.gitea.io/gitea/models/actions"
+
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.yaml.in/yaml/v4"
 )
 
 func TestHasMatrixWithNeeds(t *testing.T) {
@@ -67,6 +71,15 @@ fail-fast: false
 `,
 			want: false,
 		},
+		{
+			name: "multi-dimension dynamic matrix",
+			strategy: `
+matrix:
+  os: [ubuntu-latest, windows-latest]
+  version: ${{ fromJson(needs.setup.outputs.versions) }}
+`,
+			want: true,
+		},
 	}
 
 	for _, tt := range tests {
@@ -75,3 +88,101 @@ fail-fast: false
 		})
 	}
 }
+
+func TestMergeNeedsIntoVars(t *testing.T) {
+	base := map[string]string{"MY_VAR": "hello"}
+	needs := map[string]*TaskNeed{
+		"setup": {
+			Result:  actions_model.StatusSuccess,
+			Outputs: map[string]string{"versions": `["1","2"]`, "extra": "val"},
+		},
+	}
+	merged := mergeNeedsIntoVars(base, needs)
+
+	assert.Equal(t, "hello", merged["MY_VAR"])
+	assert.Equal(t, `["1","2"]`, merged["needs.setup.outputs.versions"])
+	assert.Equal(t, "val", merged["needs.setup.outputs.extra"])
+	// base must not be mutated
+	assert.NotContains(t, base, "needs.setup.outputs.versions")
+}
+
+func TestConstructWorkflowWithNeeds(t *testing.T) {
+	// Minimal WorkflowPayload with a strategy referencing a needs output.
+	payload, err := yaml.Marshal(map[string]any{
+		"jobs": map[string]any{
+			"build": map[string]any{
+				"runs-on": "ubuntu-latest",
+				"strategy": map[string]any{
+					"matrix": map[string]any{
+						"version": `${{ fromJson(needs.setup.outputs.versions) }}`,
+					},
+				},
+				"steps": []any{},
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	job := &actions_model.ActionRunJob{
+		JobID:           "build",
+		WorkflowPayload: payload,
+		RawStrategy: `
+matrix:
+  version: ${{ fromJson(needs.setup.outputs.versions) }}
+`,
+		Needs: []string{"setup"},
+	}
+	needs := map[string]*TaskNeed{
+		"setup": {
+			Result:  actions_model.StatusSuccess,
+			Outputs: map[string]string{"versions": `["1.20","1.21"]`},
+		},
+	}
+
+	out, err := constructWorkflowWithNeeds(job, needs)
+	require.NoError(t, err)
+
+	// The resulting YAML should contain both the build job and a stub for setup.
+	var wf map[string]any
+	require.NoError(t, yaml.Unmarshal(out, &wf))
+
+	jobs, ok := wf["jobs"].(map[string]any)
+	require.True(t, ok)
+	assert.Contains(t, jobs, "build")
+	assert.Contains(t, jobs, "setup", "stub for needs dependency must be present")
+
+	// build job needs must list the dependency
+	buildJob, ok := jobs["build"].(map[string]any)
+	require.True(t, ok)
+	assert.Contains(t, buildJob, "needs")
+
+	// RawStrategy must be re-injected (not the pre-baked array form)
+	strategy, ok := buildJob["strategy"].(map[string]any)
+	require.True(t, ok)
+	matrix, ok := strategy["matrix"].(map[string]any)
+	require.True(t, ok)
+	versionExpr, ok := matrix["version"].(string)
+	require.True(t, ok)
+	assert.Contains(t, versionExpr, "fromJson")
+}
+
+func TestConstructWorkflowWithNeeds_InvalidPayload(t *testing.T) {
+	job := &actions_model.ActionRunJob{
+		JobID:           "build",
+		WorkflowPayload: []byte("not: valid: yaml: ["),
+	}
+	_, err := constructWorkflowWithNeeds(job, nil)
+	assert.Error(t, err)
+}
+
+func TestConstructWorkflowWithNeeds_MissingJobsSection(t *testing.T) {
+	payload, err := yaml.Marshal(map[string]any{"name": "test"})
+	require.NoError(t, err)
+
+	job := &actions_model.ActionRunJob{
+		JobID:           "build",
+		WorkflowPayload: payload,
+	}
+	_, err = constructWorkflowWithNeeds(job, nil)
+	assert.Error(t, err)
+}