diff --git a/e2e/harness/act.go b/e2e/harness/act.go
index 8c843f3..4eca800 100644
--- a/e2e/harness/act.go
+++ b/e2e/harness/act.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"strings"
 
 	"github.com/moby/moby/api/types/container"
 	"github.com/moby/moby/api/types/mount"
@@ -123,6 +124,38 @@ func (a *ActRunner) Terminate(ctx context.Context) error {
 	return a.container.Terminate(ctx)
 }
 
+// eventFilePath is the in-container path the event payload is written to when
+// RunOpts.EventJSON is set. act reads it via its -e flag to seed the
+// github.event context (e.g. a merged pull_request payload).
+const eventFilePath = "/tmp/cascade-event.json"
+
+// writeEventFile writes the run's EventJSON payload to eventFilePath inside the
+// act container via CopyToContainer. It is a no-op (returning "" with no error)
+// when EventJSON is empty, so callers can unconditionally invoke it and only
+// append the -e flag when a path comes back. CopyToContainer transfers the raw
+// bytes, so arbitrary JSON (quotes, newlines, shell metacharacters) round-trips
+// intact without heredoc or shell-escaping hazards.
+func (a *ActRunner) writeEventFile(ctx context.Context, eventJSON string) (string, error) {
+	if eventJSON == "" {
+		return "", nil
+	}
+	if err := a.container.CopyToContainer(ctx, []byte(eventJSON), eventFilePath, 0644); err != nil {
+		return "", fmt.Errorf("failed to write event payload: %w", err)
+	}
+	return eventFilePath, nil
+}
+
+// eventFileArgs returns the act flag fragment that points act at the event
+// payload file. eventPath is the path returned by writeEventFile (empty when no
+// EventJSON was supplied), so the result is empty in that case. Kept pure so the
+// command construction is unit-testable without a container.
+func eventFileArgs(eventPath string) []string {
+	if eventPath == "" {
+		return nil
+	}
+	return []string{"-e", eventPath}
+}
+
 // RunWorkflow executes a GitHub Actions workflow using act
 func (a *ActRunner) RunWorkflow(ctx context.Context, opts RunOpts) (*ExtendedWorkflowResult, error) {
 	// Create temp directory for workflow
@@ -158,6 +191,15 @@ func (a *ActRunner) RunWorkflow(ctx context.Context, opts RunOpts) (*ExtendedWor
 		"--network=" + network,
 	}
 
+	// When an event payload is supplied, write it into the container and point
+	// act at it with -e so the github.event context is seeded (e.g. a merged
+	// pull_request payload for the hotfix post-merge path).
+	eventPath, evErr := a.writeEventFile(ctx, opts.EventJSON)
+	if evErr != nil {
+		return nil, evErr
+	}
+	cmd = append(cmd, eventFileArgs(eventPath)...)
+
 	// Add Gitea environment variables
 	if a.giteaURL != "" {
 		cmd = append(cmd, "--env", fmt.Sprintf("GITHUB_SERVER_URL=%s", a.giteaURL))
@@ -229,6 +271,15 @@ func (a *ActRunner) RunWorkflowFromRepo(ctx context.Context, opts RunOpts) (*Ext
 	if a.networkName != "" {
 		network = a.networkName
 	}
+	// When an event payload is supplied, write it into the container so
+	// buildActArgs can append the act -e flag pointing at it. This seeds the
+	// github.event context (e.g. the merged pull_request payload that drives the
+	// hotfix context/build/deploy/finalize jobs).
+	eventPath, err := a.writeEventFile(ctx, opts.EventJSON)
+	if err != nil {
+		return nil, err
+	}
+
 	actCmd := "cd /tmp/repo && act " + opts.Event +
 		" -W " + workflowsPath +
 		" --detect-event" +
@@ -241,7 +292,7 @@ func (a *ActRunner) RunWorkflowFromRepo(ctx context.Context, opts RunOpts) (*Ext
 		// Provide token for Gitea authentication
 		" --secret GITHUB_TOKEN=" + a.giteaToken
 
-	actCmd += a.buildActArgs(opts)
+	actCmd += a.buildActArgs(opts, eventPath)
 
 	cmd := []string{
 		"bash", "-c",
@@ -296,8 +347,10 @@ func normalizeWorkflowResult(result *ExtendedWorkflowResult, workflowPath string
 	}
 }
 
-// buildActArgs builds additional act command arguments
-func (a *ActRunner) buildActArgs(opts RunOpts) string {
+// buildActArgs builds additional act command arguments. eventPath is the
+// in-container event-payload file written by writeEventFile (empty when no
+// EventJSON was supplied); when set it is appended as the act -e flag.
+func (a *ActRunner) buildActArgs(opts RunOpts, eventPath string) string {
 	var args string
 
 	// Add provided env vars
@@ -310,6 +363,11 @@ func (a *ActRunner) buildActArgs(opts RunOpts) string {
 		args += fmt.Sprintf(" --input %s=%s", k, v)
 	}
 
+	// Point act at the event payload file when one was written.
+	if flags := eventFileArgs(eventPath); len(flags) > 0 {
+		args += " " + strings.Join(flags, " ")
+	}
+
 	return args
 }
 
diff --git a/e2e/harness/act_test.go b/e2e/harness/act_test.go
index 4059fb2..d42e829 100644
--- a/e2e/harness/act_test.go
+++ b/e2e/harness/act_test.go
@@ -57,6 +57,89 @@ jobs:
 	assert.Contains(t, result.Logs, "Hello from act")
 }
 
+func TestEventFileArgs(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name      string
+		eventPath string
+		want      []string
+	}{
+		{
+			name:      "no event path yields no flag",
+			eventPath: "",
+			want:      nil,
+		},
+		{
+			name:      "event path yields -e flag",
+			eventPath: eventFilePath,
+			want:      []string{"-e", eventFilePath},
+		},
+		{
+			name:      "custom event path is passed through",
+			eventPath: "/tmp/other-event.json",
+			want:      []string{"-e", "/tmp/other-event.json"},
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			assert.Equal(t, tt.want, eventFileArgs(tt.eventPath))
+		})
+	}
+}
+
+// TestBuildActArgs_EventFlag verifies the act command picks up `-e <file>` when
+// an event payload was written, and omits it otherwise, without requiring a
+// real act run or container.
+func TestBuildActArgs_EventFlag(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name         string
+		opts         RunOpts
+		eventPath    string
+		wantContains []string
+		wantOmits    []string
+	}{
+		{
+			name:         "event payload adds -e flag",
+			opts:         RunOpts{},
+			eventPath:    eventFilePath,
+			wantContains: []string{"-e " + eventFilePath},
+		},
+		{
+			name:      "no event payload omits -e flag",
+			opts:      RunOpts{},
+			eventPath: "",
+			wantOmits: []string{"-e"},
+		},
+		{
+			name:         "event flag coexists with env and inputs",
+			opts:         RunOpts{Env: map[string]string{"FOO": "bar"}, Inputs: map[string]string{"k": "v"}},
+			eventPath:    eventFilePath,
+			wantContains: []string{"-e " + eventFilePath, "--env FOO=bar", "--input k=v"},
+		},
+	}
+
+	a := &ActRunner{}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			args := a.buildActArgs(tt.opts, tt.eventPath)
+			for _, want := range tt.wantContains {
+				assert.Contains(t, args, want)
+			}
+			for _, omit := range tt.wantOmits {
+				assert.NotContains(t, args, omit)
+			}
+		})
+	}
+}
+
 func TestNormalizeWorkflowResult(t *testing.T) {
 	t.Parallel()
 
diff --git a/e2e/harness/harness.go b/e2e/harness/harness.go
index 22e0f10..dda8032 100644
--- a/e2e/harness/harness.go
+++ b/e2e/harness/harness.go
@@ -704,6 +704,14 @@ func (h *Harness) ensureCLIBinary(ctx context.Context) (string, error) {
 // `./` prefix act needs for local resolution. Each pass is checked for
 // success and verified by grepping for any remaining `stablekernel/...` ref;
 // the operation retries on transient failure.
+//
+// The `.github/workflows/*.yaml` glob is intentionally broad: it covers every
+// generated workflow, including cascade-hotfix.yaml (whose plan/apply/finalize
+// jobs reference the same setup-cli action ref). No hotfix-specific localization
+// is required beyond this glob. The companion `name:` namespacing in
+// GenerateWorkflows only appends a per-scenario suffix to the workflow-level
+// `name:` line, so workflow_files assertions over hotfix job/trigger content
+// remain stable as long as they do not assert on the top-level name line.
 func (h *Harness) localizeWorkflows(ctx context.Context) error {
 	const maxAttempts = 3
 	const retryDelay = 200 * time.Millisecond
@@ -766,9 +774,21 @@ func (h *Harness) SyncRepoToActContainer(ctx context.Context) error {
 	// push converged. Re-fetching resolves those; a persistent miss after the
 	// bound is a real lost-commit and is reported with this call site's own
 	// message rather than the generation-phase one.
+	//
+	// After the load-bearing `git fetch origin main && git reset --hard
+	// origin/main` (which still gates the lost-commit detection and bounded
+	// retry below), pull the env/* integration branches and tags too, mirroring
+	// the generated hotfix workflow's fetch step (internal/generate/hotfix.go,
+	// writeFetchEnvBranches). Hotfix plan/apply/finalize jobs inspect
+	// env/<env> branches and hotfix tags, so they must be present in /tmp/repo.
+	// This extra fetch is chained with `|| true`: env/* branches and tags do not
+	// exist in most scenarios, and their absence must never fail the sync or
+	// regress the main-branch convergence guarantee.
 	syncCmd := []string{
 		"bash", "-c",
-		"cd /tmp/repo && git fetch origin main && git reset --hard origin/main && (git branch -f master HEAD 2>/dev/null || true)",
+		"cd /tmp/repo && git fetch origin main && git reset --hard origin/main && " +
+			"(git fetch origin '+refs/heads/env/*:refs/remotes/origin/env/*' --tags 2>/dev/null || true) && " +
+			"(git branch -f master HEAD 2>/dev/null || true)",
 	}
 
 	const maxAttempts = 5