feat(02-02): capture, scrub, and strictly diff stateful flows

Resolve named placeholders from a private variable store, mask
dates and ids after shape checks, and keep comparing independent steps.

Co-authored-by: Cursor <cursoragent@cursor.com>

tide/replay.go

@@ -19,22 +19,44 @@ func ReplayFlow(ctx context.Context, flow Flow, cfg ReplayConfig) (Result, error
 		client = defaultClient()
 	}
 	limit := maxBody(cfg.MaxBody)
+	store := cfg.Store
+	if store == nil {
+		store = mustMemoryStore()
+	}
 	result := Result{OK: true, Steps: make([]StepResult, 0, len(flow.Steps))}
+	skipRest := false
 	for _, step := range flow.Steps {
-		got, err := doStep(ctx, client, cfg.Target, step.Request, limit)
+		if skipRest {
+			result.Steps = append(result.Steps, StepResult{ID: step.ID, Skipped: true})
+			continue
+		}
+		sr := StepResult{ID: step.ID, OK: true}
+		req, err := expandRequest(step.Request, store)
+		if err != nil {
+			sr.OK = false
+			result.OK = false
+			sr.Diffs = append(sr.Diffs, Diff{Path: "request", Expected: "resolved placeholders", Actual: err.Error()})
+			result.Steps = append(result.Steps, sr)
+			skipRest = true
+			continue
+		}
+		got, err := doStep(ctx, client, cfg.Target, req, limit)
 		if err != nil {
 			return result, fmt.Errorf("tide: replay step %s: %w", step.ID, err)
 		}
-		sr := StepResult{ID: step.ID, OK: true}
-		if step.Response.Status != 0 && got.Status != step.Response.Status {
+		live := step
+		live.Request = req
+		live.Response = got
+		if err := CaptureStep(store, &live); err != nil {
 			sr.OK = false
-			sr.Diffs = append(sr.Diffs, Diff{
-				Path:     "status",
-				Expected: fmt.Sprintf("%d", step.Response.Status),
-				Actual:   fmt.Sprintf("%d", got.Status),
-			})
+			result.OK = false
+			sr.Diffs = append(sr.Diffs, Diff{Path: "capture", Expected: "captured value", Actual: err.Error()})
+			result.Steps = append(result.Steps, sr)
+			skipRest = true
+			continue
 		}
-		sr.Diffs = append(sr.Diffs, compareBodies(step.Response, got)...)
+		_ = ScrubStep(store, &live)
+		sr.Diffs = append(sr.Diffs, compareStep(step, live.Response)...)
 		if len(sr.Diffs) > 0 {
 			sr.OK = false
 			result.OK = false
@@ -46,3 +68,22 @@ func ReplayFlow(ctx context.Context, flow Flow, cfg ReplayConfig) (Result, error
 	}
 	return result, nil
 }
+
+func mustMemoryStore() *Store {
+	s, _ := OpenStore("")
+	return s
+}
+
+func compareStep(want Step, got Response) []Diff {
+	var diffs []Diff
+	if want.Response.Status != 0 && got.Status != want.Response.Status {
+		diffs = append(diffs, Diff{
+			Path:     "status",
+			Expected: fmt.Sprintf("%d", want.Response.Status),
+			Actual:   fmt.Sprintf("%d", got.Status),
+		})
+	}
+	diffs = append(diffs, compareHeaders(want.Response.Headers, got.Headers, want.Headers)...)
+	diffs = append(diffs, compareBodies(want.Response, got, want)...)
+	return diffs
+}