fix: wire env var collapse into test handler for cross-env matching

The test handler now collapses incoming request URLs before hashing,
using the same EnvExpander as the record handler. This means:

1. Record against prod: URL stored as {{BASE_URL}}/users
2. Test against staging: incoming https://api.staging.com/users
   gets collapsed to {{BASE_URL}}/users before hash computation
3. Hashes match → snapshot found → comparison works

Both record and test handlers now use Collapse() symmetrically,
making env var support fully bidirectional.

Author: ojuschugh1

cmd/etch/main.go

@@ -321,6 +321,12 @@ func runTest(args []string) int {
 	}
 
 	handler := proxy.NewTestHandler(hc, ss, de, am)
+
+	// wire env var support for cross-environment matching
+	if len(cfg.Env) > 0 {
+		handler.EnvExpander = envvar.NewExpander(cfg.Env)
+	}
+
 	addr := fmt.Sprintf(":%d", cfg.Port)
 	srv := proxy.NewProxyServer(addr, proxy.ModeTest, cam, handler)
 

internal/proxy/test_handler.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/ojuschugh1/etch/internal/approval"
 	"github.com/ojuschugh1/etch/internal/diff"
+	"github.com/ojuschugh1/etch/internal/envvar"
 	"github.com/ojuschugh1/etch/internal/hash"
 	"github.com/ojuschugh1/etch/internal/snapshot"
 )
@@ -20,6 +21,7 @@ type TestHandler struct {
 	SnapshotStore   *snapshot.SnapshotStore
 	DiffEngine      *diff.DiffEngine
 	ApprovalManager *approval.ApprovalManager
+	EnvExpander     *envvar.Expander // optional, collapses URLs before hashing
 	Summary         *snapshot.TestSummary
 	mu              sync.Mutex
 }
@@ -39,8 +41,16 @@ func NewTestHandler(hc *hash.HashComputer, ss *snapshot.SnapshotStore, de *diff.
 // and compares the live response against it. Counters are updated
 // thread-safely.
 func (h *TestHandler) HandleRequest(req *http.Request, resp *http.Response) error {
-	// Compute request hash.
-	reqHash, err := h.HashComputer.ComputeHash(req.Method, req.URL.String(), req.Header)
+	// Collapse the URL to match how it was stored during recording.
+	// If env vars are configured, https://api.staging.com/users becomes
+	// {{BASE_URL}}/users — matching the snapshot's collapsed URL.
+	requestURL := req.URL.String()
+	if h.EnvExpander != nil {
+		requestURL = h.EnvExpander.Collapse(requestURL)
+	}
+
+	// Compute request hash from the (possibly collapsed) URL.
+	reqHash, err := h.HashComputer.ComputeHash(req.Method, requestURL, req.Header)
 	if err != nil {
 		return fmt.Errorf("test: compute hash: %w", err)
 	}