diff --git a/CLAUDE.md b/CLAUDE.md
index c0e0c80..66eb510 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -43,6 +43,10 @@ Token resolution order:
 1. `PIPEBOARD_API_TOKEN` env var
 2. `~/.pipeboard/config.json` token field
 
+`VERCEL_AUTOMATION_BYPASS_SECRET` (optional) is sent as `x-vercel-protection-bypass`
+on every request so `PIPEBOARD_API_URL` can target SSO-protected Vercel preview
+deployments. See `internal/client/headers.go`.
+
 ### Build-time variables
 
 Version and commit are injected via ldflags (see Makefile and .goreleaser.yml):
diff --git a/README.md b/README.md
index 9c1d81f..39b53b1 100644
--- a/README.md
+++ b/README.md
@@ -51,6 +51,24 @@ Get your API token at [pipeboard.co/api-tokens](https://pipeboard.co/api-tokens)
 pipeboard login
 ```
 
+### Targeting a Vercel preview deployment
+
+`PIPEBOARD_API_URL` can point at any Pipeboard deployment, including a pull
+request's Vercel preview. Previews are protected by Vercel SSO, so set the
+project's [Protection Bypass for Automation](https://vercel.com/docs/deployment-protection/methods-to-bypass-deployment-protection/protection-bypass-automation)
+secret and the CLI sends it as `x-vercel-protection-bypass` on every request:
+
+```bash
+export VERCEL_AUTOMATION_BYPASS_SECRET=...   # from the Vercel project settings
+export PIPEBOARD_API_URL=https://<deployment>.vercel.app
+pipeboard mcp --server meta-ads-mcp tools-list
+```
+
+Hosts without deployment protection ignore the header, so it is safe to leave
+set. Without it, a protected preview answers
+`HTTP 401 {"error":{"message":"Protected deployment"}}` before the app sees the
+request.
+
 ## Quick Start
 
 ```bash
diff --git a/internal/client/headers.go b/internal/client/headers.go
new file mode 100644
index 0000000..ba46531
--- /dev/null
+++ b/internal/client/headers.go
@@ -0,0 +1,31 @@
+package client
+
+import (
+	"net/http"
+	"os"
+)
+
+// BypassSecretEnv is the environment variable holding a Vercel "Protection
+// Bypass for Automation" secret. Pipeboard preview deployments
+// (PIPEBOARD_API_URL=https://<deployment>.vercel.app) sit behind Vercel SSO
+// and answer HTTP 401 "Protected deployment" to any request that does not
+// present the secret. When the variable is set, every request carries it as
+// the x-vercel-protection-bypass header; hosts without deployment protection
+// ignore the header, so leaving it set is harmless.
+const BypassSecretEnv = "VERCEL_AUTOMATION_BYPASS_SECRET"
+
+// bypassHeader is the header Vercel's edge reads the secret from.
+const bypassHeader = "x-vercel-protection-bypass"
+
+// setCommonHeaders applies the headers every Pipeboard request needs: bearer
+// auth (skipped when token is empty, e.g. the unauthenticated tools-hash
+// endpoint), User-Agent, and the Vercel protection bypass when configured.
+func setCommonHeaders(req *http.Request, token, userAgent string) {
+	if token != "" {
+		req.Header.Set("Authorization", "Bearer "+token)
+	}
+	req.Header.Set("User-Agent", userAgent)
+	if secret := os.Getenv(BypassSecretEnv); secret != "" {
+		req.Header.Set(bypassHeader, secret)
+	}
+}
diff --git a/internal/client/headers_test.go b/internal/client/headers_test.go
new file mode 100644
index 0000000..1e79a19
--- /dev/null
+++ b/internal/client/headers_test.go
@@ -0,0 +1,114 @@
+package client
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+// recordingServer answers every request with a minimal valid body and keeps
+// the headers of the most recent request for assertions.
+type recordingServer struct {
+	*httptest.Server
+	last http.Header
+}
+
+func newRecordingServer(t *testing.T) *recordingServer {
+	t.Helper()
+	rs := &recordingServer{}
+	rs.Server = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		rs.last = r.Header.Clone()
+		w.Header().Set("Content-Type", "application/json")
+		if r.Method == http.MethodGet {
+			_, _ = w.Write([]byte(`{"hash":"abc"}`))
+			return
+		}
+		var req struct {
+			ID int64 `json:"id"`
+		}
+		_ = json.NewDecoder(r.Body).Decode(&req)
+		_ = json.NewEncoder(w).Encode(map[string]interface{}{
+			"jsonrpc": "2.0",
+			"id":      req.ID,
+			"result":  map[string]interface{}{"tools": []interface{}{}},
+		})
+	}))
+	t.Cleanup(rs.Close)
+	return rs
+}
+
+func (rs *recordingServer) bypass() (string, bool) {
+	v, ok := rs.last[http.CanonicalHeaderKey(bypassHeader)]
+	if !ok || len(v) == 0 {
+		return "", false
+	}
+	return v[0], true
+}
+
+func TestBypassHeader_SentOnEveryRequestKindWhenConfigured(t *testing.T) {
+	t.Setenv(BypassSecretEnv, "s3cret")
+	srv := newRecordingServer(t)
+
+	c := New(srv.URL, "tok", "test")
+	if _, err := c.ListTools("meta-ads-mcp"); err != nil {
+		t.Fatalf("ListTools: %v", err)
+	}
+	if got, ok := srv.bypass(); !ok || got != "s3cret" {
+		t.Errorf("tools/list: bypass header = %q, %v; want s3cret", got, ok)
+	}
+	if got := srv.last.Get("Authorization"); got != "Bearer tok" {
+		t.Errorf("tools/list: Authorization = %q; want Bearer tok", got)
+	}
+	if got := srv.last.Get("User-Agent"); got != "pipeboard-cli/test" {
+		t.Errorf("tools/list: User-Agent = %q", got)
+	}
+
+	if err := c.notify("meta-ads-mcp", "notifications/initialized", nil); err != nil {
+		t.Fatalf("notify: %v", err)
+	}
+	if got, ok := srv.bypass(); !ok || got != "s3cret" {
+		t.Errorf("notify: bypass header = %q, %v; want s3cret", got, ok)
+	}
+
+	rest := NewREST(srv.URL, "tok", "test")
+	if _, err := rest.Post("/api/debug/x", map[string]string{"a": "b"}); err != nil {
+		t.Fatalf("REST Post: %v", err)
+	}
+	if got, ok := srv.bypass(); !ok || got != "s3cret" {
+		t.Errorf("REST: bypass header = %q, %v; want s3cret", got, ok)
+	}
+
+	if _, err := FetchToolsHash(srv.URL, "test"); err != nil {
+		t.Fatalf("FetchToolsHash: %v", err)
+	}
+	if got, ok := srv.bypass(); !ok || got != "s3cret" {
+		t.Errorf("tools-hash: bypass header = %q, %v; want s3cret", got, ok)
+	}
+	if got := srv.last.Get("Authorization"); got != "" {
+		t.Errorf("tools-hash must stay unauthenticated, got Authorization=%q", got)
+	}
+}
+
+func TestBypassHeader_OmittedWhenUnset(t *testing.T) {
+	t.Setenv(BypassSecretEnv, "")
+	srv := newRecordingServer(t)
+
+	c := New(srv.URL, "tok", "test")
+	if _, err := c.ListTools("meta-ads-mcp"); err != nil {
+		t.Fatalf("ListTools: %v", err)
+	}
+	if got, ok := srv.bypass(); ok {
+		t.Errorf("bypass header should be absent when env is unset, got %q", got)
+	}
+	if got := srv.last.Get("Authorization"); got != "Bearer tok" {
+		t.Errorf("Authorization = %q; want Bearer tok", got)
+	}
+
+	if _, err := FetchToolsHash(srv.URL, "test"); err != nil {
+		t.Fatalf("FetchToolsHash: %v", err)
+	}
+	if got, ok := srv.bypass(); ok {
+		t.Errorf("tools-hash: bypass header should be absent, got %q", got)
+	}
+}
diff --git a/internal/client/mcp.go b/internal/client/mcp.go
index 4a8027d..dbd6b36 100644
--- a/internal/client/mcp.go
+++ b/internal/client/mcp.go
@@ -178,8 +178,7 @@ func (c *Client) call(serverPath, method string, params interface{}) (json.RawMe
 	}
 
 	httpReq.Header.Set("Content-Type", "application/json")
-	httpReq.Header.Set("Authorization", "Bearer "+c.token)
-	httpReq.Header.Set("User-Agent", c.userAgent)
+	setCommonHeaders(httpReq, c.token, c.userAgent)
 
 	resp, err := c.httpClient.Do(httpReq)
 	if err != nil {
@@ -215,13 +214,14 @@ type ToolsHashResult struct {
 
 // FetchToolsHash retrieves the combined tools hash from the server.
 // baseURL is the MCP base URL (e.g. https://mcp.pipeboard.co).
-// This endpoint requires no authentication.
+// This endpoint requires no authentication, but it still needs the Vercel
+// protection bypass when baseURL is a preview deployment.
 func FetchToolsHash(baseURL, version string) (*ToolsHashResult, error) {
 	req, err := http.NewRequest("GET", baseURL+"/api/tools-hash", nil)
 	if err != nil {
 		return nil, fmt.Errorf("creating request: %w", err)
 	}
-	req.Header.Set("User-Agent", "pipeboard-cli/"+version)
+	setCommonHeaders(req, "", "pipeboard-cli/"+version)
 
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
@@ -266,8 +266,7 @@ func (c *Client) notify(serverPath, method string, params interface{}) error {
 	}
 
 	httpReq.Header.Set("Content-Type", "application/json")
-	httpReq.Header.Set("Authorization", "Bearer "+c.token)
-	httpReq.Header.Set("User-Agent", c.userAgent)
+	setCommonHeaders(httpReq, c.token, c.userAgent)
 
 	resp, err := c.httpClient.Do(httpReq)
 	if err != nil {
diff --git a/internal/client/rest.go b/internal/client/rest.go
index b23d108..7583cb0 100644
--- a/internal/client/rest.go
+++ b/internal/client/rest.go
@@ -40,8 +40,7 @@ func (c *RESTClient) Post(path string, body interface{}) (map[string]interface{}
 	}
 
 	req.Header.Set("Content-Type", "application/json")
-	req.Header.Set("Authorization", "Bearer "+c.token)
-	req.Header.Set("User-Agent", c.userAgent)
+	setCommonHeaders(req, c.token, c.userAgent)
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {