fix(antigravity): launch the managed agy with a CSRF token

internal/api/antigravity_cli.go

@@ -2,6 +2,8 @@ package api
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -40,6 +42,9 @@ type agySession struct {
 	pty  pty.Pty
 	cmd  *pty.Cmd
 	conn *AntigravityConnection
+	// csrfToken is the token agy was launched with. Its language server
+	// rejects Connect-RPC calls without it (missing CSRF token, HTTP 401).
+	csrfToken string
 }
 
 // AntigravityCLIRunner manages a bounded warm agy process so onWatch can read
@@ -134,8 +139,8 @@ func (r *AntigravityCLIRunner) Fetch(ctx context.Context) (*AntigravitySnapshot,
 		return nil, err
 	}
 
-	base := r.sess.conn.BaseURL
-	summary, status, err := r.post(ctx, base, agyQuotaSummaryRPC)
+	conn := r.sess.conn
+	summary, status, err := r.post(ctx, conn, agyQuotaSummaryRPC)
 	if err != nil || status != http.StatusOK {
 		r.recordFailureLocked()
 		if err == nil {
@@ -158,7 +163,7 @@ func (r *AntigravityCLIRunner) Fetch(ctx context.Context) (*AntigravitySnapshot,
 	}
 
 	// Identity/plan are best-effort; the quota summary already succeeded.
-	if statusBody, st, serr := r.post(ctx, base, agyUserStatusRPC); serr == nil && st == http.StatusOK {
+	if statusBody, st, serr := r.post(ctx, conn, agyUserStatusRPC); serr == nil && st == http.StatusOK {
 		if us, perr := ParseAntigravityResponse(statusBody); perr == nil && us.UserStatus != nil {
 			snap.Email = us.UserStatus.Email
 			if us.UserStatus.PlanStatus != nil {
@@ -206,13 +211,33 @@ func (r *AntigravityCLIRunner) ensureLocked(ctx context.Context) error {
 	return nil
 }
 
+// newAgyCSRFToken returns a fresh random token for one managed agy launch.
+func newAgyCSRFToken() (string, error) {
+	b := make([]byte, 16)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(b), nil
+}
+
+// agyLaunchArgs sets the CSRF token agy's language server will require. Without
+// it, agy on Windows rejects every call as "missing CSRF token" (HTTP 401), so
+// the session never becomes ready (issue #140).
+func agyLaunchArgs(csrfToken string) []string {
+	return []string{"--csrf_token", csrfToken}
+}
+
 // launch starts agy inside a pseudo-terminal and drains its output.
 func (r *AntigravityCLIRunner) launch(binPath string) (*agySession, error) {
+	token, err := newAgyCSRFToken()
+	if err != nil {
+		return nil, fmt.Errorf("antigravity cli: csrf token: %w", err)
+	}
 	p, err := pty.New()
 	if err != nil {
 		return nil, fmt.Errorf("antigravity cli: open pty: %w", err)
 	}
-	cmd := p.CommandContext(r.rootCtx, binPath)
+	cmd := p.CommandContext(r.rootCtx, binPath, agyLaunchArgs(token)...)
 	cmd.Env = append(os.Environ(), "TERM=xterm-256color")
 	if err := cmd.Start(); err != nil {
 		_ = p.Close()
@@ -221,7 +246,7 @@ func (r *AntigravityCLIRunner) launch(binPath string) (*agySession, error) {
 	// Drain PTY output so the process is not blocked on a full buffer.
 	go func() { _, _ = io.Copy(io.Discard, p) }()
 	r.logger.Debug("launched managed agy", "pid", cmd.Process.Pid, "path", binPath)
-	return &agySession{pty: p, cmd: cmd}, nil
+	return &agySession{pty: p, cmd: cmd, csrfToken: token}, nil
 }
 
 // awaitReady polls until the quota endpoint parses, since a fresh agy can bind
@@ -235,8 +260,8 @@ func (r *AntigravityCLIRunner) awaitReady(ctx context.Context, sess *agySession)
 		}
 		ports, err := r.client.discoverPorts(ctx, pid)
 		if err == nil && len(ports) > 0 {
-			if conn, _ := r.client.probeForConnectAPI(ctx, ports, ""); conn != nil {
-				if _, status, perr := r.post(ctx, conn.BaseURL, agyQuotaSummaryRPC); perr == nil && status == http.StatusOK {
+			if conn, _ := r.client.probeForConnectAPI(ctx, ports, sess.csrfToken); conn != nil {
+				if _, status, perr := r.post(ctx, conn, agyQuotaSummaryRPC); perr == nil && status == http.StatusOK {
 					return conn, nil
 				}
 			}
@@ -257,19 +282,22 @@ func (r *AntigravityCLIRunner) sessionHealthy(ctx context.Context) bool {
 	}
 	checkCtx, cancel := context.WithTimeout(ctx, 3*time.Second)
 	defer cancel()
-	_, status, err := r.post(checkCtx, r.sess.conn.BaseURL, agyQuotaSummaryRPC)
+	_, status, err := r.post(checkCtx, r.sess.conn, agyQuotaSummaryRPC)
 	return err == nil && status == http.StatusOK
 }
 
-// post issues a Connect-RPC POST against the agy language server. No CSRF token
-// is required for the CLI's server.
-func (r *AntigravityCLIRunner) post(ctx context.Context, baseURL, rpcPath string) ([]byte, int, error) {
-	req, err := http.NewRequestWithContext(ctx, http.MethodPost, baseURL+rpcPath, strings.NewReader(agyMetadataBody))
+// post issues a Connect-RPC POST against the agy language server, with the
+// CSRF token the managed agy was launched with.
+func (r *AntigravityCLIRunner) post(ctx context.Context, conn *AntigravityConnection, rpcPath string) ([]byte, int, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, conn.BaseURL+rpcPath, strings.NewReader(agyMetadataBody))
 	if err != nil {
 		return nil, 0, err
 	}
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Connect-Protocol-Version", "1")
+	if conn.CSRFToken != "" {
+		req.Header.Set("X-Codeium-Csrf-Token", conn.CSRFToken)
+	}
 
 	resp, err := r.client.httpClient.Do(req)
 	if err != nil {

internal/api/antigravity_cli_test.go

@@ -2,6 +2,8 @@ package api
 
 import (
 	"context"
+	"net/http"
+	"net/http/httptest"
 	"os"
 	"path/filepath"
 	"testing"
@@ -159,3 +161,41 @@ func TestResolveAgyPath_EnvMissingFileErrors(t *testing.T) {
 		t.Error("expected error when ANTIGRAVITY_CLI_PATH points at a missing file")
 	}
 }
+
+// agy's language server rejects Connect-RPC calls that lack the CSRF token it
+// was launched with (issue #140). The runner must launch agy with a token and
+// send the same token on every call.
+func TestAgyRunner_SendsCSRFToken(t *testing.T) {
+	const token = "test-csrf-token"
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Header.Get("X-Codeium-Csrf-Token") != token {
+			w.WriteHeader(http.StatusUnauthorized)
+			_, _ = w.Write([]byte(`{"code":"unauthenticated","message":"missing CSRF token"}`))
+			return
+		}
+		_, _ = w.Write([]byte(`{}`))
+	}))
+	defer srv.Close()
+
+	r := NewAntigravityCLIRunner(nil)
+	defer r.Stop()
+	_, status, err := r.post(context.Background(), &AntigravityConnection{BaseURL: srv.URL, CSRFToken: token}, agyQuotaSummaryRPC)
+	if err != nil || status != http.StatusOK {
+		t.Fatalf("post with token: status=%d err=%v", status, err)
+	}
+}
+
+func TestAgyLaunchArgs_PassCSRFToken(t *testing.T) {
+	a, err := newAgyCSRFToken()
+	if err != nil {
+		t.Fatal(err)
+	}
+	b, _ := newAgyCSRFToken()
+	if len(a) < 32 || a == b {
+		t.Fatalf("tokens must be long and unique per launch: %q %q", a, b)
+	}
+	args := agyLaunchArgs(a)
+	if len(args) != 2 || args[0] != "--csrf_token" || args[1] != a {
+		t.Fatalf("agyLaunchArgs(%q) = %q", a, args)
+	}
+}