fix(github): bound the default HTTP client with a timeout

internal/gitprovider/github/app_auth.go

@@ -70,7 +70,7 @@ func newGitHubAppFromConfig(ctx context.Context, profile string, store credentia
 	}
 	httpClient := opts.HTTPClient
 	if httpClient == nil {
-		httpClient = http.DefaultClient
+		httpClient = defaultBoundedHTTPClient()
 	}
 	now := opts.Now
 	if now == nil {

internal/gitprovider/github/client.go

@@ -20,6 +20,11 @@ const (
 	credentialTypePAT       = "pat"
 	credentialTypeGitHubApp = "github_app" // #nosec G101 -- credential type label, not a secret.
 	gitHubAppInitTimeout    = 30 * time.Second
+	// defaultHTTPTimeout bounds every REST/GraphQL request made with the
+	// default client. All responses here are JSON payloads, so two minutes is
+	// generous — the bound exists because an unbounded client parks the whole
+	// run indefinitely on a connection the server's edge silently abandoned.
+	defaultHTTPTimeout = 2 * time.Minute
 	gitHubAppRefreshSkew    = 5 * time.Minute
 	gitHubAppJWTBackdate    = 60 * time.Second
 	gitHubAppJWTLifetime    = 9 * time.Minute
@@ -135,7 +140,7 @@ func New(opts Options) (*Client, error) {
 	}
 	httpClient := opts.HTTPClient
 	if httpClient == nil {
-		httpClient = http.DefaultClient
+		httpClient = defaultBoundedHTTPClient()
 	}
 	return &Client{
 		host:       normalizedHost,
@@ -146,6 +151,14 @@ func New(opts Options) (*Client, error) {
 	}, nil
 }
 
+// defaultBoundedHTTPClient is the fallback for construction paths where the
+// caller supplies no HTTPClient. Never http.DefaultClient: it has no timeout,
+// so a connection the server's edge silently abandons would park the request
+// — and the whole run — indefinitely.
+func defaultBoundedHTTPClient() *http.Client {
+	return &http.Client{Timeout: defaultHTTPTimeout}
+}
+
 // Host returns the normalized host this client is bound to.
 func (c *Client) Host() string {
 	if c == nil {

internal/gitprovider/github/client_test.go

@@ -31,6 +31,23 @@ func TestCapabilities(t *testing.T) {
 	}
 }
 
+func TestDefaultHTTPClientIsBounded(t *testing.T) {
+	// A stalled connection must never park a run indefinitely: the fallback
+	// client (used by both the PAT and GitHub-App construction paths whenever
+	// the caller doesn't supply one) needs a timeout.
+	fallback := defaultBoundedHTTPClient()
+	if fallback.Timeout <= 0 {
+		t.Fatalf("default HTTP client has no timeout; a silently dropped connection would hang forever")
+	}
+	if fallback == http.DefaultClient {
+		t.Fatalf("default HTTP client must not be http.DefaultClient (shared, unbounded)")
+	}
+	client := mustClient(t, Options{Token: "token"})
+	if client.httpClient.Timeout <= 0 {
+		t.Fatalf("NewClient without an explicit HTTPClient must use the bounded fallback")
+	}
+}
+
 func TestNewFromGitConfigBuildsPATClientAndCredential(t *testing.T) {
 	store := tokenStore{"work": {credentials.GitTokenKey: "token"}}
 	client, credential, err := NewFromGitConfig(config.GitConfig{