modelerrors: include HTTP status code in StatusError.Error()

StatusError.Error() previously delegated directly to the wrapped error,
discarding the status code. This made debugging harder since log lines
wouldn't reveal the HTTP status. Now Error() returns a message like
"HTTP 429: rate limit exceeded" for better observability.

Assisted-By: docker-agent

Author: dgageot

pkg/modelerrors/modelerrors.go

@@ -7,6 +7,7 @@ package modelerrors
 import (
 	"context"
 	"errors"
+	"fmt"
 	"log/slog"
 	"net"
 	"net/http"
@@ -38,7 +39,7 @@ type StatusError struct {
 }
 
 func (e *StatusError) Error() string {
-	return e.Err.Error()
+	return fmt.Sprintf("HTTP %d: %s", e.StatusCode, e.Err.Error())
 }
 
 func (e *StatusError) Unwrap() error {

pkg/modelerrors/modelerrors_test.go

@@ -265,11 +265,11 @@ func TestParseRetryAfterHeader(t *testing.T) {
 func TestStatusError(t *testing.T) {
 	t.Parallel()
 
-	t.Run("Error() delegates to wrapped error", func(t *testing.T) {
+	t.Run("Error() includes status code and wrapped message", func(t *testing.T) {
 		t.Parallel()
 		underlying := errors.New("rate limit exceeded")
 		se := &StatusError{StatusCode: 429, Err: underlying}
-		assert.Equal(t, underlying.Error(), se.Error())
+		assert.Equal(t, "HTTP 429: rate limit exceeded", se.Error())
 	})
 
 	t.Run("Unwrap() allows errors.Is traversal", func(t *testing.T) {
@@ -315,7 +315,7 @@ func TestWrapHTTPError(t *testing.T) {
 		require.ErrorAs(t, result, &se)
 		assert.Equal(t, 429, se.StatusCode)
 		assert.Equal(t, time.Duration(0), se.RetryAfter)
-		assert.Equal(t, origErr.Error(), se.Error())
+		assert.Equal(t, "HTTP 429: rate limited", se.Error())
 	})
 
 	t.Run("429 with Retry-After header sets RetryAfter", func(t *testing.T) {