diff --git a/server/internal/assistant/claude.go b/server/internal/assistant/claude.go
index 0cd2210..86f9663 100644
--- a/server/internal/assistant/claude.go
+++ b/server/internal/assistant/claude.go
@@ -295,7 +295,10 @@ func (c *Client) workspace() string {
 // a 400 buried in a log, while the user just sees "something went wrong at our
 // end" - which is true and useless.
 func NeedsWorkspace(err error) bool {
-	return err != nil && strings.Contains(err.Error(), "anthropic-workspace-id is required")
+	// The API has worded this two ways so far: "anthropic-workspace-id is
+	// required" and "must include the anthropic-workspace-id header". Match
+	// the header name, which is the part that will not be reworded.
+	return err != nil && strings.Contains(err.Error(), "anthropic-workspace-id")
 }
 
 func (c *Client) modelID() string {