Function anchorUserMessage

internal/ctx/ctx.go:201–213

anchorUserMessage guarantees the packed window carries a user-role message whenever history has one. The newest-first walk drops oldest-first, so a long single turn (one task message, then dozens of assistant+tool rounds that fill the budget) evicts the sole user task and hands the backend a userles

(kept, history []Message)

}

// anchorUserMessage guarantees the packed window carries a user-role message
// whenever history has one. The newest-first walk drops oldest-first, so a long
// single turn (one task message, then dozens of assistant+tool rounds that fill
// the budget) evicts the sole user task and hands the backend a userless window,
// which 400s every OpenAI-compatible server ("no user query found in messages").
// When no user survived, recover the FIRST user message (the original task, the
// agent's anchor against drift), prepended chronologically over budget: the same
// deliberately-over-budget guarantee newestToolGroup and the always-keep-newest
// path already make. A lone user message carries no tool-call pairing, so this is
// safe after the dangling/orphan passes. No-op when a recent user already
// survived (normal multi-turn) or history has no user message at all.
func anchorUserMessage(kept, history []Message) []Message {
	for _, m := range kept {
		if m.Role == RoleUser {
			return kept
		}