refactor(server): share prompt validation before background dispatch

Christian Rocha and Charm Crush created 2 weeks ago

Use the same prompt and session checks before accepting background work
that synchronous runs already use. This keeps rejected prompts
consistent as the server begins accepting requests asynchronously.

Co-Authored-By: Charm Crush <[e-mail]>

Change summary

internal/agent/agent.go | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)

Detailed changes

internal/agent/agent.go

@@ -183,12 +183,25 @@ func NewSessionAgent(
 	}
 }
 
-func (a *sessionAgent) Run(ctx context.Context, call SessionAgentCall) (result *fantasy.AgentResult, retErr error) {
+// ValidateCall performs the cheap structural validation that
+// sessionAgent.Run requires before a call can be dispatched: a call must
+// carry either a non-empty prompt or a text attachment, and it must name a
+// session. It is exported so callers that accept a run before dispatching it
+// (e.g. backend.SendMessage) can apply the same checks and keep the error
+// contract consistent.
+func ValidateCall(call SessionAgentCall) error {
 	if call.Prompt == "" && !message.ContainsTextAttachment(call.Attachments) {
-		return nil, ErrEmptyPrompt
+		return ErrEmptyPrompt
 	}
 	if call.SessionID == "" {
-		return nil, ErrSessionMissing
+		return ErrSessionMissing
+	}
+	return nil
+}
+
+func (a *sessionAgent) Run(ctx context.Context, call SessionAgentCall) (result *fantasy.AgentResult, retErr error) {
+	if err := ValidateCall(call); err != nil {
+		return nil, err
 	}
 
 	// Queue the message if busy. Strip OnComplete: the caller that