charmbracelet/crush · error

session id missing from context

Error message

session id missing from context

What it means

After validating the prompt, validateAgenticFetchParams reads the session id from the context (tools.GetSessionFromContext). The agentic_fetch sub-agent needs the parent session to record messages and stream events; an empty id means the execution context was not properly set up, so validation fails.

Source

Thrown at internal/agent/agentic_fetch_tool.go:36

//go:embed templates/agentic_fetch.md
var agenticFetchToolDescription string

// agenticFetchValidationResult holds the validated parameters from the tool call context.
type agenticFetchValidationResult struct {
	SessionID      string
	AgentMessageID string
}

// validateAgenticFetchParams validates the tool call parameters and extracts required context values.
func validateAgenticFetchParams(ctx context.Context, params tools.AgenticFetchParams) (agenticFetchValidationResult, error) {
	if params.Prompt == "" {
		return agenticFetchValidationResult{}, errors.New("prompt is required")
	}

	sessionID := tools.GetSessionFromContext(ctx)
	if sessionID == "" {
		return agenticFetchValidationResult{}, errors.New("session id missing from context")
	}

	agentMessageID := tools.GetMessageFromContext(ctx)
	if agentMessageID == "" {
		return agenticFetchValidationResult{}, errors.New("agent message id missing from context")
	}

	return agenticFetchValidationResult{
		SessionID:      sessionID,
		AgentMessageID: agentMessageID,
	}, nil
}

//go:embed templates/agentic_fetch_prompt.md.tpl
var agenticFetchPromptTmpl []byte

func (c *coordinator) agenticFetchTool(_ context.Context, client *http.Client) (fantasy.AgentTool, error) {
	if client == nil {

View on GitHub (pinned to 7944b8e522)

Solutions

1. Execute the tool via the standard agent loop so the session context value is installed.
2. In custom code, wrap the context with the session context helper (tools.WithSessionContext) before calling.
3. Update tests to mirror the production context setup.

Example fix

// before
res, err := validateAgenticFetchParams(context.Background(), params)
// after
ctx := tools.WithSessionContext(ctx, sessionID)
ctx = tools.WithMessageContext(ctx, agentMessageID)
res, err := validateAgenticFetchParams(ctx, params)

if tools.GetSessionFromContext(ctx) == "" {
    return errors.New("agentic fetch requires session context")
}

res, err := validateAgenticFetchParams(ctx, params)
if err != nil && strings.Contains(err.Error(), "session id missing from context") {
    ctx = tools.WithSessionContext(ctx, sessionID)
    res, err = validateAgenticFetchParams(ctx, params)
}

When it happens

Trigger: agentic_fetch tool executed with a context that lacks the session context value — typically a direct/test invocation bypassing the coordinator's dispatch path that normally installs it.

Common situations: Unit tests calling the tool handler with context.Background(); custom tool runners that forget the session decorator; invoking the tool from a non-standard integration.

Related errors

• agent message id missing from context
• session id missing from context
• prompt is required
• session ID is required for downloading files
• session ID is required for creating a new file

AI-assisted analysis of charmbracelet/crush@7944b8e522 (2026-08-29). Data as JSON: /api/errors/bdc2f73252d6d8b2. Report an issue: GitHub.