Function buildStreamSystemContext

src/node/services/streamContextBuilder.ts:501–654

(
  opts: BuildStreamSystemContextOptions
)

 * 6. Counting system message tokens
 */
export async function buildStreamSystemContext(
  opts: BuildStreamSystemContextOptions
): Promise<StreamSystemContextResult> {
  const {
    runtime,
    metadata,
    workspacePath,
    workspaceId,
    agentDefinition,
    effectiveMode,
    agentDiscoveryRuntime,
    agentDiscoveryPath,
    isSubagentWorkspace,
    effectiveAdditionalInstructions,
    planFilePath,
    modelString,
    cfg,
    providersConfig,
    mcpServers,
    muxScope,
    loadDesktopCapability,
    advisorToolAvailable,
  } = opts;

  const workspaceLog = log.withFields({ workspaceId, workspaceName: metadata.name });

  // Resolve the body with inheritance (prompt.append merges with base).
  // Use agentDefinition.id (may have fallen back to exec) instead of effectiveAgentId.
  const resolvedBody = await resolveAgentBody(
    agentDiscoveryRuntime,
    agentDiscoveryPath,
    agentDefinition.id,
    {
      skipScopesAbove: getSkipScopesAboveForKnownScope(agentDefinition.scope),
    }
  );

  let subagentAppendPrompt: string | undefined;
  if (isSubagentWorkspace) {
    try {
      const resolvedFrontmatter = await resolveAgentFrontmatter(
        agentDiscoveryRuntime,
        agentDiscoveryPath,
        agentDefinition.id,
        {
          skipScopesAbove: getSkipScopesAboveForKnownScope(agentDefinition.scope),
        }
      );
      subagentAppendPrompt = resolvedFrontmatter.subagent?.append_prompt;
    } catch (error: unknown) {
      workspaceLog.debug("Failed to resolve agent frontmatter for subagent append_prompt", {
        agentId: agentDefinition.id,
        error: getErrorMessage(error),
      });
    }
  }

  const agentSystemPromptSections = [resolvedBody];