A SAFe portfolio is a collection of development value streams. A development value stream is a long-lived series of steps that an enterprise uses to continuously deliver value to a customer or stakeholder. A development value stream typically consists of one or more ARTs and Solution Trains that build and deliver solutions. A SAFe portfolio aligns and governs one or more development value streams that share a common business mission, vision, strategy, and funding. A SAFe portfolio helps enterprises achieve Lean Portfolio Management, which is one of the core competencies of business agility in SAFe. References: SAFe Portfolio, Development Value Streams

The SAFe Lean-Agile Principle that includes the critical part of "delaying decisions to the last responsible moment" is "Assume variability; preserve options". This principle is based on the concept of set-based design, which is a way of managing uncertainty and complexity in product development. Set-based design means exploring multiple possible solutions in parallel, eliminating inferior options over time, and converging on the best solution as more information becomes available. Delaying decisions to the last responsible moment means keeping multiple options open until enough data and feedback are gathered to make an informed decision, which reduces risk and waste. References: SAFe Lean-Agile Principles, SAFe Principle #4

The SAFe Implementation Roadmap provides an ordered sequence of transformation activities. After training leaders, the next step is:
"Identify Value Streams and ARTs - this step is essential to organizing around value, ensuring future trains are aligned with value delivery." Reference: SAFe Workbook, Page 6-12, SAFe Implementation Roadmap

Cadence and synchronization are applied in events like PI Planning:
"PI Planning provides cadence-based alignment of multiple Agile Teams... Synchronization allows all stakeholders to align and collaborate."

The Agile Manifesto states:
"We have come to value: Customer collaboration over contract negotiation" This is one of the four core value statements of the Agile Manifesto and is cited verbatim in the SAFe Workbook.
Source: Workbook, Page 2-13