Version 1.5 connects individual Device assumptions to complete mission decisions. TRANSPARENT DEVICE AVAILABILITY - Review a complete calculation breakdown: base MTBF, redundant-power benefit, spare logistics, EOL delay, eligible support benefit, hands-on repair time, and modeled restoration time. - Edit app-wide defaults for generic Device MTBF, redundant power, logistics, EOL sourcing, and support-agreement behavior. - See exactly when support changes the result. Support reduces eligible logistics and EOL delay only; it never reduces hands-on repair time. - Preserve the assumptions and MTBF provenance used by every saved Device, even when app-wide defaults later change. REUSE REAL DEVICE DATA - Select saved Devices directly as named Components in Series, Parallel, N:M, and Cross-Connected topologies. - Preserve Device names, availability, MTBF, and provenance through Blocks, Systems, exports, imports, and edits. NEW MISSION RELIABILITY - Evaluate whether a saved Device, Block, or System can complete a continuous mission measured in hours, days, or weeks without a service interruption. - Use stored MTBF when available, or explicitly model availability-only inputs using average restoration time or a reliability reference period. - Keep strict MTBF validation when assumptions are not appropriate. - Compare Mission Success, Interruption Risk, any-Component failure probability, expected failed Components, and the weakest contributor. - Apply existing Series, Parallel, heterogeneous N:M, Cross-Connected, Stage, and Handoff logic to mission survival. - See clear provided, estimated, assumption-based, and mixed data-quality labels. BETTER GUIDANCE - Follow an expanded Guided Tour from Device calculation and reuse through complex System construction, Live Modeling, SLO Analysis, System Comparison, and Mission Reliability. - Review new formulas, assumptions, limitations, worked examples, and Reliability Block Diagram guidance in Reference. - Benefit from additional layout, naming, and consistency improvements across iPhone and iPad. Mission Reliability uses a constant-rate, independent-failure model with no repair during the mission. Availability-only methods require an explicit assumption and are clearly labeled as approximate.

Version 1.4 turns saved Systems into interactive resilience models you can test, inspect, and share. LIVE MODELING - Apply temporary failures without changing the saved System. - Fail an entire Block, an internal Component, or a modeled output switch. - See Remaining Availability and service status recalculate immediately. - Restore individual elements or reset the complete simulation. VISIBLE INPUT FLOWS - Follow animated Red and Blue dashed paths through the surviving topology. - See shared connections become Purple when both inputs use the same route. - Distinguish enabled, delivered, and interrupted inputs. - Observe a single-output switch select one healthy handoff. FULL-SCREEN SIMULATION - Expand Live Modeling into a dedicated interactive canvas. - Rotate iPhone or iPad for a wider landscape view of longer Systems. - Keep topology, flow behavior, availability, and failure state visible together. EDITABLE SYSTEM SHARING - Export and share complete Systems as portable .slosla files. - Use the documented JSON-based data model to preserve Blocks, Components, stages, handoffs, switches, and calculated values. - Send designs through Files, AirDrop, Mail, Messages, or other compatible apps. - Preview, validate, recalculate, and safely import a shared System without overwriting local work. - Edit imported Block Components and update their availability values. - Continue modeling, comparing, reporting, and simulating the imported design. MORE MODELING CONTROL - Add an explicit 100% Ideal Path to represent an intentional passive bypass. Ideal Paths are non-failable during simulation. - Use topology-aware failure behavior for Series, Parallel, N:M, and Cross-Connected Blocks. - Compare extremely close designs with additional precision when fixed decimal places would hide the difference. - Share either a professional PDF report or the complete editable System model. LEARNING AND POLISH - Expanded Guided Tour covering Live Modeling and editable System sharing. - Updated How to Use and Reference material for the new workflow and terminology. - Refined failure labels, flow legends, output-switch behavior, and full-screen layouts. - Refreshed app icon. SLO/SLA Calc still works entirely offline. Simulations never modify a saved System, and files leave your device only when you choose to export or share them.

Version 1.3 makes advanced availability modeling easier to build, understand, and explain. CROSS-CONNECTED TOPOLOGIES - Model two-layer and three-layer Cross-Connected Blocks. - Assign a different availability value to every component. - Connect compatible multi-path stages using Direct or Full Cross handoffs. - Add an optional output switch when multiple paths converge into one handoff. SYSTEM COMPARISON - Compare two saved Systems side by side. - See availability differences, calculated downtime reduction, and design complexity. - Optionally evaluate both Systems against the same target SLO. - Get a clear decision summary explaining which design provides greater modeled availability. IMPROVED GUIDANCE - Follow an expanded guided tour with a worked Parallel example. - Load the example directly into the calculator and explore the result. - Review consistent definitions for Components, Blocks, Layers, Paths, Stages, Handoffs, and Systems. - Learn about common availability design pitfalls involving infrastructure, shared failure domains, cloud regions, security, manual intervention, and recovery testing. REPORTING AND RELIABILITY - View Cross-Connected architecture and handoffs in System diagrams and PDF reports. - Improved editing and deletion behavior for complex System stages. - Additional usability and stability improvements throughout the app.

Version 1.2 turns SLO/SLA Calc into a more complete availability design workspace. • Organize saved calculations into reusable Blocks and complete Systems • Build larger systems by connecting Blocks in series or parallel • Add optional output-switch availability to parallel stages • Edit saved Blocks and Systems as designs evolve • Automatically identify Systems that require recalculation after a Block changes • Visualize the complete system topology with availability values • Generate and share a professional PDF system report • Improved guidance, terminology, empty states, and reference documentation • Additional usability, stability, and interface improvements for iPhone and iPad