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W^X (write xor execute) is the rule that no memory page is writable and executable at the same time. In .NET it is the DOTNET_EnableWriteXorExecute knob, on by default since .NET 7, and it exists entirely for the JIT. Native AOT never reads it. Here is how the runtime implements it, what it costs, and when turning it off is a legitimate fix.

Conversation history can live in your process, in your database, in the provider, or on the machine that ran the agent. Where you put it does not change your token bill, it decides your retention exposure, and it decides whether you can ever change providers. The numbers, the retention windows, and a storage shape that survives all three.

Until now the only way to hand every developer the same MCP servers was managed-mcp.json, a file at a system path that takes exclusive control of MCP. Claude Code 2.1.259 adds a managedMcpServers setting for HTTP and SSE servers, and quietly narrows what allowedMcpServers governs.

Defensive system prompts are heuristic. Information-flow control is not: label every piece of content with integrity and confidentiality, propagate most-restrictive-wins through every tool call, and check the label at the sink before it runs. An 80-line runnable harness, the Agent Framework FIDES implementation, and the false positives the pattern buys you.

A step-by-step migration off Mono onto CoreCLR for .NET MAUI on Android: the API 24 floor, the Mono-only MSBuild properties that now break your build, why your APK grew, how to profile the startup regression with dotnet-dsrouter and dotnet-trace, and what a rollback actually looks like now that the Mono path is gone.

A step-by-step migration off the deprecated dart:html, dart:js_util, and package:js onto package:web 1.1.1 and dart:js_interop: how to find every offending import with the dart2wasm compiler, what dart fix does and does not rename, the JSImmutableListWrapper and innerHTML traps, and how to verify with flutter build web --wasm.

The full migration off package:flutter/material.dart and package:flutter/cupertino.dart onto material_ui 1.1.1 and cupertino_ui 1.0.2: what dart fix --code=migrate_design_widgets rewrites, why third-party widgets start throwing ancestor-lookup errors, what MaterialUiCompatibilityBridge actually fixes, and how the flutter_localizations dependency changes.

A step-by-step migration from VSTest to Microsoft.Testing.Platform 2.3.3: the OutputType Exe opt-in, the global.json runner switch, loggers becoming reporters, .runsettings becoming testconfig.json, and the exit codes that turn a green CI job red.

ModelContextProtocol 2.0.0 flipped HTTP transport to stateless by default, which is the one change that can drop every client still speaking 2025-11-25. HttpServerSessionMode.StatefulForInitializeClients in 2.2.0 serves both revisions on one endpoint. Here is the ordered upgrade, the ten breaking changes that matter, and the discover-probe bug that only a 2.1.0 client fixes.

BinaryFormatter's implementation was deleted in .NET 9 and still throws PlatformNotSupportedException on .NET 10 and .NET 11: how to choose a replacement serializer, read already-persisted NRBF blobs with NrbfDecoder, and what breaks in WinForms, WPF, and ResX.