Drive the .NET SDK breaking-change documentation-and-notification process for a NuGet change that has already been implemented. Invoke this once a NuGet/Home issue (or its implementing NuGet.Client PR) is labeled `Breaking-Change`. It makes sure the correct documentation issues are filed/completed (the NuGet NUxxxx reference-docs issue and the official dotnet/docs breaking-change issue) and helps author the draft notification email to the .NET Breaking Change Notifications alias. Trigger on phrases like "breaking change process", "file the breaking change doc issue", "the issue got the Breaking-Change label", "draft the breaking change email", or "notify dotnetbcn".

Fix F# debugging issues (breakpoints, .pdb, sequence points). Build, run VS integration tests, inspect IL/PDB.

Performs multi-agent, multi-model code review of F# compiler PRs across 19 dimensions including type checking, IL emission, binary compatibility, and IDE performance. Dispatches parallel assessment agents per dimension, consolidates with cross-model agreement scoring, and filters false positives. Invoke when reviewing compiler changes, requesting expert feedback, or performing pre-merge quality checks.

Write release notes for completed changes. Use when PR modifies tracked paths and needs release notes entry.

Debug and fix --realsig+ (RealInternalSignature) codegen bugs in IlxGen — MethodAccessException / FieldAccessException / TypeAccessException at runtime, IL `private` vs `assembly` visibility, closure and TLR-lift placement (cloc / NestedTypeRefForCompLoc / effectiveCloc / moduleCloc). Use when a program compiles cleanly but crashes only under --realsig+, when IL accessibility differs between realsig modes, or when reasoning about where compiler-synthesized closures/state-machines/quotation helpers are nested.

Use when drafting, proposing, creating, or editing prose for a dotnet/fsharp GitHub PR or issue — body, title, comment, review summary, edits — including bare asks like "open a PR", "ship this", "write up what I did", "summarise the change", "reply on the PR", "edit the issue body", "gh pr create", "gh pr comment", "gh pr edit --body", "gh issue comment", "gh pr review --body". Primary use case is PR descriptions; same rules apply to PR/issue comments and review summaries. Not for labels, reviewers, merging, or code-review findings (just the prose write-up of them).

Retrieve and analyze Azure DevOps build failures for GitHub PRs. Use when CI fails. CRITICAL: Collect ALL errors from ALL platforms FIRST, write hypotheses to file, then fix systematically.

Write a postmortem for a regression that escaped to production, broke real users, and traces back to a design flaw worth documenting for future implementors. Only invoke after confirming no existing postmortem or doc covers the same root cause.

Fix ILVerify baseline failures when IL shape changes (codegen, new types, method signatures). Use when CI fails on ILVerify job.

Investigate compiler failures, test errors, or unexpected behavior through systematic minimal reproduction, 3-hypothesis testing, and verification. Always re-run builds and tests after changes.

Always invoke after editing `.fs` files under `src/Compiler/`. Fast parse/typecheck without `dotnet build`, plus symbol references and inferred type hints. Use whenever the user asks about F# errors, compile errors, type inference, finding usages, or renaming a symbol in the compiler tree.

Detect flaky tests by scanning recent AzDo CI builds for test failures recurring across multiple unrelated PRs. Use when investigating intermittent failures, CI instability, deciding which tests to quarantine, or checking if RunTestCasesInSequence no-ops are causing parallel-safety issues.

Create custom agent capabilities when discovering novel tools, receiving task-agnostic tips from reviewers, or after researching specialized workflows not covered in existing instructions. Teaches structure, YAML optimization for LLM discoverability, and token efficiency.

Use when a code/test/comment diff is called bloated, slop, LLM slop, bullshit, WTF, crap, rubbish, embarrassing, overengineered, adhoc, or "not paid by LOC"; or when symptoms include bloated comments, superfluous planning .md / .tools / one-time setup / phase-or-sprint tags, huge-file growth instead of new-file extraction, 5 copy-pasted tests that should be 1 parametrized test, duplicated test setup, reinvented helpers, near-duplicate logic across files, low reuse, 4+ new module-level helpers for one bugfix, fresh whole-AST/IR/syntax-tree walkers, or 150+ added LOC for one bugfix. Also use proactively before opening a PR whose diff smells like any of the above.

Triage a build / compile / restore / WarnAsError failure from its MSBuild binary log. Fetches the binlog (a local build's, or a failed dotnet/fsharp Azure DevOps PR build's published artifact) and analyzes it live via the `binlog-mcp` MCP server — structured errors, root-cause diagnosis, and an MSBuild perf X-ray. NOT for test failures or CheckCodeFormatting: a build binlog has no errors there.

Implementation details for EF Core SaveChanges and the update pipeline. Use when changing CommandBatchPreparer, UpdateSqlGenerator, ModificationCommand, or related classes.

Use this skill to triage an incoming issue on the EF Core repo (bug report or feature request). Sets the issue type (bug/feature), assigns EF area labels, attempts to arrive at a minimal repro reproducing the bug, checks whether it represents a regression, finds possible duplicates, etc.

Implementation details for the EF Core dotnet-ef CLI and tooling. Use when changing dotnet-ef commands, the ef wrapper, EFCore.Tools (PMC), or EFCore.Tasks MSBuild integration.

Implementation details for EF Core test infrastructure. Use when changing test fixtures, SQL baseline assertions, test helpers, the test class hierarchy, or when adding new tests.

Implementation details for the Microsoft.Data.Sqlite ADO.NET provider. Use when changing files under `src/Microsoft.Data.Sqlite.Core/`.