filtrace

Analyze .NET CPU, allocation, exception, GC, JIT, and wall-clock (thread-time) data in .nettrace, .etl, and speedscope files with the filtrace CLI or MCP server. Use when a user asks where time or allocation volume goes in a trace or benchmark, which method or source line is hot, why a run regressed against a baseline, what a captured .nettrace / .etl contains, or to rank / drill / diff / export a profile - including profiling .NET Framework (net481) via ETW, where an EventPipe ranking would mislead. Also covers capturing the trace first - choosing EventPipe vs ETW, elevation, and the recording tool (dotnet-trace, BenchmarkDotNet, PerfView, wpr).

Create, revise, debug, test, and review production PowerShell scripts and modules. Use when writing or reviewing .ps1, .psm1, or .psd1 files; investigating PowerShell PR feedback; designing parameters, output streams, native-command calls, Start-Process or elevation flows, cleanup, locking, file and JSON output, Pester tests, PSScriptAnalyzer checks, or Windows PowerShell 5.1 versus PowerShell 7 compatibility. Also use for PowerShell security and reliability review.

Self-review checklist - plus an agentic review pass (a read-only reviewer persona over the diff) - before opening a PR. Use before invoking `create-pr`, when reviewing your own draft, or when a reviewer flags issues that should have been caught earlier. Codifies recurring mistakes from multi-targeted polyfill work - missing tests for new public surface, unchecked length sums, null-pointer foot-guns from `MemoryMarshal.GetReference` on empty spans, drift from `ArgumentNullException.ThrowIfNull` and `checked()` conventions, TFM phrasing errors, and stale PR descriptions.

Address feedback on an existing pull request - review comments, requested changes, CI failures, or any post-PR follow-up work. Use when the user says "address the review", "fix the comments", "address Copilot's feedback", "fix the CI failure", or any similar phrasing. Distinct from `create-pr`, which covers opening the *initial* PR.

Review changes to AI-agent customization files (AGENTS.md, .github/copilot-instructions.md, *.instructions.md, *.prompt.md, *.agent.md, SKILL.md, the validator, the CI workflow). Use when asked to review or validate agent-file changes, fix CI failures from the agent-files workflow, or audit a draft of any of these files.

Create a pull request for the current changes. Use when asked to "make a PR", "open a pull request", "push and PR", or otherwise publish in-progress work for review. Ensures changes are on a non-`main` branch, commits are made and pushed, and the PR targets `upstream/main` when an `upstream` remote exists, otherwise `origin/main`.

Find, add, update, and share agent skills in this repo. Use when asked to "find a skill" for a task, "build a skill" or "create a skill" (this skill checks whether one already exists - in the repo, the shared commons, or a public catalog - before authoring a new one), "update a skill", or reconcile a local skill change against the upstream commons vs a repo-local overlay. Covers the find-first build path, the tiered search, and the pull/push update flow. Not for validating one agent file's syntax - that is `agent-files-review`.

Author and run BenchmarkDotNet performance tests in a multi-targeted .NET library's perf project, and translate a user's outcome-shaped performance question into a measurement. Use when adding new benchmarks, running existing ones, comparing implementations, profiling to find which method or source line dominates, evaluating allocations / memory usage, reading the generated code (sharplab / DisassemblyDiagnoser / HardwareCounters), or when a user asks how long something takes, how much memory it uses, where time is spent, or to help make a method faster - which this skill turns into a scenario, a benchmark, and a drill-down.

Security-focused review of pending changes. Audit any change that could affect safety or correctness under abusive input or unchecked preconditions - oversized values, malformed structures, integer/length overflow, catastrophic backtracking, allocation pressure, other denial-of-service shapes, and any use of `unsafe` code or the `Unsafe` / `MemoryMarshal` / `Marshal` static helpers (which trade compiler safety guarantees for speed and need extra scrutiny). Add regression tests that pin safe behavior even when the current implementation already handles the input correctly. Use when asked to "assess for security vulnerabilities", "do a security review", "check for ReDoS / DoS", "audit untrusted input handling", or before publishing any change that adds or modifies code that parses, decodes, encodes, compiles, marshals, or reinterprets memory.