jylhis-skills

Spawn the `explorer` subagent to answer a "where is X / how does Y work" question across the codebase, read-only.

Show which language servers shipped by jylhis-skills are reachable, and which Nix packages they would fetch on first use.

Diagnose a bug end-to-end without speculative fixes. Use when a test is failing, behavior is wrong, a stack trace needs interpretation, or production logs point at an unclear cause. Drives reproduce → minimize → hypothesize → instrument → fix → regression-test. May propose a fix; the caller decides whether to apply it.

Locate code, trace symbols, and answer "where is X defined / which files reference Y" questions across an unfamiliar codebase. Use for breadth-first surveys of a repo, mapping module boundaries, and finding existing patterns before adding new ones. Read-only — never modifies files.

Review pull requests, branches, and local diffs for correctness, regressions, missing tests, security issues, and risky migrations. Use when asked to review code, audit a diff, or prepare blocking/non-blocking review feedback. Read-only — never modifies files.

Use for Emacs and Emacs Lisp work — modern Elisp conventions (lexical-binding, use-package, keymap-set, setopt, defvar-keymap, if-let*, tree-sitter ts-mode), authoring major modes (define-derived-mode, font-lock, indent-line-function, syntax tables, treesit-simple-indent-rules), package publishing (MELPA / GNU ELPA / NonGNU ELPA, ;;;###autoload, package-lint, checkdoc), code review (linting, byte-compile, obsolete API detection), ERT testing, debugging (--debug-init, Edebug, profiler, native-comp), gptel + MCP integration, introspection (describe-*, apropos, find-function), and keybinding design (keymap layers, key-valid-p). Read the matching reference before acting.

Use for low-level filesystem topics on macOS, Linux, and NixOS — APFS (clonefile, copy-on-write, Spotlight exclusion, Time Machine snapshots, /nix synthetic mounts, dedicated APFS volumes), Btrfs (flat subvolume layout, impermanence + erase-your-darlings root rollback, compress=zstd, NOCOW vs SQLite WAL, bees deduplication, cross-subvolume reflinks), and ZFS / OpenZFS (pool / dataset layout, recordsize, ashift, compression, ARC sizing, block cloning, mirrors vs RAIDZ, sanoid / syncoid replication, NixOS generations + ZFS snapshots). Read the matching reference before recommending filesystem changes.

Use for GitLab work — CI/CD pipeline configuration in `.gitlab-ci.yml` (pipeline templates, downstream pipelines, Docker builds, caching strategies, CI/CD components, runner config, artifacts vs cache, pipeline inputs, duplicate pipeline traps) and the `glab` CLI for terminal-based GitLab workflows (merge requests, issues, epics, work items, comments, Quick Actions, GitLab API queries, inline review comments). Read the matching reference before editing pipelines or running glab.

Use for modern Go work keyed to the project's Go version — `any` over `interface{}`, errors.Is / errors.Join, slices / maps / cmp packages (Contains, Index, SortFunc, Sorted, Collect, Clone, Copy, Keys, Values), sync.OnceFunc / OnceValue, context.AfterFunc / WithCancelCause, atomic.Bool / Int64 / Pointer[T], `for i := range n` loops, cmp.Or, http.ServeMux method-and-path patterns + r.PathValue, t.Context() in tests, omitzero JSON tags, b.Loop() benchmarks, strings.SplitSeq / FieldsSeq iterators, sync.WaitGroup wg.Go(fn), errors.AsType[T], `new(value)` pointer expressions. Read the matching reference before reviewing Go code for outdated patterns.

Use for JVM build, packaging, and testing — Gradle 8.10+ with Kotlin DSL, libs.versions.toml version catalogs, java/kotlin toolchains, convention plugins (buildSrc / build-logic), configuration cache + parallel builds; publishing libraries to Maven Central via maven-publish + nmcp + JReleaser, signing with useInMemoryPgpKeys, JPMS module-info, GitHub Actions release-on-tag; testing with JUnit 5 (Jupiter), AssertJ, kotest (Kotlin), mockk / mockito, Testcontainers, JaCoCo, awaitility. Read the matching reference before acting.

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