# Bengous Agents Skills Effect Language Service Cc > Effect Language Service - Skill: `tomevault-io/bengous-agents-skills-effect-language-service-cc` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/bengous-agents-skills-effect-language-service-cc` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/bengous-agents-skills-effect-language-service-cc/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/bengous-agents-skills-effect-language-service-cc --- # Effect Language Service Operational guide for `@effect/language-service` CLI and configuration. This skill handles **tooling**: running commands, interpreting output, applying fixes, configuring projects. For architecture decisions about when/how to use Effect, see `effect-usage-cc` instead. ## Command Decision Table Always run from the **project root** via the local binary (`bunx effect-language-service` or `./node_modules/.bin/effect-language-service`). Commands like `check` resolve paths relative to cwd — running from a subdirectory breaks them. | Intent | Command | Key flags | |---|---|---| | Check for Effect issues | `diagnostics --project tsconfig.json` | `--format pretty` human, `--format json` parseable | | Check single file | `diagnostics --file ` | Faster than full project scan | | See available fixes | `quickfixes --project tsconfig.json` | `--code ` filter by rule | | Fix specific issue | `quickfixes --file --line --fix ` | Shows diff to apply | | Generate from directives | `codegen --project tsconfig.json` | `--force` regenerates all | | Understand project structure | `overview --project tsconfig.json` | `--max-symbol-depth 2` (depth 3 adds noise) | | Analyze layer composition | `layerinfo --file --name ` | Outputs composition order | | Check TS patch status | `check` | Verifies patch version | | Patch TypeScript for tsc | `patch` | `--force` re-patches | | Interactive setup | `setup` | Wizard for first-time config | | Configure rule severities | `config` | Interactive severity editor | | CI gate | `diagnostics --format github-actions --strict` | Non-zero exit on warnings | ## Interpreting Output ### Diagnostic format ``` src/service.ts:42:3 effect(floatingEffect): This Effect is not yielded or assigned ``` Structure: `file:line:col effect(ruleName): message`. The `ruleName` maps directly to the `diagnosticSeverity` config key in tsconfig.json and to the inline suppression syntax. ### Quickfix format Output: diagnostic line followed by one or more unified diffs per available fix. Each fix has a `fixName` (e.g., `floatingEffect_yieldStar`) that can be used with `--fix` to filter. ### Severity levels - **error** — Must fix. Blocks CI (always non-zero exit) - **warning** — Should fix. Blocks CI only with `--strict` - **message/suggestion** — Informational. Never blocks CI even with `--strict` (emits `::notice` in github-actions format, not `::error`). Only blocks tsc if `includeSuggestionsInTsc` enabled ## Key Workflows ### Fix all issues in a file ```bash # 1. See what's wrong effect-language-service diagnostics --file src/service.ts --format pretty # 2. See available fixes with diffs effect-language-service quickfixes --file src/service.ts # 3. Filter to a specific rule effect-language-service quickfixes --file src/service.ts --code floatingEffect ``` Review the diffs before applying. Correctness fixes (floatingEffect, missingReturnYieldStar) are safe to apply. Style fixes (effectMapVoid, unnecessaryPipe) are preferences — check project conventions. ### Onboard a new project ```bash # 1. Interactive setup (patches TS, configures tsconfig) effect-language-service setup # 2. Persist patch across installs # Add to package.json scripts: "prepare": "effect-language-service patch" # 3. Baseline scan effect-language-service diagnostics --project tsconfig.json --format pretty ``` ### LLM context generation `overview` and `layerinfo` produce text output (no `--format json` — only `diagnostics` supports `--format`). Both emit ANSI spinner noise that must be stripped. **Clean extraction pattern** (use for all text-output commands): ```bash # Strip ANSI codes and spinner lines from any ELS text command els_clean() { effect-language-service "$@" 2>/dev/null \ | sed 's/\x1b\[[0-9;]*m//g' \ | grep -v "^Processing file" } # Project map: services, layers, yieldable errors els_clean overview --project tsconfig.json --max-symbol-depth 2 # Specific layer: provides, requires, composition order els_clean layerinfo --file src/layers.ts --name AppLayer # Full snapshot: overview + diagnostics + quickfixes in one shot els_clean overview --project tsconfig.json --max-symbol-depth 2 > /tmp/els-overview.txt effect-language-service diagnostics --project tsconfig.json --format json > /tmp/els-diag.json els_clean quickfixes --project tsconfig.json > /tmp/els-fixes.txt ``` `overview` groups exports into "Yieldable Errors", "Services", "Layers" with file+line, type info, and JSDoc. **Warning**: each symbol appears at every re-export point (barrel files, index.ts). Deduplicate by source `file:line` — expect ~40% noise from duplicates in large projects. `layerinfo` outputs a suggested `Layer.provide` / `Layer.provideMerge` composition. Requires a **named, exported Layer** — anonymous or inline layers are not supported. Tip: write all layers in `Layer.mergeAll(...)`, run `layerinfo`, use the suggested order. ## Guardrails 1. **Scope your scans** — Use `--file` when working on a single file. Full `--project` scans are slow in large codebases and produce noise from files you're not touching. 2. **Review quickfix diffs** — Correctness fixes are generally safe. Style fixes may conflict with project conventions. Anti-pattern fixes sometimes need manual adjustment. 3. **Monorepo tsconfig** — Always specify `--project` explicitly. Without it, ELS infers the tsconfig which may be wrong in monorepos with multiple configs. 4. **codegen --force caution** — Regenerates ALL directives in the project. Use `--file` to scope to a single file. Manual edits to generated blocks will be overwritten. 5. **Patch persistence** — The TS patch modifies `node_modules/typescript/`. It disappears after `npm install`/`bun install`. Use `"prepare": "effect-language-service patch"` to persist it. 6. **diagnostics vs tsc** — Without patching, `tsc` does NOT run Effect diagnostics. The `diagnostics` CLI command works without patching. The patch is only needed for `tsc` integration and IDE features. 7. **ANSI spinner pollution** — `overview`, `layerinfo`, and `quickfixes` emit ANSI escape codes and "Processing file" spinner lines mixed into stdout. Always pipe through the `els_clean` pattern (strip ANSI + filter spinner) when capturing output programmatically. 8. **--format is diagnostics-only** — Only `diagnostics` supports `--format json|text|pretty|github-actions`. All other commands (`overview`, `layerinfo`, `quickfixes`, `codegen`) output unstructured text. Do not waste time trying `--format` on them. 9. **codegen with no directives** — If no files contain `@effect-codegens`, `codegen` throws `NoFilesToCodegenError` instead of exiting cleanly. This is not a real error — the project simply has no codegen directives. Check before running. 10. **config/setup file picker** — Both `config` and `setup` are interactive and list ALL `.json` files in the project, not just tsconfig files. This is a known UX issue — select the correct tsconfig manually. ## Fetching Documentation This skill covers tooling operations. For current API details or version-specific changes: | Need | Tool | |---|---| | ELS release notes, new rules | `mcp__exa__web_search_exa` — search Effect-TS/language-service | | Effect API docs | `mcp__Context7__query-docs` — resolve `effect` library | | Pattern guidance | Load `effect-usage-cc` skill | ## Navigating References Load references when the command table and workflows above are insufficient. | File | Answers | |---|---| | `references/cli-commands.md` | Full syntax for each command? All flags and defaults? | | `references/diagnostic-rules.md` | What does rule X mean? How to fix it? Default severity? | | `references/refactorings.md` | Which IDE refactoring to use? async→Effect variants? | | `references/codegen-directives.md` | How to use @effect-codegens? When to annotate/accessors/typeToSchema? | | `references/configuration.md` | All tsconfig options? Severity profiles? CI setup? Inline suppression? | !`echo "## ELS Project Context"` !`~/.claude/skills/effect-language-service-cc/scripts/probe-els.sh` --- > Source: [bengous/agents-skills](https://github.com/bengous/agents-skills) — distributed by [TomeVault](https://tomevault.io).