---
name: tsl-api-reference
description: "Use when writing or reviewing TSL code and you need authoritative TSL API facts: builtin functions, dotnet functions, module APIs, exact signatures, parameters, return values, examples, or Chinese keyword discovery when the function name is unknown."
---

# TSL API Reference

## Overview

Use the bundled API index and markdown references in this skill instead of
guessing from similar languages. The API index is `data/function_index.tsv`
with `name / scope / module / signature / page / anchor / summary`; the full
entries live under `references/codegen/`.

This skill is for API facts only. For TSL syntax, variables, control flow,
object model, and runtime language rules, use the TSL syntax documentation or a
future `tsl-syntax-reference` skill.

## Procedure

Use this skill's bundled lookup script. In the commands below,
`<this-skill-dir>` means the directory containing this `SKILL.md`; replace it
with the actual skill directory before running.

The script resolves bundled `data/` and `references/` relative to its own file.

1. If the function name is known, run exact lookup:

   ```bash
   python <this-skill-dir>/scripts/lookup.py --name argmax
   ```

   Use the returned entry body for the exact signature, parameters, return
   value, examples, and source location.

2. If only the intended behavior is known, run keyword discovery:

   ```bash
   python <this-skill-dir>/scripts/lookup.py --kw 数组 排序
   ```

   Terms are matched with AND semantics over `name`, `signature`, `module`, and
   `summary`. Pick a candidate, then run `--name` for the complete entry.

3. Use `--limit N` when keyword discovery returns too many rows.

4. Use `--tsv /abs/path/function_index.tsv` only when testing or overriding the
   bundled index. The normal installed skill is self-contained and does not
   require the full playbook repository.

## Output Contract

- Exact mode prints each matching markdown entry body plus its
  `scope/module · page#anchor` source marker.
- Keyword mode prints `# N matches`, then
  `name / signature / page#anchor / summary` rows.

## Failure Handling

- If exact lookup has no match, retry with Chinese keywords.
- If keyword lookup is too broad, add more terms or lower/raise `--limit`.
- If bundled data is missing, reinstall the skill or pass `--tsv` for debugging.
- If summaries or index.md counts look stale in an installed skill, reinstall
  it. An installed skill is a read-only snapshot: it ships only `lookup.py`, not
  the index generator, so it cannot and need not rebuild anything locally.
- Rebuilding the index is a playbook-repository maintenance step, not a skill
  operation. Only when developing inside the playbook repo, after editing API
  markdown, rebuild the tsv and every `index.md` by running (from the repo root)
  `python scripts/tsl_codegen_function_index.py`. The leaf pages are the source
  of truth; the tsv and all index pages are derived. Use `--check` to verify
  they are in sync without writing (exits non-zero when stale).