Youtube Transcript Native Node

YouTube Transcript (Native Node)

Version: 1.1.3 / publishable utility.

Minimal YouTube caption extractor. Native Node.js, zero npm dependencies, wraps the external yt-dlp binary.

Risk / invocation class

Risk class: external binary wrapper / YouTube network access / third-party content.

Use deliberately. This skill does not call a web API directly, but yt-dlp talks to YouTube and the local environment owns the yt-dlp PATH/binary supply-chain trust boundary.

Input packet

Required:

• url: full YouTube URL from the user.
• goal: raw transcript, summary input, quote extraction, timestamped notes, or JSON handoff.
• privacy_sensitivity: normal, private/client, or unknown.
• language: default en unless another language is requested.

Optional:

• timestamps: needed or not.
• json: needed for downstream tool use.
• dedup_preference: default auto-caption rolling-window dedup, or --no-dedup to preserve rolling-window/repeated-phrase artifacts as much as possible. Exact consecutive duplicate cue text may still be collapsed during VTT parsing.
• output_destination: chat summary, saved file, downstream summarizer, etc.

Stop or ask before use if the video/context is private or client-sensitive and sending access to YouTube via yt-dlp is not appropriate.

Output packet

Return compactly:

• source YouTube URL
• language requested and whether timestamps/JSON were used
• transcript status: success, no captions, dependency missing, private/blocked/rate-limited, or failed
• whether captions appear auto-generated when known
• saved path if the transcript was separately written to a file
• concise transcript summary or excerpt, unless the user requested raw text
• caveats and next safe step

Security behavior

• Accepts only http(s) YouTube URLs on youtube.com, www.youtube.com, m.youtube.com, or youtu.be.
• Validates --lang as a simple subtitle language code before invoking yt-dlp.
• Spawns yt-dlp with an argv array and no shell; it does not execute user-provided commands.
• Bounds the subprocess with a 120-second timeout.
• Creates and removes a temporary subtitle directory under the OS temp path.
• Refuses to print transcripts larger than 2,000,000 characters.
• Reads no API keys, env secrets, or credential/config files. Offline regression hooks are inert unless YOUTUBE_TRANSCRIPT_SELFTEST=1 is set by scripts/self-test.mjs; do not set self-test hooks for normal transcript extraction.
• Passes --ignore-config so user-level yt-dlp config does not silently alter wrapper behavior.
• Static-analysis child_process warnings are expected because this skill intentionally wraps trusted yt-dlp.

When to use

Use this when:

• the user provides a YouTube URL and wants spoken text/captions;
• clean plain text is needed for summarization, search, or quoting;
• the video has creator-uploaded subtitles or auto-generated captions.

Do not use this when:

• the user expects actual audio transcription; this extracts existing captions only;
• the platform is not YouTube;
• the video is a live stream that has not ended;
• the video/content is privacy-sensitive and should not be accessed via YouTube/yt-dlp;
• yt-dlp is not installed/on PATH and installing it has not been approved.

Commands

Script: scripts/fetch.mjs

node "<skill-dir>\scripts\fetch.mjs" --url "https://www.youtube.com/watch?v=VIDEO_ID"
node "<skill-dir>\scripts\fetch.mjs" --url "https://www.youtube.com/watch?v=VIDEO_ID" --lang es
node "<skill-dir>\scripts\fetch.mjs" --url "https://www.youtube.com/watch?v=VIDEO_ID" --timestamps
node "<skill-dir>\scripts\fetch.mjs" --url "https://www.youtube.com/watch?v=VIDEO_ID" --json
node "<skill-dir>\scripts\fetch.mjs" --help

For all flags, dedup details, output formats, dependency notes, and troubleshooting, load references/youtube-transcript-contract.md.

Operating guidance

• Pass the full user-provided YouTube URL; do not invent/transform URL forms unnecessarily.
• Default to --lang en unless another language is clear.
• Use default plain text for direct human reading and summaries.
• Use --json as the default structured handoff for research triage, summarization, and downstream tooling.
• Use --timestamps only when timestamped notes, quote traceability, or debugging are needed; it is an advanced/evidence mode, not the recommended default for reading.
• Use --json --timestamps only for machine traceability workflows that need timestamp anchors inside JSON; it is not intended as a human-readable inspection format.
• Save long transcripts to a file when useful; do not paste giant transcripts unless requested.
• Summarize first and quote sparingly by default.
• Respect copyright and platform terms; do not republish long/full transcripts unless the user has rights or permission.
• Note that captions may be auto-generated and imperfect.

Required checks before publishing/updating

Minimum no-video/no-network checks:

node --check skills\youtube-transcript-native-node\scripts\fetch.mjs
node skills\youtube-transcript-native-node\scripts\self-test.mjs
node skills\youtube-transcript-native-node\scripts\fetch.mjs --help
node skills\youtube-transcript-native-node\scripts\fetch.mjs --url "https://example.com/watch?v=not-youtube" --json

The invalid-host smoke should fail before invoking yt-dlp.

Optional environment check:

yt-dlp --version

Do not install/update yt-dlp as part of this skill without explicit approval.

Public registry exposure

Classification: publishable utility with external binary + YouTube access.

Before public update, run sanitizer/static checks and ensure docs clearly disclose:

• yt-dlp dependency and PATH/binary trust boundary;
• YouTube-only URL allowlist;
• no API keys/env secrets/config reads;
• temp-directory behavior and stderr temp-path scrubbing;
• no audio/video download and no audio transcription;
• expected child_process static-analysis warning.
• best-effort scrub of temp- and home-directory paths from the last lines of yt-dlp stderr; unrelated absolute paths emitted by yt-dlp itself may remain.

Respect copyright and platform terms in examples, docs, and outputs: prefer summaries and brief quotes; do not publish long/full third-party transcripts unless rights or permission are clear.

Do not include private/internal/client strategy, operator-specific operational notes, or full third-party transcript samples in a public release.

Changelog

• 1.1.3: Add stubbed offline yt-dlp fixture tests for dependency-missing, nonzero-exit-with-VTT, 429 hint, temp/home path scrubbing, output-size guard, timeout, and output modes; gate self-test hooks behind YOUTUBE_TRANSCRIPT_SELFTEST=1; continue when usable VTT subtitles are produced despite nonzero yt-dlp exit; kill active yt-dlp child on SIGINT/SIGTERM; broaden local-path scrubbing and scrub unexpected/read-error paths.
• 1.1.2: Add offline self-test fixtures, export parser/allowlist helpers for tests, pass --ignore-config, remove subtitle conversion postprocessor to avoid ffmpeg ambiguity, scrub temp path from yt-dlp error tails, and surface 429 retry guidance.
• 1.1.1: Public docs cleanup: normalized input/output packet wording, structured handoff wording, and changelog language; no runtime behavior change.