IDs-LE: The ID That Only Looks Like One

Find every identifier in a document, decode the time inside it, and refuse the ones that cannot be named
UUID · ULID · NanoID · MongoDB ObjectId · Snowflake

Useful? A star or rating is how other developers find it — ★ GitHub · ★ Open VSX · ★ Marketplace

What it does

A support ticket quotes 6a7bb780a1b2c3d4e5f60718 and asks when the record was made. A regex says ObjectId, minted 2026-08-12. It is the front of a git commit hash, and the date is noise that happens to land in a plausible year.

Open a document, run IDs-LE: Extract IDs, and every identifier in it is listed by kind with its line and column, the document's own key path for it, whether it is valid, and — for the six schemes that carry a clock — the instant it was minted, as ISO-8601 UTC. The report opens beside the editor. IDs-LE: Scan Workspace for IDs does the same for every file in a project, and IDs-LE: Scan Folder for IDs for one folder. Works in VS Code and in VS Code–based editors like Cursor and VSCodium (installable from Open VSX).

• Reading a log or a dump — which of these are UUID v7s, and when was each minted?
• Reviewing a config — the placeholder nil UUID that escaped into production
• Before trusting a hex string — whether the document actually says it is an identifier
• Across a project — every file that holds an identifier, and how many, in one table

A run it cannot name honestly is reported with the reason, never dropped. It rewrites nothing.

Install

It refuses rather than guesses

A tool that answers confidently and wrongly is worse than one that stops and names what it needs. So every run this crate will not name is a row in the report with a reason — never a dropped row, never a silent guess.

Some are worth spelling out, because they are the cases a regex gets confidently wrong:

• 5d41402abc4b2a76b9719d911017c592 is an unhyphenated UUID and an MD5 digest. Nothing in a document separates them, so nothing here picks.
• 6a7bb780a1b2c3d4e5f60718 is 24 hex characters. Under _id it is an ObjectId minted on 2026-08-12. Under checksum, or in prose, it is refused — an ObjectId's whole specification is 24 hex characters, so a truncated SHA-1 fits it exactly and only the document can tell them apart.
• 1536886938009600000 under channel_id is a Discord Snowflake at 2026-08-12. Under a bare user_id it is refused, because the Twitter epoch fits too and the document does not say which. Under population it is not a finding at all.

The full table, and the boundaries the tool holds itself to, are in crate/SPEC.md.

The kinds

Two of those kinds need the document's permission. An ObjectId is 24 hex characters and a Snowflake is a large integer; neither carries a version, a variant, a checksum or a restricted alphabet, so neither run can say on its own what it is — a truncated git hash is a structurally perfect ObjectId, and a byte count is a structurally perfect Snowflake. Both are named only where the field's own name ends in id (_id, userId, USER-ID, $oid), and refused as ambiguous_kind otherwise. In a plain-text file, which has no keys at all, neither is ever named.

All eight UUID versions RFC 9562 defines are recognised, and all four variants — ncs, rfc4122, microsoft, future — are reported. A version is only reported under the RFC variant, because in any other layout those four bits are not a version field.

The timestamps

This is the part nobody wants to write twice. Six of these carry a clock, in six unrelated bit layouts, over four different epochs — one of which starts in 1582:

Every one comes back as the same ISO-8601 UTC string, milliseconds always present. UUID v2 is named and not decoded: its clock has its low 32 bits overwritten by a POSIX uid, so it resolves to roughly seven minutes and is not the same claim.

A decode that lands before 1990 or more than a year from now is refused as timestamp_implausible — and the decode is on the row next to the flag, because a refusal that hides its evidence is a verdict a reader cannot check.

Formats

JSON (and JSONC), YAML, TOML, INI (.properties), dotenv, CSV and TSV give each finding a key path — service.requestId, documents.[0]._id, discord.channel_id. Everything else is read as text: the same runs, in the same places, without the key.

The key path is evidence, not decoration. ObjectId and Snowflake are named only under a field the document calls an id, so a run that is named in the .json comes back ambiguous_kind in the .md beside it — same row, same position, same decode, and a reason instead of a name.

Across a folder or a workspace

Extract reads the document you have open. A scan reads many files from disk and gives one report.

• The whole workspace: run IDs-LE: Scan Workspace for IDs from the command palette.
• One folder: right-click it in the Explorer and choose Scan Folder for IDs, or run IDs-LE: Scan Folder for IDs and pick one.

The report opens with a table of every file that holds something, then has a section per file:

# IDs-LE workspace report

`my-project` · 113 file(s) read · 2 named, 3 could not be named

| File | Named | Could not be named |
|---|---|---|
| `lib/transcripts.ts` | 2 | 3 |

## `lib/transcripts.ts` · text (2)

- **55:40** · `019ff344-cc00-7abc-8def-0123456789ab` · uuid · v7 · 2026-08-12T00:00:00.000Z
- **56:24** · `01KZSM9K00ABCDEFGH12345678` · ulid · 2026-08-12T00:00:00.000Z

> 2 file(s) larger than the safety limit were not read.

What a scan reads. Files come from disk, so an unsaved edit is not seen. A file over the safety size, or one that is not UTF-8 text, is left unread. It stops at 5,000 files or 10,000 listed identifiers. The report ends with a line for each thing it left out, so a short report is never mistaken for a clean project.

What it skips, and how to change that. Three switches are on by default, and each can be turned off on its own in Settings:

Two lists adjust the result without turning a switch off. To skip more, add a pattern to scanExcludes. To read something a switch would skip, add it to scanAlwaysInclude:

{
	// Also skip the test fixtures.
	"ids-le.workspace.scanExcludes": ["**/fixtures/**"],
	// Read the vendored code, though the built-in list skips it.
	"ids-le.workspace.scanAlwaysInclude": ["**/vendor/**"]
}

IDs-LE: Open Settings opens all of these in the Settings editor.

What it could not name. Across a project these run to thousands, mostly digests in generated files. So a scan counts them per file in the table and does not list them. ids-le.workspace.scanIncludeRefusals lists each one with its reason, and ids-le.workspace.scanProblemsEnabled also puts them in the Problems panel, where each is a line you can click.

The settings that shape a scan are under Settings.

Positions

Each row leads with the line and column of the identifier:

- **3:13** · `f47ac10b-58cc-4372-a567-0e02b2c3d479` · key `service.id` · v4

Turn ids-le.showPositions off and the same row is:

- `f47ac10b-58cc-4372-a567-0e02b2c3d479` · key `service.id` · v4

Nothing else changes: the same rows, the same counts. The copy on the clipboard is a separate choice, ids-le.clipboardIncludesPositions, so a report can show positions on screen and paste without them. Both apply to a scan as they do to Extract.

Use it from an AI agent

The same engine runs as an MCP server, so an agent can call it directly instead of guessing which hex string is which.

extract_ids(content, format?, filename?, kind?, maxResults?)

It returns the rows the editor renders, refusals included, as data — capped at 500 by default with meta.truncated. It reads no files and makes no network requests. Published as ids-le-mcp on npm and as io.github.nolindnaidoo/ids-le in the MCP registry. It answers exactly as the Rust CLI's server does: one corpus runs against both, and a differential test feeds both thousands of generated documents in every format and compares every answer.

{
  "mcpServers": {
    "ids-le": {
      "command": "npx",
      "args": ["-y", "ids-le-mcp"]
    }
  }
}

echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | npx -y ids-le-mcp

The CLI

The same extraction runs over a whole tree from a terminal or a CI step: a Rust CLI in crate/, sharing one corpus with the extension — crate/fixtures/ — so the two can never read an identifier differently.

ids-le src/                    # a tree, one JSON line per file
ids-le --kind uuid src/        # one scheme; refusals still reported
ids-le --strict src/           # exit 2 on anything that could not be named
ids-le --hidden src/           # include .env
ids-le mcp                     # extract_ids and ids_le_scan over MCP on stdio

Exit codes follow grep — 0 identifiers found, 1 none found, 2 the question was malformed. A refusal does not move the exit code; --strict is how a pipeline turns one into a failure.

Commands

No command is bound to a key by default. Give any of them one under Keyboard Shortcuts in the editor.

Settings

Languages

Twelve languages besides English:

German · Spanish · French · Indonesian · Italian · Japanese · Korean · Portuguese (Brazil) · Russian · Ukrainian · Vietnamese · Chinese (Simplified)

Both halves are covered — the manifest (command titles, setting names and descriptions) and everything shown while the extension runs (notifications, the status bar and the report's headings). A refusal's detail is the engine's English, identical to the CLI's.

Privacy & security

• No network access. The extension never sends data anywhere, and it verifies nothing against a database or an API. The telemetryEnabled setting only writes events to a local Output Channel you can inspect (IDs-LE).
• The MCP server holds the same line. It takes content as an argument and returns data: no filesystem access, no network calls, no telemetry.
• Error notifications redact home directories and credential-shaped fragments.
• One rating prompt, at most twice. On the 3rd successful use the extension asks once whether you would rate it, and once more on the 20th if you chose Later or dismissed it. Don't Ask Again ends it. Setting notificationsLevel to important or silent yourself turns it off. The counts are kept in VS Code's extension storage and nothing is sent anywhere; Rate opens the listing you installed from — the VS Code Marketplace or Open VSX — in your browser.

Documentation

Performance

Median of 7 runs after warmup, on Apple M5 Pro, 24 GB RAM, Node 24.3.0. Inputs are generated by scripts/benchmark.ts rather than checked in, so the sizes above are exactly what was measured. Reproduce with bun run benchmark.

These are machine-specific and are not asserted in CI — a benchmark that gates a build only tells you how busy the runner was.

Testing

189 test cases across 16 files, plus an integration suite that runs in a real VS Code extension host and an end-to-end test that installs the built .vsix into a clean profile.

Generated from a real run — coverage/coverage-summary.json and coverage/test-results.json — by scripts/coverage-readme.js; CI fails if this section drifts. Reproduce with bun run test:coverage, and the case count is the one vitest prints.

More from the LE family

Sixteen single-purpose tools for the work in front of every model. Each ships a Rust CLI and an MCP server. One page: letools.dev

Get it out

• String-LE — Extract every string in a codebase, with its position, so a person can read them
• Numbers-LE — Extract every hardcoded number in a codebase, so a person can check them
• Units-LE — Extract every quantity with its unit, normalized, and refuse the ambiguous ones by name
• Dates-LE — Extract every date and timestamp, and the exact instant each one resolves to
• IDs-LE — Extract every UUID, ULID, NanoID, ObjectId and Snowflake, and decode the time inside
• IPs-LE — Extract every IP address, CIDR block and MAC, normalized and classified by scope
• URLs-LE — Extract every URL in a codebase, with its protocol and exact position
• Paths-LE — Extract every file path in a codebase, and say whether it still points at anything
• Colors-LE — Extract every color in a codebase, and say which ones are not in your palette

Check it

• Regex-LE — Find every regex in a codebase, and report which can be driven into catastrophic backtracking
• Versions-LE — Find where one dependency is constrained differently across a repository's manifests
• i18n-LE — Identify the i18n library a project uses, then audit its catalogs by that library's rules
• Scrape-LE — Check whether a page is scrapeable before the scraper is written, and say when it cannot tell

Guard it

• Secrets-LE — Find hardcoded credentials in a codebase, and never print one into the report
• EnvSync-LE — Compare the dotenv files in a tree, and say which keys are missing from which
• Unicode-LE — Find the Unicode that hides meaning — bidi controls, invisibles, homoglyphs, mixed scripts

Each stands on its own: no shared crate, no published core. Where two of them agree, it is because the same answer was right twice.

Contact — nolindnaidoo.com · GitHub · LinkedIn

Also by nolindnaidoo

Rust — pixelcoords and pixelactions are one loop: pixelcoords answers where, pixelactions acts there. Their own tools, their own voice — not part of the LE family.

• pixelcoords — Freeze your screen, mark regions, get pixel-exact coordinates and crops pixelcoords.dev · crates.io · docs.rs
• pixelactions — Consume human-verified coordinates, perform the interaction, confirm it landed pixelactions.dev · crates.io · docs.rs

License

MIT © nolindnaidoo