Starlog

Vet a package before your AI coding agent uses it — authoritative facts (CVEs, license, maintenance), free, local, no account.

An AI coding agent vetting a package through the Starlog MCP server — pulling its known incidents, license, and maintenance before using it

Vet a package in one command — nothing to install, no API key, no account:

npx starloghq facts ua-parser-js

Then wire it into your coding agent (Claude Code, Cursor, Copilot, Codex):

npx starloghq init

Source-available under BUSL-1.1 — free to use, modify, and self-host; converts to Apache-2.0 in 2030. Details ↓

Why

AI coding agents (Claude Code, Cursor, Copilot) pick libraries from training recall — a snapshot of scraped code, frozen at a cutoff date and ranked by how often an option appeared, not by what fits your task or what's safe now. That recall can't know about a CVE disclosed last week, and it has never seen your company's internal libraries. The agent recommends anyway, with the same confidence either way.

The failure modes are measurable: research finds ~49% of AI-suggested dependencies carry known vulnerabilities and ~34% are hallucinated outright — the package doesn't exist. And for whole categories — most dangerously auth — agents default to hand-rolling custom code instead of reaching for a vetted library.

You can't fix recall by prompting harder. Starlog puts authoritative, dated facts in front of your agent at decision time. Its hero surface is vetting by name — starlog facts <package> returns known CVEs/incidents, SPDX license + risk, and maintenance status (or an honest "no facts on file") — so the install/avoid/pick call rides on facts, not recall. It runs entirely on your machine as an MCP server and a package-install hook, no API key, no sign-up. A companion starlog_search finds candidate packages for a capability; facts vet the pick.

Does it actually change what the agent decides? Yes — measured before/after, on the venue that matters (private libraries and post-cutoff advisories). → the validated result.

What you get

• starlog_facts MCP tool — your agent looks up authoritative facts about a specific package before recommending it: known CVEs/supply-chain incidents, SPDX license and license risk, maintenance status (active/deprecated/abandoned/compromised), and effect surface. In a 4-model benchmark, agents called this tool unprompted on package decisions (100% recall, 98% specificity) and it moved them toward the correct install/avoid/pick call. Every record is sourced, verified, and dated — each result shows an "as of <date>" line so a stale "no known vulns" is never mistaken for a fresh one. A package with no record returns an honest "no facts on file." Facts are three independent layers, composed at query time: L1 capability/effect-surface (immutable), L2 reputation/vuln/license/maintenance (mutable — carries the as of recency), L3 org policy (your suitability verdict). Override or extend any layer locally: point STARLOG_PRIVATE_FACTS at a JSON file with independent l1/l2 arrays (internal packages, license rulings) and STARLOG_POLICY at an org policy ({ org, rules }) for allow/deny/flag verdicts. With STARLOG_API_KEY set, org-private overlays and policy come from the hosted facts API (local corpus is the offline fallback); starlog facts push uploads your org's overlays + policy. See docs/FACTS-CONTRACT.md.
• Package-install hook — fires the moment your agent runs npm install / pnpm add / yarn add / pip install and surfaces that package's facts (known incidents, license, maintenance) before the agent builds on it. Advisory — it informs the next move, it doesn't block the install. Packages with no record are queued for coverage.
• starlog_search MCP tool — discovery: find candidate packages for a capability (org-sanctioned options first), then vet the named pick with starlog_facts. Discovery surfaces what exists; facts vet it.
• starlog_advise MCP tool — when your agent sees DIY or repeated capability code, advises MIGRATE to a safe library (e.g. Clerk/Auth0/Supabase over DIY auth) or PACKAGEIZE only when no safe corpus alternative exists. Tracks patterns in .starlog/patterns.json.
• starlog facts / starlog search / starlog advise / starlog patterns CLI — the same facts, discovery, and migrate-or-packageize advisories from your terminal.
• Runs on your machine — the engine and corpus are local; the default (keyless) path needs no account, no API key, and no network. Setting STARLOG_API_KEY opts into the hosted facts/search tiers (with local fallback) — get a key at starlog.dev and wire it with starlog init --api-key <key>; anonymous, opt-out usage telemetry is the only thing sent otherwise — see Telemetry.

This repo ships the engine plus a curated facts corpus and a discovery corpus of 26 capability manifests across 7 categories (including authentication playbooks for migration).

Quick start

npx starloghq init

This wires Starlog into Claude Code (and drops instruction files for Cursor, Copilot, Codex):

• MCP server added to ~/.claude/settings.json — exposes starlog_facts (vet a package by name), starlog_search (discover candidates), and starlog_advise (migrate-or-packageize for DIY patterns), and wires your per-project private overlays (${CLAUDE_PROJECT_DIR}/.starlog/*) into the agent so internal-package facts + discovery work automatically in each project
• PostToolUse hook installed — surfaces a package's facts on install
• Previews every change and asks before writing; idempotent and safe to re-run

Prefer a bare starlog command over typing npx? Install it globally:

npm install -g starloghq
starlog init

If starlog then reports command not found, your npm global bin directory isn't on your PATH (a common npm setup gap — not a Starlog issue). Either run export PATH="$(npm prefix -g)/bin:$PATH" (add it to your shell profile to persist), or just keep using npx starloghq init / npx starloghq facts <pkg>, which always work without any PATH setup. If the install itself printed an EACCES/permission error, it didn't complete — fix your npm prefix or use npx.

Add --project to also drop Starlog guidance into your project's CLAUDE.md; preview without writing, or remove cleanly:

starlog init --project
starlog init --dry-run
starlog init --uninstall

Onboard a whole org at once

Don't hand-author facts for every internal repo — point Starlog at a directory of checkouts and it derives them in one pass:

starlog org sync ~/code/my-org

For each published package it finds (npm package.json and Python pyproject.toml), it derives:

• L2 facts → .starlog/private-facts.json — license + license risk (from the manifest, or detected from the LICENSE file), maintenance from git last-commit recency, stamped source: analyzer with a dated as of. Your agent vets these by name.
• Discovery corpus → .starlog/private-corpus.json — captures each manifest's description + keywords so your agent can find internal packages by capability via starlog_search, not just vet them by name.
• Suggested policy → .starlog/policy.suggested.json — flag candidates (e.g. strong-copyleft, no declared license) derived from the signals. These are proposals the agent does not read — review them, then adopt the ones you trust with starlog facts policy <pkg> flag.

Source never leaves your machine; only derived facts are written. Re-run anytime to refresh (it merges over existing facts and regenerates suggestions). Repos with no published name — or no description — are reported, never fabricated. Known-vulnerability scanning and remote GitHub-org enumeration are on the roadmap.

From source

git clone https://github.com/starloghq/index.git starlog-index
cd starlog-index && npm install
npx tsx src/cli.ts facts ua-parser-js

Manual MCP setup

starlog init writes this for you automatically. To configure by hand, add to ~/.claude/settings.json:

{
  "mcpServers": {
    "starlog": {
      "command": "npx",
      "args": ["-y", "starloghq", "mcp"]
    }
  }
}

This is the same launch command MCP registries use. (From a local source clone instead, point node at dist/mcp.js — $(npm root -g)/starloghq/dist/mcp.js for a global install, or your clone's path.) The server exposes two tools: starlog_facts (an authoritative per-package fact lookup — CVEs, license, maintenance) and starlog_search (a natural-language capability query with optional category, stack, and top_k filters).

CLI usage

Vet a package by name — the hero. Local, no key, no network:

starlog facts ua-parser-js

## ua-parser-js (npm)
**Effect surface:** Parses User-Agent strings; pure data transformation, in-process.
**Capabilities:** parsing
**Maintenance:** active
**License:** MIT (risk: none)
**Known vulnerabilities / incidents:**
  - INCIDENT:ua-parser-js-2021 [critical] affected: 0.7.29, 0.8.0, 1.0.0 — Maintainer account hijacked (Oct 2021); these versions shipped a password stealer and cryptominer. Treat installs as account-compromise.
**Transitive risk:** Frequently a transitive dep — pin away from the three bad versions.
**Source:** GitHub Security Advisory; CISA alert Oct 2021 (hand)
**Verified:** as of 2026-06-01

A package with no record returns an honest "No facts on file" — not a guess. Add --format json for machine-readable output with the independent l1 / l2 / l3 layers.

Discover candidates for a capability, then vet the named pick with facts:

starlog search "auth for a Next.js app"

#   Library             Category          Score   Solves
--------------------------------------------------------------------------------
1   Auth0 Next.js SDK   authentication    71.36   Implements user authentication in Next.js applications using Auth0 ...
2   Clerk               authentication    60.64   Provides a fully managed authentication and user management platfor...

Search ranks locally with the keyword ranker — scores are absolute (a strong match lands in the 70s–80s), so a query outside the indexed categories returns "no strong match" rather than a confident wrong answer. Keyless, the candidate set is the bundled corpus (no network). With STARLOG_API_KEY set, candidates come from the hosted full corpus (api.starlog.dev/search) and are ranked by the same local engine — so a key widens what can be found, never how it's scored; any hosted hiccup silently falls back to the bundled corpus.

--category <cat>    Filter by category (authentication, feature-flags, etc.)
--stack <stack>     Filter by stack affinity (e.g., "next.js", "python")
--top-k <n>         Number of results (default: 5)
--format <type>     Output format: table or json
--context <desc>    Project context to tailor the "vs custom" rationale

Your internal packages — the hero case, in two commands

The model structurally can't know your private @acme/* packages exist — so this is where facts change the most decisions (DIY → the org's sanctioned library). You don't hand-write JSON; two commands author the overlays, and starlog init already wired the agent to read them per-project:

# Make it discoverable — search will surface it (private-first) for a capability:
starlog corpus add @acme/flags --solves "Feature flags + remote config for Acme Node services" \
    --category feature-flags --stack node --best-for "gradual rollout,kill switches"

# Make it vet clean — facts confirms it's active/maintained:
starlog facts add @acme/flags --status active --license MIT

These write .starlog/private-corpus.json (discovery) and .starlog/private-facts.json (vetting) in your project. Because starlog init bakes ${CLAUDE_PROJECT_DIR}/.starlog/* into the MCP server's env, your coding agent picks them up automatically in that project — no shell export, nothing to re-run. Confirm with starlog doctor (it reports the wiring and what each project has authored). For richer overlays — full l1/l2 arrays, org STARLOG_POLICY allow/deny verdicts, or pushing to the hosted API with starlog facts push — see docs/FACTS-CONTRACT.md.

How it works

Starlog vets a package as three independent layers, composed at query time — never collapsed into one blurry "score":

starlog facts <pkg> composes the three for the caller and returns them — or an honest miss — over the MCP server, the CLI, or the install hook. The corpus is local and cacheable; override or extend any layer with STARLOG_PRIVATE_FACTS (internal packages, license rulings) and STARLOG_POLICY. The full contract: docs/FACTS-CONTRACT.md.

Discovery (starlog_search) is a separate surface: it ranks capability manifests against each library's solves / best_for / stack_affinity with a local keyword ranker, reporting an absolute score so an out-of-corpus query returns "no strong match" instead of a forced result. The candidate set is the bundled corpus, or — with STARLOG_API_KEY set — the hosted full corpus, ranked by the same local engine either way. When your agent installs a package with no manifest yet, the hook queues it (.starlog/pending.json) for coverage.

For the full picture — surfaces, engine, data sources, and what telemetry leaves the machine — see docs/ARCHITECTURE.md (with diagrams).

Does it change the agent's decision?

The real test of a facts tool isn't "does it return data" — it's "does the agent decide differently." Measured before/after (control = recall only; treatment = same prompt + Starlog facts):

• Private packages (the hero case): given an informational-only fact that an active internal library exists — no "you must use it" — the agent stops hand-rolling and picks the internal library. 2/2, DIY → internal, on information alone. The model structurally can't recall your private @acme/* packages; facts are how it learns they exist.
• Post-cutoff supply chain: for posthog-node, facts add "pin away from the malicious 4.18.1 / 5.11.3 / 5.13.3" — advisory MAL-2025-190925, published after the model's training cutoff. It can't know this; the facts can.
• No spurious flips: healthy decoys (zod, fastify) don't change, and node-cache (ambiguous, no ground truth) is deliberately not counted as a win — a tool that books every change as a victory is lying to you.

Backed by a powered benchmark across four model vendors: correct adopt/avoid decisions moved ~20% → ~78%, with 100% unprompted adoption.

Full before/after, the honest scope, and the experiment we threw out → docs/VALIDATION.md.

Coverage

Facts corpus — 42 packages. Curated and dated: known supply-chain incidents (xz, event-stream, ua-parser-js, node-ipc, …), notable deprecations, and clean baselines — each with SPDX license + risk, maintenance status, and an as of date. Extend it for your org via STARLOG_PRIVATE_FACTS (internal packages) without touching the public set.

Discovery corpus — 25 capability manifests across 7 categories:

Note: facts and manifest data are point-in-time — sourced and dated, but a decision aid, not ground truth. Verify anything load-bearing; corrections via PR are welcome.

Testing

npx vitest run

Unit and e2e tests cover schema validation, corpus loading + integrity, facts/format output, the spawned-CLI round-trip, and search ranking. All run without API keys or external binaries.

Telemetry

Starlog collects anonymous, opt-out usage analytics to understand which commands, tools, and packages are used. It sends: the command/tool run (init/facts/search/doctor and the starlog_facts/starlog_search MCP tools), the CLI/Node/OS version, detected agents, coarse result counts, the public package names you look up, and your search queries / project context — with emails, secrets/tokens, absolute file paths, and IP addresses scrubbed before send.

It never sends your org-private package names (those are redacted to a boolean when you use a private overlay), your username/hostname, or any file contents. It's also disabled automatically in CI and test runs.

A notice is printed on first run and re-shown whenever the disclosure changes (so a broadened collection can never happen silently). Through the MCP tools, the server includes the disclosure in its first tool result (which your agent relays to you) and only begins recording from the next call — so MCP analytics are never collected before you've been shown what's collected. Opt out at any time:

starlog telemetry disable          # persistent opt-out
starlog telemetry status           # see current state + anonymous id
export STARLOG_TELEMETRY=0         # env opt-out
export DO_NOT_TRACK=1              # honored too
starlog <command> --no-telemetry   # one-off

Links

• Website: starlog.dev

License

Source-available under the Business Source License 1.1 — see LICENSE. Not an OSI open-source license: free to use, modify, and self-host (non-competing use), and it converts to Apache-2.0 on 2030-06-01.