pkgwatch/SPEC.md

pkgwatch — declarative package-update watcher/publisher (working name)

Status: design draft, pre-PoC. Captures the design discussion as of 2026-09-11.

Problem

Software not packaged by the distro (Arch/Manjaro here) usually gets installed one of a few ways:

• curl | sh from the vendor's own install script — the classic "trust me, bro." The script and any checksum it embeds share a trust boundary, so it verifies nothing beyond transport corruption.
• Manual download + manual checksum/signature verification, redone by hand every time you want to update. Tedious enough that people stop doing it.
• A distro package (pacman extra, AUR) — trustworthy, but version-lagged behind upstream, and someone else has to maintain the PKGBUILD.

There's no local, low-effort way to say "here's how to fetch and verify package X" once, and have that declaration stay live — checked periodically, re-verified on every new upstream release, and fed into a normal pacman-based workflow without hand-editing a PKGBUILD each time.

Scope

This is a personal tool for a small, curated list of non-critical packages — not a general-purpose supply-chain-security framework. The concrete motivating case: software (especially fast-moving AI/ML tooling) that Manjaro's extra repo lags weeks behind upstream on, where raw AUR or a vendor's curl|sh script are the only faster alternatives today.

Goal: a middle ground — fresher than Manjaro's lag, with real verification where the vendor actually offers something to check, safer than blindly piping an install script to sh.

Non-goals:

• Defending against a fully compromised vendor signing/release pipeline. If upstream's CI or signing key is itself compromised, pkgwatch cannot and does not try to catch that. Tiers 1–3 (below) raise the bar from "trust the domain" to "trust the vendor's actual release process"; they are not a guarantee against that process being subverted.
• Defending against a malicious downgrade specifically. A compromised version-check source reporting an older version as "latest" is a downstream/distro-security problem, out of scope here. (See "post-build version check" below for a related but distinct sanity check — it is not a security control.)
• Supporting an adversarial or multi-user config. The tracked-package list is curated by the one person running the daemon on their own machine; config/state file integrity relies on normal filesystem permissions, not a hardened trust boundary. Key-pinning friction on rotation (see tiers below) is acceptable, even desirable, at this scale — it's a personal, low-volume list, not something that needs to scale painlessly.

Vision

A Rust binary, run as a systemd service (service + timer, periodic not persistent), that:

1. Reads a declarative config of tracked packages — where to check for new versions, how to fetch the artifact, and how to verify it.
2. On each run, checks each tracked package for a new upstream version.
3. If a new version is found, fetches the artifact and runs the verification method declared for that package.
4. If verification succeeds (per the package's trust tier — see below), updates/generates a local PKGBUILD (bump pkgver, refresh sha256sums/signature reference) and rebuilds it into a local pacman repo via makepkg + repo-add.
5. The next pacman -Syu (with the local repo configured) picks up the new version normally — no separate tooling needed on the consuming side.

This is conceptually nvchecker (version checking) + updpkgsums (checksum refresh) + repo-add (local repo publishing), fused into one daemon with a single declarative source of truth, plus an explicit, surfaced trust model that those tools don't provide.

Verification trust tiers

Per the Scope above, the goal is to raise the bar above curl|sh where the vendor gives us something to check — not to build airtight supply-chain defense. The central design problem within that goal: from the install UX, a cryptographically strong verification and a "trust-me-bro" same-domain checksum look identical. The tool's job is to make that difference legible instead of laundering every package into an undifferentiated "verified" bucket.

Tiers, strongest to weakest:

1. Pinned-key signature — GPG/minisign/sigstore-cosign, where the signing key's fingerprint is pinned in our config (not fetched fresh from the vendor each time). Proves authorship, independent of the artifact's own hosting.
2. Build provenance attestation — GitHub/GitLab attestations, SLSA provenance. Ties the artifact to a specific CI run and source commit. Strong, but only as trustworthy as that CI pipeline.
3. Registry-native signing — crates.io, PyPI trusted publishing, npm provenance. Similar strength, scoped to that registry's trust model.
4. Same-origin checksum file — a .sha256/.sha256sum served next to the artifact by the vendor. Proves transport integrity only. If the vendor's server or account is compromised, the attacker controls the artifact and the "verification" in the same move.
5. Checksum embedded in an install script — the classic curl|sh case. The verifier and the thing being verified share a trust boundary.
6. Nothing — bare TLS to a domain, no checksum or signature at all.

Automation posture per tier

This is the load-bearing decision, not just a cosmetic label:

• Tiers 1–3: a passing verification is a real trust signal. Safe to auto-bump, auto-verify, auto-publish unattended.
• Tiers 4–6: a passing "verification" only proves internal consistency of one origin (the checksum and the artifact agree), which tells you nothing about whether that origin was compromised. For these tiers the tool should not treat a pass as "verified, ship it." Instead: treat a version/hash change as a flag-for-human-review event. The value pkgwatch adds at these tiers is diff-and-alert (notice something changed, surface the new hash for a human to look at), not verify-and-trust.

The post-build version sanity check (see Architecture below) runs regardless of tier — it's a correctness gate on the build itself, not part of the trust-tier judgment, and doesn't change this tiering.

Surfacing trust, not just gating on it

• Every tracked package carries an explicit tier + one-line justification (e.g. "minisign, key pinned 2024-03" vs. "same-domain sha256, no independent signer") in a metadata file alongside the generated PKGBUILD — something repo-add/pacman don't touch, but that a human or pkgwatch audit can read.
• pkgwatch audit (or similar) lists all tracked packages sorted worst-tier-first, so weak links don't hide among strong ones in a repo that otherwise looks uniformly trustworthy.

Config schema (draft)

[package.uv]
source = "github-release"
repo = "astral-sh/uv"
asset_pattern = "uv-x86_64-unknown-linux-gnu.tar.gz"

[package.uv.verification]
tier = 4
method = "same-origin-sha256"
checksum_asset_pattern = "uv-x86_64-unknown-linux-gnu.tar.gz.sha256"

# Post-build sanity check — correctness only, not a security control.
# Runs the built binary and confirms it reports the version pkgwatch
# believes it just built; mismatch blocks publish.
[package.uv.sanity_check]
command = "uv --version"
version_regex = 'uv (\d+\.\d+\.\d+)'

# Tier 1 example:
[package.somepkg]
source = "url-with-version-regex"
url = "https://example.com/downloads/"
version_regex = 'somepkg-(\d+\.\d+\.\d+)\.tar\.gz'

[package.somepkg.verification]
tier = 1
method = "minisign"
pinned_key = "RWQ...base64pubkey..."

Open questions on the schema:

• How much of nvchecker's source-type taxonomy (github, gitlab, pypi, crates.io, regex, htmlparser, ...) to reimplement vs. shell out to nvchecker itself for the version-check step and own only the verification + publish pipeline.
• PKGBUILD generation: full Jinja-style templates per package vs. a small fixed set of PKGBUILD "shapes" (single binary tarball, cargo-install, etc.) parameterized by the config.
• Where the local pacman repo lives and how it's registered in pacman.conf (one-time manual setup step vs. something pkgwatch manages).
• Failure/alerting channel for tier 4–6 change events — log only, or a notification hook (this box already has a wofi/Mako notification setup — see project_wofi_notification_picker in Claude's memory).

Architecture sketch

• Config loader: parses the TOML above into an in-memory package list.
• Checker: per source type, resolves "what's the latest version" — likely reuses nvchecker's logic/sources conceptually, possibly shells out to it initially for the PoC rather than reimplementing every source type in Rust.
• Fetcher: downloads the artifact (and any checksum/signature/ attestation companion) for a resolved version.
• Verifier: tier-specific verification implementations behind a common trait; returns a tier + pass/fail + justification string.
• Builder: for tiers 1–3 on pass, generates/updates the PKGBUILD (strict validation on any upstream-controlled string — version, filename — before it touches generated shell content; never unescaped interpolation) and runs makepkg.
• Sanity checker: after a successful build, runs the package's declared sanity_check.command against the built artifact and confirms the reported version matches what pkgwatch believes it just built. Mismatch = fail loud, do not publish. This is a correctness check, not a security control — it catches checker bugs and mangled/wrong-artifact downloads, not malicious releases.
• Publisher: runs repo-add against the local repo, only after the sanity check passes.
• Reviewer queue: for tiers 4–6, records the detected change instead of auto-building; a separate pkgwatch review command lets a human approve/reject, which then triggers the build → sanity-check → publish steps above.
• Scheduling: systemd .service (oneshot) + .timer running it periodically, matching the pattern already used for other periodic tasks on this box.

Prior art / reference points

• nvchecker — version-check-only, no verification or publish step.
• updpkgsums (pacman-contrib/devtools) — checksum refresh only, manual trigger.
• aurutils — local repo + AUR build automation, but AUR itself carries no stronger verification guarantee than what each PKGBUILD maintainer does.
• repology — cross-distro version tracking, no verification/publish.
• GitHub artifact attestations (gh attestation verify) — tier 2 building block for GitHub-hosted releases.

Status / next steps

• Scope decided: personal middle-ground tool for a curated package list, not a general supply-chain-security framework (see Scope above). Downgrade attacks and compromised-vendor-pipeline defense are explicit non-goals.
• Refine config schema further (see open questions above), including the sanity_check block per package.
• Decide version-check strategy: shell out to nvchecker vs. own implementation, for the PoC.
• Implement PKGBUILD generation with strict upstream-string validation from day one (see Builder, above) — cheap to do right up front, expensive to retrofit.
• PoC scope: single tier-4 package (e.g. uv, ironically) end-to-end — check, fetch, same-origin-checksum verify, flag-for-review, manual approve, build, post-build version sanity check, local repo publish.
• Decide on project home: local-only for now, or push to code.austinschaefer.com (Forgejo) once the spec settles.