Diagnosing Dependabot Alerts Agent Skill

Diagnosing Dependabot Alerts

Investigate a Dependabot/security alert in the Medusa monorepo, identify the exact affected package(s), assess real-world impact, and pick the least-invasive fix. Default output is a diagnosis; only make changes when asked.

Constraints

• Diagnose first, don't default to a fix: Never jump to a root resolutions/overrides bump. Root-level overrides are the LAST resort — see the remediation ladder.
• Root overrides don't ship: resolutions (yarn) / overrides (npm) apply only to THIS repo's install. They are NOT published with packages/*, so they do not protect downstream consumers of a published package. Never present them as a full fix for a vulnerability that reaches a published package.
• Find the fix inside the affected package first: Prefer refreshing/bumping the dependency within the workspace package that owns it (transitive refresh or direct-dep bump) before touching anything at the monorepo root.
• Reachable is not pinnable: A fixed version being resolvable within existing semver ranges (a lockfile float) is weaker than a range that GUARANTEES the fix. Call out the difference — the float can regress for downstream consumers.
• Assess impact, don't assume: Determine whether the vulnerable code path is actually reachable with untrusted input in Medusa before recommending urgency.

Workflow

Follow these steps in order. Load reference/remediation-strategies.md before proposing any fix.

1. Fetch alert details        → gh api (package, versions, scope)
2. Trace to affected package  → walk yarn.lock up to packages/*
3. Assess real impact         → is the vulnerable path reachable?
4. Choose remediation         → remediation ladder (least-invasive first)
5. Verify (only if changing)  → scoped diff, no vulnerable version remains

1. Fetch alert details

The alert number is the last path segment of the URL (.../dependabot/<N>).

gh api repos/medusajs/medusa/dependabot/alerts/<N> | jq '{
  state, package: .dependency.package.name, scope: .dependency.scope,
  relationship: .dependency.relationship, manifest: .dependency.manifest_path,
  ghsa: .security_advisory.ghsa_id, severity: .security_advisory.severity,
  summary: .security_advisory.summary,
  matched_range: .security_vulnerability.vulnerable_version_range,
  first_patched: .security_vulnerability.first_patched_version.identifier,
  all_ranges: [.security_advisory.vulnerabilities[] | {range: .vulnerable_version_range, patched: .first_patched_version.identifier}]
}'

Record: the vulnerable package name, every {vulnerable range → first patched} pair, and whether the alert is direct or transitive.

2. Trace to the exact affected Medusa package(s)

Find which version(s) are actually installed and walk up the dependency chain to the workspace package(s) under packages/ that own the dependency. See reference/remediation-strategies.md for the full tracing recipe. In short:

• grep -n "<pkg>@npm" yarn.lock — list installed versions; confirm which match the vulnerable range.
• Walk up dependents (grep the version string as a dependency of other lock entries) until you reach a package declared in a packages/*/package.json.
• For that workspace package, determine:
• Direct vs transitive — is <pkg> (or the nearest ancestor) in its dependencies/devDependencies, or purely transitive?
• Ships or not — private: false means it publishes; a runtime dependencies entry ships to consumers. devDependencies and private: true do not.
• Runtime-reachable — is the ancestor actually imported in src/ (runtime), or only used at build/test time?

The "affected package" is the workspace package whose manifest declares the dependency (or the nearest ancestor that does).

3. Assess real impact

Before recommending urgency, check whether the vulnerable code path is reachable with untrusted input in Medusa. Example from a past alert: immutable prototype pollution reached us only through @graphql-codegen/typescript, used to generate types from Medusa's OWN internal GraphQL schema — no untrusted input, so practical exploitability was negligible. State the impact explicitly; it changes how aggressive the fix needs to be.

4. Choose remediation (least-invasive first)

Load reference/remediation-strategies.md now. Apply the ladder in order and stop at the first tier that works without breaking changes:

| Tier | Fix | Scope | Ships to consumers? |

|------|-----|-------|---------------------|

| 1a | In-range transitive refresh (lockfile only) | affected pkg's tree | reflects fresh installs |

| 1b | Bump the direct dep the affected pkg declares | affected pkg's package.json | yes (enforced) |

| 2 | Root resolutions/overrides | this repo only | NO — last resort |

• Prefer 1a when a fixed version is reachable within existing ranges and introduces no breaking changes (fastest, no manifest change).
• Use 1b when the fix is only *guaranteed* by bumping the declared dep — check breaking changes (major bump, peerDeps, changed API usage) per the reference file.
• Use 2 only when no in-package option exists; always state that it does not protect downstream consumers of published packages.

5. Verify (only when making changes)

• git diff --stat — confirm the change is scoped (only yarn.lock, plus package.json if you bumped a direct dep).
• Confirm NO version matching the vulnerable range remains in yarn.lock.
• Confirm the diff touches only the vulnerable package's dependency neighborhood — no unrelated churn.
• If a direct dep was bumped: build/typecheck the affected package and exercise its use of the dependency.

Reference Files Available

reference/remediation-strategies.md  - Tracing recipe, semver reachable-vs-pinnable
                                        analysis, per-tier commands, breaking-change checks

Common Mistakes Checklist

Verify you're NOT doing these:

• [ ] Adding a root resolutions/overrides entry as the first (or only) fix
• [ ] Presenting a root override as protecting downstream consumers of a published package
• [ ] Treating a lockfile float ("reachable") as a guaranteed fix ("pinnable")
• [ ] Skipping the trace and not naming the exact affected packages/* package(s)
• [ ] Recommending a major-version bump without checking breaking changes / peerDeps / actual usage
• [ ] Reporting urgency without checking whether the vulnerable path is reachable in Medusa
• [ ] Making changes when only a diagnosis was requested