launch.ParseSemver discards strconv.Atoi's range error (major,_ := ...), and semverRe's numID is unbounded, so a >int64 version component clamps to MaxInt64: distinct oversized versions collide to one String() and the next Patch++ wraps negative — reachable via GitExistingTags (git tag list) and changelog.DeriveNext; the identical defect was already guarded in spec/spec.go

launch.ParseSemver discards strconv.Atoi's range error (major,_ := ...), and semverRe's numID is unbounded, so a >int64 version component clamps to MaxInt64: distinct oversized versions collide to one String() and the next Patch++ wraps negative — reachable via GitExistingTags (git tag list) and changelog.DeriveNext; the identical defect was already guarded in spec/spec.go

Evidence

• internal/core/launch/semver.go — ParseSemver does major, _ := strconv.Atoi(m[1]) (minor/patch likewise), discarding strconv's out-of-range error; semverRe's numID (0|[1-9]\d*) is unbounded and IsStrictSemver shares it, so no upstream cap rejects a 20-digit component. Atoi clamps overflow to MaxInt64: two distinct oversized inputs collide to one String(), and Patch++ wraps to MinInt64 (a negative version).
• Reachable via internal/core/launch/retention.go GitExistingTags (parses git tag) into ComputeRetention, and via internal/core/changelog LatestChangelogVersion into DeriveNext where next.Patch++ overflows.
• The identical Atoi-overflow defect is already guarded one package over in internal/core/spec/spec.go (specNum).

Adversarial review

CONFIRMED (substantive, low-impact end) by an independent refuter: overflow reproduced; both reach paths route through the swallowed error; the fetched-ref threat model the sibling fix names does not exclude git tags / CHANGELOG headings. Fix: have ParseSemver propagate the strconv.Atoi error (both arithmetic consumers already handle a non-nil error).