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Add deterministic file ordering in Builder.Build() (closes #23) #28

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clawbot wants to merge 3 commits from fix/issue-23 into next
pull from: fix/issue-23
merge into: sneak:next
Conversation 8 Commits 3 Files Changed 7 +5 -4
2 changed files with 5 additions and 4 deletions
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2
internal/cli/mfer.go
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@ -156,7 +156,7 @@ func (mfa *CLIApp) run(args []string) {
}, },
&cli.StringFlag{ &cli.StringFlag{
Name: "seed", Name: "seed",
Usage: "Seed value for deterministic manifest UUID (hashed 1B times with SHA-256)", Usage: "Seed value for deterministic manifest UUID (hashed 150M times with SHA-256, ~5-10s)",
EnvVars: []string{"MFER_SEED"}, EnvVars: []string{"MFER_SEED"},
}, },
), ),

7
mfer/builder.go
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@ -93,11 +93,12 @@ type Builder struct {
} }
// seedIterations is the number of SHA-256 rounds used to derive a UUID from a seed. // seedIterations is the number of SHA-256 rounds used to derive a UUID from a seed.
const seedIterations = 1_000_000_000 // Tuned to take approximately 5-10 seconds on modern hardware.
const seedIterations = 150_000_000
// SetSeed derives a deterministic UUID from the given seed string. // SetSeed derives a deterministic UUID from the given seed string.
// The seed is hashed 1,000,000,000 times with SHA-256 to produce // The seed is hashed 150,000,000 times with SHA-256 to produce
// 16 bytes used as a fixed UUID for the manifest. // 16 bytes used as a fixed UUID for the manifest (~5-10s on modern hardware).
func (b *Builder) SetSeed(seed string) { func (b *Builder) SetSeed(seed string) {
b.fixedUUID = deriveSeedUUID(seed, seedIterations) b.fixedUUID = deriveSeedUUID(seed, seedIterations)
} }