Artifact [c9fc40ba1f]

Artifact c9fc40ba1f60dc698a48c9eb1f0a32ce3daf8c408712389804e15631d70d90e5:

• File repo_sparse.go — part of check-in [774f579bfa] at 2026-10-21 11:44:51 on branch feat/submanifest-reader — feat(sparse): expose narrow-then-compact as Repo.CompactStore and repo cone compact

  The public entry point refuses a dense store, as zit's pack --drop-elided does, and drops exactly the blobs that only out-of-cone F cards name. The test computes that set from the held artifacts, then verifies the store and recovers every dropped payload by widening through SetConeContext. (user: [email protected], size: 2340) [annotate] [blame] [check-ins using]

package libfossil

import (
	"context"
	"errors"
	"fmt"

	"github.com/danmestas/go-libfossil/internal/content"
)

// StoreCone returns the repository's store cone, or nil when the store is
// dense. A store cone (draft-fossil-sparse-cone-00 §5) is local policy: an
// artifact the cone leaves out may be deliberately absent, an elided phantom,
// which synchronization does not request and verification counts apart from
// damage. A cone this version cannot read is lost policy and reads as nil, so
// the store heals toward dense.
func (r *Repo) StoreCone() (*Cone, error) {
	inner, err := content.StoreCone(r.inner.DB())
	if err != nil {
		return nil, fmt.Errorf("libfossil: store cone: %w", err)
	}
	return wrapCone(inner), nil
}

// SetStoreCone replaces the store cone; nil makes the store dense. It moves
// no content. Narrowing deletes nothing (§5.4). Widening makes the newly
// covered elided phantoms wanted again, and the next pull fetches them.
// While a cone is set, a commit carries no R card (§4.3).
func (r *Repo) SetStoreCone(c *Cone) error {
	if err := content.SetStoreCone(r.inner.DB(), unwrapCone(c)); err != nil {
		return fmt.Errorf("libfossil: set store cone: %w", err)
	}
	return nil
}

// ErrNoStoreCone is returned by CompactStore on a dense store: with no cone
// on record nothing is elided, and compaction never guesses a policy.
var ErrNoStoreCone = errors.New("libfossil: the store has no cone")

// CompactStore is the narrow-then-compact deletion (§5.4), the only one the
// sparse draft defines: it turns held blobs that only out-of-cone F cards name
// into elided phantoms and returns how many it dropped. Structural artifacts,
// sub-manifest nodes whose cards prove an elision, unsent or private content
// and the delta bases of retained artifacts stay held. A later widening
// fetches the dropped blobs again; it is not reversible locally.
func (r *Repo) CompactStore(ctx context.Context) (int, error) {
	if ctx == nil {
		panic("libfossil.Repo.CompactStore: nil context")
	}
	c, err := content.StoreCone(r.inner.DB())
	if err != nil {
		return 0, fmt.Errorf("libfossil: compact store: %w", err)
	}
	if c == nil {
		return 0, ErrNoStoreCone
	}
	n, err := content.CompactStore(ctx, r.inner.DB())
	if err != nil {
		return 0, fmt.Errorf("libfossil: compact store: %w", err)
	}
	return n, nil
}