internal/pkg: expose measured reader to extern status

This is always required by the implementation.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/pkg.go

@@ -699,13 +699,13 @@ type External interface {
 	// Artifact returns the address of the [Checksum] of the cure outcome of
 	// an [Artifact] corresponding to id, or nil if this [Artifact] is not
 	// available in the external cache.
-	Artifact(id unique.Handle[ID]) (*Checksum, error)
+	Artifact(ctx context.Context, id unique.Handle[ID]) (*Checksum, error)
 	// Checksum returns an [Artifact] producing the specified checksum.
 	Checksum(checksum unique.Handle[Checksum]) Artifact
 	// Status returns [io.ReadCloser] of the status file of an [Artifact]
 	// corresponding to id, or nil if this [Artifact] is not available or a
 	// status file is not present.
-	Status(id unique.Handle[ID]) (io.ReadCloser, error)
+	Status(r *RContext, id unique.Handle[ID]) (io.ReadCloser, error)
 }
 
 // Cache is a support layer that implementations of [Artifact] can use to store
@@ -1833,7 +1833,7 @@ func (r *RContext) NewMeasuredReader(
 }
 
 // tryExtern attempts to obtain an [Artifact] outcome from extern.
-func (c *Cache) tryExtern(id unique.Handle[ID]) (
+func (c *Cache) tryExtern(ctx context.Context, id unique.Handle[ID]) (
 	unique.Handle[Checksum],
 	io.ReadCloser,
 	error,
@@ -1845,7 +1845,7 @@ func (c *Cache) tryExtern(id unique.Handle[ID]) (
 		return zeroChecksum, nil, nil
 	}
 
-	v, err := c.extern.Artifact(id)
+	v, err := c.extern.Artifact(ctx, id)
 	if err != nil {
 		return zeroChecksum, nil, err
 	}
@@ -1862,7 +1862,7 @@ func (c *Cache) tryExtern(id unique.Handle[ID]) (
 	}
 
 	var status io.ReadCloser
-	status, err = c.extern.Status(id)
+	status, err = c.extern.Status(&RContext{common{ctx, c}}, id)
 	return checksum, status, err
 }
 
@@ -2205,7 +2205,7 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 			externChecksum unique.Handle[Checksum]
 			externStatus   io.ReadCloser
 		)
-		if externChecksum, externStatus, err = c.tryExtern(id); err != nil {
+		if externChecksum, externStatus, err = c.tryExtern(ctx, id); err != nil {
 			if c.msg.IsVerbose() {
 				c.msg.Verbosef("extern %s: %v", reportName(ca, id), err)
 			}