internal/pkg: populate substitute status

These are not created when taking the fast path, but should be inherited from the alternative.

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

internal/pkg/pkg.go

@@ -1995,10 +1995,11 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 		buf := c.getIdentBuf()
 		sh.Sum(buf[wordSize:wordSize])
 		substitute = unique.Make(ID(buf[wordSize:]))
+		substitutes := Encode(substitute.Value())
 		c.putIdentBuf(buf)
 		alternative = c.base.Append(
 			dirSubstitute,
-			Encode(substitute.Value()),
+			substitutes,
 		)
 
 		if c.flags&CIgnoreSubstitutes == 0 {
@@ -2014,6 +2015,17 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 					dirChecksum,
 					checksums,
 				)
+				if _, err = os.Lstat(c.base.Append(
+					dirStatus,
+					substitutes,
+				).String()); err == nil {
+					err = os.Symlink(substitutes, c.base.Append(
+						dirStatus,
+						ids,
+					).String())
+				} else if errors.Is(err, os.ErrNotExist) {
+					err = nil
+				}
 				return
 			}
 		}
@@ -2023,6 +2035,15 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 			return
 		}
 		err = ca.Cure(&f)
+		if err == nil && f.status != nil {
+			err = os.Link(c.base.Append(
+				dirStatus,
+				ids,
+			).String(), c.base.Append(
+				dirStatus,
+				substitutes,
+			).String())
+		}
 		c.exitCure(a, curesExempt)
 		if err != nil {
 			return