Bring F3 up to K2 on its release branch (part 2 of 3)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/builder/source.go

@@ -58,6 +58,9 @@ type sourceInputs struct {
 	// whole when an artifact's is not known (novox/hq ADR 0267).
 	own      map[string]bool
 	ownIsAll bool
+	// root is the module's build source in its own repository outside its directory, relative to the
+	// repository's root: the list of predefined keys a manifest naming one was judged against (ADR 0348 §7).
+	root map[string]bool
 	// read is, per context (repository and ref), the build source read there; nil for one read whole.
 	read   map[string]map[string]bool
 	readAs map[string]catalogue.ArtifactContext
@@ -86,6 +89,9 @@ func (s *sourceInputs) copy() *sourceInputs {
 	for k, v := range s.own {
 		c.own[k] = v
 	}
+	for k, v := range s.root {
+		c.root[k] = v
+	}
 	for k, v := range s.read {
 		if v == nil {
 			c.read[k] = nil
@@ -112,7 +118,7 @@ func (s *sourceInputs) contextOffHead() {
 
 func newSourceInputs(module string) *sourceInputs {
 	return &sourceInputs{module: module, contexts: map[string]string{}, toolchains: map[string]string{},
-		own: map[string]bool{}, read: map[string]map[string]bool{}, readAs: map[string]catalogue.ArtifactContext{},
+		own: map[string]bool{}, root: map[string]bool{}, read: map[string]map[string]bool{}, readAs: map[string]catalogue.ArtifactContext{},
 		contextsAtHead: true}
 }
 
@@ -126,6 +132,16 @@ func (s *sourceInputs) ownHas(entries ...string) {
 	}
 }
 
+// rootHas adds entries, relative to the repository's root, to the module's build source in its own repository.
+func (s *sourceInputs) rootHas(entries ...string) {
+	if s == nil {
+		return
+	}
+	for _, e := range entries {
+		s.root[e] = true
+	}
+}
+
 // ownWhole says an artifact's build source in the module's own repository is not known: the module's
 // whole directory is its source, as it was before.
 func (s *sourceInputs) ownWhole() {
@@ -178,6 +194,9 @@ func (s *sourceInputs) buildSources() []BuildSource {
 		for e := range s.own {
 			own = append(own, withPrefix(s.prefix, e))
 		}
+		for e := range s.root {
+			own = append(own, e)
+		}
 		sort.Strings(own)
 		out = append(out, BuildSource{Paths: compactSorted(own)})
 	}