Allow absent version headers below structural controls

docs/config.md

@@ -334,6 +334,10 @@ declaration is accepted by the consumer's checker; it does not establish that
 each fragment conforms to a complete application schema. Final assembled
 decoding and application validation still run once.
 
+A header that is absent below a structural control follows the same omission
+policy. Actual header/control overlap is rejected, and ordinary structural
+validation and main-version ownership protection continue independently.
+
 Accepted non-main declarations are consumed from their owned payload before
 composition; their authored ancestors remain, even if empty. The main
 declaration remains in the application. Ordinary release metadata should use a

docs/roadmap/implementation.md

@@ -707,3 +707,14 @@ classification. Focused source-version/sensitivity/history tests,
 `GOTOOLCHAIN=local GOPROXY=off go test -race ./...` passed on
 `go1.26.9 linux/amd64`. Existing historical/dependency propagation and neighboring
 public-value coverage remain green; no new sensitivity policy was introduced.
+
+Additional remediation regressions protect import opt-in
+(`TestFacadeSourceVersionModesPreserveImportOptIn`), complete absence paths
+(`TestSourceVersionAbsentPathKeepsUnresolvedSegmentIntent` and
+`TestFacadeSourceVersionAbsenceKeepsCompleteEvidencePath`), and optional missing
+headers below controls
+(`TestFacadeSourceVersionMissingHeaderDoesNotOverlapControl`). Each failed
+before its production correction and passes afterward. All four independent
+review probes, the final everyday check, and the full race suite now pass on
+`go1.26.9 linux/amd64`. The remediation record contains completion evidence;
+the agreed source-version policy and release gates are unchanged.

docs/roadmap/remediation.md

@@ -158,7 +158,8 @@ state. Main's local header is retained, accepted non-main headers are removed
 before placement/composition, and the destination-prefixed main rule reaches
 payload protection and typed conversion. Warnings, raw accounting, source
 contexts, and final loading reuse the existing pipeline. Four must-address
-issues remain. Findings 1 and 2 above remain completed historical findings.
+issues were identified and are now resolved below. Findings 1 and 2 above remain
+completed historical findings.
 
 ### 3. Preserve distinct semantic shapes during evidence classification (P1)
 
@@ -304,7 +305,15 @@ Required remediation:
 
 ### 6. Apply structural-overlap rejection only to an actual declaration (P2)
 
-Status: open. This is an unintended strengthening of the agreed restriction.
+Status: complete. Overlap rejection now requires an actually present selected
+declaration. Optional absence proceeds without a non-main checker invocation;
+required absence and malformed controls still fail under their existing rules.
+The public regression failed before the fix and now covers valid inheritance
+in separate mounted scopes, required omission with NoSource main, and invalid
+inheritance controls. Existing present-overlap tests remain green. Focused
+source-version/directive/inheritance tests, the everyday check, and the full
+race suite passed on `go1.26.9 linux/amd64`. The configuration contract clarifies
+the omission boundary. This removes the unintended strengthened restriction.
 
 Affected: `processSourceVersion` in
 [source_version.go](../../internal/engine/source_version.go), lines 197–219 at
@@ -368,3 +377,16 @@ temporary directory.
 
 No production fixes, repository regression tests, dependency updates, or release
 changes were made. Only this findings document was revised.
+
+### Remediation completion validation
+
+All four external review probes now pass against the corrected checkout,
+including both shape-collision acquisition orders. The final everyday check and
+`GOTOOLCHAIN=local GOPROXY=off go test -race ./...` passed on
+`go1.26.9 linux/amd64`. Each new regression was observed failing before its
+corresponding production fix.
+
+The earlier completed Mapping diagnostic regression was rerun successfully, and
+ADR 0011 from `## Date` onward still matches its accepted text at `7248a8b`.
+No findings remain open. No dependencies, source-version policies, or release
+gates changed, and no release was published.

facade_source_version_mode_test.go

@@ -170,6 +170,68 @@ func TestFacadeSourceVersionAbsenceKeepsCompleteEvidencePath(t *testing.T) {
 	}
 }
 
+func TestFacadeSourceVersionMissingHeaderDoesNotOverlapControl(t *testing.T) {
+	t.Parallel()
+	for _, test := range []struct {
+		name     string
+		mode     configkit.SourceVersionMode
+		control  string
+		wantCode configkit.Code
+	}{
+		{"optional omission", configkit.SourceVersionModeIfPresent, "base", ""},
+		{"required omission", configkit.SourceVersionModeRequired, "base", configkit.CodeVersionError},
+		{"invalid control", configkit.SourceVersionModeIfPresent, "true", configkit.CodeInheritanceInvalid},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			main := configkit.Bytes("main", []byte("{}\n"))
+			if test.mode == configkit.SourceVersionModeRequired {
+				main = configkit.NoSource()
+			}
+			checks := 0
+			path := configkit.Keys("entries", "child", "extends", "version")
+			loaded, err := configkit.LoadLayered(configkit.Input{Source: main, Destination: configkit.Keys("main")}, configkit.LayeredOptions[map[string]any]{
+				SourceVersionMode: test.mode,
+				Definition: configkit.Definition[map[string]any]{Version: &configkit.VersionRule{
+					Path: path, Check: func(version configkit.Version, _ *configkit.Validation) error {
+						checks++
+						if version.Present {
+							t.Error("checker received a nonexistent declaration")
+						}
+						return nil
+					},
+				}},
+				Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
+					Source: configkit.Bytes("underlay", []byte("entries:\n  base: {value: good}\n  child: {extends: "+test.control+"}\n")), Destination: configkit.Keys("under"),
+				}}}},
+			})
+			if checks != 1 {
+				t.Errorf("checker ran %d times, want absent main only", checks)
+			}
+			if test.wantCode != "" {
+				var failure *configkit.LoadError
+				if loaded != nil || !errors.As(err, &failure) {
+					t.Fatal("invalid input did not fail safely")
+				}
+				if diagnostics := failure.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != test.wantCode {
+					t.Fatalf("diagnostics=%#v", diagnostics)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			child := loaded.Config["under"].(map[string]any)["entries"].(map[string]any)["child"].(map[string]any)
+			if child["value"] != "good" {
+				t.Fatal("valid sibling inheritance was not applied")
+			}
+			check := loaded.Sources()[1].VersionCheck
+			if check == nil || check.Version.Present || check.Path.String() != path.String() {
+				t.Fatal("optional omission evidence was not retained")
+			}
+		})
+	}
+}
+
 func (reader *sourceVersionModeReader) Read(data []byte) (int, error) {
 	reader.reads++
 	return reader.Reader.Read(data)

internal/engine/source_version.go

@@ -196,7 +196,7 @@ func processSourceVersion(root *document.Node, rule *VersionRule, role sourceVer
 
 	interpreted := interpretVersion(rule, root)
 	evidence.version = interpreted.version
-	if sourceVersionControlOverlap(root, evidence.resolvedPath) {
+	if resolved.present && sourceVersionControlOverlap(root, evidence.resolvedPath) {
 		evidence.redactText()
 		result.payload = nil
 		result.diagnostics = []Diagnostic{sourceVersionOverlapDiagnostic(rule, evidence)}