diff --git a/docs/roadmap/implementation.md b/docs/roadmap/implementation.md
index 07215e8..44cc575 100644
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -1,6 +1,6 @@
 # Implement PromptKit comparison and catalogs
 
-Status: Stages 1–5 complete; remaining stages are planned.
+Status: Stages 1–6 complete; remaining stages are planned.
 
 ## Scope and authority
 
@@ -369,6 +369,19 @@ in Stage 8 once helpers are wired. Test decoded types, fields, sequence order,
 and empty inventories; incidental quoting style, private names, and indentation
 are not new contracts.
 
+**Completion evidence (2026-10-12)**
+
+- Added private YAML encoders that map native prompt identities to entries with
+  explicit string `id` and `version` fields and encode profile IDs as a bare
+  string sequence. Both return fully prepared bytes using the existing YAML
+  encoder; nil and allocated empty catalogs normalize to empty sequences.
+- Unit coverage decodes prompt entries and profile values to check field names,
+  string types, order, duplicates, whitespace, and numeric-looking values. Nil
+  and allocated empty inputs both encode as `[]`.
+- `GOTOOLCHAIN=local go test -count=1 .` passed in `integrations/ckprompt`.
+  Command-boundary schema coverage remains assigned to Stage 8; command wiring
+  and delivery remain assigned to Stage 7.
+
 ## Stage 7: Assemble and execute independent catalog commands
 
 **Outcome:** catalog commands and optional named-show commands share existing
diff --git a/integrations/ckprompt/command.go b/integrations/ckprompt/command.go
index f9a9849..0f8b1d1 100644
--- a/integrations/ckprompt/command.go
+++ b/integrations/ckprompt/command.go
@@ -322,6 +322,34 @@ func encodePromptYAML(writer io.Writer, value any) error {
 	return encoder.Encode(value)
 }
 
+type promptCatalogEntry struct {
+	ID      string `yaml:"id"`
+	Version string `yaml:"version"`
+}
+
+func encodePromptCatalog(prompts []promptkit.PromptIdentity) ([]byte, error) {
+	entries := make([]promptCatalogEntry, len(prompts))
+	for index, prompt := range prompts {
+		entries[index] = promptCatalogEntry{ID: prompt.ID, Version: prompt.Version}
+	}
+	return encodePromptYAMLBytes(entries)
+}
+
+func encodeProfileCatalog(profiles []string) ([]byte, error) {
+	if profiles == nil {
+		profiles = []string{}
+	}
+	return encodePromptYAMLBytes(profiles)
+}
+
+func encodePromptYAMLBytes(value any) ([]byte, error) {
+	var output bytes.Buffer
+	if err := encodePromptYAML(&output, value); err != nil {
+		return nil, err
+	}
+	return output.Bytes(), nil
+}
+
 func writePromptReport(invocation commandkit.Invocation, output []byte, diagnostics []commandkit.Diagnostic) commandkit.Outcome {
 	if invocation.Context != nil {
 		if err := invocation.Context.Err(); err != nil {
diff --git a/integrations/ckprompt/command_test.go b/integrations/ckprompt/command_test.go
index 92499e8..f202f92 100644
--- a/integrations/ckprompt/command_test.go
+++ b/integrations/ckprompt/command_test.go
@@ -309,3 +309,75 @@ func TestProfileTextUsesCredentialNamesAndExplicitEmptyExtraParams(t *testing.T)
 		t.Fatalf("report contains a credential value: %q", text)
 	}
 }
+
+func TestPromptCatalogYAMLPreservesSchemaStringsAndOrder(t *testing.T) {
+	want := []promptkit.PromptIdentity{
+		{ID: "  briefing ", Version: " 03 "},
+		{ID: "001", Version: "1.10"},
+		{ID: "  briefing ", Version: " 03 "},
+	}
+	output, err := encodePromptCatalog(want)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var decoded []map[string]any
+	if err := yaml.Unmarshal(output, &decoded); err != nil {
+		t.Fatalf("decode prompt catalog %q: %v", output, err)
+	}
+	if len(decoded) != len(want) {
+		t.Fatalf("catalog entry count = %d, want %d: %q", len(decoded), len(want), output)
+	}
+	for index, entry := range decoded {
+		if len(entry) != 2 {
+			t.Errorf("entry %d fields = %#v, want only id and version", index, entry)
+		}
+		id, idOK := entry["id"].(string)
+		version, versionOK := entry["version"].(string)
+		if !idOK || !versionOK || id != want[index].ID || version != want[index].Version {
+			t.Errorf("entry %d = %#v, want id/version %q/%q as strings", index, entry, want[index].ID, want[index].Version)
+		}
+	}
+}
+
+func TestCatalogYAMLEncodersRenderNilAndEmptyInventoriesAsSequences(t *testing.T) {
+	for _, test := range []struct {
+		name string
+		data func() ([]byte, error)
+	}{
+		{name: "nil prompts", data: func() ([]byte, error) { return encodePromptCatalog(nil) }},
+		{name: "empty prompts", data: func() ([]byte, error) { return encodePromptCatalog(make([]promptkit.PromptIdentity, 0)) }},
+		{name: "nil profiles", data: func() ([]byte, error) { return encodeProfileCatalog(nil) }},
+		{name: "empty profiles", data: func() ([]byte, error) { return encodeProfileCatalog(make([]string, 0)) }},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			output, err := test.data()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if strings.TrimSpace(string(output)) != "[]" {
+				t.Fatalf("empty catalog YAML = %q, want empty sequence", output)
+			}
+		})
+	}
+}
+
+func TestProfileCatalogYAMLPreservesStringValuesAndOrder(t *testing.T) {
+	want := []string{"  default ", "001", "same", "same"}
+	output, err := encodeProfileCatalog(want)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var decoded []any
+	if err := yaml.Unmarshal(output, &decoded); err != nil {
+		t.Fatalf("decode profile catalog %q: %v", output, err)
+	}
+	if len(decoded) != len(want) {
+		t.Fatalf("catalog entry count = %d, want %d: %q", len(decoded), len(want), output)
+	}
+	for index, item := range decoded {
+		value, ok := item.(string)
+		if !ok || value != want[index] {
+			t.Errorf("profile %d = %#v, want string %q", index, item, want[index])
+		}
+	}
+}