Share prompt instructions and simplify validation helpers

internal/prompts/registry.go

@@ -44,7 +44,7 @@ func (m Metadata) DiagnosticsMap() map[string]any {
 	}
 }
 
-// Filesystem contains the PromptKit definitions and the shared hardening fragment.
+// Filesystem contains the PromptKit definitions and shared instruction fragments.
 func Filesystem() fs.FS { return embeddedAssets }
 
 func LookupMetadata(promptID string) (Metadata, bool) {
@@ -75,10 +75,21 @@ func RegisteredMetadata() []Metadata {
 	return out
 }
 
-func HardeningText() string {
-	raw, err := embeddedAssets.ReadFile("assets/shared/prompt_hardening.md")
+// SharedVariables supplies embedded instructions through the normal PromptKit variables.
+func SharedVariables() map[string]string {
+	return map[string]string{
+		"HardeningPolicy":    HardeningText(),
+		"ProposalContract":   sharedText("proposal_contract.md"),
+		"ValidationContract": sharedText("validation_contract.md"),
+	}
+}
+
+func HardeningText() string { return sharedText("prompt_hardening.md") }
+
+func sharedText(name string) string {
+	raw, err := embeddedAssets.ReadFile("assets/shared/" + name)
 	if err != nil {
-		panic(fmt.Sprintf("read embedded hardening policy: %v", err))
+		panic(fmt.Sprintf("read embedded prompt fragment %s: %v", name, err))
 	}
 	return string(raw)
 }