Add exported query fragments and scoped coverage observations

src/capability-language/parser.ts

@@ -1380,6 +1380,14 @@ const lowerPackage = (
     if (exportContext.packageQuerySpecialization()) return [];
     const query = exportContext.packageQuery();
     if (query) {
+      const isFragment = query.FRAGMENT().length > 0;
+      if (isFragment && (query.FRAGMENT().length !== 2 || query.typeParameters() || query.WORKSPACE()))
+        loweringIssue(
+          state,
+          query,
+          "invalid-query-fragment",
+          "Export a fragment on an exact object interface; generic fragments and workspace fragment roots are not supported",
+        );
       const previousParameters = state.types.parameters;
       state.types.parameters = new Map();
       try {
@@ -1403,7 +1411,19 @@ const lowerPackage = (
           displayName: identifier(query.identifier()),
           root: { kind: query.WORKSPACE() ? "workspace-interface" : "object", interface: close(query.interfaceType()) },
           document: stringValue(query.stringLiteral(1)),
-          operation: stringValue(query.stringLiteral(2)),
+          operation: isFragment
+            ? query.stringLiteral(3)
+              ? stringValue(query.stringLiteral(3))
+              : "QuixosFragment"
+            : stringValue(query.stringLiteral(2)),
+          ...(isFragment
+            ? {
+                fragment: {
+                  name: stringValue(query.stringLiteral(2)),
+                  ...(query.stringLiteral(3) ? { operation: stringValue(query.stringLiteral(3)) } : {}),
+                },
+              }
+            : {}),
           fragments: [],
           views: [],
           allowances: [],
@@ -1436,8 +1456,32 @@ const lowerPackage = (
               );
               if (sourceQueryId) declaration.placement = { kind: "local", sourceQueryId };
             }
-          } else if (clause.FRAGMENTS()) declaration.fragments.push(stringValue(clause.stringLiteral()!));
-          else if (clause.VIEW()) {
+          } else if (clause.FRAGMENTS()) {
+            if (clause.stringLiteral()) declaration.fragments.push(stringValue(clause.stringLiteral()!));
+            else {
+              const imported = lowerQueryReference(
+                state,
+                identifier(clause.identifier(0)),
+                identifier(clause.identifier(1)),
+                clause,
+              );
+              if (imported) {
+                const variables: Record<string, string> = {};
+                for (const mapping of clause.fragmentVariable()) {
+                  const name = identifier(mapping.identifier(0));
+                  if (Object.hasOwn(variables, name))
+                    loweringIssue(state, mapping, "duplicate-fragment-variable", `Repeated fragment variable ${name}`);
+                  variables[name] = identifier(mapping.identifier(1));
+                }
+                (declaration.importedFragments ??= []).push({
+                  packageRevisionId: imported.packageRevisionId,
+                  packageAlias: identifier(clause.identifier(0)),
+                  fragmentId: imported.queryId,
+                  variables,
+                });
+              }
+            }
+          } else if (clause.VIEW()) {
             const name = identifier(clause.identifier(0));
             if (parameters.length) {
               const parameter = state.types.parameters.get(name);
@@ -1548,6 +1592,23 @@ const lowerPackage = (
             views: templateViews,
             allowances: templateAllowances,
           });
+        } else if (isFragment) {
+          if (declaration.placement || declaration.polling || declaration.allowances.length)
+            loweringIssue(
+              state,
+              query,
+              "invalid-query-fragment",
+              "Fragments are local projections with generated admission; remote allowances, polling and explicit placement are not supported",
+            );
+          const sourceQueryId = `${declaration.id}:fragment-inputs`;
+          queries.push({
+            ...structuredClone(declaration),
+            id: sourceQueryId,
+            displayName: `${declaration.displayName}$inputs`,
+            placement: { kind: "replica" },
+            fragment: { ...declaration.fragment!, admission: true },
+          });
+          queries.push({ ...declaration, placement: { kind: "local", sourceQueryId } });
         } else queries.push(declaration);
         return [];
       } finally {