Add elicitation utilities

Author: nbarbettini

src/shared/elicitation-utils.test.ts

@@ -0,0 +1,59 @@
+import { getSupportedElicitationModes } from './elicitation-utils.js';
+
+describe('elicitation-utils', () => {
+    describe('getSupportedElicitationModes', () => {
+        it('should support nothing when capabilities are undefined', () => {
+            const result = getSupportedElicitationModes(undefined);
+            expect(result.supportsFormMode).toBe(false);
+            expect(result.supportsUrlMode).toBe(false);
+        });
+
+        it('should default to form mode when capabilities are an empty object', () => {
+            const result = getSupportedElicitationModes({});
+            expect(result.supportsFormMode).toBe(true);
+            expect(result.supportsUrlMode).toBe(false);
+        });
+
+        it('should support form mode when form is explicitly declared', () => {
+            const result = getSupportedElicitationModes({ form: {} });
+            expect(result.supportsFormMode).toBe(true);
+            expect(result.supportsUrlMode).toBe(false);
+        });
+
+        it('should support url mode when url is explicitly declared', () => {
+            const result = getSupportedElicitationModes({ url: {} });
+            expect(result.supportsFormMode).toBe(false);
+            expect(result.supportsUrlMode).toBe(true);
+        });
+
+        it('should support both modes when both are explicitly declared', () => {
+            const result = getSupportedElicitationModes({ form: {}, url: {} });
+            expect(result.supportsFormMode).toBe(true);
+            expect(result.supportsUrlMode).toBe(true);
+        });
+
+        it('should support form mode when only applyDefaults is present', () => {
+            const result = getSupportedElicitationModes({ applyDefaults: true });
+            expect(result.supportsFormMode).toBe(true);
+            expect(result.supportsUrlMode).toBe(false);
+        });
+
+        it('should support form mode when applyDefaults and form are present', () => {
+            const result = getSupportedElicitationModes({ applyDefaults: true, form: {} });
+            expect(result.supportsFormMode).toBe(true);
+            expect(result.supportsUrlMode).toBe(false);
+        });
+
+        it('should support url mode when applyDefaults and url are present', () => {
+            const result = getSupportedElicitationModes({ applyDefaults: true, url: {} });
+            expect(result.supportsFormMode).toBe(false);
+            expect(result.supportsUrlMode).toBe(true);
+        });
+
+        it('should support both modes when applyDefaults, form, and url are present', () => {
+            const result = getSupportedElicitationModes({ applyDefaults: true, form: {}, url: {} });
+            expect(result.supportsFormMode).toBe(true);
+            expect(result.supportsUrlMode).toBe(true);
+        });
+    });
+});

src/shared/elicitation-utils.ts

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+import type { ClientCapabilities } from '../types.js';
+
+/**
+ * Utilities for working with elicitation capabilities.
+ */
+
+/**
+ * Determines which elicitation modes are supported based on declared client capabilities.
+ *
+ * According to the spec:
+ * - An empty elicitation capability object defaults to form mode support (backwards compatibility)
+ * - URL mode is only supported if explicitly declared
+ *
+ * @param capabilities - The client's elicitation capabilities
+ * @returns An object indicating which modes are supported
+ */
+export function getSupportedElicitationModes(capabilities: ClientCapabilities['elicitation']): {
+    supportsFormMode: boolean;
+    supportsUrlMode: boolean;
+} {
+    if (!capabilities) {
+        return { supportsFormMode: false, supportsUrlMode: false };
+    }
+
+    const hasFormCapability = Object.prototype.hasOwnProperty.call(capabilities, 'form');
+    const hasUrlCapability = Object.prototype.hasOwnProperty.call(capabilities, 'url');
+
+    // If neither form nor url are explicitly declared, form mode is supported (backwards compatibility)
+    const supportsFormMode = hasFormCapability || (!hasFormCapability && !hasUrlCapability);
+    const supportsUrlMode = hasUrlCapability;
+
+    return { supportsFormMode, supportsUrlMode };
+}