fix(core): #2337 review-4 — move appendTextFallbackForNonObject to leaf wire/textFallback.ts (break value cycle)

Author: felixweinberger

packages/core/src/wire/codec.ts

@@ -328,20 +328,3 @@ export function isSpecNotificationMethod(method: string): boolean {
 }
 
 const ALL_CODECS: readonly WireCodec[] = [rev2025Codec, rev2026Codec];
-
-/**
- * SEP-2106 §4.3 TextContent auto-append, era-agnostic, called from BOTH
- * codecs' {@link WireCodec.projectCallToolResult}: when `structuredContent`
- * is a non-object value (array/primitive/`null`) and the handler authored no
- * `type:'text'` block, append `{type:'text', text: JSON.stringify(value)}`.
- * Object-shaped (or absent) `structuredContent` returns the same reference.
- */
-export function appendTextFallbackForNonObject(result: CallToolResult): CallToolResult {
-    const sc = result.structuredContent;
-    if (sc === undefined) return result;
-    const isNonObjectValue = typeof sc !== 'object' || sc === null || Array.isArray(sc);
-    if (!isNonObjectValue) return result;
-    const hasTextContent = result.content?.some(c => c.type === 'text') ?? false;
-    if (hasTextContent) return result;
-    return { ...result, content: [...(result.content ?? []), { type: 'text' as const, text: JSON.stringify(sc) }] };
-}

packages/core/src/wire/rev2025-11-25/codec.ts

@@ -30,7 +30,7 @@ import type * as z from 'zod/v4';
 
 import type { CallToolResult, Result } from '../../types/types.js';
 import type { DecodedResult, EnvelopeIssue, LiftedWireMaterial, OutboundEnvelopeMaterial, ValidateOutcome, WireCodec } from '../codec.js';
-import { appendTextFallbackForNonObject } from '../codec.js';
+import { appendTextFallbackForNonObject } from '../textFallback.js';
 import { isNonObjectJsonSchemaRoot, wrapOutputSchemaForLegacy } from './legacyWrap.js';
 import { getNotificationSchema, getRequestSchema, getResultSchema, hasNotificationMethod2025, hasRequestMethod2025 } from './registry.js';
 import { CreateMessageResultSchema, CreateMessageResultWithToolsSchema } from './schemas.js';

packages/core/src/wire/rev2026-07-28/codec.ts

@@ -36,7 +36,7 @@ import {
 } from '../../types/constants.js';
 import type { CallToolResult, Result } from '../../types/types.js';
 import type { DecodedResult, EnvelopeIssue, LiftedWireMaterial, OutboundEnvelopeMaterial, ValidateOutcome, WireCodec } from '../codec.js';
-import { appendTextFallbackForNonObject } from '../codec.js';
+import { appendTextFallbackForNonObject } from '../textFallback.js';
 import { fillCacheFields, stampResultType } from './encodeContract.js';
 import { getInputRequestSchema2026, getInputResponseSchema2026 } from './inputRequired.js';
 import {

packages/core/src/wire/textFallback.ts

@@ -0,0 +1,23 @@
+import type { CallToolResult } from '../types/types.js';
+
+/**
+ * SEP-2106 §4.3 TextContent auto-append, era-agnostic, called from BOTH
+ * codecs' {@link WireCodec.projectCallToolResult}: when `structuredContent`
+ * is a non-object value (array/primitive/`null`) and the handler authored no
+ * `type:'text'` block, append `{type:'text', text: JSON.stringify(value)}`.
+ * Object-shaped (or absent) `structuredContent` returns the same reference.
+ *
+ * Leaf module: imported by both era codec modules, so it must NOT import from
+ * `./codec.js` (which value-imports the rev codecs at top level — that would
+ * make a runtime cycle and a TDZ hazard for entries that evaluate a rev codec
+ * module first).
+ */
+export function appendTextFallbackForNonObject(result: CallToolResult): CallToolResult {
+    const sc = result.structuredContent;
+    if (sc === undefined) return result;
+    const isNonObjectValue = typeof sc !== 'object' || sc === null || Array.isArray(sc);
+    if (!isNonObjectValue) return result;
+    const hasTextContent = result.content?.some(c => c.type === 'text') ?? false;
+    if (hasTextContent) return result;
+    return { ...result, content: [...(result.content ?? []), { type: 'text' as const, text: JSON.stringify(sc) }] };
+}