refactor(sdk-runner): reuse isSpecVersion for specOverrides key validation

Reuses the canonical spec-version list from #421 instead of keeping a
separate copy; SPEC_VERSION_TIMELINE is now exported so the validation
message can enumerate the valid keys.

Author: pcarleton

src/sdk-runner/config.ts

@@ -1,5 +1,9 @@
 import { z } from 'zod';
-import { DATED_SPEC_VERSIONS, DRAFT_PROTOCOL_VERSION } from '../types';
+import {
+  DRAFT_PROTOCOL_VERSION,
+  SPEC_VERSION_TIMELINE,
+  isSpecVersion
+} from '../types';
 
 // Fields an entry may vary per targeted spec version. Identity fields
 // (repo / defaultRef / specVersion) can't vary — they pick what to clone,
@@ -24,11 +28,6 @@ const SpecOverrideSchema = z.object({
 
 export type SpecOverride = z.infer<typeof SpecOverrideSchema>;
 
-const VALID_OVERRIDE_KEYS: readonly string[] = [
-  ...DATED_SPEC_VERSIONS,
-  DRAFT_PROTOCOL_VERSION
-];
-
 export const SdkConfigSchema = z.object({
   // Clone this repo instead of the KNOWN_SDKS key — lets an alias entry
   // (e.g. typescript-sdk-v1) point at the real repo (typescript-sdk).
@@ -67,12 +66,12 @@ export const SdkConfigSchema = z.object({
       // date) would silently never match, because the requested version is
       // resolved to its dated form before the lookup.
       for (const key of Object.keys(overrides)) {
-        if (!VALID_OVERRIDE_KEYS.includes(key)) {
+        if (!isSpecVersion(key)) {
           ctx.addIssue({
             code: z.ZodIssueCode.custom,
             message:
               `specOverrides key '${key}' is not a spec version. ` +
-              `Use one of: ${VALID_OVERRIDE_KEYS.join(', ')} ` +
+              `Use one of: ${SPEC_VERSION_TIMELINE.join(', ')} ` +
               `('draft' resolves to ${DRAFT_PROTOCOL_VERSION} before lookup, so key the dated form).`
           });
         }

src/types.ts

@@ -64,7 +64,7 @@ export const NEGOTIABLE_PROTOCOL_VERSIONS: readonly string[] = [
 export type SpecVersion = DatedSpecVersion | typeof DRAFT_PROTOCOL_VERSION;
 
 /** Spec versions in timeline order, dated revisions followed by the draft. */
-const SPEC_VERSION_TIMELINE: readonly SpecVersion[] = [
+export const SPEC_VERSION_TIMELINE: readonly SpecVersion[] = [
   ...DATED_SPEC_VERSIONS,
   DRAFT_PROTOCOL_VERSION
 ];