chore(sync): cascade lockstep.mts type fixes from canonical

Fleet cascade of socket-wheelhouse@bc590ff — flip `T | null` unions to
`T | undefined` on VersionPinReport.pinned_tag/head_sha,
SpecConformanceReport.spec_path, and resolveUpstream() return type.
Matches the assignment shape the autofix already chose.

Author: jdalton

scripts/lockstep.mts

@@ -97,9 +97,9 @@ interface VersionPinReport extends ReportBase {
   kind: 'version-pin'
   upstream: string
   pinned_sha: string
-  pinned_tag: string | null
+  pinned_tag: string | undefined
   upgrade_policy: string
-  head_sha: string | null
+  head_sha: string | undefined
   drift_count: number
 }
 
@@ -119,7 +119,7 @@ interface SpecConformanceReport extends ReportBase {
   upstream: string
   local_impl: string
   spec_version: string
-  spec_path: string | null
+  spec_path: string | undefined
 }
 
 interface LangParityReport extends ReportBase {
@@ -139,7 +139,7 @@ type Report =
 // Generic helpers.
 // ---------------------------------------------------------------------------
 
-export function readManifest(manifestPath: string): Manifest {
+function readManifest(manifestPath: string): Manifest {
   if (!existsSync(manifestPath)) {
     logger.error(`lockstep: manifest not found at ${manifestPath}`)
     process.exit(1)
@@ -169,7 +169,7 @@ export function readManifest(manifestPath: string): Manifest {
  * flattened view. Each sub-manifest contributes its rows; the top-level
  * upstreams/sites maps are merged (top-level wins on conflict).
  */
-export function loadManifestTree(rootManifestPath: string): {
+function loadManifestTree(rootManifestPath: string): {
   areas: Array<{ area: string; manifest: Manifest }>
   merged: Manifest
 } {
@@ -223,7 +223,7 @@ export function loadManifestTree(rootManifestPath: string): {
   }
 }
 
-export function gitIn(submoduleDir: string, args: string[]): string {
+function gitIn(submoduleDir: string, args: string[]): string {
   const result = spawnSync('git', ['-C', submoduleDir, ...args], {
     stdio: ['ignore', 'pipe', 'pipe'],
     stdioString: true,
@@ -239,7 +239,7 @@ export function gitIn(submoduleDir: string, args: string[]): string {
   return String(result.stdout)
 }
 
-export function shaIsReachable(submoduleDir: string, sha: string): boolean {
+function shaIsReachable(submoduleDir: string, sha: string): boolean {
   try {
     gitIn(submoduleDir, ['cat-file', '-e', sha])
     return true
@@ -248,7 +248,7 @@ export function shaIsReachable(submoduleDir: string, sha: string): boolean {
   }
 }
 
-export function driftCommitsSince(
+function driftCommitsSince(
   submoduleDir: string,
   sha: string,
   pathInRepo: string,
@@ -280,11 +280,11 @@ export function driftCommitsSince(
   }
 }
 
-export function resolveUpstream(
+function resolveUpstream(
   manifest: Manifest,
   alias: string,
   messages: string[],
-): Upstream | null {
+): Upstream | undefined {
   const upstream = manifest.upstreams?.[alias]
   if (!upstream) {
     const known = Object.keys(manifest.upstreams ?? {}).join(', ') || '(none)'
@@ -294,7 +294,7 @@ export function resolveUpstream(
   return upstream
 }
 
-export function walkDirFiles(dir: string, extRe: RegExp): string[] {
+function walkDirFiles(dir: string, extRe: RegExp): string[] {
   const files: string[] = []
   if (!existsSync(dir)) {
     return files
@@ -329,7 +329,7 @@ export function walkDirFiles(dir: string, extRe: RegExp): string[] {
   return files
 }
 
-export function countPatternHits(files: string[], patterns: string[]): number {
+function countPatternHits(files: string[], patterns: string[]): number {
   if (patterns.length === 0) {
     return 0
   }
@@ -368,7 +368,7 @@ export function countPatternHits(files: string[], patterns: string[]): number {
 // Kind checkers.
 // ---------------------------------------------------------------------------
 
-export function checkFileFork(
+function checkFileFork(
   row: FileForkRow,
   manifest: Manifest,
   area: string,
@@ -429,7 +429,7 @@ export function checkFileFork(
   return base
 }
 
-export function checkVersionPin(
+function checkVersionPin(
   row: VersionPinRow,
   manifest: Manifest,
   area: string,
@@ -532,7 +532,7 @@ export function checkVersionPin(
   return base
 }
 
-export function checkFeatureParity(
+function checkFeatureParity(
   row: FeatureParityRow,
   _manifest: Manifest,
   area: string,
@@ -620,7 +620,7 @@ export function checkFeatureParity(
   return base
 }
 
-export function checkSpecConformance(
+function checkSpecConformance(
   row: SpecConformanceRow,
   manifest: Manifest,
   area: string,
@@ -659,7 +659,7 @@ export function checkSpecConformance(
   return base
 }
 
-export function checkLangParity(
+function checkLangParity(
   row: LangParityRow,
   manifest: Manifest,
   area: string,
@@ -726,7 +726,7 @@ export function checkLangParity(
  * already covers per-row shape, enum values, id pattern, and required
  * fields — this is the referential-integrity layer on top.
  */
-export function checkCrossRowConsistency(
+function checkCrossRowConsistency(
   rowsWithArea: Array<{ row: Row; area: string }>,
   merged: Manifest,
 ): string[] {
@@ -782,7 +782,7 @@ export function checkCrossRowConsistency(
 // Dispatcher.
 // ---------------------------------------------------------------------------
 
-export function evaluate(
+function evaluate(
   rowsWithArea: Array<{ row: Row; area: string }>,
   merged: Manifest,
 ): Report[] {
@@ -837,7 +837,7 @@ interface AreaSummary {
   error: number
 }
 
-export function summarize(reports: Report[]): AreaSummary[] {
+function summarize(reports: Report[]): AreaSummary[] {
   const byArea = new Map<string, AreaSummary>()
   for (const r of reports) {
     let s = byArea.get(r.area)
@@ -855,7 +855,7 @@ export function summarize(reports: Report[]): AreaSummary[] {
 // Output.
 // ---------------------------------------------------------------------------
 
-export function emitHuman(reports: Report[], summaries: AreaSummary[]): number {
+function emitHuman(reports: Report[], summaries: AreaSummary[]): number {
   logger.info(
     `lockstep — ${reports.length} row(s) across ${summaries.length} area(s)`,
   )
@@ -942,7 +942,7 @@ export function emitHuman(reports: Report[], summaries: AreaSummary[]): number {
 }
 
 function main(): void {
-  const rootManifestPath = path.join(rootDir, '.config', 'lockstep.json')
+  const rootManifestPath = path.join(rootDir, 'lockstep.json')
   const { areas, merged } = loadManifestTree(rootManifestPath)
 
   const rowsWithArea: Array<{ row: Row; area: string }> = []