Add tenth capability word (STOCK_V10), protocol 0.6.0, ctx API 1.19.0, and

strict seed coverage for bits10. Extend seed RPC, replication adjuncts,
Wave 10 /proc JSON + proc index schema 6, boot.policy v10 enforcement in
kernel/init.js, sysproc:* workers, NDJSON/OTel/audit schema bumps, CI
(verify-kernel-roadmap-wave10.mjs) and doc updates across handbook,
developer-guide, compatibility matrix, and seeder kernel parity.

kernel/bin/xargs

@@ -92,12 +92,14 @@ function bareOsEmitRaw(ctx, chunk) {
  * Limits: stdin 256KiB, 4096 whitespace/null tokens, 128 args per invocation,
  * 64 invocations per run. Exceeding limits is a fatal error (exit 125).
  * Supports -0/--null, -n, -I repl (replace repl in utility argv; implies -n 1 unless -n given).
+ * -P N is accepted; stock booter runs sequentially; N is capped at MAX_P_FLAG (4).
  */
 
 const MAX_STDIN = 256 * 1024
 const MAX_TOKENS = 4096
 const MAX_PER_INVOCATION = 128
 const MAX_INVOCATIONS = 64
+const MAX_P_FLAG = 4
 
 async function run(ctx, argv) {
   if (typeof ctx.runBinCommand !== 'function') {
@@ -113,6 +115,7 @@ async function run(ctx, argv) {
   /** @type {string | null} */
   let repl = null
   let nExplicit = false
+  let pCap = 1
   let i = 0
 
   while (i < args.length && args[i].startsWith('-')) {
@@ -126,6 +129,40 @@ async function run(ctx, argv) {
       i++
       continue
     }
+    if (a === '-P' || a === '--max-procs') {
+      const n = args[i + 1]
+      if (n == null || !/^\d+$/.test(n)) {
+        ctx.console.error('xargs: -P requires a non-negative integer')
+        ctx.exitCode = 1
+        return
+      }
+      const raw = Number(n)
+      pCap = Math.min(MAX_P_FLAG, Math.max(1, raw))
+      if (raw > MAX_P_FLAG) {
+        ctx.console.error(
+          'xargs: -P ' +
+            raw +
+            ' exceeds Bare OS cap ' +
+            MAX_P_FLAG +
+            ' (parallelism hint only; sequential execution)'
+        )
+      }
+      i += 2
+      continue
+    }
+    if (a.startsWith('-P') && a.length > 2 && /^\d+$/.test(a.slice(2))) {
+      const raw = Number(a.slice(2))
+      pCap = Math.min(MAX_P_FLAG, Math.max(1, raw))
+      if (raw > MAX_P_FLAG) {
+        ctx.console.error(
+          'xargs: -P exceeds Bare OS cap ' +
+            MAX_P_FLAG +
+            ' (parallelism hint only; sequential execution)'
+        )
+      }
+      i++
+      continue
+    }
     if (a === '-n' || a === '--max-args') {
       const n = args[i + 1]
       if (n == null || !/^\d+$/.test(n) || Number(n) < 1) {
@@ -165,7 +202,9 @@ async function run(ctx, argv) {
     ctx.console.error(
       'xargs: Bare OS supports: -0/--null, -n N (max ' +
         MAX_PER_INVOCATION +
-        ' per run), -I repl'
+        ' per run), -I repl, -P N (max ' +
+        MAX_P_FLAG +
+        ', sequential)'
     )
     ctx.exitCode = 1
     return
@@ -174,6 +213,7 @@ async function run(ctx, argv) {
   /** @type {string[]} */
   let cmd = args.slice(i)
   if (cmd.length === 0) cmd = ['echo']
+  void pCap
 
   let text = bareStdin(ctx) || ''
   if (text.length > MAX_STDIN) {