Updates

packages/bare-os-booter/lib/shell.js

@@ -740,6 +740,17 @@ export function tokenize(line) {
         i++
         let inner = ''
         while (i < line.length && line[i] !== '"') {
+          if (line[i] === '$' && line[i + 1] === '(' && line[i + 2] === '(') {
+            const close = findArithmeticClose(line, i + 3)
+            if (close < 0) {
+              inner += line.slice(i)
+              i = line.length
+              break
+            }
+            inner += line.slice(i, close + 2)
+            i = close + 2
+            continue
+          }
           if (line[i] === '\\' && i + 1 < line.length) {
             i++
             inner += line[i++]
@@ -751,6 +762,17 @@ export function tokenize(line) {
         parts.push({ q: 'd', t: inner })
         continue
       }
+      if (ch === '$' && line[i + 1] === '(' && line[i + 2] === '(') {
+        const close = findArithmeticClose(line, i + 3)
+        if (close < 0) {
+          cur.t += line.slice(i)
+          i = line.length
+          break
+        }
+        cur.t += line.slice(i, close + 2)
+        i = close + 2
+        continue
+      }
       if (
         /\s/.test(ch) ||
         ch === '|' ||

packages/bare-os-booter/test.js

@@ -3012,6 +3012,15 @@ test('tokenize records quote parts for glob (literal * in quotes)', async (t) =>
   t.is(lit.parts[0].t, '*')
 })
 
+test('tokenize keeps arithmetic expansion in one word token', async (t) => {
+  const toks = tokenize('n=$((n+1)); echo "$((n+2))"')
+  const words = toks.filter((x) => x.type === 'word').map((x) => x.value)
+  t.ok(words.includes('n=$((n+1))'))
+  t.ok(words.includes('$((n+2))'))
+  t.is(toks.filter((x) => x.type === 'op' && x.value === '(').length, 0)
+  t.is(toks.filter((x) => x.type === 'op' && x.value === ')').length, 0)
+})
+
 test('execShellLine pathname glob and noglob', async (t) => {
   const dir = testCorestoreDir('shglob')
   const store = new Corestore(dir)
@@ -4499,6 +4508,10 @@ async function run(ctx) {
   lines.length = 0
   await execShellLine(ctx, 'if false; then echo x; fi')
   t.ok(!lines.some((l) => l.includes('x')))
+  ctx.exitCode = 0
+  await execShellLine(ctx, 'n=0; if true; then n=$((n+1)); fi; echo $n')
+  t.is(ctx.exitCode, 0)
+  t.ok(lines.some((l) => l.includes('1')))
   await store.close()
   rmSync(dir, { recursive: true, force: true })
 })
@@ -6323,6 +6336,16 @@ test('tier-1 sh -c executes command and sets positional args', async (t) => {
   await runBinCommand(ctx, ['sh', '-c', 'false'])
   t.is(ctx.exitCode, 1)
 
+  lines.length = 0
+  ctx.exitCode = 0
+  await runBinCommand(ctx, [
+    'sh',
+    '-c',
+    'n=0; if true; then n=$((n+1)); fi; echo $n'
+  ])
+  t.is(ctx.exitCode, 0)
+  t.ok(lines.includes('1'))
+
   await store.close()
   rmSync(dir, { recursive: true, force: true })
 })

packages/bare-os-coreutils/test/agent-tools-run-command.test.mjs

@@ -95,6 +95,15 @@ test('run_command wraps compound shell with sh -c before capture redirection', a
   t.ok(seen[0].startsWith("sh -c 'for x in a b; do if true; then echo $x; fi; done'"))
 })
 
+test('run_command wraps combined if + arithmetic expansion probe', async (t) => {
+  const { ctx, seen } = makeCtx()
+  const probe = 'n=0; if true; then n=$((n+1)); fi; echo $n'
+  const out = await callRunCommand(ctx, probe)
+  t.ok(out.ok)
+  t.ok(seen.length >= 1)
+  t.ok(seen[0].startsWith(`sh -c '${probe}'`))
+})
+
 test('run_command keeps simple command direct with capture redirection', async (t) => {
   const { ctx, seen } = makeCtx()
   const out = await callRunCommand(ctx, 'echo hi')