From b7c2635d8fa2b017e0abbae3d28cb641c6d65a99 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 26 Sep 2026 14:27:28 -0700
Subject: [PATCH 1/7] fix(shell): preserve heredoc contexts and reject
 arithmetic placeholders

---
 .../code-placeholders/compiler.test.ts        | 118 ++++++++++
 .../lib/execution/code-placeholders/shell.ts  | 216 ++++++++++--------
 2 files changed, 239 insertions(+), 95 deletions(-)

diff --git a/apps/sim/lib/execution/code-placeholders/compiler.test.ts b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
index 40c0afde1c0..fa3658ba32b 100644
--- a/apps/sim/lib/execution/code-placeholders/compiler.test.ts
+++ b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
@@ -1014,6 +1014,72 @@ describe('code placeholder compiler', () => {
     }
   })
 
+  it.each([
+    'total=$(( {{KEY}} * 2 ))',
+    'echo "$(( {{KEY}} * 2 ))"',
+    'total=$[ {{KEY}} * 2 ]',
+    'echo "$[ {{KEY}} * 2 ]"',
+    '(( total = {{KEY}} * 2 ))',
+    'for (( i = 0; i < {{KEY}}; i++ )); do :; done',
+    'echo "$(( 1 + ({{KEY}} * 2) ))"',
+    'echo "$(( $(printf %s "{{KEY}}") * 2 ))"',
+    'echo "$[ values[0] + {{KEY}} ]"',
+    'cat <<EOF\n$(( {{KEY}} * 2 ))\nEOF',
+    'cat <<EOF\n$[ {{KEY}} * 2 ]\nEOF',
+  ])('rejects shell placeholders that feed arithmetic evaluation: %s', async (code) => {
+    await expect(
+      compileCodePlaceholders({
+        code,
+        language: CodeLanguage.Shell,
+        environmentVariables: { KEY: 'x[$(printf unsafe >&2)]' },
+      })
+    ).rejects.toThrow('is not supported in a shell arithmetic expression')
+  })
+
+  it('keeps arithmetic discovery separate from runtime placeholder rejection', async () => {
+    await expect(
+      analyzeCodePlaceholders('echo "$(( {{KEY}} * 2 ))"', CodeLanguage.Shell)
+    ).resolves.toEqual(['KEY'])
+    const missing = await compileCodePlaceholders({
+      code: 'echo "$(( {{MISSING}} + 1 ))"',
+      language: CodeLanguage.Shell,
+    })
+    expect(missing.code).toContain('{{MISSING}}')
+  })
+
+  it('restores shell quote contexts after arithmetic and leaves literal arithmetic text alone', async () => {
+    const compiled = await compileCodePlaceholders({
+      code: [
+        'printf "%s\\n" "$(( (2 + 1) << 1 )):$[ 2 + 1 ]:{{KEY}}"',
+        "printf '%s\\n' '$(( {{KEY}} ))'",
+        'cat <<EOF',
+        '(( {{KEY}} ))',
+        'EOF',
+      ].join('\n'),
+      language: CodeLanguage.Shell,
+      environmentVariables: { KEY: 'one two' },
+    })
+    expect(executeShell(compiled.code, compiled.bindings)).toBe(
+      '6:3:one two\n$(( one two ))\n(( one two ))\n'
+    )
+  })
+
+  it.each([
+    ['unquoted', "cat <<EOF >/dev/null\nToday's report\nEOF"],
+    ['quoted', "cat <<'EOF' >/dev/null\nToday's report\nEOF"],
+    ['double quote in prose', 'cat <<EOF >/dev/null\nSay "hello\nEOF'],
+    ['literal backtick', "cat <<'EOF' >/dev/null\nAn unmatched `\nEOF"],
+    ['multiple bodies', "cat <<ONE <<'TWO' >/dev/null\nToday's report\nONE\nSay \"hello\nTWO"],
+  ])('preserves quoted shell values after a %s heredoc', async (_name, prefix) => {
+    const value = 'one two $(printf unsafe)'
+    const compiled = await compileCodePlaceholders({
+      code: `${prefix}\nprintf "<%s>\\n" "{{KEY}}"`,
+      language: CodeLanguage.Shell,
+      environmentVariables: { KEY: value },
+    })
+    expect(executeShell(compiled.code, compiled.bindings)).toBe(`<${value}>\n`)
+  })
+
   it('renders quoted shell heredocs nested in double-quoted command substitutions', async () => {
     const compiled = await compileCodePlaceholders({
       code: [
@@ -1261,6 +1327,58 @@ describe('direct environment reads in shell', () => {
     expect(unquoted.resolvedSecretNames).toEqual(['API_KEY'])
   })
 
+  it.each(['EOF', "'EOF'"])(
+    'records direct shell reads after a %s heredoc without lexing its prose',
+    async (delimiter) => {
+      const compiled = await compileCodePlaceholders({
+        code: `cat <<${delimiter} >/dev/null\nToday's report\nEOF\necho "$API_KEY"`,
+        language: CodeLanguage.Shell,
+        environmentVariables: { API_KEY: 'synthetic-value' },
+      })
+      expect(executeShell(compiled.code, [{ name: 'API_KEY', value: 'synthetic-value' }])).toBe(
+        'synthetic-value\n'
+      )
+      expect(compiled.resolvedSecretNames).toEqual(['API_KEY'])
+    }
+  )
+
+  it.each(["Today's $API_KEY", '# $API_KEY'])(
+    'records direct shell reads in expanding heredoc prose: %s',
+    async (body) => {
+      const compiled = await compileCodePlaceholders({
+        code: `cat <<EOF\n${body}\nEOF`,
+        language: CodeLanguage.Shell,
+        environmentVariables: { API_KEY: 'synthetic-value' },
+      })
+      expect(
+        executeShell(compiled.code, [{ name: 'API_KEY', value: 'synthetic-value' }])
+      ).toContain('synthetic-value')
+      expect(compiled.resolvedSecretNames).toEqual(['API_KEY'])
+    }
+  )
+
+  it('skips heredoc delimiters and literal bodies but keeps reads on the header line', async () => {
+    const compiled = await compileCodePlaceholders({
+      code: [
+        'cat <<$DELIMITER; echo "$HEADER"',
+        'body',
+        '$DELIMITER',
+        "cat <<'EOF'",
+        "Today's $LITERAL",
+        'EOF',
+        'echo "$AFTER"',
+      ].join('\n'),
+      language: CodeLanguage.Shell,
+      environmentVariables: {
+        DELIMITER: 'unused-delimiter',
+        HEADER: 'header-value',
+        LITERAL: 'unused-literal',
+        AFTER: 'after-value',
+      },
+    })
+    expect(compiled.resolvedSecretNames).toEqual(['HEADER', 'AFTER'])
+  })
+
   it('ignores a shell variable that is not a configured secret', async () => {
     const compiled = await compileCodePlaceholders({
       code: 'echo "$PATH $HOME"',
diff --git a/apps/sim/lib/execution/code-placeholders/shell.ts b/apps/sim/lib/execution/code-placeholders/shell.ts
index 602c44215a8..479fe400b8c 100644
--- a/apps/sim/lib/execution/code-placeholders/shell.ts
+++ b/apps/sim/lib/execution/code-placeholders/shell.ts
@@ -29,11 +29,14 @@ interface ShellScanFrame {
   kind: 'root' | 'command' | 'arithmetic' | 'backtick'
   quote: ShellQuote
   parenthesisDepth: number
+  bracketDepth?: number
   literalRoot: boolean
 }
 
 interface ShellOccurrenceContext {
   quote: ShellQuote
+  /** Enclosing arithmetic also re-evaluates the output of a nested command substitution. */
+  arithmetic?: boolean
   unsupported?: 'escaped sequence'
 }
 
@@ -70,6 +73,31 @@ function shellArithmeticCommandStarts(code: string, index: number): boolean {
   return previous === undefined || /\s|[;&|()<>]/.test(previous)
 }
 
+function readShellExpansionStart(
+  code: string,
+  index: number,
+  allowArithmeticCommand: boolean
+): { frame: ShellScanFrame; length: number } | undefined {
+  const dollar = code[index] === '$'
+  const bracket = dollar && code[index + 1] === '['
+  const arithmetic =
+    bracket ||
+    (dollar && code[index + 1] === '(' && code[index + 2] === '(') ||
+    (allowArithmeticCommand && shellArithmeticCommandStarts(code, index))
+  if (!arithmetic && !(dollar && code[index + 1] === '(')) return undefined
+
+  return {
+    frame: {
+      kind: arithmetic ? 'arithmetic' : 'command',
+      quote: 'none',
+      parenthesisDepth: bracket ? 0 : arithmetic ? 2 : 1,
+      ...(bracket ? { bracketDepth: 1 } : {}),
+      literalRoot: false,
+    },
+    length: dollar && arithmetic && !bracket ? 3 : 2,
+  }
+}
+
 function decodeAnsiCCharacter(code: string, index: number): { value: string; end: number } {
   const character = code[index]
   const simple: Record<string, string> = {
@@ -219,25 +247,17 @@ function parseHeredocHeaders(
       else if (character === "'") frame.quote = 'none'
       continue
     }
+    const expansion = readShellExpansionStart(
+      code,
+      index,
+      frame.quote === 'none' && frame.kind !== 'arithmetic'
+    )
     if (frame.quote === 'double') {
       if (character === '\\') index += 1
       else if (character === '"') frame.quote = 'none'
-      else if (character === '$' && code[index + 1] === '(' && code[index + 2] === '(') {
-        frames.push({
-          kind: 'arithmetic',
-          quote: 'none',
-          parenthesisDepth: 2,
-          literalRoot: false,
-        })
-        index += 2
-      } else if (character === '$' && code[index + 1] === '(') {
-        frames.push({
-          kind: 'command',
-          quote: 'none',
-          parenthesisDepth: 1,
-          literalRoot: false,
-        })
-        index += 1
+      else if (expansion) {
+        frames.push(expansion.frame)
+        index += expansion.length - 1
       } else if (character === '`') {
         frames.push({
           kind: 'backtick',
@@ -270,34 +290,9 @@ function parseHeredocHeaders(
       index += 1
       continue
     }
-    if (character === '$' && code[index + 1] === '(' && code[index + 2] === '(') {
-      frames.push({
-        kind: 'arithmetic',
-        quote: 'none',
-        parenthesisDepth: 2,
-        literalRoot: false,
-      })
-      index += 2
-      continue
-    }
-    if (shellArithmeticCommandStarts(code, index)) {
-      frames.push({
-        kind: 'arithmetic',
-        quote: 'none',
-        parenthesisDepth: 2,
-        literalRoot: false,
-      })
-      index += 1
-      continue
-    }
-    if (character === '$' && code[index + 1] === '(') {
-      frames.push({
-        kind: 'command',
-        quote: 'none',
-        parenthesisDepth: 1,
-        literalRoot: false,
-      })
-      index += 1
+    if (expansion) {
+      frames.push(expansion.frame)
+      index += expansion.length - 1
       continue
     }
     if (character === '`') {
@@ -309,6 +304,14 @@ function parseHeredocHeaders(
       })
       continue
     }
+    if (frame.bracketDepth !== undefined) {
+      if (character === '[') frame.bracketDepth += 1
+      if (character === ']') {
+        frame.bracketDepth -= 1
+        if (frame.bracketDepth === 0) frames.pop()
+      }
+      continue
+    }
     if ((frame.kind === 'command' || frame.kind === 'arithmetic') && character === '(') {
       frame.parenthesisDepth += 1
       continue
@@ -388,6 +391,14 @@ function collectHeredocs(code: string): HeredocDeclaration[] {
   return declarations
 }
 
+/** Delimiter words and complete bodies are data, not part of the enclosing shell's quote state. */
+function heredocExcludedRanges(heredocs: HeredocDeclaration[]): Array<[number, number]> {
+  return heredocs.flatMap((heredoc) => [
+    [heredoc.operatorStart, heredoc.operatorEnd],
+    [heredoc.bodyStart, heredoc.removalEnd],
+  ])
+}
+
 function shellExpansion(name: string, quote: ShellQuote): string {
   const expansion = `\${${name}}`
   if (quote === 'double') return expansion
@@ -422,10 +433,11 @@ function isShellAssignmentName(code: string, occurrence: CodePlaceholderOccurren
 function getUnsupportedShellPosition(
   code: string,
   occurrence: CodePlaceholderOccurrence,
-  quote: ShellQuote
+  context: ShellOccurrenceContext
 ): string | undefined {
+  if (context.arithmetic) return 'in a shell arithmetic expression'
   if (code[occurrence.start - 1] === '$') return 'immediately after "$"'
-  if (quote !== 'none') return undefined
+  if (context.quote !== 'none') return undefined
 
   const lineStart = Math.max(
     code.lastIndexOf('\n', occurrence.start - 1),
@@ -444,8 +456,10 @@ function collectShellOccurrenceContexts(
   occurrences: CodePlaceholderOccurrence[],
   start: number,
   end: number,
-  literalRoot: boolean
+  literalRoot: boolean,
+  excludedRanges: ReadonlyArray<readonly [number, number]> = []
 ): Map<CodePlaceholderOccurrence, ShellOccurrenceContext> {
+  const excludedEndByStart = new Map(excludedRanges)
   const occurrenceByStart = new Map(
     occurrences
       .filter((occurrence) => occurrence.start >= start && occurrence.end <= end)
@@ -457,12 +471,20 @@ function collectShellOccurrenceContexts(
   ]
 
   for (let index = start; index < end; ) {
+    const excludedEnd = excludedEndByStart.get(index)
+    if (excludedEnd !== undefined) {
+      index = excludedEnd
+      continue
+    }
     const frame = frames.at(-1)
     if (!frame) break
 
     const occurrence = occurrenceByStart.get(index)
     if (occurrence) {
-      contexts.set(occurrence, { quote: frame.quote })
+      contexts.set(occurrence, {
+        quote: frame.quote,
+        arithmetic: frames.some((candidate) => candidate.kind === 'arithmetic'),
+      })
       index = occurrence.end
       continue
     }
@@ -488,6 +510,11 @@ function collectShellOccurrenceContexts(
       }
       continue
     }
+    const expansion = readShellExpansionStart(
+      code,
+      index,
+      frame.quote === 'none' && !frame.literalRoot && frame.kind !== 'arithmetic'
+    )
     if (frame.quote === 'double') {
       if (character === '\\') {
         const escaped = occurrenceByStart.get(index + 1)
@@ -500,14 +527,9 @@ function collectShellOccurrenceContexts(
       } else if (character === '"') {
         frame.quote = 'none'
         index += 1
-      } else if (character === '$' && code[index + 1] === '(') {
-        frames.push({
-          kind: 'command',
-          quote: 'none',
-          parenthesisDepth: 1,
-          literalRoot: false,
-        })
-        index += 2
+      } else if (expansion) {
+        frames.push(expansion.frame)
+        index += expansion.length
       } else if (character === '`') {
         frames.push({
           kind: 'backtick',
@@ -557,14 +579,9 @@ function collectShellOccurrenceContexts(
       index += 1
       continue
     }
-    if (character === '$' && code[index + 1] === '(') {
-      frames.push({
-        kind: 'command',
-        quote: 'none',
-        parenthesisDepth: 1,
-        literalRoot: false,
-      })
-      index += 2
+    if (expansion) {
+      frames.push(expansion.frame)
+      index += expansion.length
       continue
     }
     if (character === '`') {
@@ -577,12 +594,21 @@ function collectShellOccurrenceContexts(
       index += 1
       continue
     }
-    if (frame.kind === 'command' && character === '(') {
+    if (frame.bracketDepth !== undefined) {
+      if (character === '[') frame.bracketDepth += 1
+      if (character === ']') {
+        frame.bracketDepth -= 1
+        if (frame.bracketDepth === 0) frames.pop()
+      }
+      index += 1
+      continue
+    }
+    if ((frame.kind === 'command' || frame.kind === 'arithmetic') && character === '(') {
       frame.parenthesisDepth += 1
       index += 1
       continue
     }
-    if (frame.kind === 'command' && character === ')') {
+    if ((frame.kind === 'command' || frame.kind === 'arithmetic') && character === ')') {
       frame.parenthesisDepth -= 1
       if (frame.parenthesisDepth === 0) frames.pop()
       index += 1
@@ -635,37 +661,39 @@ function recordShellDirectEnvironmentReads(
   }
   if (matches.length === 0) return
 
-  /**
-   * A heredoc with a quoted delimiter (`<<'EOF'`) is literal, so nothing in its body expands.
-   * The frame scanner below models quoting within a line, not heredoc bodies, so those are
-   * excluded up front — otherwise a `$NAME` printed verbatim would be reported as a read that
-   * never happened, and a usage trail must not claim uses that did not occur.
-   */
-  const literalHeredocBodies = collectHeredocs(code)
-    .filter((heredoc) => heredoc.quoted)
-    .map((heredoc): [number, number] => [heredoc.bodyStart, heredoc.bodyEnd])
-
-  const candidates: CodePlaceholderOccurrence[] = []
-  for (const candidate of matches) {
-    if (isOffsetInRanges(candidate.index, literalHeredocBodies)) continue
-    candidates.push({
+  const heredocs = collectHeredocs(code)
+  const candidates = matches.map(
+    (candidate): CodePlaceholderOccurrence => ({
       start: candidate.index,
       end: candidate.index + candidate[0].length,
       raw: candidate[0],
       name: (candidate[1] ?? candidate[2]) as string,
     })
+  )
+  const contexts = collectShellOccurrenceContexts(
+    code,
+    candidates,
+    0,
+    code.length,
+    false,
+    heredocExcludedRanges(heredocs)
+  )
+  /** Unquoted bodies expand parameters, but prose quotes and comment markers remain literal. */
+  for (const heredoc of heredocs) {
+    if (heredoc.quoted) continue
+    const bodyContexts = collectShellOccurrenceContexts(
+      code,
+      candidates,
+      heredoc.bodyStart,
+      heredoc.bodyEnd,
+      true
+    )
+    for (const [candidate, shellContext] of bodyContexts) contexts.set(candidate, shellContext)
   }
-  if (candidates.length === 0) return
 
-  const contexts = collectShellOccurrenceContexts(code, candidates, 0, code.length, false)
   for (const candidate of candidates) {
     const shellContext = contexts.get(candidate)
-    /**
-     * No context means the scanner never reached this offset — it skipped the region as a
-     * comment. Absence is therefore evidence the expansion does not run, not permission to
-     * record it, so this reads as an allowlist rather than a denylist. Single quotes suppress
-     * expansion outright.
-     */
+    /** Comments, delimiter words, literal bodies and single-quoted strings do not expand. */
     if (!shellContext || shellContext.quote === 'single') continue
     context.recordDirectEnvironmentRead(candidate.name, candidate.start)
   }
@@ -699,12 +727,9 @@ export async function compileShellPlaceholders(
   const heredocs = collectHeredocs(input.code)
   const shellOccurrences = context.occurrences.filter(isLegacyShellPlaceholder)
   const edits: SourceEdit[] = []
-  const excludedRanges: Array<[number, number]> = []
+  const excludedRanges = heredocExcludedRanges(heredocs)
 
   for (const heredoc of heredocs) {
-    excludedRanges.push([heredoc.operatorStart, heredoc.operatorEnd])
-    excludedRanges.push([heredoc.bodyStart, heredoc.removalEnd])
-
     const delimiterOccurrences = shellOccurrences.filter(
       (occurrence) =>
         occurrence.start >= heredoc.operatorStart && occurrence.end <= heredoc.operatorEnd
@@ -795,7 +820,7 @@ export async function compileShellPlaceholders(
       const unsupportedPosition = getUnsupportedShellPosition(
         input.code,
         occurrence,
-        occurrenceContext.quote
+        occurrenceContext
       )
       if (unsupportedPosition) {
         if (context.hasValue(occurrence.name)) {
@@ -828,7 +853,8 @@ export async function compileShellPlaceholders(
     rootOccurrences,
     0,
     input.code.length,
-    false
+    false,
+    excludedRanges
   )
   for (const occurrence of rootOccurrences) {
     const occurrenceContext = rootContexts.get(occurrence)
@@ -850,7 +876,7 @@ export async function compileShellPlaceholders(
     const unsupportedPosition = getUnsupportedShellPosition(
       input.code,
       occurrence,
-      occurrenceContext.quote
+      occurrenceContext
     )
     if (unsupportedPosition) {
       if (context.hasValue(occurrence.name)) {

From d2131688d02d7a141a18b3840750398d047eaee4 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 26 Sep 2026 14:45:24 -0700
Subject: [PATCH 2/7] fix(shell): reject arithmetic array subscript
 placeholders

---
 .../code-placeholders/compiler.test.ts        | 28 +++++++
 .../lib/execution/code-placeholders/shell.ts  | 83 +++++++++++++++++--
 2 files changed, 103 insertions(+), 8 deletions(-)

diff --git a/apps/sim/lib/execution/code-placeholders/compiler.test.ts b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
index fa3658ba32b..81ebdc05e52 100644
--- a/apps/sim/lib/execution/code-placeholders/compiler.test.ts
+++ b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
@@ -1026,6 +1026,15 @@ describe('code placeholder compiler', () => {
     'echo "$[ values[0] + {{KEY}} ]"',
     'cat <<EOF\n$(( {{KEY}} * 2 ))\nEOF',
     'cat <<EOF\n$[ {{KEY}} * 2 ]\nEOF',
+    'values[{{KEY}}]=x',
+    'values[{{KEY}}]+=x',
+    'values[ 1 + {{KEY}} ]=x',
+    'values[$(printf %s "{{KEY}}")]=x',
+    'values=([{{KEY}}]=x)',
+    'values+=([{{KEY}}]=x)',
+    `echo "\${values[{{KEY}}]}"`,
+    `echo "\${#values[{{KEY}}]}"`,
+    `cat <<EOF\n\${values[{{KEY}}]}\nEOF`,
   ])('rejects shell placeholders that feed arithmetic evaluation: %s', async (code) => {
     await expect(
       compileCodePlaceholders({
@@ -1064,6 +1073,25 @@ describe('code placeholder compiler', () => {
     )
   })
 
+  it('keeps bracket words and array values outside arithmetic positions', async () => {
+    const compiled = await compileCodePlaceholders({
+      code: [
+        'printf "%s\\n" "values[{{KEY}}]=literal" values[{{KEY}}]',
+        'values=("{{KEY}}" item[{{KEY}}])',
+        'values[0]="{{KEY}}"',
+        `printf "%s\\n" "\${values[@]}"`,
+        'cat <<EOF',
+        'values[{{KEY}}]=literal',
+        'EOF',
+      ].join('\n'),
+      language: CodeLanguage.Shell,
+      environmentVariables: { KEY: 'word' },
+    })
+    expect(executeShell(compiled.code, compiled.bindings)).toBe(
+      'values[word]=literal\nvalues[word]\nword\nitem[word]\nvalues[word]=literal\n'
+    )
+  })
+
   it.each([
     ['unquoted', "cat <<EOF >/dev/null\nToday's report\nEOF"],
     ['quoted', "cat <<'EOF' >/dev/null\nToday's report\nEOF"],
diff --git a/apps/sim/lib/execution/code-placeholders/shell.ts b/apps/sim/lib/execution/code-placeholders/shell.ts
index 479fe400b8c..2d8c4322adb 100644
--- a/apps/sim/lib/execution/code-placeholders/shell.ts
+++ b/apps/sim/lib/execution/code-placeholders/shell.ts
@@ -26,17 +26,22 @@ interface HeredocDeclaration {
 type ShellQuote = 'none' | 'single' | 'double' | 'ansi'
 
 interface ShellScanFrame {
-  kind: 'root' | 'command' | 'arithmetic' | 'backtick'
+  kind: 'root' | 'command' | 'arithmetic' | 'backtick' | 'array'
   quote: ShellQuote
   parenthesisDepth: number
   bracketDepth?: number
+  /** A bare name[index] is arithmetic only when its closing bracket is followed by assignment. */
+  arrayAssignment?: boolean
   literalRoot: boolean
 }
 
 interface ShellOccurrenceContext {
   quote: ShellQuote
-  /** Enclosing arithmetic also re-evaluates the output of a nested command substitution. */
-  arithmetic?: boolean
+  /**
+   * Enclosing arithmetic also re-evaluates nested substitutions. Keep frame references so a
+   * bare subscript can be classified when its closing bracket confirms an assignment.
+   */
+  arithmeticFrames?: ShellScanFrame[]
   unsupported?: 'escaped sequence'
 }
 
@@ -98,6 +103,49 @@ function readShellExpansionStart(
   }
 }
 
+function readShellArrayStart(
+  code: string,
+  index: number,
+  parent: ShellScanFrame
+): ShellScanFrame | undefined {
+  const character = code[index]
+  if (character !== '[' && character !== '(') return undefined
+
+  let nameEnd = index
+  if (character === '(') {
+    if (code[index - 1] !== '=') return undefined
+    nameEnd -= 1
+    if (code[nameEnd - 1] === '+') nameEnd -= 1
+  }
+  let nameStart = nameEnd
+  while (nameStart > 0 && /[A-Za-z0-9_]/.test(code[nameStart - 1])) nameStart -= 1
+  const hasName = nameStart < nameEnd && /[A-Za-z_]/.test(code[nameStart])
+  const parameterStart =
+    code[nameStart - 1] === '#' || code[nameStart - 1] === '!' ? nameStart - 3 : nameStart - 2
+  const parameter =
+    character === '[' &&
+    hasName &&
+    code.slice(parameterStart, parameterStart + 2) === '${' &&
+    !isBackslashEscaped(code, parameterStart)
+  const wordStart = nameStart === 0 || /\s|[;&|()]/.test(code[nameStart - 1])
+  const assignment =
+    parent.quote === 'none' &&
+    !parent.literalRoot &&
+    wordStart &&
+    (hasName || (character === '[' && parent.kind === 'array'))
+  if (!parameter && !assignment) return undefined
+
+  return {
+    kind: character === '[' ? 'arithmetic' : 'array',
+    quote: 'none',
+    parenthesisDepth: character === '(' ? 1 : 0,
+    ...(character === '['
+      ? { bracketDepth: 1, ...(!parameter ? { arrayAssignment: false } : {}) }
+      : {}),
+    literalRoot: false,
+  }
+}
+
 function decodeAnsiCCharacter(code: string, index: number): { value: string; end: number } {
   const character = code[index]
   const simple: Record<string, string> = {
@@ -435,7 +483,9 @@ function getUnsupportedShellPosition(
   occurrence: CodePlaceholderOccurrence,
   context: ShellOccurrenceContext
 ): string | undefined {
-  if (context.arithmetic) return 'in a shell arithmetic expression'
+  if (context.arithmeticFrames?.some((frame) => frame.arrayAssignment !== false)) {
+    return 'in a shell arithmetic expression'
+  }
   if (code[occurrence.start - 1] === '$') return 'immediately after "$"'
   if (context.quote !== 'none') return undefined
 
@@ -483,7 +533,7 @@ function collectShellOccurrenceContexts(
     if (occurrence) {
       contexts.set(occurrence, {
         quote: frame.quote,
-        arithmetic: frames.some((candidate) => candidate.kind === 'arithmetic'),
+        arithmeticFrames: frames.filter((candidate) => candidate.kind === 'arithmetic'),
       })
       index = occurrence.end
       continue
@@ -515,6 +565,12 @@ function collectShellOccurrenceContexts(
       index,
       frame.quote === 'none' && !frame.literalRoot && frame.kind !== 'arithmetic'
     )
+    const array = readShellArrayStart(code, index, frame)
+    if (array) {
+      frames.push(array)
+      index += 1
+      continue
+    }
     if (frame.quote === 'double') {
       if (character === '\\') {
         const escaped = occurrenceByStart.get(index + 1)
@@ -598,17 +654,28 @@ function collectShellOccurrenceContexts(
       if (character === '[') frame.bracketDepth += 1
       if (character === ']') {
         frame.bracketDepth -= 1
-        if (frame.bracketDepth === 0) frames.pop()
+        if (frame.bracketDepth === 0) {
+          if (frame.arrayAssignment !== undefined) {
+            frame.arrayAssignment = code[index + 1] === '=' || code.startsWith('+=', index + 1)
+          }
+          frames.pop()
+        }
       }
       index += 1
       continue
     }
-    if ((frame.kind === 'command' || frame.kind === 'arithmetic') && character === '(') {
+    if (
+      (frame.kind === 'command' || frame.kind === 'arithmetic' || frame.kind === 'array') &&
+      character === '('
+    ) {
       frame.parenthesisDepth += 1
       index += 1
       continue
     }
-    if ((frame.kind === 'command' || frame.kind === 'arithmetic') && character === ')') {
+    if (
+      (frame.kind === 'command' || frame.kind === 'arithmetic' || frame.kind === 'array') &&
+      character === ')'
+    ) {
       frame.parenthesisDepth -= 1
       if (frame.parenthesisDepth === 0) frames.pop()
       index += 1

From c4deb37c551ba803f3106231957981e44ec06891 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 26 Sep 2026 14:50:20 -0700
Subject: [PATCH 3/7] fix(shell): share nested arithmetic context ancestry

---
 .../lib/execution/code-placeholders/shell.ts  | 35 +++++++++++--------
 1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/apps/sim/lib/execution/code-placeholders/shell.ts b/apps/sim/lib/execution/code-placeholders/shell.ts
index 2d8c4322adb..def1e810f06 100644
--- a/apps/sim/lib/execution/code-placeholders/shell.ts
+++ b/apps/sim/lib/execution/code-placeholders/shell.ts
@@ -32,16 +32,17 @@ interface ShellScanFrame {
   bracketDepth?: number
   /** A bare name[index] is arithmetic only when its closing bracket is followed by assignment. */
   arrayAssignment?: boolean
+  arithmeticParent?: ShellScanFrame
   literalRoot: boolean
 }
 
 interface ShellOccurrenceContext {
   quote: ShellQuote
   /**
-   * Enclosing arithmetic also re-evaluates nested substitutions. Keep frame references so a
+   * Enclosing arithmetic also re-evaluates nested substitutions. Keep a frame reference so a
    * bare subscript can be classified when its closing bracket confirms an assignment.
    */
-  arithmeticFrames?: ShellScanFrame[]
+  arithmeticFrame?: ShellScanFrame
   unsupported?: 'escaped sequence'
 }
 
@@ -78,6 +79,12 @@ function shellArithmeticCommandStarts(code: string, index: number): boolean {
   return previous === undefined || /\s|[;&|()<>]/.test(previous)
 }
 
+function pushShellFrame(frames: ShellScanFrame[], frame: ShellScanFrame): void {
+  const parent = frames.at(-1)
+  frame.arithmeticParent = parent?.kind === 'arithmetic' ? parent : parent?.arithmeticParent
+  frames.push(frame)
+}
+
 function readShellExpansionStart(
   code: string,
   index: number,
@@ -304,10 +311,10 @@ function parseHeredocHeaders(
       if (character === '\\') index += 1
       else if (character === '"') frame.quote = 'none'
       else if (expansion) {
-        frames.push(expansion.frame)
+        pushShellFrame(frames, expansion.frame)
         index += expansion.length - 1
       } else if (character === '`') {
-        frames.push({
+        pushShellFrame(frames, {
           kind: 'backtick',
           quote: 'none',
           parenthesisDepth: 0,
@@ -339,12 +346,12 @@ function parseHeredocHeaders(
       continue
     }
     if (expansion) {
-      frames.push(expansion.frame)
+      pushShellFrame(frames, expansion.frame)
       index += expansion.length - 1
       continue
     }
     if (character === '`') {
-      frames.push({
+      pushShellFrame(frames, {
         kind: 'backtick',
         quote: 'none',
         parenthesisDepth: 0,
@@ -483,8 +490,8 @@ function getUnsupportedShellPosition(
   occurrence: CodePlaceholderOccurrence,
   context: ShellOccurrenceContext
 ): string | undefined {
-  if (context.arithmeticFrames?.some((frame) => frame.arrayAssignment !== false)) {
-    return 'in a shell arithmetic expression'
+  for (let frame = context.arithmeticFrame; frame; frame = frame.arithmeticParent) {
+    if (frame.arrayAssignment !== false) return 'in a shell arithmetic expression'
   }
   if (code[occurrence.start - 1] === '$') return 'immediately after "$"'
   if (context.quote !== 'none') return undefined
@@ -533,7 +540,7 @@ function collectShellOccurrenceContexts(
     if (occurrence) {
       contexts.set(occurrence, {
         quote: frame.quote,
-        arithmeticFrames: frames.filter((candidate) => candidate.kind === 'arithmetic'),
+        arithmeticFrame: frame.kind === 'arithmetic' ? frame : frame.arithmeticParent,
       })
       index = occurrence.end
       continue
@@ -567,7 +574,7 @@ function collectShellOccurrenceContexts(
     )
     const array = readShellArrayStart(code, index, frame)
     if (array) {
-      frames.push(array)
+      pushShellFrame(frames, array)
       index += 1
       continue
     }
@@ -584,10 +591,10 @@ function collectShellOccurrenceContexts(
         frame.quote = 'none'
         index += 1
       } else if (expansion) {
-        frames.push(expansion.frame)
+        pushShellFrame(frames, expansion.frame)
         index += expansion.length
       } else if (character === '`') {
-        frames.push({
+        pushShellFrame(frames, {
           kind: 'backtick',
           quote: 'none',
           parenthesisDepth: 0,
@@ -636,12 +643,12 @@ function collectShellOccurrenceContexts(
       continue
     }
     if (expansion) {
-      frames.push(expansion.frame)
+      pushShellFrame(frames, expansion.frame)
       index += expansion.length
       continue
     }
     if (character === '`') {
-      frames.push({
+      pushShellFrame(frames, {
         kind: 'backtick',
         quote: 'none',
         parenthesisDepth: 0,

From 449d127d43305873d950a38686bb0f02d1a20a36 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 26 Sep 2026 15:04:14 -0700
Subject: [PATCH 4/7] fix(shell): distinguish array assignments from command
 arguments

---
 .../code-placeholders/compiler.test.ts        | 19 +++++++
 .../lib/execution/code-placeholders/shell.ts  | 53 +++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/apps/sim/lib/execution/code-placeholders/compiler.test.ts b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
index 81ebdc05e52..8498ab3d580 100644
--- a/apps/sim/lib/execution/code-placeholders/compiler.test.ts
+++ b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
@@ -1028,6 +1028,10 @@ describe('code placeholder compiler', () => {
     'cat <<EOF\n$[ {{KEY}} * 2 ]\nEOF',
     'values[{{KEY}}]=x',
     'values[{{KEY}}]+=x',
+    'PREFIX=1 values[{{KEY}}]=x',
+    'if values[{{KEY}}]=x; then :; fi',
+    'declare -a values[{{KEY}}]=x',
+    'printf %s done # end of command\nvalues[{{KEY}}]=x',
     'values[ 1 + {{KEY}} ]=x',
     'values[$(printf %s "{{KEY}}")]=x',
     'values=([{{KEY}}]=x)',
@@ -1092,6 +1096,21 @@ describe('code placeholder compiler', () => {
     )
   })
 
+  it('keeps array-shaped command arguments literal', async () => {
+    const compiled = await compileCodePlaceholders({
+      code: [
+        'printf "%s\\n" config[{{KEY}}]=1',
+        'PREFIX=1 printf "%s\\n" config[{{KEY}}]+=2',
+        'if true; then printf "%s\\n" config[{{KEY}}]=3; fi',
+      ].join('\n'),
+      language: CodeLanguage.Shell,
+      environmentVariables: { KEY: 'word' },
+    })
+    expect(executeShell(compiled.code, compiled.bindings)).toBe(
+      'config[word]=1\nconfig[word]+=2\nconfig[word]=3\n'
+    )
+  })
+
   it.each([
     ['unquoted', "cat <<EOF >/dev/null\nToday's report\nEOF"],
     ['quoted', "cat <<'EOF' >/dev/null\nToday's report\nEOF"],
diff --git a/apps/sim/lib/execution/code-placeholders/shell.ts b/apps/sim/lib/execution/code-placeholders/shell.ts
index def1e810f06..4342192cec6 100644
--- a/apps/sim/lib/execution/code-placeholders/shell.ts
+++ b/apps/sim/lib/execution/code-placeholders/shell.ts
@@ -33,6 +33,10 @@ interface ShellScanFrame {
   /** A bare name[index] is arithmetic only when its closing bracket is followed by assignment. */
   arrayAssignment?: boolean
   arithmeticParent?: ShellScanFrame
+  wordStart?: number
+  commandPosition?: boolean
+  declarationCommand?: boolean
+  redirectionTarget?: boolean
   literalRoot: boolean
 }
 
@@ -139,6 +143,7 @@ function readShellArrayStart(
     parent.quote === 'none' &&
     !parent.literalRoot &&
     wordStart &&
+    (parent.kind === 'array' || parent.commandPosition !== false || parent.declarationCommand) &&
     (hasName || (character === '[' && parent.kind === 'array'))
   if (!parameter && !assignment) return undefined
 
@@ -282,6 +287,52 @@ function readHeredocDelimiterWord(
   return consumed ? { delimiter, quoted, end: cursor } : undefined
 }
 
+/** Assignment-shaped words after an ordinary command name are arguments, not arithmetic. */
+function trackShellCommandPosition(code: string, index: number, frame: ShellScanFrame): void {
+  if (
+    frame.literalRoot ||
+    frame.quote !== 'none' ||
+    (frame.kind !== 'root' && frame.kind !== 'command' && frame.kind !== 'backtick')
+  ) {
+    return
+  }
+  const character = code[index]
+  const redirection = character === '<' || character === '>' || code.startsWith('&>', index)
+  const separator =
+    /[;\n&|()]/.test(character) &&
+    !redirection &&
+    !((character === '&' || character === '|') && /[<>]/.test(code[index - 1] ?? ''))
+  if (!separator && !redirection && !/\s/.test(character)) {
+    if (character === '\\' && /^\r?\n/.test(code.slice(index + 1, index + 3))) return
+    frame.wordStart ??= index
+    return
+  }
+
+  if (frame.wordStart !== undefined) {
+    const word = code.slice(frame.wordStart, index).replace(/\\\r?\n/g, '')
+    if (frame.redirectionTarget) {
+      frame.redirectionTarget = false
+    } else if (
+      !(redirection && /^\d+$/.test(word)) &&
+      frame.commandPosition !== false &&
+      !/^[A-Za-z_][A-Za-z0-9_]*(?:\+?=|\[[\s\S]*\]\+?=)/.test(word) &&
+      !/^(?:if|then|else|elif|while|until|do|!|\{|time|command|builtin|exec)$/.test(word)
+    ) {
+      frame.commandPosition = false
+      const name = readHeredocDelimiterWord(word, 0, word.length)?.delimiter
+      frame.declarationCommand = /^(?:declare|export|local|readonly|typeset)$/.test(name ?? '')
+    }
+    frame.wordStart = undefined
+  }
+  if (separator) {
+    frame.commandPosition = true
+    frame.declarationCommand = false
+    frame.redirectionTarget = false
+  } else if (redirection) {
+    frame.redirectionTarget = true
+  }
+}
+
 function parseHeredocHeaders(
   code: string,
   lineStart: number,
@@ -536,6 +587,7 @@ function collectShellOccurrenceContexts(
     const frame = frames.at(-1)
     if (!frame) break
 
+    trackShellCommandPosition(code, index, frame)
     const occurrence = occurrenceByStart.get(index)
     if (occurrence) {
       contexts.set(occurrence, {
@@ -614,6 +666,7 @@ function collectShellOccurrenceContexts(
     }
     if (!frame.literalRoot && shellCommentStarts(code, index)) {
       const newline = code.indexOf('\n', index)
+      if (newline !== -1 && newline < end) trackShellCommandPosition(code, newline, frame)
       index = newline === -1 || newline >= end ? end : newline + 1
       continue
     }

From a9c27d854ccd0cdc1b50027b6770143d6943291d Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 26 Sep 2026 15:15:17 -0700
Subject: [PATCH 5/7] fix(shell): reject placeholders in numeric conditional
 operands

---
 .../code-placeholders/compiler.test.ts        |  19 ++++
 .../lib/execution/code-placeholders/shell.ts  | 101 ++++++++++++++++--
 2 files changed, 112 insertions(+), 8 deletions(-)

diff --git a/apps/sim/lib/execution/code-placeholders/compiler.test.ts b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
index 8498ab3d580..f48a6a4b977 100644
--- a/apps/sim/lib/execution/code-placeholders/compiler.test.ts
+++ b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
@@ -1032,6 +1032,13 @@ describe('code placeholder compiler', () => {
     'if values[{{KEY}}]=x; then :; fi',
     'declare -a values[{{KEY}}]=x',
     'printf %s done # end of command\nvalues[{{KEY}}]=x',
+    '[[ 1 -eq {{KEY}} ]]',
+    '[[ "{{KEY}}" -ne 1 ]]',
+    '[[ 1 -lt "{{KEY}}" ]]',
+    '[[ {{KEY}} -le 1 ]]',
+    '[[ 1 -gt {{KEY}} ]]',
+    '[[ {{KEY}} -ge 1 ]]',
+    '[[ "$(printf %s "{{KEY}}")" -eq 1 ]]',
     'values[ 1 + {{KEY}} ]=x',
     'values[$(printf %s "{{KEY}}")]=x',
     'values=([{{KEY}}]=x)',
@@ -1111,6 +1118,18 @@ describe('code placeholder compiler', () => {
     )
   })
 
+  it('preserves string operands beside numeric shell comparisons', async () => {
+    const compiled = await compileCodePlaceholders({
+      code: [
+        '[[ "{{KEY}}" == word && 1 -eq 1 ]] && printf "%s\\n" "{{KEY}}"',
+        '[[ 2 -gt 1 && ( "{{KEY}}" == word || "{{KEY}}" == "-eq" ) ]] && printf "%s\\n" "{{KEY}}"',
+      ].join('\n'),
+      language: CodeLanguage.Shell,
+      environmentVariables: { KEY: 'word' },
+    })
+    expect(executeShell(compiled.code, compiled.bindings)).toBe('word\nword\n')
+  })
+
   it.each([
     ['unquoted', "cat <<EOF >/dev/null\nToday's report\nEOF"],
     ['quoted', "cat <<'EOF' >/dev/null\nToday's report\nEOF"],
diff --git a/apps/sim/lib/execution/code-placeholders/shell.ts b/apps/sim/lib/execution/code-placeholders/shell.ts
index 4342192cec6..adef72c2579 100644
--- a/apps/sim/lib/execution/code-placeholders/shell.ts
+++ b/apps/sim/lib/execution/code-placeholders/shell.ts
@@ -26,13 +26,19 @@ interface HeredocDeclaration {
 type ShellQuote = 'none' | 'single' | 'double' | 'ansi'
 
 interface ShellScanFrame {
-  kind: 'root' | 'command' | 'arithmetic' | 'backtick' | 'array'
+  kind: 'root' | 'command' | 'arithmetic' | 'backtick' | 'array' | 'conditional'
   quote: ShellQuote
   parenthesisDepth: number
   bracketDepth?: number
-  /** A bare name[index] is arithmetic only when its closing bracket is followed by assignment. */
-  arrayAssignment?: boolean
+  /** Some operands become arithmetic only after a following assignment or comparison operator. */
+  arithmeticEnabled?: boolean
   arithmeticParent?: ShellScanFrame
+  conditional?: {
+    parent?: ShellScanFrame
+    previousOperand?: ShellScanFrame
+    word?: ShellScanFrame
+    numericOperand: boolean
+  }
   wordStart?: number
   commandPosition?: boolean
   declarationCommand?: boolean
@@ -142,6 +148,7 @@ function readShellArrayStart(
   const assignment =
     parent.quote === 'none' &&
     !parent.literalRoot &&
+    parent.kind !== 'conditional' &&
     wordStart &&
     (parent.kind === 'array' || parent.commandPosition !== false || parent.declarationCommand) &&
     (hasName || (character === '[' && parent.kind === 'array'))
@@ -152,7 +159,7 @@ function readShellArrayStart(
     quote: 'none',
     parenthesisDepth: character === '(' ? 1 : 0,
     ...(character === '['
-      ? { bracketDepth: 1, ...(!parameter ? { arrayAssignment: false } : {}) }
+      ? { bracketDepth: 1, ...(!parameter ? { arithmeticEnabled: false } : {}) }
       : {}),
     literalRoot: false,
   }
@@ -333,6 +340,52 @@ function trackShellCommandPosition(code: string, index: number, frame: ShellScan
   }
 }
 
+/** Keep operand contexts pending until the following conditional operator is known. */
+function trackShellConditionalOperand(code: string, index: number, frame: ShellScanFrame): void {
+  const conditional = frame.conditional
+  if (!conditional || frame.quote !== 'none') return
+  const character = code[index]
+  const closing =
+    frame.wordStart === undefined &&
+    code.startsWith(']]', index) &&
+    (index + 2 === code.length || /\s|[;&|()<>]/.test(code[index + 2]))
+  const separator = /[&|()]/.test(character) || closing
+  if (!separator && !/\s/.test(character)) {
+    if (character === '\\' && /^\r?\n/.test(code.slice(index + 1, index + 3))) return
+    if (frame.wordStart === undefined) {
+      frame.wordStart = index
+      conditional.word = {
+        kind: 'arithmetic',
+        quote: 'none',
+        parenthesisDepth: 0,
+        literalRoot: false,
+        arithmeticEnabled: conditional.numericOperand,
+        arithmeticParent: conditional.parent,
+      }
+      conditional.numericOperand = false
+      frame.arithmeticParent = conditional.word
+    }
+    return
+  }
+
+  if (frame.wordStart !== undefined) {
+    const word = code.slice(frame.wordStart, index).replace(/\\\r?\n/g, '')
+    if (/^-(?:eq|ne|lt|le|gt|ge)$/.test(word)) {
+      if (conditional.previousOperand) conditional.previousOperand.arithmeticEnabled = true
+      conditional.numericOperand = true
+    } else {
+      conditional.previousOperand = conditional.word
+    }
+    frame.wordStart = undefined
+    conditional.word = undefined
+    frame.arithmeticParent = conditional.parent
+  }
+  if (separator) {
+    conditional.previousOperand = undefined
+    conditional.numericOperand = false
+  }
+}
+
 function parseHeredocHeaders(
   code: string,
   lineStart: number,
@@ -542,7 +595,7 @@ function getUnsupportedShellPosition(
   context: ShellOccurrenceContext
 ): string | undefined {
   for (let frame = context.arithmeticFrame; frame; frame = frame.arithmeticParent) {
-    if (frame.arrayAssignment !== false) return 'in a shell arithmetic expression'
+    if (frame.arithmeticEnabled !== false) return 'in a shell arithmetic expression'
   }
   if (code[occurrence.start - 1] === '$') return 'immediately after "$"'
   if (context.quote !== 'none') return undefined
@@ -588,6 +641,7 @@ function collectShellOccurrenceContexts(
     if (!frame) break
 
     trackShellCommandPosition(code, index, frame)
+    trackShellConditionalOperand(code, index, frame)
     const occurrence = occurrenceByStart.get(index)
     if (occurrence) {
       contexts.set(occurrence, {
@@ -622,7 +676,10 @@ function collectShellOccurrenceContexts(
     const expansion = readShellExpansionStart(
       code,
       index,
-      frame.quote === 'none' && !frame.literalRoot && frame.kind !== 'arithmetic'
+      frame.quote === 'none' &&
+        !frame.literalRoot &&
+        frame.kind !== 'arithmetic' &&
+        frame.kind !== 'conditional'
     )
     const array = readShellArrayStart(code, index, frame)
     if (array) {
@@ -664,6 +721,34 @@ function collectShellOccurrenceContexts(
       index += 1
       continue
     }
+    if (
+      frame.kind === 'conditional' &&
+      frame.wordStart === undefined &&
+      code.startsWith(']]', index)
+    ) {
+      frames.pop()
+      index += 2
+      continue
+    }
+    if (
+      !frame.literalRoot &&
+      frame.commandPosition !== false &&
+      code.startsWith('[[', index) &&
+      (index === 0 || /\s|[;&|()]/.test(code[index - 1])) &&
+      (index + 2 === end || /\s|[()]/.test(code[index + 2]))
+    ) {
+      const conditional: ShellScanFrame = {
+        kind: 'conditional',
+        quote: 'none',
+        parenthesisDepth: 0,
+        literalRoot: false,
+        conditional: { numericOperand: false },
+      }
+      pushShellFrame(frames, conditional)
+      if (conditional.conditional) conditional.conditional.parent = conditional.arithmeticParent
+      index += 2
+      continue
+    }
     if (!frame.literalRoot && shellCommentStarts(code, index)) {
       const newline = code.indexOf('\n', index)
       if (newline !== -1 && newline < end) trackShellCommandPosition(code, newline, frame)
@@ -715,8 +800,8 @@ function collectShellOccurrenceContexts(
       if (character === ']') {
         frame.bracketDepth -= 1
         if (frame.bracketDepth === 0) {
-          if (frame.arrayAssignment !== undefined) {
-            frame.arrayAssignment = code[index + 1] === '=' || code.startsWith('+=', index + 1)
+          if (frame.arithmeticEnabled !== undefined) {
+            frame.arithmeticEnabled = code[index + 1] === '=' || code.startsWith('+=', index + 1)
           }
           frames.pop()
         }

From bc172c04efa71c2fcd80a9572ac5c43871422faf Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 26 Sep 2026 15:22:10 -0700
Subject: [PATCH 6/7] fix(shell): reject arithmetic placeholders passed to let

---
 .../code-placeholders/compiler.test.ts        | 17 ++++++++++++++
 .../lib/execution/code-placeholders/shell.ts  | 22 ++++++++++++++++---
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/apps/sim/lib/execution/code-placeholders/compiler.test.ts b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
index f48a6a4b977..9ff91cf063f 100644
--- a/apps/sim/lib/execution/code-placeholders/compiler.test.ts
+++ b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
@@ -1039,6 +1039,10 @@ describe('code placeholder compiler', () => {
     '[[ 1 -gt {{KEY}} ]]',
     '[[ {{KEY}} -ge 1 ]]',
     '[[ "$(printf %s "{{KEY}}")" -eq 1 ]]',
+    'let "x={{KEY}}"',
+    'let values[{{KEY}}]=1',
+    "builtin let 'x={{KEY}}'",
+    'let "x=$(printf %s "{{KEY}}")"',
     'values[ 1 + {{KEY}} ]=x',
     'values[$(printf %s "{{KEY}}")]=x',
     'values=([{{KEY}}]=x)',
@@ -1130,6 +1134,19 @@ describe('code placeholder compiler', () => {
     expect(executeShell(compiled.code, compiled.bindings)).toBe('word\nword\n')
   })
 
+  it('ends builtin arithmetic context at the next shell command', async () => {
+    const compiled = await compileCodePlaceholders({
+      code: [
+        'let "x=1"; printf "%s\\n" "{{KEY}}"',
+        'let "x=2" # end of arithmetic',
+        'printf "%s\\n" "{{KEY}}"',
+      ].join('\n'),
+      language: CodeLanguage.Shell,
+      environmentVariables: { KEY: 'two words' },
+    })
+    expect(executeShell(compiled.code, compiled.bindings)).toBe('two words\ntwo words\n')
+  })
+
   it.each([
     ['unquoted', "cat <<EOF >/dev/null\nToday's report\nEOF"],
     ['quoted', "cat <<'EOF' >/dev/null\nToday's report\nEOF"],
diff --git a/apps/sim/lib/execution/code-placeholders/shell.ts b/apps/sim/lib/execution/code-placeholders/shell.ts
index adef72c2579..4e282443d6d 100644
--- a/apps/sim/lib/execution/code-placeholders/shell.ts
+++ b/apps/sim/lib/execution/code-placeholders/shell.ts
@@ -33,6 +33,7 @@ interface ShellScanFrame {
   /** Some operands become arithmetic only after a following assignment or comparison operator. */
   arithmeticEnabled?: boolean
   arithmeticParent?: ShellScanFrame
+  commandArithmetic?: ShellScanFrame
   conditional?: {
     parent?: ShellScanFrame
     previousOperand?: ShellScanFrame
@@ -89,9 +90,14 @@ function shellArithmeticCommandStarts(code: string, index: number): boolean {
   return previous === undefined || /\s|[;&|()<>]/.test(previous)
 }
 
+function getShellArithmeticFrame(frame: ShellScanFrame | undefined): ShellScanFrame | undefined {
+  return frame?.kind === 'arithmetic'
+    ? frame
+    : (frame?.commandArithmetic ?? frame?.arithmeticParent)
+}
+
 function pushShellFrame(frames: ShellScanFrame[], frame: ShellScanFrame): void {
-  const parent = frames.at(-1)
-  frame.arithmeticParent = parent?.kind === 'arithmetic' ? parent : parent?.arithmeticParent
+  frame.arithmeticParent = getShellArithmeticFrame(frames.at(-1))
   frames.push(frame)
 }
 
@@ -328,12 +334,22 @@ function trackShellCommandPosition(code: string, index: number, frame: ShellScan
       frame.commandPosition = false
       const name = readHeredocDelimiterWord(word, 0, word.length)?.delimiter
       frame.declarationCommand = /^(?:declare|export|local|readonly|typeset)$/.test(name ?? '')
+      if (name === 'let') {
+        frame.commandArithmetic = {
+          kind: 'arithmetic',
+          quote: 'none',
+          parenthesisDepth: 0,
+          literalRoot: false,
+          arithmeticParent: frame.arithmeticParent,
+        }
+      }
     }
     frame.wordStart = undefined
   }
   if (separator) {
     frame.commandPosition = true
     frame.declarationCommand = false
+    frame.commandArithmetic = undefined
     frame.redirectionTarget = false
   } else if (redirection) {
     frame.redirectionTarget = true
@@ -646,7 +662,7 @@ function collectShellOccurrenceContexts(
     if (occurrence) {
       contexts.set(occurrence, {
         quote: frame.quote,
-        arithmeticFrame: frame.kind === 'arithmetic' ? frame : frame.arithmeticParent,
+        arithmeticFrame: getShellArithmeticFrame(frame),
       })
       index = occurrence.end
       continue

From 29d957626bf78e5bcb45e33ee7e2aa1bddc4dfa0 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 26 Sep 2026 15:28:11 -0700
Subject: [PATCH 7/7] fix(shell): preserve placeholders in let redirection
 paths

---
 .../execution/code-placeholders/compiler.test.ts   | 14 ++++++++++++++
 apps/sim/lib/execution/code-placeholders/shell.ts  |  6 +++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/apps/sim/lib/execution/code-placeholders/compiler.test.ts b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
index 9ff91cf063f..ae5cb6584ba 100644
--- a/apps/sim/lib/execution/code-placeholders/compiler.test.ts
+++ b/apps/sim/lib/execution/code-placeholders/compiler.test.ts
@@ -1043,6 +1043,8 @@ describe('code placeholder compiler', () => {
     'let values[{{KEY}}]=1',
     "builtin let 'x={{KEY}}'",
     'let "x=$(printf %s "{{KEY}}")"',
+    'let >/dev/null "x={{KEY}}"',
+    'echo "$(( $(let "x=1" > /dev/{{KEY}}; printf 1) ))"',
     'values[ 1 + {{KEY}} ]=x',
     'values[$(printf %s "{{KEY}}")]=x',
     'values=([{{KEY}}]=x)',
@@ -1147,6 +1149,18 @@ describe('code placeholder compiler', () => {
     expect(executeShell(compiled.code, compiled.bindings)).toBe('two words\ntwo words\n')
   })
 
+  it.each(['> /dev/{{KEY}}', '> "/dev/{{KEY}}"', '> "$(printf /dev/%s "{{KEY}}")"'])(
+    'keeps let redirection targets out of arithmetic context: %s',
+    async (redirect) => {
+      const compiled = await compileCodePlaceholders({
+        code: `let "x=1" ${redirect}; printf "%s\\n" "$x"`,
+        language: CodeLanguage.Shell,
+        environmentVariables: { KEY: 'null' },
+      })
+      expect(executeShell(compiled.code, compiled.bindings)).toBe('1\n')
+    }
+  )
+
   it.each([
     ['unquoted', "cat <<EOF >/dev/null\nToday's report\nEOF"],
     ['quoted', "cat <<'EOF' >/dev/null\nToday's report\nEOF"],
diff --git a/apps/sim/lib/execution/code-placeholders/shell.ts b/apps/sim/lib/execution/code-placeholders/shell.ts
index 4e282443d6d..bcb404dd7ca 100644
--- a/apps/sim/lib/execution/code-placeholders/shell.ts
+++ b/apps/sim/lib/execution/code-placeholders/shell.ts
@@ -91,9 +91,9 @@ function shellArithmeticCommandStarts(code: string, index: number): boolean {
 }
 
 function getShellArithmeticFrame(frame: ShellScanFrame | undefined): ShellScanFrame | undefined {
-  return frame?.kind === 'arithmetic'
-    ? frame
-    : (frame?.commandArithmetic ?? frame?.arithmeticParent)
+  if (frame?.kind === 'arithmetic') return frame
+  if (!frame?.redirectionTarget && frame?.commandArithmetic) return frame.commandArithmetic
+  return frame?.arithmeticParent
 }
 
 function pushShellFrame(frames: ShellScanFrame[], frame: ShellScanFrame): void {