fix(code-placeholders): reject arithmetic comparisons and heredoc operands (#8760)

* fix(code-placeholders): harden shell placeholder interpolation in arithmetic contexts

* fix(code-placeholders): keep integer attributes across re-declaration and unset -f, guard shell values against subscript expansions

* fix(code-placeholders): end assignment-value scope at the word, carry attributes into heredoc bodies

* fix(code-placeholders): treat a declaration as pending inside its own command's expansions

* fix(code-placeholders): narrow arithmetic guards and preserve literal data

* fix(code-placeholders): skip continued newlines before comparison operands

* fix(code-placeholders): preserve command scope across process substitutions

Author: waleedlatif1

.github/workflows/checks.yml

@@ -614,6 +614,22 @@ jobs:
       - name: Install ripgrep
         run: command -v rg || (sudo apt-get update && sudo apt-get install -y ripgrep)
 
+      - name: Verify shell placeholder compilation in Bash
+        if: matrix.shard == 1
+        working-directory: apps/sim
+        env:
+          SHELL_PLACEHOLDERS_REPORT_PATH: ${{ runner.temp }}/shell-placeholders.json
+        run: bun scripts/test-shell-placeholders-e2e.ts
+
+      - name: Upload shell placeholder execution report
+        if: failure() && matrix.shard == 1
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
+        with:
+          name: shell-placeholders
+          path: ${{ runner.temp }}/shell-placeholders.json
+          if-no-files-found: warn
+          retention-days: 7
+
       - name: Run tests
         env:
           NODE_OPTIONS: '--no-warnings --max-old-space-size=8192'

apps/sim/lib/execution/code-placeholders/shared.ts

@@ -327,12 +327,12 @@ export function createOffsetRangeLookup(
  * The placeholders lying wholly inside `[start, end]`. Occurrences are ordered and never
  * overlap, so the matches are one contiguous run found by bisection.
  */
-export function occurrencesWithin(
-  occurrences: readonly CodePlaceholderOccurrence[],
+export function occurrencesWithin<T extends Pick<CodePlaceholderOccurrence, 'start' | 'end'>>(
+  occurrences: readonly T[],
   start: number,
   end: number
-): CodePlaceholderOccurrence[] {
-  const matches: CodePlaceholderOccurrence[] = []
+): T[] {
+  const matches: T[] = []
   for (
     let index = partitionPoint(occurrences, (occurrence) => occurrence.start < start);
     index < occurrences.length && occurrences[index].end <= end;