fix(code-server,vscode-web): parse JSONC in extensions.json with sed

[rodmk]

Fixes coder#708. Supersedes coder#707.

Description

auto_install_extensions fails to parse .vscode/extensions.json files containing valid JSONC (block comments, trailing commas). VS Code officially supports these via its built-in JSONC parser with default options.

This PR replaces the existing sed | jq pipeline with a portable two-stage sed | sed | jq pipeline that handles all JSONC features — no new dependencies, no GNU-only extensions.

Type of Change

• Bug fix

Module Information

Path: registry/coder/modules/code-server and registry/coder/modules/vscode-web
New version: code-server 1.4.4, vscode-web 1.5.1
Breaking change: No

Problem

The sed 's|//.*||g' | jq pipeline fails on block comments and trailing commas:

https://github.com/coder/registry/blob/f1748c80f7d123d9f3a7867ea1835feaf227d1f2/registry/coder/modules/code-server/run.sh#L133

https://github.com/coder/registry/blob/f1748c80f7d123d9f3a7867ea1835feaf227d1f2/registry/coder/modules/vscode-web/run.sh#L161

https://github.com/coder/registry/blob/f1748c80f7d123d9f3a7867ea1835feaf227d1f2/registry/coder/modules/vscode-web/run.sh#L173

Fix

Extracts a strip_jsonc helper function (defined once per script) that uses a two-stage sed | sed pipeline:

strip_jsonc() {
  sed 's|//.*||g' "$1" | sed -E '
    :a
    N
    $!ba
    s#/[*]([^*]|[*]+[^*/])*[*]+/##g
    s/,[^]}"]*([]}])/\1/g
  '
}

extensions=$(strip_jsonc "$file" | jq -r '(.recommendations // [])[]' 2>/dev/null || true)

1. Strip line comments (// ...) — a separate line-by-line sed pass where .* naturally stops at the end of each input line
2. Slurp the file (:a;N;$!ba) — reads the entire file into sed's pattern space for multi-line matching
3. Strip block comments (/* ... */) — ERE regex handles nested stars, multi-line comments
4. Strip trailing commas before ] or } — [^]}"]* matches only whitespace/newlines between a trailing comma and its closing bracket

This is safe for extensions.json because extension IDs are restricted to [a-z0-9\-.] by vsce's nameRegex, so comment markers (//, /*) cannot appear inside string values, and the trailing-comma regex [^]}"]* will only ever match whitespace between a comma and its closing bracket. The function is not a general-purpose JSONC parser, but a full parser would be overengineered for this use case.

Cross-platform compatibility

The original sed 's|//.*||g' pipeline only handled line comments. A natural fix would use sed -z to slurp the file for multi-line block comment matching, but -z is a GNU sed extension that does not work on macOS (BSD sed). Since Coder workspaces support macOS (the vscode-web module accepts platform = "darwin"), the fix must be portable.

Line comment stripping is done in a separate first-stage sed (before slurping) because after slurping with :a;N;$!ba, . matches \n in the pattern space, so .* would greedily eat across lines. A single-sed approach using [^\n]* instead of .* works on GNU sed but fails on BSD sed (macOS), where \n inside a bracket expression is interpreted as literal backslash + n per POSIX — causing silent corruption of extension IDs containing the letter n.

This implementation uses only:

• sed and sed -E — POSIX-standard flags, supported by both GNU and BSD sed
• :a;N;$!ba — standard sed idiom for slurping, works on both platforms
• No \+, \s, [^\n], or other GNU-only regex extensions

Alternatives considered

Approach	Tradeoff
sed -z	Simpler regex, but -z is a GNU sed extension — breaks on macOS BSD sed
Single sed -E with [^\n]*	Works on GNU sed, but \n in bracket expressions is not portable — BSD sed treats it as literal \ + n, silently corrupting output
perl -0777 -pe	Clean one-liner, but no module in the repo uses perl and Apple may remove it from future macOS
Node.js state machine	Correct JSONC parsing, but rejected in #707 as overengineered — 74-line JS file, undocumented bundled node paths, duplicated across modules
Python3	Could parse JSONC natively, but not guaranteed on all workspaces and would need a command -v guard
Two-stage sed | sed (this PR)	Extra pipe, but zero new dependencies, fully portable across GNU and BSD sed, minimal diff

Testing & Validation

• Tests pass (bun test) — 490 pass, 4 pre-existing failures unrelated to this PR
• Code formatted (bun fmt)
• Changes tested locally
• All 19 JSONC parsing test cases pass
• Version bumped via version-bump.sh
• Portable across GNU sed (Linux) and BSD sed (macOS)
• E2E verified in container: terraform apply with auto_install_extensions = true + JSONC extensions.json (line comments, block comments, trailing commas) correctly extracts and installs all extensions on both ubuntu:22.04 and alpine:latest

Note: E2E was validated locally against code-server only. The same strip_jsonc_for_extensions function is used identically in vscode-web, but vscode-web cannot be E2E tested because use_cached = true (needed to skip the real install) causes the script to exit 0 before reaching the extension installation code path.

Tested the sed+jq pipeline against 19 cases:

Category	Test Cases	Result
Issue coder#708 reproduction	Block comment + trailing comma (exact issue example)	pass
Strict JSON	No JSONC features	pass
Line comments	End-of-line, standalone line	pass
Block comments	Inline, multi-line, starred, stars inside	pass
Trailing commas	Array, object, same-line, nested	pass
Combined	All JSONC features together	pass
Edge cases	Empty array, missing key, single ext, workspace format, consecutive block comments, empty file	pass

Standalone test script (requires jq)

#!/bin/bash
set -euo pipefail

PASS=0
FAIL=0

strip_jsonc() {
  sed 's|//.*||g' "$1" | sed -E '
    :a
    N
    $!ba
    s#/[*]([^*]|[*]+[^*/])*[*]+/##g
    s/,[^]}"]*([]}])/\1/g
  '
}

run_test() {
  local name="$1" input="$2" jq_expr="$3" expected="$4"
  local tmpfile
  tmpfile=$(mktemp)
  printf '%s' "$input" > "$tmpfile"

  local actual
  actual=$(strip_jsonc "$tmpfile" | jq -r "$jq_expr" 2>/dev/null || true)
  rm -f "$tmpfile"

  if [ "$actual" = "$expected" ]; then
    printf "  ✓ %s\n" "$name"
    PASS=$((PASS + 1))
  else
    printf "  ✗ %s\n" "$name"
    printf "    expected: |%s|\n" "$(echo "$expected" | head -5)"
    printf "    actual:   |%s|\n" "$(echo "$actual" | head -5)"
    FAIL=$((FAIL + 1))
  fi
}

echo "=== Issue #708 reproduction case ==="
run_test "Issue example" '{
  "recommendations": [
    "ms-python.python",
    /* a block comment */
    "dbaeumer.vscode-eslint", // trailing comma
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

echo ""
echo "=== Strict JSON (no JSONC features) ==="
run_test "Strict JSON" '{
  "recommendations": [
    "ms-python.python",
    "dbaeumer.vscode-eslint"
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

echo ""
echo "=== Line comments ==="
run_test "Line comment at end of line" '{
  "recommendations": [
    "ms-python.python", // python support
    "dbaeumer.vscode-eslint" // linting
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

run_test "Line comment on own line" '{
  "recommendations": [
    // this is python
    "ms-python.python",
    "dbaeumer.vscode-eslint"
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

echo ""
echo "=== Block comments ==="
run_test "Inline block comment" '{
  "recommendations": [
    "ms-python.python",
    /* eslint */ "dbaeumer.vscode-eslint"
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

run_test "Multi-line block comment" '{
  "recommendations": [
    "ms-python.python",
    /*
     * This is a multi-line
     * block comment
     */
    "dbaeumer.vscode-eslint"
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

run_test "Block comment with stars /***/" '{
  "recommendations": [
    "ms-python.python",
    /*** starred comment ***/
    "dbaeumer.vscode-eslint"
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

run_test "Block comment with * inside" '{
  "recommendations": [
    "ms-python.python",
    /* foo * bar */
    "dbaeumer.vscode-eslint"
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

echo ""
echo "=== Trailing commas ==="
run_test "Trailing comma in array" '{
  "recommendations": [
    "ms-python.python",
    "dbaeumer.vscode-eslint",
  ]
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

run_test "Trailing comma in object" '{
  "recommendations": [
    "ms-python.python",
  ],
}' '(.recommendations // [])[]' "ms-python.python"

run_test "Trailing comma same line as bracket" '{
  "recommendations": ["ms-python.python",]
}' '(.recommendations // [])[]' "ms-python.python"

echo ""
echo "=== Combined JSONC features ==="
run_test "All features combined" '{
  // Top-level comment
  "recommendations": [
    "ms-python.python", // inline comment
    /* block comment */
    "dbaeumer.vscode-eslint",
    /*
     * Multi-line
     */
    "esbenp.prettier-vscode", // trailing comma below
  ],
}' '(.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint
esbenp.prettier-vscode"

echo ""
echo "=== Edge cases ==="
run_test "Empty recommendations" '{
  "recommendations": []
}' '(.recommendations // [])[]' ""

run_test "Missing recommendations key" '{
  "unwanted": ["foo"]
}' '(.recommendations // [])[]' ""

run_test "Single extension" '{
  "recommendations": ["ms-python.python"]
}' '(.recommendations // [])[]' "ms-python.python"

run_test "Workspace file format (.extensions.recommendations)" '{
  "extensions": {
    "recommendations": [
      "ms-python.python",
      "dbaeumer.vscode-eslint"
    ]
  }
}' '(.extensions.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

run_test "Workspace file with JSONC" '{
  "extensions": {
    // Recommended extensions
    "recommendations": [
      "ms-python.python",
      /* linting */ "dbaeumer.vscode-eslint", // trailing comma
    ],
  },
}' '(.extensions.recommendations // [])[]' "ms-python.python
dbaeumer.vscode-eslint"

run_test "Consecutive block comments" '{
  "recommendations": [
    /* first */ /* second */
    "ms-python.python"
  ]
}' '(.recommendations // [])[]' "ms-python.python"

run_test "Empty file" '' '(.recommendations // [])[]' ""

echo ""
echo "=== Results ==="
echo "Passed: $PASS"
echo "Failed: $FAIL"
[ "$FAIL" -eq 0 ] && echo "All tests passed!" || exit 1

Related Issues

• Fixes auto_install_extensions fails on JSONC comments and trailing commas coder/registry#708
• Supersedes fix: properly parse JSONC in extensions.json and batch extension installs coder/registry#707

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