diff --git a/cli/bash/commands/basectl/subcommands/setup_common.sh b/cli/bash/commands/basectl/subcommands/setup_common.sh
index 11a0dea..cf7b816 100644
--- a/cli/bash/commands/basectl/subcommands/setup_common.sh
+++ b/cli/bash/commands/basectl/subcommands/setup_common.sh
@@ -24,6 +24,11 @@ _BASE_SETUP_CHECK_OK=()
 _BASE_SETUP_CHECK_MESSAGES=()
 _BASE_SETUP_CHECK_RECOVERIES=()
 _BASE_SETUP_CHECK_DEBUG_MESSAGES=()
+_BASE_SETUP_PARSED_CHECK_NAME=""
+_BASE_SETUP_PARSED_CHECK_OK=""
+_BASE_SETUP_PARSED_CHECK_MESSAGE=""
+_BASE_SETUP_PARSED_CHECK_RECOVERY=""
+_BASE_SETUP_PARSED_CHECK_DEBUG_MESSAGE=""
 _BASE_SETUP_VENV_HEALTH_MESSAGE=""
 
 setup_refresh_cached_paths() {
@@ -1000,94 +1005,257 @@ setup_add_check_result() {
     _BASE_SETUP_CHECK_DEBUG_MESSAGES+=("$debug_message")
 }
 
-setup_collect_base_check_results() {
-    local brew_bin click_ok=false click_package
-    local missing=0
-    local pyyaml_ok=false pyyaml_package
-    local refresh_brew_failure_mode="${1:-warn}"
+setup_write_check_result_file() {
+    local debug_message="${6:-}"
+    local message="$4"
+    local name="$2"
+    local ok="$3"
+    local path="$1"
+    local recovery="${5:-}"
 
-    setup_clear_check_results
-    setup_require_macos
-    click_package="$(setup_click_package)"
-    pyyaml_package="$(setup_pyyaml_package)"
-    setup_ensure_cached_paths
+    {
+        printf 'name=%s\n' "$name"
+        printf 'ok=%s\n' "$ok"
+        printf 'message=%s\n' "$message"
+        printf 'recovery=%s\n' "$recovery"
+        printf 'debug=%s\n' "$debug_message"
+    } >"$path"
+}
 
-    if brew_bin="$(setup_find_brew_bin)"; then
+setup_parse_check_result_file() {
+    local line path="$1"
+
+    [[ -f "$path" ]] || fatal_error "Base check probe did not produce result file '$path'."
+
+    _BASE_SETUP_PARSED_CHECK_NAME=""
+    _BASE_SETUP_PARSED_CHECK_OK=""
+    _BASE_SETUP_PARSED_CHECK_MESSAGE=""
+    _BASE_SETUP_PARSED_CHECK_RECOVERY=""
+    _BASE_SETUP_PARSED_CHECK_DEBUG_MESSAGE=""
+
+    while IFS= read -r line || [[ -n "$line" ]]; do
+        case "$line" in
+            name=*)
+                _BASE_SETUP_PARSED_CHECK_NAME="${line#name=}"
+                ;;
+            ok=*)
+                _BASE_SETUP_PARSED_CHECK_OK="${line#ok=}"
+                ;;
+            message=*)
+                _BASE_SETUP_PARSED_CHECK_MESSAGE="${line#message=}"
+                ;;
+            recovery=*)
+                _BASE_SETUP_PARSED_CHECK_RECOVERY="${line#recovery=}"
+                ;;
+            debug=*)
+                _BASE_SETUP_PARSED_CHECK_DEBUG_MESSAGE="${line#debug=}"
+                ;;
+        esac
+    done <"$path"
+
+    [[ -n "$_BASE_SETUP_PARSED_CHECK_NAME" ]] || fatal_error "Base check probe result '$path' is missing a name."
+    case "$_BASE_SETUP_PARSED_CHECK_OK" in
+        true|false)
+            ;;
+        *)
+            fatal_error "Base check probe result '$path' has invalid ok value '$_BASE_SETUP_PARSED_CHECK_OK'."
+            ;;
+    esac
+    [[ -n "$_BASE_SETUP_PARSED_CHECK_MESSAGE" ]] || fatal_error "Base check probe result '$path' is missing a message."
+}
+
+setup_add_parsed_check_result() {
+    setup_add_check_result \
+        "$_BASE_SETUP_PARSED_CHECK_NAME" \
+        "$_BASE_SETUP_PARSED_CHECK_OK" \
+        "$_BASE_SETUP_PARSED_CHECK_MESSAGE" \
+        "$_BASE_SETUP_PARSED_CHECK_RECOVERY" \
+        "$_BASE_SETUP_PARSED_CHECK_DEBUG_MESSAGE"
+}
+
+setup_read_check_result_file() {
+    setup_parse_check_result_file "$1"
+    setup_add_parsed_check_result
+    [[ "$_BASE_SETUP_PARSED_CHECK_OK" == true ]]
+}
+
+setup_read_homebrew_check_result_file() {
+    local path="$1"
+    local refresh_brew_failure_mode="$2"
+
+    setup_parse_check_result_file "$path"
+    [[ "$_BASE_SETUP_PARSED_CHECK_NAME" == homebrew ]] ||
+        fatal_error "Base check probe result '$path' contains unexpected name '$_BASE_SETUP_PARSED_CHECK_NAME'."
+
+    if [[ "$_BASE_SETUP_PARSED_CHECK_OK" == true ]]; then
         if setup_refresh_brew_path; then
-            setup_add_check_result "homebrew" true "Homebrew is installed." "" "Resolved Homebrew binary: $brew_bin"
-        else
-            if [[ "$refresh_brew_failure_mode" == fatal ]]; then
-                fatal_error "Homebrew is installed, but its bin directory could not be added to PATH. $(setup_recovery_brew_path)"
-            fi
-            setup_add_check_result \
-                "homebrew" \
-                false \
-                "Homebrew is installed, but its bin directory could not be added to PATH." \
-                "$(setup_recovery_brew_path)"
-            missing=1
+            setup_add_parsed_check_result
+            return 0
         fi
+        if [[ "$refresh_brew_failure_mode" == fatal ]]; then
+            fatal_error "Homebrew is installed, but its bin directory could not be added to PATH. $(setup_recovery_brew_path)"
+        fi
+        setup_add_check_result \
+            "homebrew" \
+            false \
+            "Homebrew is installed, but its bin directory could not be added to PATH." \
+            "$(setup_recovery_brew_path)"
+        return 1
+    fi
+
+    setup_add_parsed_check_result
+    return 1
+}
+
+setup_write_homebrew_check_probe() {
+    local brew_bin
+    local result_file="$1"
+
+    if brew_bin="$(setup_find_brew_bin)"; then
+        setup_write_check_result_file \
+            "$result_file" \
+            "homebrew" \
+            true \
+            "Homebrew is installed." \
+            "" \
+            "Resolved Homebrew binary: $brew_bin"
     else
-        setup_add_check_result "homebrew" false "Homebrew is not installed." "$(setup_recovery_homebrew)"
-        missing=1
+        setup_write_check_result_file \
+            "$result_file" \
+            "homebrew" \
+            false \
+            "Homebrew is not installed." \
+            "$(setup_recovery_homebrew)"
     fi
+}
+
+setup_write_xcode_check_probe() {
+    local result_file="$1"
 
     if setup_xcode_tools_installed; then
-        setup_add_check_result "xcode_command_line_tools" true "Xcode Command Line Tools are installed."
+        setup_write_check_result_file \
+            "$result_file" \
+            "xcode_command_line_tools" \
+            true \
+            "Xcode Command Line Tools are installed."
     else
-        setup_add_check_result \
+        setup_write_check_result_file \
+            "$result_file" \
             "xcode_command_line_tools" \
             false \
             "Xcode Command Line Tools are not installed." \
             "$(setup_recovery_xcode_tools)"
-        missing=1
     fi
+}
+
+setup_write_python_check_probe() {
+    local result_file="$1"
 
     if setup_python_installed; then
-        setup_add_check_result \
+        setup_write_check_result_file \
+            "$result_file" \
             "python" \
             true \
             "Python formula '$(setup_python_formula)' is installed via Homebrew."
     else
-        setup_add_check_result \
+        setup_write_check_result_file \
+            "$result_file" \
             "python" \
             false \
             "Python formula '$(setup_python_formula)' is not installed via Homebrew." \
             "$(setup_recovery_python)"
-        missing=1
     fi
+}
+
+setup_write_virtualenv_check_probe() {
+    local result_file="$1"
 
     if setup_virtualenv_healthy; then
-        setup_add_check_result "base_virtualenv" true "$_BASE_SETUP_VENV_HEALTH_MESSAGE"
+        setup_write_check_result_file \
+            "$result_file" \
+            "base_virtualenv" \
+            true \
+            "$_BASE_SETUP_VENV_HEALTH_MESSAGE"
     else
-        setup_add_check_result \
+        setup_write_check_result_file \
+            "$result_file" \
             "base_virtualenv" \
             false \
             "$_BASE_SETUP_VENV_HEALTH_MESSAGE" \
             "$(setup_recovery_venv)"
-        missing=1
     fi
+}
 
-    if setup_base_python_package_installed "$pyyaml_package"; then
-        pyyaml_ok=true
-    else
-        missing=1
-    fi
-    setup_add_check_result \
-        "pyyaml" \
-        "$pyyaml_ok" \
-        "$(setup_base_python_package_check_message "$pyyaml_package" "$pyyaml_ok")" \
-        "$(setup_recovery_base_python_package)"
+setup_write_python_package_check_probe() {
+    local ok=false
+    local package="$3"
+    local result_file="$1"
+    local result_name="$2"
 
-    if setup_base_python_package_installed "$click_package"; then
-        click_ok=true
-    else
-        missing=1
+    if setup_base_python_package_installed "$package"; then
+        ok=true
     fi
-    setup_add_check_result \
-        "click" \
-        "$click_ok" \
-        "$(setup_base_python_package_check_message "$click_package" "$click_ok")" \
+
+    setup_write_check_result_file \
+        "$result_file" \
+        "$result_name" \
+        "$ok" \
+        "$(setup_base_python_package_check_message "$package" "$ok")" \
         "$(setup_recovery_base_python_package)"
+}
+
+setup_wait_for_base_check_probes() {
+    local failed=0
+    local pid
+
+    for pid in "$@"; do
+        wait "$pid" || failed=1
+    done
+
+    return "$failed"
+}
+
+setup_collect_base_check_results() {
+    local click_package
+    local missing=0
+    local probe_pids=()
+    local pyyaml_package
+    local refresh_brew_failure_mode="${1:-warn}"
+    local tmpdir
+
+    setup_clear_check_results
+    setup_require_macos
+    click_package="$(setup_click_package)"
+    pyyaml_package="$(setup_pyyaml_package)"
+    setup_ensure_cached_paths
+
+    tmpdir="$(mktemp -d "${TMPDIR:-/tmp}/base-check.XXXXXX")" ||
+        fatal_error "Unable to create temporary directory for Base check probes."
+
+    setup_write_homebrew_check_probe "$tmpdir/homebrew" &
+    probe_pids+=("$!")
+    setup_write_xcode_check_probe "$tmpdir/xcode" &
+    probe_pids+=("$!")
+    setup_write_python_check_probe "$tmpdir/python" &
+    probe_pids+=("$!")
+    setup_write_virtualenv_check_probe "$tmpdir/base_virtualenv" &
+    probe_pids+=("$!")
+    setup_write_python_package_check_probe "$tmpdir/pyyaml" "pyyaml" "$pyyaml_package" &
+    probe_pids+=("$!")
+    setup_write_python_package_check_probe "$tmpdir/click" "click" "$click_package" &
+    probe_pids+=("$!")
+
+    setup_wait_for_base_check_probes "${probe_pids[@]}" ||
+        fatal_error "One or more Base check probes failed before writing results."
+
+    setup_read_homebrew_check_result_file "$tmpdir/homebrew" "$refresh_brew_failure_mode" || missing=1
+    setup_read_check_result_file "$tmpdir/xcode" || missing=1
+    setup_read_check_result_file "$tmpdir/python" || missing=1
+    setup_read_check_result_file "$tmpdir/base_virtualenv" || missing=1
+    setup_read_check_result_file "$tmpdir/pyyaml" || missing=1
+    setup_read_check_result_file "$tmpdir/click" || missing=1
+
+    rm -rf "$tmpdir"
 
     return "$missing"
 }
diff --git a/cli/bash/commands/basectl/tests/check.bats b/cli/bash/commands/basectl/tests/check.bats
index 7ae65cb..6f24351 100644
--- a/cli/bash/commands/basectl/tests/check.bats
+++ b/cli/bash/commands/basectl/tests/check.bats
@@ -42,6 +42,38 @@ load ./setup_helpers.bash
     [ "$(grep -c '^click$' "$TEST_STATE_DIR/pip-show.log")" -eq 1 ]
 }
 
+@test "basectl check preserves text order while base probes overlap" {
+    local click_line homebrew_line python_line pyyaml_line venv_line xcode_line
+    local venv_dir="$TEST_HOME/.base.d/base/.venv"
+
+    create_brew_stub
+    create_xcode_stubs
+    touch "$TEST_STATE_DIR/xcode-installed"
+    mkdir -p "$TEST_TMPDIR/CommandLineTools"
+    touch "$TEST_STATE_DIR/python-installed"
+    touch "$TEST_STATE_DIR/pyyaml-installed"
+    touch "$TEST_STATE_DIR/click-installed"
+    create_base_venv_stub "$venv_dir"
+
+    run_base_command \
+        BASE_SETUP_TEST_XCODE_WAIT_FOR_PIP_SHOW=true \
+        BASE_SETUP_TEST_XCODE_PIP_WAIT_SECONDS=2 \
+        check
+
+    [ "$status" -eq 0 ]
+    homebrew_line="$(printf '%s\n' "$output" | grep -n "Homebrew is installed." | head -n 1 | cut -d: -f1)"
+    xcode_line="$(printf '%s\n' "$output" | grep -n "Xcode Command Line Tools are installed." | head -n 1 | cut -d: -f1)"
+    python_line="$(printf '%s\n' "$output" | grep -n "Python formula 'python@3.13' is installed via Homebrew." | head -n 1 | cut -d: -f1)"
+    venv_line="$(printf '%s\n' "$output" | grep -n "Virtual environment is healthy at '$venv_dir'." | head -n 1 | cut -d: -f1)"
+    pyyaml_line="$(printf '%s\n' "$output" | grep -n "Python package 'PyYAML' is installed in the Base virtual environment." | head -n 1 | cut -d: -f1)"
+    click_line="$(printf '%s\n' "$output" | grep -n "Python package 'click' is installed in the Base virtual environment." | head -n 1 | cut -d: -f1)"
+    [ "$homebrew_line" -lt "$xcode_line" ]
+    [ "$xcode_line" -lt "$python_line" ]
+    [ "$python_line" -lt "$venv_line" ]
+    [ "$venv_line" -lt "$pyyaml_line" ]
+    [ "$pyyaml_line" -lt "$click_line" ]
+}
+
 @test "basectl check ignores inherited setup dry-run and recreate state" {
     local venv_dir="$TEST_HOME/.base.d/base/.venv"
 
@@ -233,6 +265,49 @@ load ./setup_helpers.bash
     [ "${stderr:-}" = "" ]
 }
 
+@test "basectl check --format json preserves finding order while base probes overlap" {
+    local click_line homebrew_line python_line pyyaml_line venv_line xcode_line
+    local venv_dir="$TEST_HOME/.base.d/base/.venv"
+
+    create_brew_stub
+    create_xcode_stubs
+    touch "$TEST_STATE_DIR/xcode-installed"
+    mkdir -p "$TEST_TMPDIR/CommandLineTools"
+    touch "$TEST_STATE_DIR/python-installed"
+    touch "$TEST_STATE_DIR/pyyaml-installed"
+    touch "$TEST_STATE_DIR/click-installed"
+    create_base_venv_stub "$venv_dir"
+
+    run --separate-stderr env \
+        HOME="$TEST_HOME" \
+        PATH="$TEST_MOCKBIN:$TEST_BASH_BIN_DIR:/usr/bin:/bin:/usr/sbin:/sbin" \
+        OSTYPE="darwin24" \
+        BASE_SETUP_BREW_BIN="$TEST_MOCKBIN/brew" \
+        BASE_SETUP_TEST_STATE_DIR="$TEST_STATE_DIR" \
+        BASE_SETUP_TEST_MOCKBIN="$TEST_MOCKBIN" \
+        BASE_SETUP_TEST_PYTHON_PREFIX="$TEST_TMPDIR/python-prefix" \
+        BASE_SETUP_TEST_XCODE_WAIT_FOR_PIP_SHOW=true \
+        BASE_SETUP_TEST_XCODE_PIP_WAIT_SECONDS=2 \
+        BASE_SETUP_XCODE_COMMAND_LINE_TOOLS_DIR="$TEST_TMPDIR/CommandLineTools" \
+        "$BASE_REPO_ROOT/bin/basectl" check --format json
+
+    [ "$status" -eq 0 ]
+    [[ "$output" == *'"schema_version": 1'* ]]
+    [[ "$output" == *'"status": "ok"'* ]]
+    homebrew_line="$(printf '%s\n' "$output" | grep -n '"id":"BASE-D001","status":"ok","name":"homebrew"' | cut -d: -f1)"
+    xcode_line="$(printf '%s\n' "$output" | grep -n '"id":"BASE-D002","status":"ok","name":"xcode_command_line_tools"' | cut -d: -f1)"
+    python_line="$(printf '%s\n' "$output" | grep -n '"id":"BASE-D003","status":"ok","name":"python"' | cut -d: -f1)"
+    venv_line="$(printf '%s\n' "$output" | grep -n '"id":"BASE-D004","status":"ok","name":"base_virtualenv"' | cut -d: -f1)"
+    pyyaml_line="$(printf '%s\n' "$output" | grep -n '"id":"BASE-D005","status":"ok","name":"pyyaml"' | cut -d: -f1)"
+    click_line="$(printf '%s\n' "$output" | grep -n '"id":"BASE-D006","status":"ok","name":"click"' | cut -d: -f1)"
+    [ "$homebrew_line" -lt "$xcode_line" ]
+    [ "$xcode_line" -lt "$python_line" ]
+    [ "$python_line" -lt "$venv_line" ]
+    [ "$venv_line" -lt "$pyyaml_line" ]
+    [ "$pyyaml_line" -lt "$click_line" ]
+    [ "${stderr:-}" = "" ]
+}
+
 @test "basectl check --format json reports broken Base virtualenv integrity" {
     local missing_home="$TEST_TMPDIR/missing-python-home"
     local venv_dir="$TEST_HOME/.base.d/base/.venv"
diff --git a/cli/bash/commands/basectl/tests/setup_helpers.bash b/cli/bash/commands/basectl/tests/setup_helpers.bash
index e21e3db..da99665 100644
--- a/cli/bash/commands/basectl/tests/setup_helpers.bash
+++ b/cli/bash/commands/basectl/tests/setup_helpers.bash
@@ -24,6 +24,15 @@ installed_file="$state_dir/xcode-installed"
 case "${1:-}" in
     -p)
         if [[ -f "$installed_file" ]]; then
+            if [[ "${BASE_SETUP_TEST_XCODE_WAIT_FOR_PIP_SHOW:-}" == true ]]; then
+                waited=0
+                wait_seconds="${BASE_SETUP_TEST_XCODE_PIP_WAIT_SECONDS:-5}"
+                while [[ ! -s "$state_dir/pip-show.log" && "$waited" -lt "$wait_seconds" ]]; do
+                    sleep 1
+                    waited=$((waited + 1))
+                done
+                [[ -s "$state_dir/pip-show.log" ]] || exit 1
+            fi
             mkdir -p "$tools_dir/usr/bin"
             touch "$tools_dir/usr/bin/clang"
             printf '%s\n' "$tools_dir"
diff --git a/docs/superpowers/plans/2026-06-09-parallel-base-check-probes.md b/docs/superpowers/plans/2026-06-09-parallel-base-check-probes.md
new file mode 100644
index 0000000..d67a73b
--- /dev/null
+++ b/docs/superpowers/plans/2026-06-09-parallel-base-check-probes.md
@@ -0,0 +1,146 @@
+# Parallel Base Check Probes Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use
+> superpowers:subagent-driven-development (recommended) or
+> superpowers:executing-plans to implement this plan task-by-task. Steps use
+> checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Run independent Base environment probes concurrently for
+`basectl check` while preserving deterministic text and JSON output.
+
+**Architecture:** Keep the existing result arrays and renderers. Add
+result-file helpers plus background probe helpers inside
+`setup_common.sh`; the collector waits for probes, reads files in the old order,
+and then appends to the existing arrays.
+
+**Tech Stack:** Bash 4-compatible shell functions, existing BATS test helpers,
+and the current Base check/doctor rendering functions.
+
+---
+
+## File Structure
+
+- Modify `cli/bash/commands/basectl/subcommands/setup_common.sh`: result file
+  writer/parser, background Base probe helpers, and parallel
+  `setup_collect_base_check_results()`.
+- Modify `cli/bash/commands/basectl/tests/setup_helpers.bash`: test-only Xcode
+  wait hook used to prove probes overlap.
+- Modify `cli/bash/commands/basectl/tests/check.bats`: RED coverage for
+  deterministic ordered text and JSON output while probes overlap.
+- Add `docs/superpowers/specs/2026-06-09-parallel-base-check-probes-design.md`:
+  design record.
+- Add `docs/superpowers/plans/2026-06-09-parallel-base-check-probes.md`: this
+  plan.
+
+## Task 1: RED Text Ordering and Parallelism Test
+
+**Files:**
+- Modify: `cli/bash/commands/basectl/tests/setup_helpers.bash`
+- Modify: `cli/bash/commands/basectl/tests/check.bats`
+
+- [ ] Add a test-only wait hook to `create_xcode_stubs()` so `xcode-select -p`
+  waits for the package probe marker when
+  `BASE_SETUP_TEST_XCODE_WAIT_FOR_PIP_SHOW=true`.
+- [ ] Add a `basectl check` text-mode test that enables the hook, sets all
+  dependencies as installed, and expects status 0.
+- [ ] Assert the output line order remains Homebrew, Xcode, Python, venv,
+  PyYAML, click.
+- [ ] Run the focused BATS file and verify the new test fails on the current
+  serial collector.
+
+Command:
+
+```bash
+bats cli/bash/commands/basectl/tests/check.bats
+```
+
+Expected RED result: the new text test fails because serial collection checks
+Xcode before any package probe can create `pip-show.log`.
+
+## Task 2: RED JSON Ordering and Parallelism Test
+
+**Files:**
+- Modify: `cli/bash/commands/basectl/tests/check.bats`
+
+- [ ] Add a `basectl check --format json` test using the same Xcode wait hook.
+- [ ] Assert status 0 and empty stderr.
+- [ ] Assert JSON finding order remains BASE-D001 through BASE-D006.
+- [ ] Run the focused BATS file and verify the new JSON test fails on the
+  current serial collector.
+
+Command:
+
+```bash
+bats cli/bash/commands/basectl/tests/check.bats
+```
+
+Expected RED result: the JSON test fails for the same serial-order reason.
+
+## Task 3: Result File Helpers
+
+**Files:**
+- Modify: `cli/bash/commands/basectl/subcommands/setup_common.sh`
+
+- [ ] Add `setup_write_check_result_file()` that writes `name`, `ok`,
+  `message`, `recovery`, and `debug` lines to a probe result file.
+- [ ] Add `setup_parse_check_result_file()` that loads those fields into
+  internal scratch variables.
+- [ ] Add `setup_add_parsed_check_result()` that appends parsed fields to the
+  existing `_BASE_SETUP_CHECK_*` arrays.
+- [ ] Add a fatal error when a probe result file is missing or malformed.
+
+## Task 4: Probe Helpers
+
+**Files:**
+- Modify: `cli/bash/commands/basectl/subcommands/setup_common.sh`
+
+- [ ] Add one result-producing helper for each Base environment check:
+  Homebrew, Xcode, Python formula, Base venv, PyYAML, and click.
+- [ ] Make each probe write exactly one result file and return 0 for expected
+  missing-dependency outcomes.
+- [ ] Keep `setup_refresh_brew_path` out of the Homebrew background probe.
+
+## Task 5: Parallel Collector
+
+**Files:**
+- Modify: `cli/bash/commands/basectl/subcommands/setup_common.sh`
+
+- [ ] Replace the serial body of `setup_collect_base_check_results()` with a
+  temporary directory, six background probes, `wait`, ordered result loading,
+  and cleanup.
+- [ ] Read the Homebrew result first and run `setup_refresh_brew_path` in the
+  parent when Homebrew exists.
+- [ ] Preserve fatal refresh behavior for text `basectl check`.
+- [ ] Preserve warning-style refresh behavior for JSON/doctor callers.
+- [ ] Preserve existing finding names, messages, recovery text, debug messages,
+  and return status.
+
+## Task 6: Validation
+
+- [ ] Run focused BATS coverage:
+
+```bash
+bats cli/bash/commands/basectl/tests/check.bats
+```
+
+- [ ] Run full Base validation:
+
+```bash
+env -u BASE_HOME ./bin/base-test
+```
+
+- [ ] Run whitespace validation:
+
+```bash
+git diff --check
+```
+
+## Task 7: Publish
+
+- [ ] Commit the implementation.
+- [ ] Push `enhancement/510-20260609-parallel-base-check-probes`.
+- [ ] Open a PR closing #510.
+- [ ] Watch CI.
+- [ ] Merge when checks are green.
+- [ ] Sync local `master`.
+- [ ] Remove the #510 worktree and local branch.
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+# Parallel Base Check Probes Design
+
+Issue: #510
+
+## Goal
+
+Make the Base environment portion of `basectl check` faster by running
+independent probes in parallel while preserving the existing deterministic text
+and JSON output order.
+
+## Scope
+
+This change is limited to the shared Base check collector in
+`cli/bash/commands/basectl/subcommands/setup_common.sh`.
+
+The affected paths are:
+
+- `basectl check`
+- `basectl check --format json`
+- `basectl doctor --format json`, because it already reuses the same collector
+
+The text `basectl doctor` path prints findings directly through separate helper
+functions. It is intentionally left out of this slice so #510 can stay focused
+on high-frequency `check` behavior and avoid a broader doctor refactor.
+
+Prerequisite profile checks and project artifact checks remain serial after the
+Base environment collector has finished.
+
+## Current Behavior
+
+`setup_collect_base_check_results()` clears the result arrays, runs each Base
+probe serially, and appends findings directly to the arrays consumed by text and
+JSON renderers.
+
+The serial order is:
+
+1. Homebrew presence and path discovery
+2. Xcode Command Line Tools
+3. Homebrew Python formula
+4. Base virtual environment integrity
+5. PyYAML in the Base virtual environment
+6. click in the Base virtual environment
+
+The output order is good, but the probe order is slower than necessary.
+
+## Design
+
+Add small result-producing probe helpers that write one structured result file
+per check:
+
+```text
+name=homebrew
+ok=true
+message=Homebrew is installed.
+recovery=
+debug=Resolved Homebrew binary: /opt/homebrew/bin/brew
+```
+
+The parent collector will:
+
+1. create a temporary directory
+2. start one background probe per independent Base check
+3. wait for all probes to finish
+4. read result files in the existing display order
+5. append findings to the existing `_BASE_SETUP_CHECK_*` arrays
+6. remove the temporary directory
+
+The renderers do not change. They continue to print from the result arrays in
+array order, which keeps text and JSON deterministic even though probes complete
+out of order.
+
+## Homebrew PATH Boundary
+
+`setup_refresh_brew_path` mutates the parent shell's `PATH`, so it must not run
+inside a background probe. The Homebrew probe will only discover whether a brew
+binary exists and record the debug path.
+
+After all probes complete, the parent reads the Homebrew result first. If
+Homebrew exists, the parent calls `setup_refresh_brew_path` before appending the
+Homebrew finding. If refresh fails:
+
+- `basectl check` text mode keeps the existing fatal behavior when the collector
+  is called with `fatal`
+- JSON/doctor collector callers keep the existing warning-style result
+
+## Probe Independence
+
+The first implementation parallelizes only probes that can produce independent
+read-only observations:
+
+- Homebrew discovery
+- Xcode Command Line Tools presence
+- Homebrew Python formula presence
+- Base virtual environment health
+- PyYAML package presence
+- click package presence
+
+The package probes may report missing packages when the venv is absent, but
+they must not emit stderr or abort the collector. This preserves the existing
+behavior where a missing venv and missing packages are both reported as
+findings.
+
+## Tests
+
+Add BATS coverage in `cli/bash/commands/basectl/tests/check.bats` that proves:
+
+- text output remains in the current order while probes are allowed to overlap
+- JSON output remains in the current order while probes are allowed to overlap
+- missing Homebrew still allows the other Base findings to be reported
+- missing venv/package checks still produce structured output without stderr
+
+Use a test-only Xcode stub mode that waits for a pip-show marker. Serial probe
+collection fails that scenario because Xcode runs before package checks;
+parallel collection passes because package probes can create the marker while
+the Xcode probe is waiting.