diff --git a/.claude-plugin/marketplace.json b/.claude-plugin/marketplace.json
index 00b7dbe0..29c57193 100644
--- a/.claude-plugin/marketplace.json
+++ b/.claude-plugin/marketplace.json
@@ -20,14 +20,15 @@
     },
     {
       "name": "macdoc",
-      "version": "1.4.0",
+      "version": "1.4.1",
       "description": "macOS 原生文件處理 CLI — 格式轉換、VLM OCR（含 host profile 設定）、SRT 處理。v1.2.0: session-start hook 自動安裝 signed CLI binary（arm64）。",
       "author": {
         "name": "Che Cheng"
       },
       "source": "./plugins/macdoc",
       "category": "productivity",
-      "binary_version": "0.7.0"
+      "binary_version": "0.7.0",
+      "binary_sha256": "9fe09f26b6c8f97f13520ec2f618b8918b475de9ebc8a9980fd64897b39ec298"
     },
     {
       "name": "che-pdf-mcp",
diff --git a/plugins/macdoc/.claude-plugin/plugin.json b/plugins/macdoc/.claude-plugin/plugin.json
index 03e6e063..dbd3dec9 100644
--- a/plugins/macdoc/.claude-plugin/plugin.json
+++ b/plugins/macdoc/.claude-plugin/plugin.json
@@ -1,8 +1,9 @@
 {
   "name": "macdoc",
   "description": "macOS 原生文件處理 CLI — 格式轉換、VLM OCR（含 host profile 設定）、SRT 處理。v1.2.0: session-start hook 自動安裝 signed CLI binary（arm64）。",
-  "version": "1.4.0",
+  "version": "1.4.1",
   "binary_version": "0.7.0",
+  "binary_sha256": "9fe09f26b6c8f97f13520ec2f618b8918b475de9ebc8a9980fd64897b39ec298",
   "author": {
     "name": "Che Cheng"
   }
diff --git a/plugins/macdoc/CHANGELOG.md b/plugins/macdoc/CHANGELOG.md
index 554a7e52..62713a9a 100644
--- a/plugins/macdoc/CHANGELOG.md
+++ b/plugins/macdoc/CHANGELOG.md
@@ -9,6 +9,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 > `plugin.json` description field. Section categorization is best-effort —
 > review and refine `Added` / `Changed` / `Fixed` etc. as needed.
 
+## [1.4.1] - 2026-08-24
+
+### Fixed
+
+- SessionStart 不再執行常駐 `~/bin/macdoc --version`（PsychQuant/macdoc#161）。它先固定 system PATH，再以 `/usr/bin/codesign` 與 plugin-pinned `binary_sha256` 重驗 exact release bytes，只讀 installer sidecar 判斷版本；簽章／digest 不符、sidecar 缺失或版本不同時改嘗試一次 verified download。下載的 `.sha256` asset 也必須等於 plugin pin。這消除驗簽後從可替換路徑執行的 swap window，也避免 user-writable `~/bin` 劫持 trust-chain 工具；下載失敗仍維持 session fail-soft。
+
+### Tests
+
+- 新增共用驗證 library 與 resident binary 對抗測試：簽章不符的 binary 不得被執行；合法且 digest／sidecar 相符的 binary 只驗簽、不執行、不連網；release-pin、下載 bytes 與 codesign 三個 candidate gate 各有獨立負向測試，並以實際 signed v0.7.0 fixture 驗證正向路徑。
+
 ## [1.4.0] - 2026-08-19
 
 ### Changed
diff --git a/plugins/macdoc/hooks/session-start-verify.sh b/plugins/macdoc/hooks/session-start-verify.sh
new file mode 100644
index 00000000..9efaec55
--- /dev/null
+++ b/plugins/macdoc/hooks/session-start-verify.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+# Shared verification primitives for the macdoc SessionStart hook. Production
+# and tests call these exact functions; trust-chain executables are fixed.
+
+macdoc_verify_binary() {
+    /usr/bin/codesign --verify --strict -R "$2" "$1" 2>/dev/null
+}
+
+macdoc_sha256_file() {
+    /usr/bin/shasum -a 256 "$1" 2>/dev/null | /usr/bin/awk '{print $1}'
+}
+
+# Return codes identify the failed gate without parsing prose:
+# 10 = release asset digest differs from plugin pin
+# 11 = downloaded bytes differ from plugin pin
+# 12 = candidate does not satisfy the Developer ID requirement
+macdoc_verify_candidate() {
+    local candidate=$1
+    local release_sha=$2
+    local pinned_sha=$3
+    local requirement=$4
+
+    [ "$release_sha" = "$pinned_sha" ] || return 10
+    [ "$(macdoc_sha256_file "$candidate")" = "$pinned_sha" ] || return 11
+    macdoc_verify_binary "$candidate" "$requirement" || return 12
+}
diff --git a/plugins/macdoc/hooks/session-start.sh b/plugins/macdoc/hooks/session-start.sh
index 3fa8d32e..ec8df516 100755
--- a/plugins/macdoc/hooks/session-start.sh
+++ b/plugins/macdoc/hooks/session-start.sh
@@ -14,6 +14,11 @@
 
 set -u
 
+# The install target commonly lives in ~/bin, which may also lead PATH. Never
+# resolve trust-chain utilities through a user-writable directory (#161).
+PATH="/usr/bin:/bin:/usr/sbin:/sbin"
+export PATH
+
 REPO="PsychQuant/macdoc"
 BINARY_NAME="macdoc"
 [ -n "${HOME:-}" ] || exit 0   # no HOME (exotic env) — nothing sane to do, never break session
@@ -24,52 +29,64 @@ REQUIREMENT='=anchor apple generic and certificate 1[field.1.2.840.113635.100.6.
 note() { echo "macdoc plugin: $1" >&2; }
 soft_exit() { note "$1"; exit 0; }   # fail-soft: never break session start
 
-[ "$(uname -m)" = "arm64" ] || exit 0   # arm64-only release; Intel builds from source (silent — not an error)
+[ "$(/usr/bin/uname -m)" = "arm64" ] || exit 0   # arm64-only release; Intel builds from source (silent — not an error)
 
 PLUGIN_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 PLUGIN_JSON="$PLUGIN_ROOT/.claude-plugin/plugin.json"
 [ -f "$PLUGIN_JSON" ] || exit 0
+VERIFY_LIB="$PLUGIN_ROOT/hooks/session-start-verify.sh"
+[ -f "$VERIFY_LIB" ] || soft_exit "verification library missing — refusing to trust or install a resident binary"
+# Runtime path is derived from this plugin root.
+# shellcheck disable=SC1090,SC1091
+. "$VERIFY_LIB"
 
 WANT=$(grep -oE '"binary_version"[[:space:]]*:[[:space:]]*"[^"]+"' "$PLUGIN_JSON" 2>/dev/null \
     | head -1 | sed -E 's/.*"([^"]+)"$/\1/' || true)
 [ -n "$WANT" ] || exit 0   # no pinned CLI version — nothing to manage
+WANT_SHA=$(grep -oE '"binary_sha256"[[:space:]]*:[[:space:]]*"[^"]+"' "$PLUGIN_JSON" 2>/dev/null \
+    | head -1 | sed -E 's/.*"([^"]+)"$/\1/' || true)
+[[ "$WANT_SHA" =~ ^[0-9a-fA-F]{64}$ ]] \
+    || soft_exit "missing/malformed binary_sha256 in plugin.json — refusing to trust or install a resident binary"
 
-# --version with a 5s alarm (a hung/planted binary must not stall every
-# session start — fail-soft covers errors, not hangs; codex V114 HIGH-1).
-# Probe writes to a FILE, not a pipe: a killed probe may leave grandchildren
-# holding an inherited pipe fd, and command substitution would then wait on
-# the pipe far past the alarm (empirically reproduced with a sleep-300 fake).
-# Normalize to the semver token so banner-style output doesn't force a
-# re-download loop (codex V114 M-2).
-HAVE=""
-PROBE=$(mktemp "${TMPDIR:-/tmp}/.macdoc.probe.XXXXXX" 2>/dev/null) || PROBE=""
-if [ -n "$PROBE" ]; then
-    { perl -e 'alarm 5; exec @ARGV' -- "$BINARY" --version </dev/null >"$PROBE" 2>/dev/null; } 2>/dev/null || true
-    HAVE=$(head -1 "$PROBE" 2>/dev/null | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' | head -1 || true)
-    rm -f "$PROBE"
+# Exec-time re-verification happens before even asking the resident binary for
+# its version. A binary that merely prints WANT must never reach a fast path
+# unless its Developer ID chain + Team requirement is valid (#161).
+RESIDENT_VERIFIED=false
+if [ -x "$BINARY" ]; then
+    if macdoc_verify_binary "$BINARY" "$REQUIREMENT"; then
+        RESIDENT_SHA=$(macdoc_sha256_file "$BINARY")
+        [ "$RESIDENT_SHA" = "$WANT_SHA" ] && RESIDENT_VERIFIED=true
+    fi
 fi
-[ "$HAVE" = "$WANT" ] && exit 0   # fast path: version matches, zero network
 
-# Loop-guard sidecar: if a previous session already installed WANT but the
-# binary self-reports an unparsable/odd version, do not re-download forever.
+# SessionStart never executes the resident binary. Its version comes only from
+# the installer-written sidecar, after the resident bytes pass codesign. This
+# removes the verify-then-exec path-swap window; missing/stale sidecars cause a
+# verified replacement download rather than probing untrusted executable code.
 GUARD="$INSTALL_DIR/.${BINARY_NAME}.installed_version"
-[ -x "$BINARY" ] && [ "$(cat "$GUARD" 2>/dev/null)" = "$WANT" ] && exit 0
+HAVE=$(tr -d '[:space:]' < "$GUARD" 2>/dev/null || true)
+$RESIDENT_VERIFIED && [ "$HAVE" = "$WANT" ] && exit 0
 
 mkdir -p "$INSTALL_DIR" 2>/dev/null || soft_exit "cannot create $INSTALL_DIR — skipping auto-install"
 TMP=$(mktemp "$INSTALL_DIR/.${BINARY_NAME}.download.XXXXXX" 2>/dev/null) || soft_exit "mktemp failed — skipping auto-install"
 trap 'rm -f "$TMP"' EXIT
 
 URL="https://github.com/$REPO/releases/download/v$WANT/$BINARY_NAME"
-curl -fsSL --proto '=https' --tlsv1.2 --max-time 300 "$URL" -o "$TMP" 2>/dev/null \
-    || soft_exit "download failed for v$WANT (keeping existing ${HAVE:-none}); manual: https://github.com/$REPO/releases"
+/usr/bin/curl -fsSL --proto '=https' --tlsv1.2 --max-time 300 "$URL" -o "$TMP" 2>/dev/null \
+    || soft_exit "download failed for v$WANT; resident binary was not executed. Manual: https://github.com/$REPO/releases"
 
-EXPECTED=$(curl -fsSL --proto '=https' --tlsv1.2 --max-time 30 "$URL.sha256" 2>/dev/null | head -1 | awk '{print $1}')
+EXPECTED=$(/usr/bin/curl -fsSL --proto '=https' --tlsv1.2 --max-time 30 "$URL.sha256" 2>/dev/null | /usr/bin/head -1 | /usr/bin/awk '{print $1}')
 [[ "$EXPECTED" =~ ^[0-9a-fA-F]{64}$ ]] \
     || soft_exit "missing/malformed .sha256 asset — refusing to install unverified binary"
-[[ "$(shasum -a 256 "$TMP" | awk '{print $1}')" == "$EXPECTED" ]] \
-    || soft_exit "sha256 mismatch — refusing to install"
-codesign --verify --strict -R "$REQUIREMENT" "$TMP" 2>/dev/null \
-    || soft_exit "code-signature verification failed (not Developer ID Team 6W377FS7BS) — refusing to install"
+macdoc_verify_candidate "$TMP" "$EXPECTED" "$WANT_SHA" "$REQUIREMENT"
+CANDIDATE_RC=$?
+case "$CANDIDATE_RC" in
+    0) ;;
+    10) soft_exit "release sha256 asset does not match pinned binary_sha256 — refusing to install" ;;
+    11) soft_exit "sha256 mismatch — refusing to install" ;;
+    12) soft_exit "code-signature verification failed (not Developer ID Team 6W377FS7BS) — refusing to install" ;;
+    *) soft_exit "candidate verification failed unexpectedly — refusing to install" ;;
+esac
 
 chmod +x "$TMP" || soft_exit "chmod failed"
 mv "$TMP" "$BINARY" || soft_exit "install mv failed"
diff --git a/plugins/macdoc/tests/session-start-reverify.sh b/plugins/macdoc/tests/session-start-reverify.sh
new file mode 100644
index 00000000..9e6c42a7
--- /dev/null
+++ b/plugins/macdoc/tests/session-start-reverify.sh
@@ -0,0 +1,111 @@
+#!/bin/bash
+
+set -euo pipefail
+
+ROOT=$(cd "$(dirname "${BASH_SOURCE[0]}")/../../.." && pwd)
+HOOK="$ROOT/plugins/macdoc/hooks/session-start.sh"
+VERIFY_LIB="$ROOT/plugins/macdoc/hooks/session-start-verify.sh"
+TEST_ROOT=$(mktemp -d "${TMPDIR:-/tmp}/macdoc-session-start-test.XXXXXX")
+trap 'rm -rf "$TEST_ROOT"' EXIT
+
+FAKE_PATH="$TEST_ROOT/hostile-path"
+INSTALL_DIR="$TEST_ROOT/install"
+EVENT_LOG="$TEST_ROOT/events.log"
+HOOK_STDERR="$TEST_ROOT/hook.stderr"
+RESIDENT="$INSTALL_DIR/macdoc"
+GUARD="$INSTALL_DIR/.macdoc.installed_version"
+UNSIGNED_CANDIDATE="$TEST_ROOT/unsigned-candidate"
+SIGNED_FIXTURE="${MACDOC_SIGNED_FIXTURE:-$HOME/bin/macdoc}"
+REQUIREMENT='=anchor apple generic and certificate 1[field.1.2.840.113635.100.6.2.6] exists and certificate leaf[field.1.2.840.113635.100.6.1.13] exists and certificate leaf[subject.OU] = "6W377FS7BS"'
+PINNED_SHA=9fe09f26b6c8f97f13520ec2f618b8918b475de9ebc8a9980fd64897b39ec298
+mkdir -p "$FAKE_PATH" "$INSTALL_DIR"
+
+for tool in uname awk codesign curl; do
+    cat > "$FAKE_PATH/$tool" <<EOF
+#!/bin/bash
+echo fake-$tool >> "\$EVENT_LOG"
+exit 22
+EOF
+    chmod +x "$FAKE_PATH/$tool"
+done
+
+cat > "$RESIDENT" <<'EOF'
+#!/bin/bash
+echo resident-executed >> "$EVENT_LOG"
+echo 'macdoc 0.7.0'
+EOF
+
+cat > "$UNSIGNED_CANDIDATE" <<'EOF'
+#!/bin/bash
+echo candidate-executed >> "$EVENT_LOG"
+echo 'macdoc 0.7.0'
+EOF
+chmod +x "$RESIDENT" "$UNSIGNED_CANDIDATE"
+
+run_hook() {
+    : > "$EVENT_LOG"
+    EVENT_LOG="$EVENT_LOG" \
+    MACDOC_CODESIGN_BIN="$FAKE_PATH/codesign" \
+    MACDOC_CURL_BIN="$FAKE_PATH/curl" \
+    MACDOC_INSTALL_DIR="$INSTALL_DIR" \
+    HTTPS_PROXY="http://127.0.0.1:9" \
+    ALL_PROXY="http://127.0.0.1:9" \
+    NO_PROXY="" \
+    PATH="$FAKE_PATH:$PATH" \
+    bash "$HOOK" >/dev/null 2>"$HOOK_STDERR"
+}
+
+assert_no_hostile_tool_or_binary() {
+    if [ -s "$EVENT_LOG" ]; then
+        echo "FAIL: SessionStart executed a hostile PATH/env tool or binary: $(tr '\n' ' ' < "$EVENT_LOG")" >&2
+        exit 1
+    fi
+}
+
+# A rejected resident must ignore hostile command overrides, never execute,
+# and fail soft when the real download cannot connect.
+echo 0.7.0 > "$GUARD"
+run_hook
+assert_no_hostile_tool_or_binary
+grep -q 'resident binary was not executed' "$HOOK_STDERR"
+
+# Candidate integrity functions are the same fixed-tool functions sourced by
+# production. Test each negative gate independently.
+# Test derives the checked-out plugin root.
+# shellcheck disable=SC1090,SC1091
+. "$VERIFY_LIB"
+
+set +e
+macdoc_verify_candidate "$UNSIGNED_CANDIDATE" 0000000000000000000000000000000000000000000000000000000000000000 "$PINNED_SHA" "$REQUIREMENT"
+rc_asset_pin=$?
+macdoc_verify_candidate "$UNSIGNED_CANDIDATE" "$PINNED_SHA" "$PINNED_SHA" "$REQUIREMENT"
+rc_bytes=$?
+unsigned_sha=$(/usr/bin/shasum -a 256 "$UNSIGNED_CANDIDATE" | /usr/bin/awk '{print $1}')
+macdoc_verify_candidate "$UNSIGNED_CANDIDATE" "$unsigned_sha" "$unsigned_sha" "$REQUIREMENT"
+rc_signature=$?
+set -e
+
+[[ "$rc_asset_pin" -eq 10 ]]
+[[ "$rc_bytes" -eq 11 ]]
+[[ "$rc_signature" -eq 12 ]]
+
+# Full positive coverage needs a real Team-signed fixture. Mandatory hostile
+# cases above still run on CI machines without one.
+if ! /usr/bin/codesign --verify --strict -R "$REQUIREMENT" "$SIGNED_FIXTURE" 2>/dev/null; then
+    echo "SKIP: positive signed-fixture cases (set MACDOC_SIGNED_FIXTURE)"
+    echo "PASS: hostile resident/candidate paths were rejected"
+    exit 0
+fi
+
+signed_sha=$(/usr/bin/shasum -a 256 "$SIGNED_FIXTURE" | /usr/bin/awk '{print $1}')
+[[ "$signed_sha" = "$PINNED_SHA" ]]
+macdoc_verify_candidate "$SIGNED_FIXTURE" "$PINNED_SHA" "$PINNED_SHA" "$REQUIREMENT"
+
+# Verified resident + matching sidecar is a zero-network, zero-execution path.
+cp "$SIGNED_FIXTURE" "$RESIDENT"
+chmod +x "$RESIDENT"
+echo 0.7.0 > "$GUARD"
+run_hook
+assert_no_hostile_tool_or_binary
+
+echo "PASS: SessionStart uses fixed trust tools and verifies exact candidate bytes"