diff --git a/.gitignore b/.gitignore
index 6035a54b..377a2c49 100644
--- a/.gitignore
+++ b/.gitignore
@@ -118,6 +118,12 @@ src/aipass/*/apps/integrations/**
 !src/aipass/commons/apps/handlers/artifacts/
 !src/aipass/commons/apps/handlers/artifacts/*.py
 
+# hooks boot-shim installer — must ship so fresh clones can install the claude()
+# shell function. Collides with the blanket tools/ ignore (line 51).
+!src/aipass/hooks/tools/
+src/aipass/hooks/tools/*
+!src/aipass/hooks/tools/install_boot_shim.sh
+
 # CI artifacts
 windows-pytest-results/
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f27e6f6f..9527231b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -63,6 +63,17 @@ PyPI version — not the changelog header.
 
 ### Fixed
 
+- **The `claude()` boot shim now ships and installs on onboarding (issue #666).**
+  Its installer (`hooks/tools/install_boot_shim.sh`) lived under a gitignored
+  `tools/` dir — never version-controlled, never shipped — so the
+  attach-if-live / start-in-tmux boot feature (and presence-gate-via-boot) was
+  dev-local only; a macOS user could not attach/resume their session. A root
+  `.gitignore` negation now tracks exactly that one file (`tools/` re-ignored,
+  only the installer whitelisted — README stays out), and `setup.sh` runs it
+  right after hook installation (idempotent via a marker check, non-fatal on
+  error, venv Python resolved from the script's own location for POSIX/Windows).
+  Fresh clones and `aipass install` now get the shim.
+
 - **Interactive-occupancy detection is now cross-platform — the wake-back guard
   no longer goes blind on macOS (issue #680).** `_is_branch_occupied()` and
   `_read_session_type()` (duplicated in `dispatch/wake.py` and `dispatch/daemon.py`)
diff --git a/setup.sh b/setup.sh
index 0d433094..85feb0d6 100755
--- a/setup.sh
+++ b/setup.sh
@@ -804,6 +804,16 @@ else
     echo "Skipping Claude hooks (bridge not found at src/aipass/hooks/apps/handlers/bridges/claude.py)"
 fi
 
+# --- Install claude() boot shim (attach-if-live / start-in-tmux) ---
+# Ships via the .gitignore negation (#666). Idempotent: the installer checks for
+# its marker before appending to the shell rc, and resolves the venv Python from
+# its own location (POSIX/Windows/fallback). Composes with presence_gate seeding.
+BOOT_SHIM="$SCRIPT_DIR/src/aipass/hooks/tools/install_boot_shim.sh"
+if [ -f "$BOOT_SHIM" ]; then
+    echo "Installing claude() boot shim ..."
+    bash "$BOOT_SHIM" || echo "  boot shim install skipped (non-fatal)"
+fi
+
 # --- Install Claude Code commands (provider level) ---
 # memo.md belongs at provider level — works in all projects.
 # prep.md stays at repo root only — it's AIPass-specific.
diff --git a/src/aipass/hooks/tools/install_boot_shim.sh b/src/aipass/hooks/tools/install_boot_shim.sh
new file mode 100755
index 00000000..e49cf4b0
--- /dev/null
+++ b/src/aipass/hooks/tools/install_boot_shim.sh
@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# install_boot_shim.sh — append the claude() shell function to ~/.bashrc and ~/.zshrc
+#
+# Usage: bash tools/install_boot_shim.sh
+#
+# The shim intercepts 'claude' in AIPass branch directories (those with .trinity/)
+# and delegates to the session_boot wrapper. Everywhere else, claude runs normally.
+# Safe to run multiple times — skips if already installed.
+
+set -euo pipefail
+
+MARKER="# >>> AIPass boot shim >>>"
+
+# Resolve THIS repo's venv Python from the script's own location — no hardcoded
+# user path. POSIX (.venv/bin/python) + Windows/git-bash (.venv/Scripts/python.exe)
+# aware; falls back to PATH python3 if no venv is found.
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../../../.." && pwd)"
+if [ -x "$REPO_ROOT/.venv/bin/python" ]; then
+    VENV_PY="$REPO_ROOT/.venv/bin/python"
+elif [ -x "$REPO_ROOT/.venv/Scripts/python.exe" ]; then
+    VENV_PY="$REPO_ROOT/.venv/Scripts/python.exe"
+else
+    VENV_PY="python3"
+fi
+
+SHIM='
+# >>> AIPass boot shim >>>
+# Intercepts claude in AIPass branch dirs to attach-if-live / start-in-tmux.
+# Installed by: tools/install_boot_shim.sh
+claude() {
+    if [ -d ".trinity" ]; then
+        __VENV_PY__ \
+            -m aipass.hooks.apps.handlers.lifecycle.session_boot "$@"
+    else
+        command claude "$@"
+    fi
+}
+# <<< AIPass boot shim <<<
+'
+
+# Bake the resolved interpreter into the shim (single-quoted above kept "$@" literal).
+SHIM="${SHIM//__VENV_PY__/$VENV_PY}"
+
+for rc in "$HOME/.bashrc" "$HOME/.zshrc"; do
+    if [ ! -f "$rc" ]; then
+        echo "⏭  $rc does not exist, skipping"
+        continue
+    fi
+    if grep -qF "$MARKER" "$rc"; then
+        echo "✓  $rc already has the shim"
+    else
+        printf '%s\n' "$SHIM" >> "$rc"
+        echo "✓  Appended shim to $rc"
+    fi
+done
+
+echo ""
+echo "Done. Source your shell rc or open a new terminal to activate:"
+echo "  source ~/.bashrc   # or ~/.zshrc"