diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8678759..fee9f62 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,8 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- `scripts/install.sh` — the one-line `curl … | bash` install now works. The installer previously located its hook sources via `${BASH_SOURCE[0]}` relative to its own file, which is empty when the script is read from stdin; under `set -u` this aborted with `BASH_SOURCE[0]: unbound variable` and then failed to find the sibling `hooks/` directory. The installer now copies from a local checkout when present and otherwise downloads the hook scripts from the repo. New `CLAUDE_CONTEXT_TICK_REF` (default `main`) pins the download ref; `CLAUDE_CONTEXT_TICK_RAW_BASE` overrides the base URL (internal mirror / tests). Regression covered by `tests/test_install_piped.sh`.
+
 ### Added
 
+- `tests/test_install_piped.sh` — hermetic regression test that runs the installer via stdin (reproducing the empty-`BASH_SOURCE` `curl | bash` condition) and resolves hook downloads from the local checkout via a `file://` base, so it needs no network.
 - `scripts/generate-social-preview.py` — Pillow-based generator for the GitHub social preview / Open Graph card. Re-runnable; portable font fallback chain (JetBrains Mono → SF Mono → Menlo → DejaVu).
 - `assets/social-preview.png` — 1280×640 social preview card. Uploaded to repo Settings → Social preview to replace the default grey link unfurl.
 - `scripts/demo.sh` — reproducible mechanism demo (~22 sec): first-run injection → silent rerun → fast-forward state → quarter-hour-tick injection. Cross-platform (BSD/GNU `date`); self-cleans state on exit.
diff --git a/README.md b/README.md
index f441f98..911231e 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,13 @@ State is tracked per-session in `~/.claude/state/time-inject/` with atomic write
 curl -fsSL https://raw.githubusercontent.com/DoubleNode/claude-context-tick/main/scripts/install.sh | bash
 ```
 
-**Security note:** Always review scripts before piping to `bash`. The script simply merges the hook entry into `~/.claude/settings.json`.
+By default the installer pulls the hook scripts from `main`. Pin a specific tag or branch with `CLAUDE_CONTEXT_TICK_REF`:
+
+```bash
+CLAUDE_CONTEXT_TICK_REF=v0.2.0 bash -c "$(curl -fsSL https://raw.githubusercontent.com/DoubleNode/claude-context-tick/v0.2.0/scripts/install.sh)"
+```
+
+**Security note:** Always review scripts before piping to `bash`. When run this way (no local checkout), the installer downloads the two hook scripts (`inject-time-context.sh`, `session-end.sh`) into `~/.claude/hooks/` and merges the hook entries into `~/.claude/settings.json` (backing it up first). It makes no other changes and never touches the network at hook runtime.
 
 ### Manual Install
 
diff --git a/scripts/install.sh b/scripts/install.sh
index 2ec2c6a..eb590bf 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -6,20 +6,43 @@
 # without clobbering any existing hooks.
 #
 # Usage:
-#   bash scripts/install.sh
+#   bash scripts/install.sh                                    # from a checkout
+#   curl -fsSL .../scripts/install.sh | bash                   # one-liner
 #   CLAUDE_CONTEXT_TICK_DIR=/custom/path bash scripts/install.sh
+#   CLAUDE_CONTEXT_TICK_REF=v0.2.0 curl ... | bash             # pin a ref
 #
-# Dependencies: bash 3.2+, jq, python3
+# Dependencies: bash 3.2+, jq, python3 (plus curl when not run from a checkout)
 
 set -euo pipefail
 
 # ---------------------------------------------------------------------------
 # Resolve paths
 # ---------------------------------------------------------------------------
-SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
-REPO_ROOT="$( cd "$SCRIPT_DIR/.." && pwd )"
-HOOK_SRC="$REPO_ROOT/hooks/inject-time-context.sh"
-SESSION_END_SRC="$REPO_ROOT/hooks/session-end.sh"
+# When run from a checked-out repo, ${BASH_SOURCE[0]} points at this file and we
+# copy the hook scripts from the sibling hooks/ directory. When piped through
+# `curl ... | bash`, the script is read from stdin: BASH_SOURCE is empty and
+# there is no local hooks/ dir, so we download the hooks from the repo instead
+# (see install_hook below). The :- guard stops `set -u` from aborting on the
+# empty BASH_SOURCE in the piped case.
+SCRIPT_SOURCE="${BASH_SOURCE[0]:-}"
+if [ -n "$SCRIPT_SOURCE" ]; then
+  SCRIPT_DIR="$( cd "$( dirname "$SCRIPT_SOURCE" )" && pwd )"
+  REPO_ROOT="$( cd "$SCRIPT_DIR/.." && pwd )"
+  HOOK_SRC="$REPO_ROOT/hooks/inject-time-context.sh"
+  SESSION_END_SRC="$REPO_ROOT/hooks/session-end.sh"
+else
+  # Piped via stdin (curl | bash): no local checkout to copy from.
+  SCRIPT_DIR=""
+  REPO_ROOT=""
+  HOOK_SRC=""
+  SESSION_END_SRC=""
+fi
+
+# Base URL for downloading hooks when no local checkout is present.
+# CLAUDE_CONTEXT_TICK_REF pins a branch/tag (default: main).
+# CLAUDE_CONTEXT_TICK_RAW_BASE overrides the whole base (internal mirror / tests).
+CLAUDE_CONTEXT_TICK_REF="${CLAUDE_CONTEXT_TICK_REF:-main}"
+RAW_BASE="${CLAUDE_CONTEXT_TICK_RAW_BASE:-https://raw.githubusercontent.com/DoubleNode/claude-context-tick/${CLAUDE_CONTEXT_TICK_REF}}"
 
 INSTALL_DIR="${CLAUDE_CONTEXT_TICK_DIR:-$HOME/.claude/hooks}"
 SETTINGS_FILE="$HOME/.claude/settings.json"
@@ -53,32 +76,44 @@ if [ "$preflight_fail" -ne 0 ]; then
   exit 1
 fi
 
-if [ ! -f "$HOOK_SRC" ]; then
-  echo "ERROR: Hook source not found: $HOOK_SRC" >&2
-  echo "Run install.sh from inside the claude-context-tick repository." >&2
-  exit 1
-fi
-
-if [ ! -f "$SESSION_END_SRC" ]; then
-  echo "ERROR: Hook source not found: $SESSION_END_SRC" >&2
-  echo "Run install.sh from inside the claude-context-tick repository." >&2
-  exit 1
-fi
-
 # ---------------------------------------------------------------------------
-# Install hook script
+# Install hook scripts
 # ---------------------------------------------------------------------------
-mkdir -p "$INSTALL_DIR"
-
-cp "$HOOK_SRC" "$HOOK_DEST"
-chmod +x "$HOOK_DEST"
-
-echo "Installed hook: $HOOK_DEST"
+# Copy from the local checkout when available; otherwise download from the repo
+# (the curl | bash case, where there is no sibling hooks/ dir).
+#   $1 = local source path (may be empty / nonexistent)
+#   $2 = destination path
+#   $3 = repo-relative path used for the download fallback
+install_hook() {
+  local src="$1" dest="$2" relpath="$3"
+  if [ -n "$src" ] && [ -f "$src" ]; then
+    cp "$src" "$dest"
+    echo "Installed hook (from checkout): $dest"
+  else
+    if ! command -v curl >/dev/null 2>&1; then
+      echo "ERROR: 'curl' is required to download hooks when not running from a checkout." >&2
+      echo "Install curl, or clone the repo and run scripts/install.sh from inside it." >&2
+      exit 1
+    fi
+    echo "No local checkout — downloading $relpath from $RAW_BASE"
+    if ! curl -fsSL "$RAW_BASE/$relpath" -o "$dest"; then
+      echo "ERROR: Failed to download $relpath from $RAW_BASE" >&2
+      echo "Check your connection, or clone the repo and run the installer locally." >&2
+      exit 1
+    fi
+    if [ ! -s "$dest" ]; then
+      echo "ERROR: Downloaded $relpath is empty — refusing to install." >&2
+      exit 1
+    fi
+    echo "Installed hook (downloaded): $dest"
+  fi
+  chmod +x "$dest"
+}
 
-cp "$SESSION_END_SRC" "$SESSION_END_DEST"
-chmod +x "$SESSION_END_DEST"
+mkdir -p "$INSTALL_DIR"
 
-echo "Installed hook: $SESSION_END_DEST"
+install_hook "$HOOK_SRC" "$HOOK_DEST" "hooks/inject-time-context.sh"
+install_hook "$SESSION_END_SRC" "$SESSION_END_DEST" "hooks/session-end.sh"
 
 # ---------------------------------------------------------------------------
 # Merge into ~/.claude/settings.json
diff --git a/tests/test_install_piped.sh b/tests/test_install_piped.sh
new file mode 100755
index 0000000..6e8aad4
--- /dev/null
+++ b/tests/test_install_piped.sh
@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+# test_install_piped.sh — verify install.sh works when piped via stdin (curl | bash).
+#
+# Regression for the "BASH_SOURCE[0]: unbound variable" crash: when the installer
+# is read from stdin there is no script file (BASH_SOURCE is empty) and no sibling
+# hooks/ dir to copy from. The installer must instead DOWNLOAD the hook scripts.
+#
+# This test is hermetic (no network): it feeds install.sh on stdin to reproduce
+# the empty-BASH_SOURCE condition, and points the download base at the local
+# checkout via a file:// URL using CLAUDE_CONTEXT_TICK_RAW_BASE.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="${REPO_ROOT:-$(cd "$SCRIPT_DIR/.." && pwd)}"
+
+# Standalone sandbox: the runner exports a sandboxed HOME; create one otherwise.
+if [[ "${_RUNNER_SANDBOX:-0}" != "1" ]]; then
+  _TMP_HOME=$(mktemp -d)
+  export HOME="$_TMP_HOME"
+  trap 'rm -rf "$_TMP_HOME"' EXIT
+fi
+
+# shellcheck source=tests/lib.sh
+source "${REPO_ROOT}/tests/lib.sh"
+
+# The download path requires curl; skip cleanly if it is unavailable.
+if ! command -v curl >/dev/null 2>&1; then
+  echo "[SKIP] test_install_piped — curl not available"
+  exit 0
+fi
+
+HOOK_DEST="${HOME}/.claude/hooks/inject-time-context.sh"
+SESSION_END_DEST="${HOME}/.claude/hooks/session-end.sh"
+SETTINGS_FILE="${HOME}/.claude/settings.json"
+
+# Simulate `curl ... | bash`: read the installer from stdin so BASH_SOURCE is
+# empty, and resolve hook downloads from the local checkout via file://.
+OUTPUT=$(CLAUDE_CONTEXT_TICK_RAW_BASE="file://${REPO_ROOT}" bash < "${REPO_ROOT}/scripts/install.sh" 2>&1)
+
+# The original failure modes must not reappear.
+assert_not_contains "$OUTPUT" "unbound variable" "piped install must not crash on empty BASH_SOURCE"
+assert_not_contains "$OUTPUT" "Hook source not found" "piped install must not bail looking for siblings"
+
+# Both hooks must be installed via the download path.
+assert_file_exists "$HOOK_DEST" "inject hook must be installed via download path"
+assert_file_exists "$SESSION_END_DEST" "session-end hook must be installed via download path"
+assert_file_exists "$SETTINGS_FILE" "settings.json must be created"
+
+# Installed hook must be non-empty and executable.
+[[ -s "$HOOK_DEST" ]] || { echo "ASSERT FAILED: installed hook is empty" >&2; exit 1; }
+[[ -x "$HOOK_DEST" ]] || { echo "ASSERT FAILED: installed hook is not executable" >&2; exit 1; }
+
+# settings.json must register both hooks pointing at the installed scripts.
+UPS_CMD=$(jq -r '.hooks.UserPromptSubmit[0].hooks[0].command' "$SETTINGS_FILE")
+SE_CMD=$(jq -r '.hooks.SessionEnd[0].hooks[0].command' "$SETTINGS_FILE")
+assert_contains "$UPS_CMD" "inject-time-context.sh" "UserPromptSubmit must register the inject hook"
+assert_contains "$SE_CMD" "session-end.sh" "SessionEnd must register the session-end hook"
+
+echo "[PASS] test_install_piped"