diff --git a/docs/configuration.md b/docs/configuration.md
index 71cad9d..be29785 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -28,7 +28,7 @@
 
 All configuration is stored via `git config`, making it easy to manage per-repository or globally. You can also use a `.gtrconfig` file for team-shared settings.
 
-**Configuration precedence** (highest to lowest):
+**Configuration precedence for single-value settings** (highest to lowest):
 
 1. `git config --local` (`.git/config`) - personal overrides
 2. `.gtrconfig` (repo root) - team defaults
@@ -37,6 +37,30 @@ All configuration is stored via `git config`, making it easy to manage per-repos
 5. Environment variables
 6. Default values
 
+Multi-valued copy settings merge values from local, `.gtrconfig`, global, and
+system configuration, removing duplicates. For example, a local
+`gtr.copy.includeDirs=vendor` and `.gtrconfig` `copy.includeDirs=node_modules`
+can cause both directories to be copied; the local value does not replace the
+team value.
+
+Git configuration is a trusted input: GTR runs hooks from local, global, and
+system Git configuration without a separate `git gtr trust` approval. Anyone
+who can modify that configuration can affect commands run by both GTR and Git
+itself. Keep local, global, and system Git configuration files, their included
+files, and any symlink targets writable only by people you trust to run commands
+as your user. Protect their parent directories as well, so untrusted users
+cannot replace files or links. The `.gtrconfig` approval gate does not isolate
+users sharing writable Git configuration.
+
+`git gtr trust` approves executable `.gtrconfig` entries (hooks and editor/AI
+defaults). Other settings do not require that approval. Most single-value
+settings use the precedence above, and multi-valued copy settings merge across
+scopes. UI color is an exception: `.gtrconfig` `ui.color` is not used for runtime
+color, and a nonempty `NO_COLOR` overrides Git configuration
+(see [UI Settings](#ui-settings)).
+For example, `worktrees.dir` selects the worktree destination; honoring this
+path does not approve `.gtrconfig` hooks.
+
 For the CLI, a bare repository's root is the bare Git directory itself, including
 when a command is run from one of its linked worktrees. `.gtrconfig`,
 `.worktreeinclude`, relative worktree locations, and the default copy source use
@@ -469,7 +493,7 @@ Control color output behavior.
 
 | Git Config Key | `.gtrconfig` Key | Description       | Values                              |
 | -------------- | ---------------- | ----------------- | ----------------------------------- |
-| `gtr.ui.color` | `ui.color`       | Color output mode | `auto` (default), `always`, `never` |
+| `gtr.ui.color` | `ui.color` (not used for runtime color) | Color output mode | `auto` (default), `always`, `never` |
 
 ```bash
 # Disable color output
@@ -479,9 +503,15 @@ git gtr config set gtr.ui.color never
 git gtr config set gtr.ui.color always
 ```
 
-**Precedence**: `NO_COLOR` env (highest) > `GTR_COLOR` env > `gtr.ui.color` config > auto-detect (TTY).
+Color is initialized from `GTR_COLOR`: `always` enables it, `never` disables it,
+and `auto` uses TTY detection. Then `gtr.ui.color` is read using Git's native
+configuration precedence. A value of `always` or `never` overrides the initial
+mode; `auto` leaves the initial mode unchanged. The `.gtrconfig` value is not
+used for runtime color, but `git gtr config get gtr.ui.color` and
+`git gtr config list` can still display it.
 
-The `NO_COLOR` environment variable ([no-color.org](https://no-color.org)) always wins regardless of other settings.
+A nonempty `NO_COLOR` environment variable ([no-color.org](https://no-color.org))
+disables color regardless of either source.
 
 ---
 
diff --git a/tests/config_trust_policy.bats b/tests/config_trust_policy.bats
new file mode 100644
index 0000000..1a1591b
--- /dev/null
+++ b/tests/config_trust_policy.bats
@@ -0,0 +1,184 @@
+#!/usr/bin/env bats
+# Git configuration is user-controlled; .gtrconfig commands require approval.
+# Fixture commands expand variables only when invoked by the child shell.
+# BATS owns the status/output variables across its test functions.
+# shellcheck disable=SC2016,SC2030,SC2031
+load test_helper
+
+# Create an isolated repository and configuration/cache paths for each test.
+setup() {
+  POLICY_FIXTURE=$(cd -P "$(mktemp -d)" && pwd)
+  export XDG_CONFIG_HOME="$POLICY_FIXTURE/config"
+  export XDG_CACHE_HOME="$POLICY_FIXTURE/cache"
+  export XDG_DATA_HOME="$POLICY_FIXTURE/data"
+  export GIT_CONFIG_GLOBAL="$POLICY_FIXTURE/global.gitconfig"
+  export GIT_CONFIG_NOSYSTEM=1
+  export POLICY_EVENTS="$POLICY_FIXTURE/events"
+  : > "$GIT_CONFIG_GLOBAL"
+  setup_integration_repo
+  source_gtr_commands
+}
+
+# Remove registered worktrees before deleting the test's configuration fixtures.
+teardown() {
+  teardown_integration_repo
+  rm -rf "$POLICY_FIXTURE"
+}
+
+# Configure marker hooks for a phase in Git config and unapproved .gtrconfig.
+# Usage: configure_policy_hooks <phase>
+# Writes globals by explicit filename so setup cannot modify user config.
+configure_policy_hooks() {
+  local phase="$1"
+  git config -f "$GIT_CONFIG_GLOBAL" --add "gtr.hook.$phase" \
+    "printf '%s\\n' 'global.$phase' >> \"\$POLICY_EVENTS\""
+  git config --local --add "gtr.hook.$phase" \
+    "printf '%s\\n' 'local.$phase' >> \"\$POLICY_EVENTS\""
+  git config -f "$TEST_REPO/.gtrconfig" --add "hooks.$phase" \
+    "printf '%s\\n' 'untrusted.$phase' >> \"\$POLICY_EVENTS\""
+}
+
+# Verify destination precedence and hook trust across real CLI create/remove.
+# Usage: check_policy_lifecycle <local|global>
+# Asserts that Git hooks run, file hooks stay blocked, and no approval is stored.
+check_policy_lifecycle() {
+  local scope="$1" destination="$POLICY_FIXTURE/worktrees with spaces"
+  local phase result
+  for phase in postCreate preRemove postRemove; do
+    configure_policy_hooks "$phase"
+  done
+  git config -f "$GIT_CONFIG_GLOBAL" gtr.worktrees.dir "$destination"
+  if [ "$scope" = local ]; then
+    # Local configuration must override both team and global destinations.
+    git config -f "$GIT_CONFIG_GLOBAL" gtr.worktrees.dir "$POLICY_FIXTURE/global-unused"
+    git config -f "$TEST_REPO/.gtrconfig" worktrees.dir "$POLICY_FIXTURE/team-unused"
+    git config --local gtr.worktrees.dir "$destination"
+  fi
+
+  # Use the actual CLI (set -e), with all network operations disabled.
+  result=$("$PROJECT_ROOT/bin/gtr" new policy-feature --from HEAD --no-fetch --no-copy \
+    --porcelain 2> "$POLICY_FIXTURE/create.stderr")
+  [ "$result" = $'path\t'"$destination/policy-feature"$'\nbranch\tpolicy-feature\nhook_status\tpartial' ]
+  [ -d "$destination/policy-feature" ]
+  [ ! -e "$POLICY_FIXTURE/global-unused" ]
+  [ ! -e "$POLICY_FIXTURE/team-unused" ]
+  [ "$(cat "$POLICY_EVENTS")" = $'global.postCreate\nlocal.postCreate' ]
+
+  run "$PROJECT_ROOT/bin/gtr" rm policy-feature --yes
+  [ "$status" -eq 0 ]
+  [ ! -e "$destination/policy-feature" ]
+  [ "$(cat "$POLICY_EVENTS")" = $'global.postCreate\nlocal.postCreate\nglobal.preRemove\nlocal.preRemove\nglobal.postRemove\nlocal.postRemove' ]
+  [ ! -d "$_GTR_TRUST_DIR" ]
+}
+
+@test "local worktrees.dir and Git lifecycle hooks work while untrusted file hooks stay blocked" {
+  check_policy_lifecycle local
+}
+
+@test "global worktrees.dir and Git lifecycle hooks work while untrusted file hooks stay blocked" {
+  check_policy_lifecycle global
+}
+
+@test "untrusted worktrees.dir selects a literal destination without approving file hooks" {
+  local destination="$POLICY_FIXTURE/"'$(touch should-not-run)'
+  git config -f "$TEST_REPO/.gtrconfig" worktrees.dir "$destination"
+  git config -f "$TEST_REPO/.gtrconfig" hooks.postCreate 'printf untrusted > "$POLICY_EVENTS"'
+
+  run "$PROJECT_ROOT/bin/gtr" new literal-path --from HEAD --no-fetch --no-copy --porcelain
+  [ "$status" -eq 0 ]
+  [[ "$output" == *$'hook_status\tskipped-untrusted'* ]]
+  [ -d "$destination/literal-path" ]
+  [ ! -e "$TEST_REPO/should-not-run" ]
+  [ ! -e "$POLICY_EVENTS" ]
+  [ ! -d "$_GTR_TRUST_DIR" ]
+}
+
+@test "postCd export dispatcher runs Git hooks while untrusted file hooks stay blocked" {
+  configure_policy_hooks postCd
+  git config --local --add gtr.hook.postCd 'export POLICY_LOCAL_EXPORT=local'
+  git config -f "$TEST_REPO/.gtrconfig" --add hooks.postCd 'export POLICY_LOCAL_EXPORT=untrusted'
+
+  # Run with strict mode in a child shell, as used by the AI launch path.
+  run bash -e -c '
+    source "$GTR_DIR/lib/config.sh"
+    source "$GTR_DIR/lib/hooks.sh"
+    run_hooks_export postCd
+    [ "$POLICY_LOCAL_EXPORT" = local ]
+  '
+  [ "$status" -eq 0 ]
+  [ "$(cat "$POLICY_EVENTS")" = $'global.postCd\nlocal.postCd' ]
+  [ ! -d "$_GTR_TRUST_DIR" ]
+}
+
+# Verify a generated shell helper preserves only trusted hooks and exports.
+# Usage: check_generated_policy_hooks <bash|zsh|fish>
+# Skips unavailable shells; assertion failures propagate to the BATS test.
+check_generated_policy_hooks() {
+  local shell_name="$1"
+  command -v "$shell_name" >/dev/null 2>&1 || skip "$shell_name is not installed"
+  configure_policy_hooks postCd
+  local trusted_export_hook untrusted_export_hook
+  case "$shell_name" in
+    bash|zsh)
+      trusted_export_hook='export POLICY_TRUSTED_EXPORT=trusted'
+      untrusted_export_hook='export POLICY_UNTRUSTED_EXPORT=untrusted'
+      ;;
+    fish)
+      trusted_export_hook='set -gx POLICY_TRUSTED_EXPORT trusted'
+      untrusted_export_hook='set -gx POLICY_UNTRUSTED_EXPORT untrusted'
+      ;;
+  esac
+  git config --local --add gtr.hook.postCd "$trusted_export_hook"
+  git config -f "$TEST_REPO/.gtrconfig" --add hooks.postCd "$untrusted_export_hook"
+  export POLICY_INIT="$POLICY_FIXTURE/init.$shell_name"
+  export POLICY_WORKTREE="$POLICY_FIXTURE/linked worktree"
+  git worktree add --quiet "$POLICY_WORKTREE" -b policy-cd HEAD
+  "$PROJECT_ROOT/bin/gtr" init "$shell_name" > "$POLICY_INIT"
+
+  unset POLICY_TRUSTED_EXPORT POLICY_UNTRUSTED_EXPORT
+  local shell_args=()
+  if [ "$shell_name" = zsh ]; then
+    shell_args=(-f)
+  fi
+  case "$shell_name" in
+    bash|zsh)
+      run "$shell_name" "${shell_args[@]}" -c '
+        set -e
+        # Completion registration is outside this non-interactive hook fixture.
+        compdef() { :; }
+        source "$POLICY_INIT"
+        gtr_run_post_cd_hooks "$POLICY_WORKTREE"
+        [ "$POLICY_TRUSTED_EXPORT" = trusted ]
+        [ -z "${POLICY_UNTRUSTED_EXPORT+x}" ]
+      '
+      ;;
+    fish)
+      run fish -c '
+        source "$POLICY_INIT"; or exit 1
+        gtr_run_post_cd_hooks "$POLICY_WORKTREE"; or exit 1
+        test "$POLICY_TRUSTED_EXPORT" = trusted; or exit 1
+        not set -q POLICY_UNTRUSTED_EXPORT
+      '
+      ;;
+  esac
+  [ "$status" -eq 0 ]
+  [[ "$output" == *"Untrusted .gtrconfig hooks skipped"* ]]
+  [ "$(cat "$POLICY_EVENTS")" = $'global.postCd\nlocal.postCd' ]
+  [ ! -d "$_GTR_TRUST_DIR" ]
+}
+
+@test "bash generated postCd runs Git hooks while untrusted file hooks stay blocked" {
+  check_generated_policy_hooks bash
+}
+
+@test "zsh generated postCd runs Git hooks while untrusted file hooks stay blocked" {
+  # The helper shell must skip user startup files that could replace fixture config.
+  export ZDOTDIR="$POLICY_FIXTURE/zsh-startup"
+  mkdir -p "$ZDOTDIR"
+  printf 'exit 99\n' > "$ZDOTDIR/.zshenv"
+  check_generated_policy_hooks zsh
+}
+
+@test "fish generated postCd runs Git hooks while untrusted file hooks stay blocked" {
+  check_generated_policy_hooks fish
+}