diff --git a/lib/config.sh b/lib/config.sh
index f1935f9..4c1a19e 100644
--- a/lib/config.sh
+++ b/lib/config.sh
@@ -10,24 +10,38 @@
 # 5. Environment variables
 # 6. Fallback values
 
+# Resolve the main repo root from the current git context.
+# Works from the main repo root, a subdirectory, or a linked worktree.
+# Returns: absolute path to main repo root or empty on failure
+_resolve_main_repo_root() {
+  local git_common_dir repo_root
+  git_common_dir=$(git rev-parse --git-common-dir 2>/dev/null) || return 1
+
+  [ -n "$git_common_dir" ] || return 1
+
+  case "$git_common_dir" in
+    /*)
+      repo_root="${git_common_dir%/.git}"
+      ;;
+    *)
+      repo_root=$(
+        unset CDPATH
+        cd -P -- "$git_common_dir/.." 2>/dev/null && pwd -P
+      ) || return 1
+      ;;
+  esac
+
+  [ -n "$repo_root" ] || return 1
+  printf "%s" "$repo_root"
+}
+
 # Get the path to .gtrconfig file in main repo root
 # Usage: _gtrconfig_path
 # Returns: path to .gtrconfig or empty if not in a repo
-# Note: Uses --git-common-dir to find main repo even from worktrees
+# Note: Uses _resolve_main_repo_root to find main repo even from worktrees/subdirectories
 _gtrconfig_path() {
-  local git_common_dir repo_root
-  git_common_dir=$(git rev-parse --git-common-dir 2>/dev/null) || return 0
-
-  # git-common-dir returns:
-  # - ".git" when in main repo (relative)
-  # - "/absolute/path/to/repo/.git" when in worktree (absolute)
-  if [ "$git_common_dir" = ".git" ]; then
-    # In main repo - use show-toplevel
-    repo_root=$(git rev-parse --show-toplevel 2>/dev/null) || return 0
-  else
-    # In worktree - strip /.git suffix from absolute path
-    repo_root="${git_common_dir%/.git}"
-  fi
+  local repo_root
+  repo_root=$(_resolve_main_repo_root) || return 0
 
   printf "%s/.gtrconfig" "$repo_root"
 }
diff --git a/lib/core.sh b/lib/core.sh
index 37a53e4..5bd4dba 100644
--- a/lib/core.sh
+++ b/lib/core.sh
@@ -15,24 +15,8 @@ declare _ctx_is_main _ctx_worktree_path _ctx_branch
 # Returns: absolute path to main repo root
 # Exit code: 0 on success, 1 if not in a git repo
 discover_repo_root() {
-  local root git_common_dir
-  git_common_dir=$(git rev-parse --git-common-dir 2>/dev/null)
-
-  if [ -z "$git_common_dir" ]; then
-    log_error "Not in a git repository"
-    return 1
-  fi
-
-  # --git-common-dir returns:
-  #   ".git" (relative) when in the main repo
-  #   "/absolute/path/to/repo/.git" when in a worktree
-  if [ "$git_common_dir" = ".git" ]; then
-    root=$(git rev-parse --show-toplevel 2>/dev/null)
-  else
-    root="${git_common_dir%/.git}"
-  fi
-
-  if [ -z "$root" ]; then
+  local root
+  if ! root=$(_resolve_main_repo_root); then
     log_error "Not in a git repository"
     return 1
   fi
diff --git a/tests/cmd_list.bats b/tests/cmd_list.bats
index 2b37693..bc96502 100644
--- a/tests/cmd_list.bats
+++ b/tests/cmd_list.bats
@@ -76,3 +76,12 @@ teardown() {
   [[ "$output" == *"$TEST_REPO"* ]]
   [[ "$output" == *"wt-porcelain"* ]]
 }
+
+@test "cmd_list from a repo subdirectory shows the main repo root" {
+  mkdir -p "$TEST_REPO/subdir/nested"
+  cd "$TEST_REPO/subdir/nested"
+  run cmd_list
+  [ "$status" -eq 0 ]
+  [[ "$output" == *"$TEST_REPO"* ]]
+  [[ "$output" != *"subdir/..-worktrees"* ]]
+}
diff --git a/tests/config.bats b/tests/config.bats
index e8abb5f..8d85f61 100644
--- a/tests/config.bats
+++ b/tests/config.bats
@@ -6,6 +6,13 @@ setup() {
   source "$PROJECT_ROOT/lib/config.sh"
 }
 
+teardown() {
+  if [ -n "${TEST_REPO:-}" ]; then
+    teardown_integration_repo
+    unset TEST_REPO TEST_WORKTREES_DIR
+  fi
+}
+
 # ── Key mapping ──────────────────────────────────────────────────────────────
 
 @test "cfg_map_to_file_key maps gtr.copy.include to copy.include" {
@@ -125,3 +132,27 @@ setup() {
   [[ "$result" == *"vscode"* ]]
   [[ "$result" == *"[local]"* ]]
 }
+
+# ── Repo context integration ─────────────────────────────────────────────────
+
+@test "_resolve_main_repo_root returns the repo root from a subdirectory" {
+  setup_integration_repo
+  mkdir -p "$TEST_REPO/subdir/nested"
+  cd "$TEST_REPO/subdir/nested"
+  local expected
+  expected=$(cd "$TEST_REPO" && pwd -P)
+
+  result=$(_resolve_main_repo_root)
+  [ "$result" = "$expected" ]
+}
+
+@test "_gtrconfig_path points at the repo root from a subdirectory" {
+  setup_integration_repo
+  mkdir -p "$TEST_REPO/subdir/nested"
+  cd "$TEST_REPO/subdir/nested"
+  local expected
+  expected="$(cd "$TEST_REPO" && pwd -P)/.gtrconfig"
+
+  result=$(_gtrconfig_path)
+  [ "$result" = "$expected" ]
+}
diff --git a/tests/core_resolve_target.bats b/tests/core_resolve_target.bats
index 7d8f9b3..1ab1a3f 100644
--- a/tests/core_resolve_target.bats
+++ b/tests/core_resolve_target.bats
@@ -112,3 +112,23 @@ teardown() {
   expected=$(pwd -P)
   [ "$root" = "$expected" ]
 }
+
+@test "discover_repo_root returns main repo root when called from a repo subdirectory" {
+  mkdir -p "$TEST_REPO/subdir/nested"
+  cd "$TEST_REPO/subdir/nested"
+  local root expected
+  root=$(discover_repo_root)
+  expected=$(cd "$TEST_REPO" && pwd -P)
+  [ "$root" = "$expected" ]
+}
+
+@test "discover_repo_root returns 1 outside a git repository" {
+  local outside_repo
+  outside_repo=$(mktemp -d)
+  cd "$outside_repo"
+
+  run discover_repo_root
+  [ "$status" -eq 1 ]
+
+  rm -rf "$outside_repo"
+}