diff --git a/claude-notion/bin/task-work b/claude-notion/bin/task-work
index 58756e2..fb32134 100755
--- a/claude-notion/bin/task-work
+++ b/claude-notion/bin/task-work
@@ -85,7 +85,11 @@ fi
 [[ ${#POSITIONAL[@]} -lt 1 ]] && usage
 
 is_notion_url() {
-  [[ "$1" == *"notion.so"* || "$1" == *"notion.site"* ]]
+  # Anchored to the URL host so a free-form slug that merely contains the text
+  # (e.g. "my-notion.com-feature") is not misclassified as a URL. Allows any
+  # subdomain (www., app., or a published-site workspace) so the original
+  # *.notion.site behavior is preserved. (#158)
+  [[ "$1" =~ ^https?://([a-zA-Z0-9-]+\.)*notion\.(so|site|com)/ ]]
 }
 
 derive_slug_from_url() {
diff --git a/kiro-notion/bin/task-work b/kiro-notion/bin/task-work
index 921f006..8a6f7fe 100755
--- a/kiro-notion/bin/task-work
+++ b/kiro-notion/bin/task-work
@@ -91,7 +91,11 @@ done
 [[ ${#POSITIONAL[@]} -lt 1 ]] && usage
 
 is_notion_url() {
-  [[ "$1" == *"notion.so"* || "$1" == *"notion.site"* ]]
+  # Anchored to the URL host so a free-form slug that merely contains the text
+  # (e.g. "my-notion.com-feature") is not misclassified as a URL. Allows any
+  # subdomain (www., app., or a published-site workspace) so the original
+  # *.notion.site behavior is preserved. (#158)
+  [[ "$1" =~ ^https?://([a-zA-Z0-9-]+\.)*notion\.(so|site|com)/ ]]
 }
 
 derive_slug_from_url() {
diff --git a/tests/claude_notion_task_work.bats b/tests/claude_notion_task_work.bats
index 8d7eac9..432e2f3 100644
--- a/tests/claude_notion_task_work.bats
+++ b/tests/claude_notion_task_work.bats
@@ -53,6 +53,36 @@ teardown() {
   assert [ -d "$WORKTREE_BASE/my-explicit-slug" ]
 }
 
+@test "app.notion.com single-arg: derives slug from title segment (#158)" {
+  run "$CLAUDE_NOTION_TASK_WORK" "https://app.notion.com/My-Feature-abc123def456abc123def456abc123de"
+  assert_success
+  assert [ -d "$WORKTREE_BASE/my-feature" ]
+}
+
+@test "app.notion.com <slug> <url>: records NOTION_URL in .info (#158)" {
+  local url="https://app.notion.com/My-Feature-abc123def456abc123def456abc123de"
+  run "$CLAUDE_NOTION_TASK_WORK" my-feature "$url"
+  assert_success
+  source "$WORKTREE_BASE/.my-feature.info"
+  assert_equal "$NOTION_URL" "$url"
+}
+
+@test "false-positive guard: slug containing 'notion.com' resolves URL, not slug (#158)" {
+  # A free-form slug that merely contains "notion.com" must NOT be treated as a
+  # URL — the real app.notion.com arg must win and land in NOTION_URL.
+  local url="https://app.notion.com/Real-Page-abc123def456abc123def456abc123de"
+  run "$CLAUDE_NOTION_TASK_WORK" "my-notion.com-feature" "$url"
+  assert_success
+  source "$WORKTREE_BASE/.my-notioncom-feature.info"
+  assert_equal "$NOTION_URL" "$url"
+}
+
+@test "notion.site subdomain URL still recognized (#158)" {
+  run "$CLAUDE_NOTION_TASK_WORK" "https://myworkspace.notion.site/My-Feature-abc123def456abc123def456abc123de"
+  assert_success
+  assert [ -d "$WORKTREE_BASE/my-feature" ]
+}
+
 # ---------------------------------------------------------------------------
 # Worktree + branch creation
 # ---------------------------------------------------------------------------
diff --git a/tests/kiro_task_work.bats b/tests/kiro_task_work.bats
index e1217ca..4058f29 100644
--- a/tests/kiro_task_work.bats
+++ b/tests/kiro_task_work.bats
@@ -53,6 +53,36 @@ teardown() {
   assert [ -d "$WORKTREE_BASE/my-explicit-slug" ]
 }
 
+@test "app.notion.com single-arg: derives slug from title segment (#158)" {
+  run "$KIRO_TASK_WORK" "https://app.notion.com/My-Feature-abc123def456abc123def456abc123de"
+  assert_success
+  assert [ -d "$WORKTREE_BASE/my-feature" ]
+}
+
+@test "app.notion.com <slug> <url>: records NOTION_URL in .info (#158)" {
+  local url="https://app.notion.com/My-Feature-abc123def456abc123def456abc123de"
+  run "$KIRO_TASK_WORK" my-feature "$url"
+  assert_success
+  source "$WORKTREE_BASE/.my-feature.info"
+  assert_equal "$NOTION_URL" "$url"
+}
+
+@test "false-positive guard: slug containing 'notion.com' resolves URL, not slug (#158)" {
+  # A free-form slug that merely contains "notion.com" must NOT be treated as a
+  # URL — the real app.notion.com arg must win and land in NOTION_URL.
+  local url="https://app.notion.com/Real-Page-abc123def456abc123def456abc123de"
+  run "$KIRO_TASK_WORK" "my-notion.com-feature" "$url"
+  assert_success
+  source "$WORKTREE_BASE/.my-notioncom-feature.info"
+  assert_equal "$NOTION_URL" "$url"
+}
+
+@test "notion.site subdomain URL still recognized (#158)" {
+  run "$KIRO_TASK_WORK" "https://myworkspace.notion.site/My-Feature-abc123def456abc123def456abc123de"
+  assert_success
+  assert [ -d "$WORKTREE_BASE/my-feature" ]
+}
+
 # ---------------------------------------------------------------------------
 # Worktree + branch creation
 # ---------------------------------------------------------------------------