diff --git a/src/agent_loop.py b/src/agent_loop.py
index a4525e93c..5effc54b5 100644
--- a/src/agent_loop.py
+++ b/src/agent_loop.py
@@ -262,6 +262,11 @@ _DOMAIN_RULES = {
 - Use `manage_settings` for preferences and tool enable/disable.
 - Use named tools over `app_api` when a named wrapper exists.
 - `app_api` is only for safe UI/API actions without a named tool; do not use it for shell, package installs, engine rebuilds, or sensitive auth/admin paths.""",
+    "contacts": """\
+## Contacts rules
+- Use `resolve_contact` to look up a contact's email or phone number by name. Searches the CardDAV address book and sent email history.
+- Use `manage_contact` to list, add, update, or delete contacts in the address book.
+- Do NOT use `manage_memory` for contact lookups — contact details live in the address book, not memory.""",
 }
 
 _DOMAIN_TOOL_MAP = {
@@ -274,6 +279,7 @@ _DOMAIN_TOOL_MAP = {
     "sessions": {"create_session", "list_sessions", "manage_session", "send_to_session", "search_chats"},
     "files": {"bash", "python", "read_file", "write_file", "edit_file", "grep", "glob", "ls", "get_workspace"},
     "settings": {"manage_settings", "manage_endpoints", "manage_mcp", "manage_webhooks", "manage_tokens", "app_api"},
+    "contacts": {"resolve_contact", "manage_contact"},
 }
 
 def _domain_rules_for_tools(tool_names: set) -> list[str]:
@@ -797,6 +803,8 @@ def _classify_agent_request(messages: List[Dict], last_user: str) -> Dict[str, o
         domains.add("files")
     if has(r"\b(endpoint|api token|mcp|webhook|preference|configure|config|setting)\b"):
         domains.add("settings")
+    if has(r"\b(contact|contacts|phone|phone number|address book|vcard)\b"):
+        domains.add("contacts")
 
     low_signal = not continuation and not domains
     return {
diff --git a/tests/test_tool_rag_contacts_domain.py b/tests/test_tool_rag_contacts_domain.py
new file mode 100644
index 000000000..a1f8660ae
--- /dev/null
+++ b/tests/test_tool_rag_contacts_domain.py
@@ -0,0 +1,72 @@
+"""Regression: the agent tool-RAG domain classifier had no contacts domain,
+so contact-lookup requests matched no domain, were flagged low_signal, and had
+tool retrieval SKIPPED entirely — the model only received ALWAYS_AVAILABLE tools
+(manage_memory, ask_user, update_plan) and never `resolve_contact`/`manage_contact`,
+so it could not look up contacts from the CardDAV address book (it looped on
+manage_memory instead).
+
+Root cause: `_classify_agent_request` in src/agent_loop.py sets
+`low_signal = not continuation and not domains`; with no `contacts` domain,
+prompts like "What is Massimo's contact?" matched nothing → low_signal →
+retrieval skipped.
+
+The classifier is deterministic string matching (no embeddings / no DB), so it
+can be exercised directly.
+"""
+
+from src.agent_loop import (
+    _classify_agent_request,
+    _DOMAIN_TOOL_MAP,
+    _DOMAIN_RULES,
+    _domain_rules_for_tools,
+)
+
+
+def _classify(text):
+    return _classify_agent_request([{"role": "user", "content": text}], text)
+
+
+def test_contact_lookup_requests_get_contacts_domain():
+    """Contact-lookup phrasings must match the `contacts` domain and NOT be
+    treated as low-signal (which would skip tool retrieval)."""
+    prompts = [
+        "What is Massimo's contact?",
+        "What's John's phone number?",
+        "Show me my contacts",
+        "Look up Kevin's contact info",
+        "Find Alice's phone number",
+    ]
+    for p in prompts:
+        intent = _classify(p)
+        assert "contacts" in intent["domains"], f"expected contacts domain for: {p!r}"
+        assert intent["low_signal"] is False, f"must not be low_signal: {p!r}"
+
+
+def test_contact_management_requests_get_contacts_domain():
+    """Add/update/delete contact phrasings also resolve to the contacts domain."""
+    for p in ("add a new contact", "update Bob's phone number", "delete that contact",
+              "save this person to contacts"):
+        intent = _classify(p)
+        assert "contacts" in intent["domains"], f"expected contacts domain for: {p!r}"
+
+
+def test_contacts_domain_seeds_resolve_and_manage_contact():
+    """The domain must seed the actual contacts tools so they are offered even
+    when semantic retrieval misses."""
+    assert _DOMAIN_TOOL_MAP["contacts"] == {"resolve_contact", "manage_contact"}
+
+
+def test_contacts_domain_has_a_rule_pack():
+    """Every domain in _DOMAIN_TOOL_MAP needs a matching _DOMAIN_RULES entry,
+    otherwise _domain_rules_for_tools raises KeyError when the tools are selected."""
+    assert "contacts" in _DOMAIN_RULES
+    rules = _domain_rules_for_tools({"resolve_contact"})
+    assert any("Contacts rules" in r for r in rules)
+
+
+def test_non_contact_requests_do_not_match_contacts_domain():
+    """Guard against over-triggering: ordinary prompts must not be flagged contacts."""
+    assert "contacts" not in _classify("what is the capital of France")["domains"]
+    assert "contacts" not in _classify("reply to the latest email in my inbox")["domains"]
+    assert "contacts" not in _classify("generate an image of a sunset")["domains"]
+    assert "contacts" not in _classify("what's 2 plus 2")["domains"]