feat(graph): namespace topic-tunnel rooms with "topic:" prefix + kind field

Previously a cross-wing topic tunnel for "Angular" stored the room as
"Angular" — colliding with a wing's literal folder-derived "Angular" room
at follow_tunnels/list_tunnels read time, and exposing raw topic strings
(which may contain characters rejected by sanitize_name) to the MCP
surface.

Topic tunnels now store their room as "topic:<original-casing>" and carry
kind="topic" on the stored dict. Explicit tunnels get kind="explicit"
(default). follow_tunnels("wing", "Angular") on a literal Angular room
no longer surfaces topic connections for the same name, and any LLM
scanning list_tunnels has a visible discriminator.

CHANGELOG.md

@@ -10,7 +10,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Added
 
-- **Cross-wing topic tunnels.** When two wings have confirmed `TOPIC` labels in common (the LLM-refine bucket from `mempalace init --llm`), the miner now drops a symmetric tunnel between them at mine time so the palace graph reflects shared themes (frameworks, vendors, recurring concepts). Tunnels are routed through the existing `create_tunnel` storage so they share dedup and persistence with explicit tunnels. Threshold is configurable via `MEMPALACE_TOPIC_TUNNEL_MIN_COUNT` env var or `topic_tunnel_min_count` in `~/.mempalace/config.json` (default `1`). Manifest-dependency overlap and per-topic allow/deny lists remain out of scope. (#1180)
+- **Cross-wing topic tunnels.** When two wings have confirmed `TOPIC` labels in common (the LLM-refine bucket from `mempalace init --llm`), the miner now drops a symmetric tunnel between them at mine time so the palace graph reflects shared themes (frameworks, vendors, recurring concepts). Tunnels are routed through the existing `create_tunnel` storage so they share dedup and persistence with explicit tunnels. Topic tunnels are stored under a synthetic `topic:<name>` room and tagged with `kind: "topic"` on the stored dict — this keeps them distinct from literal folder-derived rooms of the same name (a wing with both an `Angular` folder room and an `Angular` topic tunnel no longer collides at `follow_tunnels` read time) and gives LLMs scanning `list_tunnels` a visible discriminator. Threshold is configurable via `MEMPALACE_TOPIC_TUNNEL_MIN_COUNT` env var or `topic_tunnel_min_count` in `~/.mempalace/config.json` (default `1`). Manifest-dependency overlap and per-topic allow/deny lists remain out of scope. (#1180)
 
 ---
 

mempalace/palace_graph.py

@@ -362,6 +362,7 @@ def create_tunnel(
     label: str = "",
     source_drawer_id: str = None,
     target_drawer_id: str = None,
+    kind: str = "explicit",
 ):
     """Create an explicit (symmetric) tunnel between two locations in the palace.
 
@@ -382,6 +383,11 @@ def create_tunnel(
         label: Description of the connection.
         source_drawer_id: Optional specific drawer ID.
         target_drawer_id: Optional specific drawer ID.
+        kind: Tunnel category — ``"explicit"`` (default, user-created link
+            between real rooms) or ``"topic"`` (auto-generated cross-wing
+            topical link where rooms are synthetic ``topic:<name>``
+            identifiers). Preserved on the stored dict so readers can
+            distinguish real-room traversals from topic connections.
 
     Returns:
         The stored tunnel dict.
@@ -401,6 +407,7 @@ def create_tunnel(
         "source": {"wing": source_wing, "room": source_room},
         "target": {"wing": target_wing, "room": target_room},
         "label": label,
+        "kind": kind,
         "created_at": datetime.now(timezone.utc).isoformat(),
     }
     if source_drawer_id:
@@ -511,9 +518,15 @@ def follow_tunnels(wing: str, room: str, col=None, config=None):
 # ``~/.mempalace/known_entities.json`` under ``topics_by_wing``.
 #
 # Tunnels are created via the existing ``create_tunnel`` API so they share
-# storage and dedup with explicit tunnels. The room is the topic name —
+# storage and dedup with explicit tunnels. The room is a synthetic
-# this matches the "two wings share an idea" mental model and keeps the
+# ``topic:<original-casing>`` identifier — the ``topic:`` prefix namespaces
-# graph homogeneous.
+# these tunnels away from literal folder-derived rooms so a wing with an
+# auto-detected "Angular" folder room and a "shared topic: Angular" tunnel
+# remain distinct at ``follow_tunnels`` / ``list_tunnels`` time. The prefix
+# is also visible to any LLM scanning the tunnel list. The ``kind: "topic"``
+# field on the stored dict gives callers a machine-readable discriminator.
+
+TOPIC_ROOM_PREFIX = "topic:"
 
 
 def _normalize_topic(name: str) -> str:
@@ -521,6 +534,16 @@ def _normalize_topic(name: str) -> str:
     return str(name).strip().lower()
 
 
+def topic_room(name: str) -> str:
+    """Return the synthetic room identifier for a topic tunnel.
+
+    Prefixing avoids collisions with literal folder-derived rooms of the
+    same name (e.g. a wing that has both an "Angular" folder room and an
+    "Angular" topic tunnel).
+    """
+    return f"{TOPIC_ROOM_PREFIX}{name}"
+
+
 def compute_topic_tunnels(
     topics_by_wing: dict,
     min_count: int = 1,
@@ -586,13 +609,15 @@ def compute_topic_tunnels(
             for key in sorted(shared_keys):
                 # Prefer the casing from whichever wing sorts first — both
                 # are valid; this just keeps the displayed room consistent.
-                room = topics_a[key] if topics_a[key] else topics_b[key]
+                topic_name = topics_a[key] if topics_a[key] else topics_b[key]
+                room = topic_room(topic_name)
                 tunnel = create_tunnel(
                     source_wing=wa,
                     source_room=room,
                     target_wing=wb,
                     target_room=room,
-                    label=f"{label_prefix}: {room}",
+                    label=f"{label_prefix}: {topic_name}",
+                    kind="topic",
                 )
                 created.append(tunnel)
     return created

tests/test_miner.py

@@ -536,7 +536,10 @@ def test_mine_creates_topic_tunnels_for_shared_topics(tmp_path, monkeypatch):
     listed = palace_graph.list_tunnels()
     assert len(listed) == 1
     rooms = {listed[0]["source"]["room"], listed[0]["target"]["room"]}
-    assert rooms == {"foo"}
+    # Topic tunnels use a ``topic:<name>`` synthetic room so they can't
+    # collide with literal folder-derived rooms of the same name.
+    assert rooms == {"topic:foo"}
+    assert listed[0]["kind"] == "topic"
     wings = {listed[0]["source"]["wing"], listed[0]["target"]["wing"]}
     assert wings == {"wing_one", "wing_two"}
 

tests/test_palace_graph_tunnels.py

@@ -156,9 +156,15 @@ class TestTopicTunnels:
         assert len(created) == 1
         assert created[0]["source"]["wing"] in {"wing_alpha", "wing_beta"}
         assert created[0]["target"]["wing"] in {"wing_alpha", "wing_beta"}
-        # Room is the topic itself (case preserved from the first wing).
+        # Room is namespaced with the ``topic:`` prefix so it can't collide
-        assert created[0]["source"]["room"] == "OpenAPI"
+        # with a literal folder-derived room of the same name. Casing of the
+        # topic is preserved for display.
+        assert created[0]["source"]["room"] == "topic:OpenAPI"
+        assert created[0]["target"]["room"] == "topic:OpenAPI"
+        assert created[0]["kind"] == "topic"
+        # Label carries the human-readable topic without the prefix.
         assert "OpenAPI" in created[0]["label"]
+        assert "topic:OpenAPI" not in created[0]["label"]
 
         # Tunnel is retrievable via the standard list_tunnels API.
         listed = palace_graph.list_tunnels()
@@ -187,7 +193,7 @@ class TestTopicTunnels:
         created = palace_graph.compute_topic_tunnels(topics_by_wing, min_count=2)
         # Two shared topics × one wing pair = two tunnels.
         rooms = sorted(t["source"]["room"] for t in created)
-        assert rooms == ["Angular", "OpenAPI"]
+        assert rooms == ["topic:Angular", "topic:OpenAPI"]
 
     def test_compute_topic_tunnels_case_insensitive_overlap(self, tmp_path, monkeypatch):
         _use_tmp_tunnel_file(monkeypatch, tmp_path)
@@ -258,3 +264,38 @@ class TestTopicTunnels:
         # not multiply the stored tunnels.
         assert first[0]["id"] == second[0]["id"]
         assert len(palace_graph.list_tunnels()) == 1
+
+    def test_topic_tunnel_room_does_not_collide_with_literal_room(self, tmp_path, monkeypatch):
+        """Regression: a literal "Angular" folder-room and a topic tunnel
+        for "Angular" must resolve to distinct endpoints so ``follow_tunnels``
+        from the real room doesn't accidentally surface topic connections
+        (issue raised in review of #1184)."""
+        _use_tmp_tunnel_file(monkeypatch, tmp_path)
+
+        # Explicit tunnel anchored at a literal "Angular" room in wing_alpha.
+        palace_graph.create_tunnel(
+            "wing_alpha", "Angular", "wing_gamma", "frontend", label="explicit"
+        )
+        # Topic tunnel between the same wings that share the "Angular" topic.
+        palace_graph.compute_topic_tunnels(
+            {"wing_alpha": ["Angular"], "wing_beta": ["Angular"]}, min_count=1
+        )
+
+        # follow_tunnels on the literal Angular room only sees the explicit link.
+        literal = palace_graph.follow_tunnels("wing_alpha", "Angular")
+        assert len(literal) == 1
+        assert literal[0]["connected_wing"] == "wing_gamma"
+
+        # The topic tunnel is stored under the namespaced room.
+        topical = palace_graph.follow_tunnels("wing_alpha", "topic:Angular")
+        assert len(topical) == 1
+        assert topical[0]["connected_wing"] == "wing_beta"
+
+    def test_topic_tunnels_carry_kind_field(self, tmp_path, monkeypatch):
+        _use_tmp_tunnel_file(monkeypatch, tmp_path)
+        palace_graph.create_tunnel("wing_a", "auth", "wing_b", "users", label="x")
+        palace_graph.compute_topic_tunnels({"wing_a": ["Redis"], "wing_b": ["Redis"]}, min_count=1)
+
+        tunnels = palace_graph.list_tunnels()
+        kinds = sorted(t["kind"] for t in tunnels)
+        assert kinds == ["explicit", "topic"]