refactor(session): pick the browse/discovery limit default in one place

Collapse the browse and discovery limit defaults into a single mode-aware
_clamp_int call in _dispatch and fold the three new tests into one that
covers the function, registry handler and inline executor entry points.

tests/tools/test_session_search.py

@@ -1209,46 +1209,25 @@ class TestDiscoverySessionExclusion:
             query="unique lineage token alpha", limit=5, exclude_session_ids=["s_child"], db=db))
         assert not {r["session_id"] for r in excluded["results"]} & {"s_root", "s_child"}
 
-class TestBrowseResultCap:
-    """A no-argument call browses; it must not inherit discovery's three-hit cap."""
 
-    @staticmethod
-    def _seed_sessions(db, count=12):
-        for i in range(count):
-            sid = f"s_browse_{i:02d}"
-            db.create_session(sid, source="cli")
-            db.append_message(sid, role="user", content=f"browse seed {i}")
-
-    def test_no_args_browse_defaults_to_ten_sessions(self, db):
-        self._seed_sessions(db)
-
-        result = json.loads(session_search(db=db))
-
-        assert result["success"] is True
-        assert result["mode"] == "browse"
-        assert len(result["results"]) == 10
-
-    def test_explicit_limit_still_wins(self, db):
-        self._seed_sessions(db)
-
-        result = json.loads(session_search(db=db, limit=4))
-
-        assert result["mode"] == "browse"
-        assert len(result["results"]) == 4
-
-    def test_no_args_browse_keeps_ten_through_the_inline_executor(self, db):
-        """The inline dispatcher maps schema args explicitly, so a default baked into its
-        arg spec would narrow browse before the tool ever sees the call."""
+class TestBrowseDefaultLimit:
+    def test_no_limit_browse_returns_ten_on_every_entry_point(self, db):
+        """Browse must not inherit discovery's default of 3 via the function, the registry
+        handler, or the inline executor (the live path), each of which used to bake in 3."""
         from types import SimpleNamespace
 
         from agent.inline_tool_executors import INLINE_TOOL_EXECUTORS, InlineToolContext
+        from tools.registry import registry
 
-        self._seed_sessions(db)
+        for i in range(12):
+            db.create_session(f"s_browse_{i:02d}", source="cli")
+            db.append_message(f"s_browse_{i:02d}", role="user", content=f"browse seed {i}")
         agent = SimpleNamespace(_get_session_db_for_recall=lambda: db, session_id="current")
         ctx = InlineToolContext(effective_task_id="task-1", tool_call_id="call-1")
 
-        result = json.loads(INLINE_TOOL_EXECUTORS["session_search"](agent, {}, ctx))
-
-        assert result["success"] is True
-        assert result["mode"] == "browse"
-        assert len(result["results"]) == 10
+        for raw in (session_search(db=db), registry.get_entry("session_search").handler({}, db=db),
+                    INLINE_TOOL_EXECUTORS["session_search"](agent, {}, ctx)):
+            result = json.loads(raw)
+            assert result["mode"] == "browse"
+            assert len(result["results"]) == 10
+        assert len(json.loads(session_search(db=db, limit=4))["results"]) == 4

tools/session_search_tool.py

@@ -38,11 +38,6 @@ _DEMOTED_SESSION_SOURCES = ("cron",)
 # Bounding message COUNT (head/tail) is not enough when content per message is
 # unbounded; the agent can scroll around a message for detail (#114344).
 _READ_MAX_CONTENT = 2000
-# Result caps: a no-argument call browses recent sessions, where the caller wants to see
-# enough of the list to pick one; a query is discovery, where three ranked hits suffice.
-_DEFAULT_BROWSE_LIMIT = 10
-_DEFAULT_DISCOVERY_LIMIT = 3
-_MAX_SESSION_SEARCH_LIMIT = 10
 # FTS rows scanned before dedup-by-lineage — well above the distinct sessions a query
 # returns, so interactive matches buried under cron hits survive the demotion pass.
 _DISCOVER_SCAN_LIMIT = 300
@@ -587,11 +582,11 @@ def _dispatch(query, role_filter, limit, db, current_session_id, session_id,
         if around_message_id is not None:
             return _scroll(db, session_id.strip(), around_message_id, window, current_session_id)
         return _read_scoped(db, session_id.strip(), profile)
-    if not query or not isinstance(query, str) or not query.strip():
-        return _list_recent_sessions(
-            db, _clamp_int(limit, _DEFAULT_BROWSE_LIMIT, 1, _MAX_SESSION_SEARCH_LIMIT),
-            current_session_id, link_profile=profile)
-    limit = _clamp_int(limit, _DEFAULT_DISCOVERY_LIMIT, 1, _MAX_SESSION_SEARCH_LIMIT)
+    browse = not query or not isinstance(query, str) or not query.strip()
+    # Browse lists enough recent sessions to pick from; discovery returns a few ranked hits.
+    limit = _clamp_int(limit, 10 if browse else 3, 1, 10)
+    if browse:
+        return _list_recent_sessions(db, limit, current_session_id, link_profile=profile)
     sort_norm = sort.strip().lower() if isinstance(sort, str) else None
     try:
         after_ts, before_ts = _parse_iso_bound(after), _parse_iso_bound(before)