diff --git a/tracker/api.py b/tracker/api.py
index 1071411..d3edbd8 100644
--- a/tracker/api.py
+++ b/tracker/api.py
@@ -259,7 +259,9 @@ def breakdown_series(
         if tool:
             clauses.append("mc.tool = ?"); params.append(tool)
         if model:
-            clauses.append("s.model = ?"); params.append(model)
+            clauses.append("EXISTS (SELECT 1 FROM messages mm WHERE mm.source_file=mc.source_file "
+                           "AND mm.source_line=mc.source_line AND mm.model = ?)")
+            params.append(model)
         if project:
             clauses.append("s.cwd = ?"); params.append(project)
         if start:
@@ -490,6 +492,7 @@ def _per_call_lifecycle_cost(tokens: int, tool: str, model: str | None, subseque
 @app.get("/api/mcp")
 def mcp(
     tool: str | None = Query(None),
+    model: str | None = Query(None),
     project: str | None = Query(None),
     start: str | None = Query(None),
     end: str | None = Query(None),
@@ -501,6 +504,11 @@ def mcp(
     params: list = []
     if tool:
         clauses.append("mc.tool = ?"); params.append(tool)
+    if model:
+        # An MCP call is issued by the assistant message at the same source_file/source_line.
+        clauses.append("EXISTS (SELECT 1 FROM messages mm WHERE mm.source_file=mc.source_file "
+                       "AND mm.source_line=mc.source_line AND mm.model = ?)")
+        params.append(model)
     if project:
         clauses.append("s.cwd = ?"); params.append(project)
     if start:
diff --git a/tracker/parse_claude.py b/tracker/parse_claude.py
index 6e1d1fd..333fea3 100644
--- a/tracker/parse_claude.py
+++ b/tracker/parse_claude.py
@@ -101,13 +101,22 @@ def _tool_result_chars(content) -> tuple[int, int]:
     return len(json.dumps(content, default=str)), 0
 
 
+def _session_uuid_for(path: Path) -> str:
+    """Sub-agent JSONLs live at <project>/<parent-session-uuid>/subagents/agent-*.jsonl
+    and must roll up into the parent session. Top-level files use their own stem.
+    """
+    if path.parent.name == "subagents":
+        return path.parent.parent.name
+    return path.stem
+
+
 def parse_file(path: Path, *, start_offset: int = 0) -> tuple[ParsedFile, int]:
     """Parse from byte offset; returns (parsed, new_offset).
 
     new_offset is the byte position AFTER the last fully-parsed line. If a
     trailing partial line exists, we stop before it so the next run picks it up.
     """
-    session_uuid = path.stem
+    session_uuid = _session_uuid_for(path)
     session_id = f"claude:{session_uuid}"
     meta = SessionMeta(
         session_id=session_id,
@@ -244,4 +253,7 @@ def parse_file(path: Path, *, start_offset: int = 0) -> tuple[ParsedFile, int]:
 def discover_files() -> list[Path]:
     if not CLAUDE_ROOT.exists():
         return []
-    return sorted(CLAUDE_ROOT.glob("*/*.jsonl"))
+    top = CLAUDE_ROOT.glob("*/*.jsonl")
+    # Sub-agent (Task tool) sessions are written to <project>/<sessionId>/subagents/agent-*.jsonl.
+    sub = CLAUDE_ROOT.glob("*/*/subagents/agent-*.jsonl")
+    return sorted({*top, *sub})