feat: add model_usage table and tracker methods

Adds model_usage schema, record_model_usage(), get_raw_model_stats(), and get_model_stats() to UsageTracker, with reset() support and 8 passing tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tracker.py

@@ -40,8 +40,17 @@ CREATE TABLE IF NOT EXISTS prompt_log (
     class_types TEXT NOT NULL
 );
 
+CREATE TABLE IF NOT EXISTS model_usage (
+    model_name TEXT PRIMARY KEY,
+    model_type TEXT NOT NULL,
+    count INTEGER NOT NULL DEFAULT 0,
+    first_seen TEXT NOT NULL,
+    last_seen TEXT NOT NULL
+);
+
 CREATE INDEX IF NOT EXISTS idx_node_usage_package ON node_usage(package);
 CREATE INDEX IF NOT EXISTS idx_prompt_log_timestamp ON prompt_log(timestamp);
+CREATE INDEX IF NOT EXISTS idx_model_usage_type ON model_usage(model_type);
 """
 
 
@@ -116,6 +125,46 @@ class UsageTracker:
             finally:
                 conn.close()
 
+    def record_model_usage(self, models):
+        """Record usage of model files from a single prompt.
+
+        models: list of (model_name, model_type) tuples
+        """
+        if not models:
+            return
+        now = datetime.now(timezone.utc).isoformat()
+        with self._lock:
+            self._ensure_db()
+            conn = self._connect()
+            try:
+                for model_name, model_type in models:
+                    conn.execute(
+                        """INSERT INTO model_usage (model_name, model_type, count, first_seen, last_seen)
+                           VALUES (?, ?, 1, ?, ?)
+                           ON CONFLICT(model_name) DO UPDATE SET
+                               count = count + 1,
+                               last_seen = excluded.last_seen""",
+                        (model_name, model_type, now, now),
+                    )
+                conn.commit()
+            finally:
+                conn.close()
+
+    def get_raw_model_stats(self):
+        """Return raw per-model usage rows from DB."""
+        with self._lock:
+            self._ensure_db()
+            conn = self._connect()
+            try:
+                conn.row_factory = sqlite3.Row
+                rows = conn.execute(
+                    "SELECT model_name, model_type, count, first_seen, last_seen "
+                    "FROM model_usage ORDER BY count DESC"
+                ).fetchall()
+                return [dict(r) for r in rows]
+            finally:
+                conn.close()
+
     def get_node_stats(self):
         """Return raw per-node usage data."""
         with self._lock:
@@ -216,6 +265,98 @@ class UsageTracker:
         result.sort(key=lambda p: p["total_executions"])
         return result
 
+    def get_model_stats(self, installed_by_type):
+        """Return per-type grouped model stats with tier classification.
+
+        installed_by_type: {model_type: [model_name, ...]} from ModelMapper
+        """
+        db_rows = self.get_raw_model_stats()
+        db_models = {r["model_name"]: r for r in db_rows}
+
+        now = datetime.now(timezone.utc)
+        one_month_ago = (now - timedelta(days=30)).isoformat()
+        two_months_ago = (now - timedelta(days=60)).isoformat()
+        tracking_start = self._get_first_prompt_time()
+
+        STATUS_ORDER = {
+            "safe_to_remove": 0,
+            "consider_removing": 1,
+            "unused_new": 2,
+            "used": 3,
+            "uninstalled": 4,
+        }
+
+        result_by_type = {}
+
+        # Process installed models
+        for model_type, filenames in installed_by_type.items():
+            entries = []
+            for model_name in filenames:
+                if model_name in db_models:
+                    row = db_models[model_name]
+                    last_seen = row["last_seen"]
+                    if last_seen < two_months_ago:
+                        status = "safe_to_remove"
+                    elif last_seen < one_month_ago:
+                        status = "consider_removing"
+                    else:
+                        status = "used"
+                    entry = {
+                        "model_name": model_name,
+                        "model_type": model_type,
+                        "count": row["count"],
+                        "first_seen": row["first_seen"],
+                        "last_seen": last_seen,
+                        "installed": True,
+                        "status": status,
+                    }
+                else:
+                    if tracking_start is None:
+                        status = "unused_new"
+                    elif tracking_start < two_months_ago:
+                        status = "safe_to_remove"
+                    elif tracking_start < one_month_ago:
+                        status = "consider_removing"
+                    else:
+                        status = "unused_new"
+                    entry = {
+                        "model_name": model_name,
+                        "model_type": model_type,
+                        "count": 0,
+                        "first_seen": None,
+                        "last_seen": None,
+                        "installed": True,
+                        "status": status,
+                    }
+                entries.append(entry)
+            result_by_type[model_type] = entries
+
+        # Add uninstalled (in DB but not on disk)
+        installed_names = {
+            name for names in installed_by_type.values() for name in names
+        }
+        for model_name, row in db_models.items():
+            if model_name not in installed_names:
+                model_type = row["model_type"]
+                result_by_type.setdefault(model_type, []).append({
+                    "model_name": model_name,
+                    "model_type": model_type,
+                    "count": row["count"],
+                    "first_seen": row["first_seen"],
+                    "last_seen": row["last_seen"],
+                    "installed": False,
+                    "status": "uninstalled",
+                })
+
+        # Sort each type's models by status tier then name
+        result = []
+        for model_type in sorted(result_by_type):
+            models = result_by_type[model_type]
+            models.sort(key=lambda m: (STATUS_ORDER.get(m["status"], 5), m["model_name"]))
+            result.append({"model_type": model_type, "models": models})
+
+        return result
+
     def _get_first_prompt_time(self):
         """Return the timestamp of the earliest recorded prompt, or None."""
         with self._lock:
@@ -237,6 +378,7 @@ class UsageTracker:
             try:
                 conn.execute("DELETE FROM node_usage")
                 conn.execute("DELETE FROM prompt_log")
+                conn.execute("DELETE FROM model_usage")
                 conn.commit()
             finally:
                 conn.close()