fix(state): repair FTS5 delete trigger and add v11 migration for tool-call indexing

Follow-up on top of the cherry-picked contributor commit for #16751:

1. Delete triggers: the original PR switched FTS5 from external to inline
   content mode and concatenated content || tool_name || tool_calls in
   the insert/update triggers, but left the delete triggers passing
   old.content to the FTS5 delete-command. FTS5 inline delete requires
   the content to match what was stored, so every DELETE on messages
   raised 'SQL logic error'. Replaced with plain DELETE FROM ... WHERE
   rowid = old.id on all four delete paths (normal + trigram, delete +
   update-delete).

2. v11 migration: existing DBs have the old external-content FTS tables
   and triggers. Because CREATE VIRTUAL TABLE IF NOT EXISTS / CREATE
   TRIGGER IF NOT EXISTS skip when the objects already exist, upgraders
   would have kept the broken behavior forever. Bumped SCHEMA_VERSION
   to 11 and added a migration that drops both FTS tables + all 6 old
   triggers, recreates them via FTS_SQL / FTS_TRIGRAM_SQL, and backfills
   from messages using the same concatenation expression.

3. Regression tests: 6 new tests cover INSERT / UPDATE / DELETE paths
   for tool_name + tool_calls indexing plus the full v10 -> v11 upgrade
   path on a hand-built legacy DB.

hermes_state.py

@@ -33,7 +33,7 @@ T = TypeVar("T")
 
 DEFAULT_DB_PATH = get_hermes_home() / "state.db"
 
-SCHEMA_VERSION = 10
+SCHEMA_VERSION = 11
 
 SCHEMA_SQL = """
 CREATE TABLE IF NOT EXISTS schema_version (
@@ -113,11 +113,11 @@ CREATE TRIGGER IF NOT EXISTS messages_fts_insert AFTER INSERT ON messages BEGIN
 END;
 
 CREATE TRIGGER IF NOT EXISTS messages_fts_delete AFTER DELETE ON messages BEGIN
-    INSERT INTO messages_fts(messages_fts, rowid, content) VALUES('delete', old.id, old.content);
+    DELETE FROM messages_fts WHERE rowid = old.id;
 END;
 
 CREATE TRIGGER IF NOT EXISTS messages_fts_update AFTER UPDATE ON messages BEGIN
-    INSERT INTO messages_fts(messages_fts, rowid, content) VALUES('delete', old.id, old.content);
+    DELETE FROM messages_fts WHERE rowid = old.id;
     INSERT INTO messages_fts(rowid, content) VALUES (
         new.id,
         COALESCE(new.content, '') || ' ' || COALESCE(new.tool_name, '') || ' ' || COALESCE(new.tool_calls, '')
@@ -143,11 +143,11 @@ CREATE TRIGGER IF NOT EXISTS messages_fts_trigram_insert AFTER INSERT ON message
 END;
 
 CREATE TRIGGER IF NOT EXISTS messages_fts_trigram_delete AFTER DELETE ON messages BEGIN
-    INSERT INTO messages_fts_trigram(messages_fts_trigram, rowid, content) VALUES('delete', old.id, old.content);
+    DELETE FROM messages_fts_trigram WHERE rowid = old.id;
 END;
 
 CREATE TRIGGER IF NOT EXISTS messages_fts_trigram_update AFTER UPDATE ON messages BEGIN
-    INSERT INTO messages_fts_trigram(messages_fts_trigram, rowid, content) VALUES('delete', old.id, old.content);
+    DELETE FROM messages_fts_trigram WHERE rowid = old.id;
     INSERT INTO messages_fts_trigram(rowid, content) VALUES (
         new.id,
         COALESCE(new.content, '') || ' ' || COALESCE(new.tool_name, '') || ' ' || COALESCE(new.tool_calls, '')
@@ -436,6 +436,51 @@ class SessionDB:
                         "INSERT INTO messages_fts_trigram(rowid, content) "
                         "SELECT id, content FROM messages WHERE content IS NOT NULL"
                     )
+            if current_version < 11:
+                # v11: re-index FTS5 tables to cover tool_name + tool_calls and
+                # switch from external-content to inline mode. Existing DBs have
+                # old-schema FTS tables and triggers that IF NOT EXISTS won't
+                # overwrite, so we drop them explicitly and let the post-migration
+                # existence checks (below) recreate them from FTS_SQL /
+                # FTS_TRIGRAM_SQL, then backfill every message row. Fixes #16751.
+                for _trig in (
+                    "messages_fts_insert",
+                    "messages_fts_delete",
+                    "messages_fts_update",
+                    "messages_fts_trigram_insert",
+                    "messages_fts_trigram_delete",
+                    "messages_fts_trigram_update",
+                ):
+                    try:
+                        cursor.execute(f"DROP TRIGGER IF EXISTS {_trig}")
+                    except sqlite3.OperationalError:
+                        pass
+                for _tbl in ("messages_fts", "messages_fts_trigram"):
+                    try:
+                        cursor.execute(f"DROP TABLE IF EXISTS {_tbl}")
+                    except sqlite3.OperationalError:
+                        pass
+                # Recreate virtual tables + triggers with the new inline-mode
+                # schema that indexes content || tool_name || tool_calls.
+                cursor.executescript(FTS_SQL)
+                cursor.executescript(FTS_TRIGRAM_SQL)
+                # Backfill both indexes from every existing messages row.
+                cursor.execute(
+                    "INSERT INTO messages_fts(rowid, content) "
+                    "SELECT id, "
+                    "COALESCE(content, '') || ' ' || "
+                    "COALESCE(tool_name, '') || ' ' || "
+                    "COALESCE(tool_calls, '') "
+                    "FROM messages"
+                )
+                cursor.execute(
+                    "INSERT INTO messages_fts_trigram(rowid, content) "
+                    "SELECT id, "
+                    "COALESCE(content, '') || ' ' || "
+                    "COALESCE(tool_name, '') || ' ' || "
+                    "COALESCE(tool_calls, '') "
+                    "FROM messages"
+                )
             if current_version < SCHEMA_VERSION:
                 cursor.execute(
                     "UPDATE schema_version SET version = ?",