chore: commit remaining workspace updates

include AGENTS guidance updates, plan doc replacements, and utility script changes left in working tree

backend/AGENTS.md

@@ -103,6 +103,25 @@ Use `schemas / repository / service` pattern:
 - Raw SQL (policies, triggers, functions) → `op.execute()`
 - Migrations must be reversible; no reliance on generated IDs
 
+### Enum Storage Convention
+**Store enum names (strings), not integer values.**
+
+- Use `VARCHAR(20)` + `CHECK` constraint in database
+- Use Python `Enum` class with `str` base in code
+- Benefits: debugging readability, easy to add new values without data migration, ORM-friendly
+
+```python
+# Correct
+class AgentType(str, Enum):
+    INTENT_RECOGNITION = "INTENT_RECOGNITION"
+    TASK_EXECUTION = "TASK_EXECUTION"
+    RESULT_REPORTING = "RESULT_REPORTING"
+
+# Migration
+ALTER TABLE user_agents ADD CONSTRAINT chk_agent_type 
+  CHECK (agent_type IN ('INTENT_RECOGNITION', 'TASK_EXECUTION', 'RESULT_REPORTING'));
+```
+
 ### RLS Guidance
 - Backend does not rely on RLS for correctness (uses service_role), but RLS is mandatory as a defensive boundary for tables in PostgREST-exposed schemas.
 - **Mandatory default**: any new business table in `public` must enable RLS in the same Alembic migration.