docs: every write example states its status; security explains sensitive columns and how to serve one

docs/writes.md

@@ -56,6 +56,8 @@ POST /tags
 [{ "id": 7, "name": "a" }, { "name": "b" }]
 ```
 
+Answer: 400
+
 ```json
 { "error": "mixed_columns" }
 ```
@@ -68,6 +70,8 @@ POST /todos
 { "name": "book dentist", "status": "open", "pinned": false }
 ```
 
+Answer: 400
+
 ```json
 { "error": "not_writable", "message": "pinned" }
 ```
@@ -101,6 +105,8 @@ A row still referenced by another is not deleted:
 DELETE /tags/3
 ```
 
+Answer: 409
+
 ```json
 { "error": "still_referenced" }
 ```
@@ -109,6 +115,8 @@ DELETE /tags/3
 DELETE /todos/1
 ```
 
+Answer: 405
+
 ```json
 { "error": "method_not_allowed" }
 ```
@@ -130,6 +138,8 @@ Answer: 200
 DELETE /steps
 ```
 
+Answer: 400
+
 ```json
 { "error": "filter_required" }
 ```
@@ -144,6 +154,8 @@ POST /tags
 { "id": 1, "name": "duplicate key" }
 ```
 
+Answer: 409
+
 ```json
 { "error": "duplicate" }
 ```
@@ -154,6 +166,8 @@ POST /steps
 { "id": 9, "title": "Call the clinic", "todo_id": 99, "priority": 1, "due_on": "2026-04-01" }
 ```
 
+Answer: 409
+
 ```json
 { "error": "reference_missing" }
 ```
@@ -170,6 +184,8 @@ POST /todos/3/complete
 { "note": "bought a new one" }
 ```
 
+Answer: 200
+
 ```json
 3
 ```
@@ -180,6 +196,8 @@ A function returning a set answers an array of its rows. File taxes belongs to A
 POST /tags/home/todos
 ```
 
+Answer: 200
+
 ```json
 [
   { "id": 2, "name": "file taxes", "status": "open", "owner_id": 1, "estimate": 1, "pinned": true, "created_at": "2026-01-05T09:30:00+00:00" },
@@ -193,6 +211,8 @@ POST /todos/3/complete
 { "why": "too busy" }
 ```
 
+Answer: 400
+
 ```json
 { "error": "unknown_argument", "message": "why" }
 ```