app/db/migrations/026_community_pseudonyms.sql

@@ -0,0 +1,21 @@
+-- 026_community_pseudonyms.sql
+-- Per-user pseudonym store: maps the user's chosen community display name
+-- to their Directus user ID. This table lives in per-user kiwi.db only.
+-- It is NEVER replicated to the community PostgreSQL — pseudonym isolation is by design.
+--
+-- A user may have one active pseudonym. Old pseudonyms are retained for reference
+-- (posts published under them keep their pseudonym attribution) but only one is
+-- flagged as current (is_current = 1).
+
+CREATE TABLE IF NOT EXISTS community_pseudonyms (
+    id              INTEGER PRIMARY KEY AUTOINCREMENT,
+    pseudonym       TEXT NOT NULL,
+    directus_user_id TEXT NOT NULL,
+    is_current      INTEGER NOT NULL DEFAULT 1 CHECK (is_current IN (0, 1)),
+    created_at      TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
+-- Only one pseudonym can be current at a time per user
+CREATE UNIQUE INDEX IF NOT EXISTS idx_community_pseudonyms_current
+    ON community_pseudonyms (directus_user_id)
+    WHERE is_current = 1;

tests/db/test_migration_026.py

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+# tests/db/test_migration_026.py
+import pytest
+from pathlib import Path
+from app.db.store import Store
+
+
+def test_migration_026_adds_community_pseudonyms(tmp_path):
+    """Migration 026 adds community_pseudonyms table to per-user kiwi.db."""
+    store = Store(tmp_path / "test.db")
+    cur = store.conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name='community_pseudonyms'"
+    )
+    assert cur.fetchone() is not None, "community_pseudonyms table must exist after migrations"
+    store.close()
+
+
+def test_migration_026_unique_index_enforces_single_current_pseudonym(tmp_path):
+    """Only one is_current=1 pseudonym per directus_user_id is allowed."""
+    store = Store(tmp_path / "test.db")
+    store.conn.execute(
+        "INSERT INTO community_pseudonyms (pseudonym, directus_user_id, is_current) VALUES (?, ?, 1)",
+        ("PastaWitch", "user-abc-123"),
+    )
+    store.conn.commit()
+
+    import sqlite3
+    with pytest.raises(sqlite3.IntegrityError):
+        store.conn.execute(
+            "INSERT INTO community_pseudonyms (pseudonym, directus_user_id, is_current) VALUES (?, ?, 1)",
+            ("NoodleNinja", "user-abc-123"),
+        )
+        store.conn.commit()
+
+    store.close()
+
+
+def test_migration_026_allows_historical_pseudonyms(tmp_path):
+    """Multiple is_current=0 pseudonyms are allowed for the same user."""
+    store = Store(tmp_path / "test.db")
+    store.conn.executemany(
+        "INSERT INTO community_pseudonyms (pseudonym, directus_user_id, is_current) VALUES (?, ?, 0)",
+        [("OldName1", "user-abc-123"), ("OldName2", "user-abc-123")],
+    )
+    store.conn.commit()
+    cur = store.conn.execute(
+        "SELECT COUNT(*) FROM community_pseudonyms WHERE directus_user_id='user-abc-123'"
+    )
+    assert cur.fetchone()[0] == 2
+    store.close()