feat(community): migration 028 — community_pseudonyms table in per-user kiwi.db

app/db/migrations/028_community_pseudonyms.sql

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+-- 028_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_migrations.py

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+import pytest
+from pathlib import Path
+from app.db.store import Store
+
+
+@pytest.fixture
+def tmp_db(tmp_path: Path) -> Path:
+    return tmp_path / "test.db"
+
+
+def test_migration_028_adds_community_pseudonyms(tmp_db):
+    """Migration 028 adds community_pseudonyms table to per-user kiwi.db."""
+    store = Store(tmp_db)
+    cur = store.conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name='community_pseudonyms'"
+    )
+    assert cur.fetchone() is not None
+    store.close()