federation refinement

crates/adapters/sqlite/migrations/0004_username.sql

@@ -0,0 +1,33 @@
+-- Recreate users table with username column
+CREATE TABLE users_new (
+    id           TEXT PRIMARY KEY,
+    email        TEXT NOT NULL UNIQUE,
+    username     TEXT NOT NULL UNIQUE,
+    password_hash TEXT NOT NULL,
+    created_at   TEXT NOT NULL
+);
+
+-- Derive username from email local part, sanitising common invalid chars.
+-- REPLACE chains handle the most common email chars. The NOT NULL UNIQUE
+-- constraint will surface any remaining collision (rare for personal instances).
+INSERT INTO users_new (id, email, username, password_hash, created_at)
+SELECT
+    id,
+    email,
+    CASE
+        WHEN LENGTH(REPLACE(REPLACE(REPLACE(REPLACE(
+            LOWER(SUBSTR(email, 1, INSTR(email, '@') - 1)),
+            '.', '_'), '+', '_'), '-', '-'), ' ', '_')) < 2
+        THEN REPLACE(REPLACE(REPLACE(REPLACE(
+            LOWER(SUBSTR(email, 1, INSTR(email, '@') - 1)),
+            '.', '_'), '+', '_'), '-', '-'), ' ', '_') || '_x'
+        ELSE REPLACE(REPLACE(REPLACE(REPLACE(
+            LOWER(SUBSTR(email, 1, INSTR(email, '@') - 1)),
+            '.', '_'), '+', '_'), '-', '-'), ' ', '_')
+    END,
+    password_hash,
+    created_at
+FROM users;
+
+DROP TABLE users;
+ALTER TABLE users_new RENAME TO users;