feat: migrate one-time and signup tokens to an actor (#1611)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/resources/migrations/postgres/20260723000000_actor_tokens.down.sql

@@ -0,0 +1,56 @@
+-- Recreate the one_time_access_tokens table with the schema it had before it was dropped.
+CREATE TABLE one_time_access_tokens
+(
+    id           UUID NOT NULL PRIMARY KEY,
+    created_at   TIMESTAMPTZ,
+    token        VARCHAR(255) NOT NULL UNIQUE,
+    expires_at   TIMESTAMPTZ NOT NULL,
+    user_id      UUID NOT NULL REFERENCES users ON DELETE CASCADE,
+    device_token VARCHAR(16)
+);
+CREATE INDEX IF NOT EXISTS idx_one_time_access_tokens_expires_at ON one_time_access_tokens (expires_at);
+
+-- Recreate the signup token tables with the schema they had before they were frozen.
+CREATE TABLE signup_tokens (
+    id UUID NOT NULL PRIMARY KEY,
+    created_at TIMESTAMPTZ NOT NULL,
+    token VARCHAR(255) NOT NULL UNIQUE,
+    expires_at TIMESTAMPTZ NOT NULL,
+    usage_limit INTEGER NOT NULL DEFAULT 1,
+    usage_count INTEGER NOT NULL DEFAULT 0
+);
+CREATE INDEX idx_signup_tokens_token ON signup_tokens(token);
+CREATE INDEX idx_signup_tokens_expires_at ON signup_tokens(expires_at);
+
+CREATE TABLE signup_tokens_user_groups
+(
+    signup_token_id UUID NOT NULL,
+    user_group_id   UUID NOT NULL,
+    PRIMARY KEY (signup_token_id, user_group_id),
+    FOREIGN KEY (signup_token_id) REFERENCES signup_tokens (id) ON DELETE CASCADE,
+    FOREIGN KEY (user_group_id) REFERENCES user_groups (id) ON DELETE CASCADE
+);
+
+-- Restore the signup tokens from the frozen JSON document stored in the "kv" table.
+-- json_array_elements expands the JSON array into one row per token object.
+INSERT INTO signup_tokens (id, created_at, token, expires_at, usage_limit, usage_count)
+SELECT
+    (e ->> 'id')::uuid,
+    to_timestamp((e ->> 'createdAt')::bigint),
+    e ->> 'token',
+    to_timestamp((e ->> 'expiresAt')::bigint),
+    (e ->> 'usageLimit')::int,
+    (e ->> 'usageCount')::int
+FROM kv, json_array_elements(kv."value"::json) AS e
+WHERE kv."key" = 'signup_tokens_migrated';
+
+-- Restore the token/user-group associations, expanding each token's nested userGroupIds array.
+INSERT INTO signup_tokens_user_groups (signup_token_id, user_group_id)
+SELECT
+    (e ->> 'id')::uuid,
+    g.value::uuid
+FROM kv, json_array_elements(kv."value"::json) AS e, json_array_elements_text(e -> 'userGroupIds') AS g
+WHERE kv."key" = 'signup_tokens_migrated';
+
+-- Remove the frozen signup tokens from the "kv" table.
+DELETE FROM kv WHERE "key" = 'signup_tokens_migrated';

backend/resources/migrations/postgres/20260723000000_actor_tokens.up.sql

@@ -0,0 +1,28 @@
+-- One-time access tokens are now stored in the actor state store, so the table is no longer needed.
+DROP TABLE IF EXISTS one_time_access_tokens;
+
+-- Freeze the signup tokens.
+-- Encode every signup token (with its user group IDs) as a single JSON array and store it in the "kv" table under the "signup_tokens_migrated" key, so the singleton signup token actor can seed its state from it on first startup.
+-- The "HAVING count(*) > 0" clause ensures nothing is written to the "kv" table when there are no signup tokens.
+-- Timestamps are stored as Unix seconds so the frozen format is identical across databases.
+INSERT INTO kv ("key", "value")
+SELECT 'signup_tokens_migrated', json_agg(
+    json_build_object(
+        'id', st.id,
+        'token', st.token,
+        'expiresAt', extract(epoch FROM st.expires_at)::bigint,
+        'usageLimit', st.usage_limit,
+        'usageCount', st.usage_count,
+        'createdAt', extract(epoch FROM st.created_at)::bigint,
+        'userGroupIds', COALESCE(
+            (SELECT json_agg(stug.user_group_id) FROM signup_tokens_user_groups stug WHERE stug.signup_token_id = st.id),
+            '[]'::json
+        )
+    )
+)::text
+FROM signup_tokens st
+HAVING count(*) > 0;
+
+-- Drop the now-frozen signup token tables.
+DROP TABLE signup_tokens_user_groups;
+DROP TABLE signup_tokens;