Expand/migrate/contract check (WS-P task 12): a new DROP TABLE, DROP COLUMN or rename of a real table in server/ fails the suite until test/fixtures/destructive-migrations.json lists it with its dated contract step; the five known table rebuilds are recorded

ddiff --git a/test/destructive-migrations.test.js b/test/destructive-migrations.test.js
nnew file mode 100644
iindex 00000000..8e7c94a7
---- /dev/null
++++ b/test/destructive-migrations.test.js
@@@ -0,0 +1,45 @@
++'use strict';
++/**
++ * Expand/migrate/contract (roadmap WS-P task 12; ADR-028 in OpenVibe.Contracts): a schema change that
++ * removes or renames something (DROP TABLE, DROP COLUMN, RENAME COLUMN, RENAME TO) breaks the release
++ * production may roll back to, so it is only allowed as a contract step: listed in
++ * test/fixtures/destructive-migrations.json with the dated plan entry that runs it after a release where
++ * nothing reads the old shape. Everything else is additive (CREATE … IF NOT EXISTS, ADD COLUMN, new
++ * tables) and test/rollback-newer-writes.test.js proves the older release still works on it.
++ */
++const assert = require('assert');
++const fs = require('fs');
++const path = require('path');
++
++const ROOT = path.join(__dirname, '..');
++const RE = /\b(DROP\s+TABLE(?:\s+IF\s+EXISTS)?\s+[`"]?([A-Za-z_][A-Za-z0-9_]*)|DROP\s+COLUMN\s+[`"]?([A-Za-z_][A-Za-z0-9_]*)|RENAME\s+COLUMN\s+[`"]?([A-Za-z_][A-Za-z0-9_]*)|RENAME\s+TO\s+[`"]?([A-Za-z_][A-Za-z0-9_]*))/gi;
++const TEMP = /^_|_new$|_old$|_tmp$|^tmp_/i;
++
++const found = new Map();   // "file|STATEMENT" -> count
++(function walk(dir) {
++    for (const e of fs.readdirSync(dir, { withFileTypes: true })) {
++        const p = path.join(dir, e.name);
++        if (e.isDirectory()) { if (e.name !== 'node_modules') walk(p); continue; }
++        if (!p.endsWith('.js')) continue;
++        const src = fs.readFileSync(p, 'utf8');
++        let m;
++        while ((m = RE.exec(src))) {
++            const name = m[2] || m[3] || m[4] || m[5];
++            if (TEMP.test(name) || /\$\{/.test(name)) continue;
++            const statement = m[1].replace(/[`"]/g, '').replace(/\s+/g, ' ').toUpperCase();
++            const key = `${path.relative(ROOT, p)}|${statement}`;
++            found.set(key, (found.get(key) || 0) + 1);
++        }
++    }
++})(path.join(ROOT, 'server'));
++
++const allow = JSON.parse(fs.readFileSync(path.join(__dirname, 'fixtures', 'destructive-migrations.json'), 'utf8')).allowed;
++const allowed = new Map(allow.map((a) => [`${a.file}|${a.statement}`, a]));
++const unlisted = [];
++for (const [key, n] of found) {
++    const a = allowed.get(key);
++    if (!a || n > a.count) unlisted.push(`${key.replace('|', ': ')} ×${n}`);
++}
++assert.deepStrictEqual(unlisted, [], 'a destructive schema change needs its contract step in test/fixtures/destructive-migrations.json');
++for (const a of allow) assert.ok(a.contract && a.contract.length > 10, `${a.statement}: say which contract step runs it`);
++console.log(`destructive migrations: ${found.size} known statement(s), each with its contract step; nothing new`);
ddiff --git a/test/fixtures/destructive-migrations.json b/test/fixtures/destructive-migrations.json
nnew file mode 100644
iindex 00000000..a60aac8a
---- /dev/null
++++ b/test/fixtures/destructive-migrations.json
@@@ -0,0 +1,15 @@
++{
++  "_about": "Destructive schema statements in server/ that are known and accounted for (roadmap WS-P task 12, expand/migrate/contract). A new DROP TABLE, DROP COLUMN, RENAME COLUMN or RENAME TO of a real table fails test/destructive-migrations.test.js until it is listed here with its contract step: the dated plan entry (section 10) that runs it after a release where nothing reads the old shape, with a backup. Temporary tables (_x, x_new, x_old, x_tmp) are not counted.",
++  "allowed": [
++    { "file": "server/db/database.js", "statement": "DROP TABLE CHAT_MESSAGES", "count": 2, "contract": "pre-ADR table rebuild (copy every column into chat_messages_new, drop, rename); guarded, one-time" },
++    { "file": "server/db/database.js", "statement": "RENAME TO CHAT_MESSAGES", "count": 2, "contract": "the same rebuild" },
++    { "file": "server/db/database.js", "statement": "DROP TABLE ROBOTSTREAMER_INTEGRATIONS", "count": 1, "contract": "pre-ADR table rebuild keeping every row; guarded, one-time" },
++    { "file": "server/db/database.js", "statement": "RENAME TO ROBOTSTREAMER_INTEGRATIONS", "count": 1, "contract": "the same rebuild" },
++    { "file": "server/db/database.js", "statement": "DROP TABLE EMOTES", "count": 1, "contract": "pre-ADR table rebuild keeping every row; guarded, one-time" },
++    { "file": "server/db/database.js", "statement": "RENAME TO EMOTES", "count": 1, "contract": "the same rebuild" },
++    { "file": "server/db/database.js", "statement": "DROP TABLE CHANNEL_SOUNDS", "count": 1, "contract": "pre-ADR table rebuild keeping every row; guarded, one-time" },
++    { "file": "server/db/database.js", "statement": "RENAME TO CHANNEL_SOUNDS", "count": 1, "contract": "the same rebuild" },
++    { "file": "server/db/database.js", "statement": "DROP TABLE STREAM_CONTROLS", "count": 1, "contract": "pre-ADR table rebuild keeping every row; guarded, one-time" },
++    { "file": "server/db/database.js", "statement": "RENAME TO STREAM_CONTROLS", "count": 1, "contract": "the same rebuild" }
++  ]
++}