LockSmith: IBM Bob fixes locking DB migrations

Problem. Database schema migrations ship through the same pull-request review as application code, but their risk is invisible in a diff. On PostgreSQL, a one-line CREATE INDEX holds a ShareLock that blocks every write for the whole index build; ALTER COLUMN … TYPE takes an AccessExclusiveLock and rewrites the table; a column rename is instant but breaks every running app instance that still uses the old name; and any heavy DDL without lock_timeout can queue behind one slow query and freeze all traffic behind it. Catching this requires lock-semantics expertise and table-size arithmetic most reviewers don't carry in their heads. Misses cause outages; the safe expand → backfill → contract rewrite costs a senior engineer hours per migration. Solution. LockSmith turns that review into a measured, automated gate — and hands the fix to IBM Bob. 1. Detect: 12 deterministic rules (LS001–LS012) over parsed SQL: non-concurrent indexes, NOT NULL adds, volatile defaults, type changes, SET NOT NULL, validated FK/CHECK constraints, renames/drops still referenced by application code, missing lock_timeout, CONCURRENTLY inside transactions, un-batched backfills. 2. Prove: every statement is replayed in an in-process PostgreSQL (PGlite). LockSmith reads pg_locks for the lock actually taken and compares relfilenode to detect table rewrites — evidence, not guesses. 3. Impact: declared production table sizes turn locks into "≈N seconds, ≈M writes blocked". 4. Rewrite with IBM Bob: the repo ships a custom Bob mode (Migration Surgeon), a Postgres lock reference Bob reads, and a lock-audit skill. Bob runs the gate, spawns one subagent per flagged migration in parallel, rewrites each into safe ordered files (concurrent indexes, NOT VALID + VALIDATE constraints, batched backfills, lock timeouts, dual-write app code for renames), then re-runs the gate on its own output. 5. Gate: the CLI exits non-zero while any critical finding remains, so CI blocks unsafe deploys. Target users: backend and platform engineers, reviewers and SREs at teams running PostgreSQL. They interact through the CLI in CI, the web report (per-migration lock evidence and impact), the paste-a-migration analyzer, and Bob IDE for the rewrite. Result on the demo repo (fictional e-commerce app, 8 pending migrations, orders = 42M rows): gate FAIL, risk 100 → after Bob's rewrite gate PASS, risk 0, with 6 dangerous migrations replaced by 13 safe, ordered files and the app code updated for dual-writes. What makes it different: the AI is not trusted — it is verified. A deterministic engine with real Postgres lock measurements judges; IBM Bob does the tedious, judgement-heavy surgery, in parallel, and must pass the same gate.