feat(metrics): instrument per-stage and pipeline_total latency; count pipeline_runs_total (ok/error/ambiguous)

feat(metrics): integrate Prometheus; expose /metrics; instrument safety & verifier

refactor(core): DI-ready Pipeline; add registry + YAML factory + typed trace/result

fix(verifier): robust aggregate detection and projection-level semantic check

feat(trace): standardize StageTrace (add summary) and coerce duration_ms to int at API boundary

refactor(core): DI-ready Pipeline; add registry + YAML factory + typed trace/result

refactor(core): DI-ready Pipeline; add registry + YAML factory + typed trace/result

test-mode: stub runner in router; factory stubs accept positional calls

fix(router): lazy pipeline build for pytest; fix(factory): stubs accept positional/keyword args

refactor(core): DI-ready Pipeline; add registry + YAML factory + typed trace/result

refactor(core): DI-ready Pipeline; add registry + YAML factory + typed trace/result

refactor(core): DI-ready Pipeline; add registry + YAML factory + typed trace/result

refactor(core): DI-ready Pipeline; add registry + YAML factory + typed trace/result

fix(pipeline): allow optional schema_preview in run() for better typing compatibility with benchmarks

feat(safety): harden SQL validation (multi-CTE, recursive WITH, unicode normalization, precise errors, EXPLAIN gate)

tests green: fix pipeline reference in router and adjust verifier logic for aggregation & error handling

fix(pipeline): align backend-frontend schema and stabilize SQL flow

build(mypy): fix type errors and add safety guards for None values

style: fix Ruff issues (F401 unused import, E741 ambiguous var)

style: format code with ruff

refactor: unify pipeline output via FinalResult model

Fix some typo

style: format code with ruff

style: format code with ruff

init: NL2SQL Copilot base with API and Dockerfile