ADR-0014: Turborepo + Bun workspaces over NX#

Date: 2026-06-18
Status: accepted
Deciders: Project owner (@...)

Context#

Recorded retroactively. HashHive is a monorepo (@hashhive/backend,
@hashhive/frontend, @hashhive/shared). The project migrated off an
earlier NX-based setup as part of the broader stack change
(Express→Hono, Next.js→Vite+React, MongoDB→PostgreSQL+Drizzle, Jest→bun).
Monorepo tooling touches every build, test, and lint command and the CI
pipeline.

Decision#

Use Turborepo for task orchestration over Bun workspaces. Bun is the runtime
and package manager; Turborepo provides the task graph and caching. NX and
Lerna are not used.

Alternatives Considered#

Alternative 1: NX (prior tooling)#

• Pros: powerful generators, mature task graph.
• Cons: heavier conceptual surface and config than this project needs;
  was being shed along with the rest of the legacy stack.
• Why not: Turborepo + Bun is lighter and aligns with the Bun-native
  toolchain.

Alternative 2: Lerna#

• Why not: largely superseded for task running/caching; explicitly not
  chosen.

Alternative 3: Plain Bun workspaces, no orchestrator#

• Pros: zero extra tooling.
• Why not: loses cross-package task caching and the dependency-aware task
  graph Turborepo provides.

Consequences#

Positive#

• Light, Bun-native monorepo with cached, dependency-aware task running
  (turbo run build|test|lint|type-check).
• Consistent local and CI command surface (the just recipes wrap it).

Negative#

• Turborepo remote-cache features are unused (disabled); caching is local
  only.

Risks#

• The Tech Plan still lists the older tooling and is stale; ARCHITECTURE.md is
  authoritative.