Glossary
May 9, 2026 · View on GitHub
Bernstein-specific terms used throughout the codebase and documentation.
Bulletin Board
An append-only communication channel where agents post findings, blockers, and status updates visible to all other agents in the same run. Implemented in src/bernstein/core/bulletin.py.
CAS Store
A content-addressed store that deduplicates artifact content by SHA-256 hash. When two agents emit identical output (e.g., the same generated file), only one copy is persisted on disk and both runs reference the same blob. Backs the workspace-sync optimization in bridges/r2_sync.py and the local artifact pool. Implemented in src/bernstein/core/persistence/cas_store.py.
Cascade Router
The cost-aware, bandit-driven model escalator that picks the cheapest viable Claude tier for a given task and escalates on failure. Default chain is haiku -> sonnet -> opus; high-stakes roles (manager, architect, security) start at sonnet -> opus. Escalation triggers on (1) explicit task failure, (2) janitor verification rejection, or (3) low-confidence regex scan over the agent's last 2000 chars (e.g., "I'm not sure", "TODO: escalate"). Per-(role, model) success rates persist to .sdd/metrics/bandit_state.json; chain reports to .sdd/metrics/cascade_chains.jsonl. Implemented in src/bernstein/core/routing/cascade_router.py.
Cross-Model Verifier
An optional quality-pipeline component that re-runs a completed task on a second model and compares outputs to detect plausible-but-wrong code. Off by default; doubles cost for the verified subset. Used in conjunction with the janitor when correctness matters more than budget. Implemented in src/bernstein/core/quality/cross_model_verifier.py.
Caching Adapter
A wrapper adapter that intercepts spawn calls to enable prompt prefix deduplication and response reuse. Delegates actual execution to the underlying adapter while tracking cache break events across agents. Implemented in src/bernstein/adapters/caching_adapter.py.
Circuit Breaker
A state machine (CLOSED → OPEN → HALF_OPEN) that prevents infinite retry loops when an agent or provider repeatedly fails. After N consecutive failures, the breaker "opens" and blocks further attempts until a recovery probe succeeds. Implemented in src/bernstein/core/circuit_breaker.py.
Conformance Harness
A testing framework that replays golden transcripts against live adapters (with mocked subprocesses) to detect protocol drift and adapter regressions. Implemented in src/bernstein/adapters/conformance.py.
Debug Bundle
A diagnostic archive containing logs, state files, configuration, and runtime metadata collected via bernstein debug for troubleshooting. Implemented in src/bernstein/core/observability/debug_bundle.py.
Drain
Stop accepting new work and wait for active agents to finish their current tasks. Used during graceful shutdown or rolling upgrades. Implemented in src/bernstein/core/drain.py.
Fast Path
An optimization that skips full planning for simple, single-file tasks. Instead of decomposing into subtasks, the agent handles the work directly. Implemented in src/bernstein/core/fast_path.py.
Lethal Trifecta
The structural shape of a prompt-injection exfiltration: an execution path
that simultaneously accesses private data, ingests untrusted input,
and can externally communicate. Bernstein's capability matrix tags
every tool/MCP server/adapter with which of the three it carries and
refuses any spawn whose tool chain unions all three. Engine-layer check,
runs in the spawner before any agent process starts, bypass-immune in the
policy graph. See docs/security/lethal-trifecta.md
for the threat model and default capability table; implementation in
src/bernstein/core/security/capability_matrix.py.
Janitor
The verification system that checks whether an agent's work is correct — runs lint, type-checks, tests, and other quality gates before accepting work. Distinct from the Cross-Model Verifier (which double-checks output by re-running on a second model) and the Reviewer (which performs LLM-based review). Implemented in src/bernstein/core/quality/janitor.py.
The janitor also has a maintenance role: it periodically reaps orphaned worktrees and stale agent state. The cleanup interval is governed by janitor.worktree_cleanup_interval_s and janitor.max_orphan_age_s in bernstein.yaml.
Env Isolation
The process of filtering environment variables before spawning agents to prevent credential leakage. Only variables required for the agent's function are passed through. Implemented in src/bernstein/adapters/env_isolation.py.
Nudge
A message sent to a stalled agent to prompt it to continue working. Part of the heartbeat and idle detection system. Implemented in src/bernstein/core/nudge_manager.py.
Peak-Hour Router
A cost-aware scheduling component that routes tasks to cheaper providers or defers non-urgent work during peak pricing hours. Implemented in src/bernstein/core/cost/peak_hour_router.py.
Protocol Negotiation
Runtime handshake that determines which protocol version (MCP, A2A, ACP) a connected client or agent supports, ensuring compatibility is verified at connection time rather than at failure time. Implemented in src/bernstein/core/protocols/protocol_negotiation.py.
Quality Gate
Automated checks (lint, type-check, tests, coverage) that must pass before work is accepted or merged. Gates run in sequence and any failure blocks the pipeline. Implemented in src/bernstein/core/quality_gates.py.
Reap
Killing or collecting agents that have exceeded their timeout or become unresponsive. Part of the agent lifecycle management. Implemented in src/bernstein/core/agent_lifecycle.py.
SDD
Software-Defined Development — the .sdd/ directory where all runtime state lives: worktrees, sessions, task logs, and agent data. Initialized in src/bernstein/core/bootstrap.py.
Schema Registry
A versioned catalog of message schemas for MCP, A2A, and ACP protocols, enabling forward/backward compatibility checks and migration paths. Implemented in src/bernstein/core/protocols/schema_registry.py.
Skills Injector
Writes role-specific Claude Code skills (.claude/skills/*.md) into the agent's worktree before spawn. This moves orchestration boilerplate into skills that survive context compaction, reducing prompt size by 30-40%. Implemented in src/bernstein/adapters/skills_injector.py.
Spawn
Creating a short-lived agent process for a task batch. The spawner handles prompt construction, worktree setup, and process management. Implemented in src/bernstein/core/spawner.py.
Tick
The orchestrator's polling cycle (approximately 3 seconds). Each tick fetches pending tasks, spawns agents, checks heartbeats, and evaluates quality gates. Implemented in src/bernstein/core/orchestrator.py.
WAL
Write-Ahead Log -- the durable journal of state transitions used for crash recovery. Every task or agent state change is appended to .sdd/wal/wal.jsonl before being applied to in-memory state. On startup, wal_replay.py walks any incomplete entries and re-applies them so the orchestrator picks up exactly where it stopped. Combined with the CAS Store and Merkle integrity hashing, this gives Bernstein process-crash, host-reboot, and partial-merge survival without an external database. Implemented in src/bernstein/core/persistence/wal.py (writer) and src/bernstein/core/persistence/wal_replay.py (replay). The fsync policy is configurable via wal.fsync in bernstein.yaml.
Warm Pool
A pre-spawn pool of agent processes kept idle so newly-claimed tasks see lower spawn latency. Instead of fork-and-init on every task, the orchestrator hands a queued process its prompt and the agent is already past CLI startup costs. Sized for typical concurrency; can be disabled if RAM is constrained (each pre-spawned process holds its baseline working set). Implemented in src/bernstein/core/agents/warm_pool.py and src/bernstein/core/agents/spawner_warm_pool.py.
Worktree
An isolated git worktree per agent, located at .sdd/worktrees/{session_id}. Each agent works in its own branch without interfering with others. Implemented in src/bernstein/core/worktree.py.
ACP Bridge
The ACP (Agent Client Protocol) adapter that lets ACP-aware editors (e.g. Zed) use Bernstein as their multi-agent backend over stdio or HTTP. Implemented in src/bernstein/core/protocols/acp/. See bernstein acp serve --stdio | --http :PORT.
Autofix Daemon
A persistent background process that watches Bernstein-opened PRs for CI failures, pulls the failure logs, and dispatches a scoped repair agent. Caps at three attempts per PR and labels each attempt in the audit log. Implemented in src/bernstein/core/autofix/. CLI: bernstein autofix {start|stop|status|attach}.
Audit Chain
The HMAC-SHA256-chained, append-only JSONL log under .sdd/audit/. Every orchestrator action is signed with a key concatenated with the prior entry's HMAC, so editing any line invalidates every following signature. Key lives outside .sdd/ (XDG state default) so a writer of the log can't read or rotate the key. Implemented in src/bernstein/core/security/audit.py. Operator guide: docs/security/audit-log.md. CLI: bernstein audit {show|verify|seal|query|export}.
Credential Vault
OS-keychain-backed token store for provider credentials (GitHub, OpenAI, Anthropic, etc.). Agents receive scoped credentials at spawn time without touching .env files. Implemented in src/bernstein/core/security/vault/. CLI: bernstein connect <provider>, bernstein creds {list|revoke|test}.
Fleet Dashboard
A unified view of all Bernstein orchestrator instances reachable on the current host or configured server. Useful for monitoring parallel sessions and CI fleets. Implemented in src/bernstein/core/fleet/. CLI: bernstein fleet [--web HOST:PORT].
MCP Catalog
A community-maintained index of installable MCP servers. Bernstein can browse, search, and install entries without leaving the terminal. Schema: docs/reference/mcp-catalog-schema.json. Implemented in src/bernstein/core/protocols/mcp_catalog/. CLI: bernstein mcp catalog {browse|search|install}.
Review Pipeline DSL
A YAML format for expressing multi-phase quality-review flows (lint, type-check, security scan, etc.) that run sequentially before a task is accepted. Starter templates live in templates/review/*.yaml. Implemented in src/bernstein/core/quality/review_pipeline/. CLI: bernstein review --pipeline review.yaml.