build-gate

Machine-checkable fitness-to-build gate (ADLC C13 — issue #48).

Nothing else in ADLC deterministically prevents starting a high-blast-radius ticket's build (P4) when the executing session's context is degraded ("context rot"). build-gate closes that gap: it derives a ticket's risk tier, checks a machine-checkable context-fitness signal, and denies the build unless an audited override is recorded.

ADLC Phase

P3 → P4 entry gate. Sits between rail-freeze (P3) and supervised build execution (P4). Guards one invariant: a high-risk ticket must not begin its build in a degraded session.

Usage

build-gate <ticket-id> [--depth <n>] [--session-bytes <n>] [--transcript <path>]
           [--depth-threshold <n>] [--bytes-threshold <n>] [--tickets <path>]
           [--reason <text>] [--json]

Flags

The library export DEFAULT_BYTES_THRESHOLD (lib/depth-signal.mjs) remains HARD_BYTES (256 KiB) by design, so the two numbers are not expected to agree: this binary's flag default is the recalibrated operating threshold.

A CLI process can't observe its own caller's context state — the caller (a hook, CI wrapper, or any harness) must supply the signal via --depth/ --session-bytes, or point --transcript at a transcript file to derive it from. Supplying neither defaults the signal to "not degraded" — a gate given no signal cannot deny.

Exit codes

0  allow (gate passes)
1  operational error (bad ticket id, missing tickets file, bad thresholds)
2  deny (gate fails)

Risk tier

A ticket is high risk if it declares "risk": "high", OR any of these derived signals fire from fields already on the ticket:

• external: true — writes back to / creates / deletes in an external system
• mutatesIdentity: true — mutates identity
• scope/rails glob-matches .adlc/manifest.jsonl — mutates the gate-evidence ledger
• scope/rails glob-matches .adlc/tickets.json or .adlc/current-ticket.json — touches the trust root
• category is contract or architecture

A declared "risk": "normal" can never downgrade a derived-high signal — that would be a silent, undetectable way to defeat the gate.

Context-fitness signal

A proxy for "this session is deep," mirroring @adlc/flail-detector's existing transcript-size / tool-call-count scanning approach: a tool-call-count (--depth) and a transcript byte count (--session-bytes), each compared to a threshold. Either signal past its threshold means the session is degraded.

Audited override

Set ADLC_BUILD_GATE_BYPASS=1 to deliberately override a deny (mirrors the ADLC_RAILS_BYPASS pattern used by rails-guard). The override is only honored if it can be durably recorded to .adlc/manifest.jsonl as a build-gate-bypass entry — an override that cannot be recorded is refused, never silently allowed.

Toolkit modules (Path A — reusable by any harness)

• lib/risk.mjs — computeRiskTier(ticket) / deriveRiskSignals(ticket)
• lib/depth-signal.mjs — computeDepthSignal({ text, bytes }) / isDegraded({...}) (absolute hard band via @adlc/context-handoff isHardDegraded; inclusive >= at HARD_DEPTH / HARD_BYTES)
• lib/decide.mjs — decideBuildGate({ riskTier, degraded, bypass, recordBypass })
• lib/override.mjs — recordOverride({...})
• lib/active-ticket.mjs — resolveActiveTicketId({ dir, env }), the shared ADLC_TICKET env var / .adlc/current-ticket.json convention already used by every other harness integration (codex, opencode, cursor, antigravity)

Claude Code integration (Path B — self-enforcing)

plugins/adlc-claude-code/hooks/adlc-hook.mjs's buildgate PreToolUse mode supplies the in-session context signal (the same transcript-window staging the flail mode already does) and computes the risk tier, context-fitness signal, and allow/deny decision entirely locally — verbatim ports of this package's lib/risk.mjs / lib/depth-signal.mjs / lib/decide.mjs logic, marked "KEEP IN SYNC" in the hook source. It does not shell out to adlc build-gate for the decision; adlc (via gate-manifest) is invoked only to durably record an audited override, mirroring how rails never needs adlc for its own core decision either. See docs/specs/build-gate-fitness.md, including its Known limitations section (unreadable-transcript fail-closed behavior, and the unprotected .adlc/current-ticket.json pointer as a Bash-reachable, CI-unbackstopped escape hatch).