Files
deepseek-harness/packages/support/invariants/README.md
T
Tianyi Cui 483e0e5edf fix(events): address Codex review — protect post-execute result, purge stale tools/execute refs
Codex's PR-C review found two (A) blockers:

- tools/post-execute could corrupt the protected outcome. postExecute passed the
  mutable `result` to listeners and then read result.callId / spread result on the
  return paths, so a listener mutating the reference (flipping isError, rewriting
  callId, injecting an error) escaped the decision channel. Now the authoritative
  callId/isError/error are SNAPSHOT before the waterfall and the return value is
  rebuilt from the snapshot + the typed PostToolDecision — the decision is the only
  sanctioned way to change the outcome, and callId is always exec.callId. Added a
  regression test that mutates the result reference and asserts it has no effect;
  proven to fail red on the unfixed code.

- Public docs/JSDoc still advertised the removed `tools/execute` waterfall after the
  split. Swept every current-state reference to tools/pre-execute + tools/post-execute:
  the ToolRegistry class JSDoc (and the regenerated catalog), loop.ts's ASCII flow
  (also added the prompt-submit/session-start steps it was missing), the package-map
  READMEs (packages, core, agent-core), core-data-structures core.md/tools.md, the
  bash + acp + invariants src/READMEs (the deferred permission gate is the
  tools/pre-execute deny/ask seam now), the cookbook, and the implemented RFCs whose
  factual seam catalog drifted. codec.ts's totality prose now lists `rejected`.
  Proposed-RFC references are left as-is (frozen proposals, validated when built).
2026-06-30 20:25:30 +08:00

3.2 KiB

dsh-invariants

Dev-mode event-contract invariants and session-log freeze. A pure-listener plugin (everything is a plugin) that asserts the harness event contract at runtime and, optionally, freezes logged session-event data so any code that mutates history throws instead of corrupting silently.

Off in production. Enable it in tests and the demos, where a contract violation should fail loudly. It costs nothing when not registered, and doubles as executable documentation of the event taxonomy — the assertions are the contract.

Plugin

A functional plugin — register the module namespace (this is what loading by name in cordis.yml does):

import type { Context } from 'cordis'
import * as Invariants from '@deepseek-ai/dsh-invariants'

declare const ctx: Context

await ctx.plugin(Invariants)                     // freeze on (default)
await ctx.plugin(Invariants, { freeze: false })  // assert contract, don't freeze

inject: ['sessions'] — it reads ctx.sessions.list() at apply time to rebuild trace state for sessions that already exist (so a hot reload mid-turn doesn't falsely reject the next event). It listens on session/created, session/event, and agent/status.

Config

Key Default Meaning
freeze true Deep-freeze each logged event's data so mutating a logged event throws. Set false to assert the contract without freezing.

Invariants asserted

Session log (per session):

  • seq strictly increases — the spine of replay equivalence.
  • turns pair and nestturn/start opens a turn, turn/end closes the matching one; no overlapping turns.
  • steps nest in turnsstep/start opens a step in the open turn; step/end closes the matching step.
  • chunks belong to an open stepstep/start precedes its assistant/chunks.
  • a tool/result needs a prior tool/call — but NOT the converse: a tool/call may have no result (a thrown tool-execution pipeline step ends the turn with no tool/result, which is legal).

Agent status (per agent):

  • legal transitions onlyidle↔running and (idle|running)→disposed. A no-op transition (setStatus dedups, so it never fires) and leaving the terminal disposed state are violations.

On any violation it throws InvariantError (code: 'INVARIANT').

Why runtime, not deep-readonly types

A DeepReadonly<SessionEvent> is high type-noise across every log consumer, and a plugin can cast straight through it. A dev-mode freeze plus these assertions catch real corruption at zero production cost and zero type noise. The always-on half of that defense — cloning derived messages so request/adapter mutation can't reach back into the log — lives in dsh-session's deriveMessages. This package is the dev-mode tripwire. See dev-mode invariants.

Seeded sessions

A seeded/forked session arrives with events already in its log (the Session constructor copies the seed without emitting session/event). On session/created the plugin replays the existing log through the checker and freezes those entries, so seeded history is held to the same contract.