Type-only change (brands are zero-cost casts; no runtime/wire impact). Closes the two gaps in the "brand ids that cross package boundaries" policy and fixes the dependency direction so a capability package never pulls in an unrelated one. - Extract the `Branded<B>` primitive into a new standalone type-only package `@deepseek-ai/dsh-brand` (packages/util/brand) with no harness-package deps. dsh-llm keeps its owned CallId but imports Branded from dsh-brand; dsh-session, dsh-agent, and dsh-bash all import Branded from there. dsh-bash depends on dsh-brand ALONE — never on dsh-llm or dsh-session (the architectural fix: a generic execution backend must not couple to the LLM or session vocabulary). - Mint BashTaskId + OwnerToken in dsh-bash and thread them through BashTask.id, the get/ownerOf/list/readOutput/kill seam, the bash-local generation site, and the dsh-tool-bash validate/access surface. OwnerToken is a DISTINCT brand from SessionId so the seam stays decoupled; dsh-tool-bash is the single boundary that casts SessionId -> OwnerToken. - Brand at the SOURCE, not via mid-pipeline casts: agent-loop's Config types agents[].id as AgentId and resumeSessionId as SessionId, so the brand enters at the config boundary and the inner create()/resume casts disappear (only the genuinely-new per-run session-id string is cast). - Stop brand erosion: propagate CallId/SessionId/AgentId to the registry/store Map keys and public params/exports (SessionStore, AgentRegistry + factory options, the ACP session-id surface + ToolPresenter CallId map, the persistence coordinator, invariants pendingCalls, the pi-ai tool-call maps). - Docs: document BashTaskId/OwnerToken in bash.md (type-equiv re-pasted), point the Branded type-equiv at dsh-brand, fix stale param types in the session/ agent/bash READMEs, regenerate the cordis catalog + module graph. Implements docs/rfc/proposed/architecture/2026-06-20-branded-ids.md
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):
seqstrictly increases — the spine of replay equivalence.- turns pair and nest —
turn/startopens a turn,turn/endcloses the matching one; no overlapping turns. - steps nest in turns —
step/startopens a step in the open turn;step/endcloses the matching step. - chunks belong to an open step —
step/startprecedes itsassistant/chunks. - a
tool/resultneeds a priortool/call— but NOT the converse: atool/callmay have no result (a throwntools/executewaterfall ends the step with notool/result, which is legal).
Agent status (per agent):
- legal transitions only —
idle↔runningand(idle|running)→disposed. A no-op transition (setStatusdedups, so it never fires) and leaving the terminaldisposedstate 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.