Every session event now lives inside a turn (between turn/start and its turn/end). The loop records queued user/message events AFTER turn/start; an idle agent.inject() wraps its context/message in a one-shot injection turn. This makes the turn the single durability/replay boundary so a persistence backend can treat anything after the last turn/end as a crash tail without dropping legitimate between-turn context. A failure once the turn is already closed (rejecting session/flush, a throwing agent/turn-end listener) has no in-turn position for a session error event, so it is reported via agent/error + logger only; the turn stays balanced. failTurn appends an error event only while the turn is open. The dsh-invariants plugin enforces turn-enclosure via a default case: every non-boundary event type — including plugin-added merge-extensible keys — must sit inside an open turn or it throws. Documented in ADR 0017 + architecture.md.
Architecture Decision Records
Short, immutable records of the why behind decisions that shape this codebase. Code and docs say what the system does; ADRs say why it does it that way and what we gave up.
Format: one file per decision, numbered, with Status / Context / Decision / Consequences. An ADR is never edited into a different decision — supersede it with a new one and cross-link.
When to write an ADR
Write one when a decision is all three of: durable (it shapes the codebase beyond a single function or package), contested (there was a real alternative you rejected, and a reasonable engineer might have chosen it), and surprising (a future reader would otherwise ask "why on earth is it done this way?"). The ADR captures the why and what we gave up — the parts code and docs can't.
Do NOT write an ADR for: a mechanical or local choice (a variable name, a one-file refactor); anything already enforced and explained by a gate or a convention in AGENTS.md; or a still-provisional decision tagged TODO(...) in the code — record those as TODOs and promote to an ADR only once they settle. When in doubt, the test is the "why on earth" question: if the code alone would mislead a careful reader about intent, write the ADR.
| # | Title | Status |
|---|---|---|
| 0001 | Vendor Cordis as source, not npm dependencies | accepted |
| 0002 | Microkernel: extension via Cordis event taxonomy, one concrete loop | accepted |
| 0003 | Event-sourced sessions with derived message history | accepted |
| 0004 | Provider-neutral content-block vocabulary owned by dsh-llm | accepted |
| 0005 | Custom typed tool-schema DSL instead of schemastery | accepted |
| 0006 | Tool schemas are part of the system-prompt assembly | accepted |
| 0007 | Mechanical quality gates over prose guidelines | accepted |
| 0008 | tsdown for JS bundling instead of dumble | accepted |
| 0009 | Capability seams — interface / implementation / consumer split | accepted |
| 0010 | Two LLM adapters as a design-verification twin | accepted |
| 0011 | Runtime arg validation at the model boundary | accepted |
| 0012 | Dev-mode invariants over compile-time deep-readonly | accepted |
| 0013 | Property-based testing for protocol-shaped code | accepted |
| 0014 | Doc-sync enforcement (doc code blocks + event taxonomy) | accepted |
| 0015 | Structured error taxonomy (HarnessError base) | accepted |
| 0017 | Every session event is enclosed in a turn | accepted |