Tianyi Cui
4209e4af3f
Model-driving ACP snapshot scenarios shipped both session.jsonl (the replay fixture) and session.golden.jsonl (the expected re-persisted log). For recorded scenarios the normalized fixture and golden were byte-identical — pure duplication. Remove session.golden.jsonl entirely: every model scenario now has at most one committed session-log artifact, session.jsonl, which doubles as the replay source AND the expected produced log. The snapshot test compares the replay run's persisted log against the session.jsonl fixture, normalizing BOTH sides — but each against its OWN volatile values, not a shared context. A raw harvested fixture bakes in the recording run's session id / cwd / timestamps, distinct from the live replay run's; since normalizeSessionLog scrubs cwd by exact string match, the fixture must be normalized against its own header (new fixtureContext helper) or its stale recorded cwd would leak unscrubbed and the compare would fail. The session side uses a normalized-string toEqual, NOT toMatchFileSnapshot, so a run never overwrites the fixture. Authored override scenarios (error-finish, cancel) now hold their expected produced log in session.jsonl. Verified llm-replay ignores the fixture for model chunks when an override exists: loadReplayScript() returns the override array and never reads config.file, so committing the full expected log there does not affect replay behavior. The required-fixture guard is now per-kind: every scenario needs input.json + stdout.golden.jsonl; model scenarios need session.jsonl; authored ones additionally need replay.override.json. Updates the ACP-snapshot-tests RFC to the reduced fixture set and moves the proposing RFC proposed -> implemented.
RFCs
One kind of design doc lives here. An RFC records a decision or proposal that shapes this codebase — the why and what we gave up, the parts code and docs can't carry. (Earlier this split into separate "ADR" and "RFC" trees; they were unified, since most ADRs were simply implemented RFCs.)
Layout and naming
Every RFC has two axes, both encoded in its path — {lifecycle}/{class}/yyyy-mm-dd-topic-title.md:
- Lifecycle (the top-level folder) is the RFC's status, and an RFC moves between folders as that status changes:
proposed/— proposals reviewed before implementation; not yet built (or only partly).implemented/— the decision shipped. The file records what was decided and what was rejected, and is kept current with what actually shipped: when the code later moves a file, renames a package, or changes a key/default, the RFC is updated in the same change to match (facts only — paths, names, structure — not the decision itself). See implemented/AGENTS.md.rejected/— the proposal was considered and declined. Kept for the record so the rejection isn't re-litigated.
- Class (the nested folder) is the kind of decision — see Classification below.
The date in the filename is when the topic was first proposed (per git history). Cross-references between RFCs use relative markdown links ([topic](../../implemented/architecture/2026-…-….md)) — never bare prose or numbers — so they are mechanically checkable and survive moves between folders.
Classification
Each RFC is filed under exactly one class — the kind of decision it records. The class is encoded in the path (the folder is the label, so a file's location declares its class) and the set is closed: scripts/verify-rfc-classification.ts rejects any folder outside the set and asserts this index lists every RFC under the heading matching its path. Adding a new class means amending that gate and this section, not just dropping a new folder. See the classification RFC for why the taxonomy is path-encoded and gated.
| Class | What it covers |
|---|---|
feature |
A new user- or model-facing capability. |
bug-fix |
Corrects a defect or closes a gap a postmortem surfaced. |
simplification |
Removes code, behavior, or surface area without adding a capability. |
architecture |
A structural decision about the shipped source — how packages relate, what the runtime vocabulary is. |
process |
Tooling, policy, or workflow around the code — gates, the package manager, vendoring — not runtime behavior. |
testing |
Test infrastructure and strategy. |
The architecture / process line: architecture is about the source we ship; process is the surrounding tooling and workflow. (refactor is deliberately absent — it overlaps simplification, whose discriminator, "does observable behavior change?", already covers it.)
When to write one
Write an RFC when a decision is durable (it shapes the codebase beyond a single function or package), contested (there was a real alternative a reasonable engineer might have chosen), and surprising (a future reader would otherwise ask "why on earth is it done this way?"). A proposal for substantial future work starts in proposed/; a decision already made starts in implemented/. Pick the class folder that matches the decision (see Classification).
Do NOT write one for a mechanical or local choice (a variable name, a one-file refactor), for anything already enforced and explained by a gate or a convention in AGENTS.md, or for a still-provisional decision tagged TODO(...) in the code — record those as TODOs and promote to an RFC only once they settle. An RFC is never edited into a different decision: supersede it with a new one and cross-link. (Editing an implemented/ RFC to track where its already-made decision now lives — a moved file, a renamed package — is not a different decision and is required, not forbidden; see implemented/AGENTS.md.)
Proposed
Feature
| Title | First proposed |
|---|---|
| Agent Client Protocol (ACP) support for external editors | 2026-06-14 |
| Multiplex concurrent ACP sessions over one connection | 2026-06-14 |
| Optional Code Mode — model writes TypeScript against an SDK of all tools | 2026-06-15 |
Simplification
| Title | First proposed |
|---|---|
| Unify the agent id and the session id | 2026-06-20 |
| Stop mirroring durable boundaries as agent events | 2026-06-20 |
Architecture
| Title | First proposed |
|---|---|
| Runtime schemas for the event vocabulary (Zod vs the merge-extensible-map pattern) | 2026-06-16 |
| Extract a generic long-running tool runtime | 2026-06-20 |
| Extract example apps into packages | 2026-06-20 |
Process
| Title | First proposed |
|---|---|
| Architectural conformance — dependency rules and the adapter kit | 2026-06-11 |
| API extractor reports | 2026-06-11 |
| Supply chain checks and vendor drift verification | 2026-06-11 |
| Discover package inventories instead of maintaining static lists | 2026-06-20 |
Testing
| Title | First proposed |
|---|---|
| Mutation testing as the coverage counterweight | 2026-06-11 |
| Deterministic tests, the replay invariant fixture, and race stress | 2026-06-11 |
Implemented
Feature
| Title | First proposed |
|---|---|
Rich ACP bash rendering — the terminal card (_meta) and command classification |
2026-06-18 |
Simplification
| Title | First proposed |
|---|---|
| Drop the mutable session summary | 2026-06-19 |
| Drop unconsumed assembled LLM convenience surfaces | 2026-06-20 |
Drop the unconsumed llm/adapter-change event |
2026-06-20 |
| Prune dead methods from the persistence and bash seams | 2026-06-20 |
| Keep one public stop primitive | 2026-06-20 |
| Fold trace-only session facts into load-bearing events | 2026-06-20 |
Architecture
| Title | First proposed |
|---|---|
| Microkernel: extension via Cordis event taxonomy, one concrete loop | 2026-06-11 |
| Event-sourced sessions with derived message history | 2026-06-11 |
| Provider-neutral content-block vocabulary owned by dsh-llm | 2026-06-11 |
| Custom typed tool-schema DSL instead of schemastery | 2026-06-11 |
| Tool schemas are part of the system-prompt assembly | 2026-06-11 |
| Runtime arg validation at the model boundary | 2026-06-11 |
| Dev-mode invariants over compile-time deep-readonly | 2026-06-11 |
| Structured error taxonomy | 2026-06-11 |
| Capability seams — interface / implementation / consumer split | 2026-06-13 |
| Two LLM adapters as a design-verification twin | 2026-06-13 |
Session persistence as an abstract service over SessionEvent |
2026-06-14 |
| Every session event is enclosed in a turn | 2026-06-15 |
| Shared persistence write coordinator | 2026-06-18 |
| Agent lifecycle and ownership seams | 2026-06-18 |
| Reorganize packages into a modular hierarchy | 2026-06-20 |
| Branded IDs everywhere they belong | 2026-06-20 |
Process
| Title | First proposed |
|---|---|
| Vendor Cordis as source, not npm dependencies | 2026-06-11 |
| Mechanical quality gates over prose guidelines | 2026-06-11 |
| tsdown for JS bundling instead of dumble | 2026-06-11 |
| Doc-sync enforcement | 2026-06-11 |
| pnpm as the package manager instead of Yarn 4 | 2026-06-16 |
| Markdown cross-link validity linting | 2026-06-18 |
Core-data-structures catalog and the ts type-equiv drift gate |
2026-06-20 |
| Generated cordis events + services catalog | 2026-06-20 |
| Classify RFCs by kind via path-encoded subdirectories | 2026-06-20 |
Testing
| Title | First proposed |
|---|---|
| Property-based testing for protocol-shaped code | 2026-06-11 |
| ACP snapshot tests — record-once / replay-deterministic | 2026-06-19 |
| Real-API e2e in CI against the external DeepSeek API | 2026-06-19 |
Use session.jsonl as the only snapshot session-log artifact |
2026-06-20 |
Rejected
Simplification
| Title | First proposed |
|---|---|
| Persist assembled assistant messages, not stream chunks | 2026-06-20 |
| Drop ACP session/load until resume has a product shape | 2026-06-20 |
Drop ACP terminal _meta rendering |
2026-06-20 |
| Drop bash full-output spill files | 2026-06-20 |
| Drop durable step boundary events | 2026-06-20 |
| Drop unused session lineage metadata | 2026-06-20 |
| Fold the persistence interface into dsh-session | 2026-06-20 |
| Collapse tool-owned UI presentation | 2026-06-20 |
| Retire mid-turn steering | 2026-06-20 |
| Return the ACP bridge to one live session per connection | 2026-06-20 |
| Truncate interrupted final turns on load | 2026-06-20 |
Architecture
| Title | First proposed |
|---|---|
| Deep-readonly public surfaces | 2026-06-11 |
| Make the shared example base providerless | 2026-06-20 |