The first OUT-OF-PROCESS subagent backend, proving the seam generalizes past the
in-process backends. @deepseek-ai/dsh-subagent-acp runs each child agent in a
spawned subprocess, driven over the Agent Client Protocol as the CLIENT — the
direction-inverted twin of the dsh-acp server bridge. Point the configured
command at the acp-agent example and the harness talks to its own process.
- Fresh process per run: start spawns, runs one ACP session (initialize →
newSession → prompt), dispose kills the subprocess and awaits its exit.
- Minimal client stub: advertises no fs/terminal; accumulates agent_message_chunk
text as the result output; auto-answers session/request_permission by a
configured policy (reject default / allow). No start-time capabilities (an
out-of-process child can't enforce the parent's depth/tool-filter); ignores
request.parent; injects only `subagents`.
- StopReason mapping (end_turn→completed, cancelled→aborted, …); result resolves
error/aborted on a child failure, never rejects (seam contract).
- Security: credential-shaped ambient env vars are scrubbed; the child's own key
is forwarded only via explicit config.env. A spawn-level error (ENOENT) is
captured and raced against the ACP drive so a bad command settles error rather
than crashing the parent.
Testing designed at every tier: keyless integration drives a scripted mock ACP
server subprocess (cancellation incl. the pre-newSession race and a
torn-pipe-after-cancel, permission auto-answer, non-message updates, spawn
failure, HMR, export shape) at 100% coverage; a with-key e2e drives the REAL
acp-agent example process (PONG + real file write, verified on disk) — the
harness driving itself. Snapshot coverage of an ACP child is deferred as
TODO(acp-subagent-replay) (each child is its own process with its own replay).
Stayed on @agentclientprotocol/sdk 0.25.1: the proposed 0.28.x bump only
deprecates the stable ClientSideConnection/AgentSideConnection API this layer
uses (33 sites incl. the server bridge), turning no-deprecated red across code
this PR shouldn't rewrite — that fluent-API migration is its own follow-up. The
backend needs nothing 0.28.x adds.
This completes the subagent seam stack (PR1 interface → PR2 in-process → PR2.5
snapshot infra → PR3 ACP); the seam RFC moves to implemented/, amended.
The second PR of the subagent seam: the two in-process backends that run a
child agent on the same cordis context, reusing the agent factory's quiescent
AgentHandle teardown. Both register on ctx.subagents (PR1's named-provider
registry) and share one run driver.
- dsh-subagent-spawn: a FRESH child via ctx.agents.create — own session, the
parent's model by default (overridable), zero inherited conversation. Also
exports the shared in-process run driver (startInProcessRun): mint ids, stamp
cwd/parentSession-lineage/depth, drive the one-shot (send → whenIdle), read
the last assistant/message + turn/end reason, dispose to quiescence.
- dsh-subagent-fork: a child SEEDED with the parent's balanced completed-turn
prefix (the log up to and including its last turn/end), so the child inherits
context. The in-flight unbalanced turn is excluded — a raw seed would fail the
invariants replay. Proven: a regression test goes red if the boundary seeds
the open turn.
- Seam extension: CreateAgentOptions.seed, threaded through AgentLoop.createAgent
→ ctx.sessions.prepare({ seed }) (the primitive resume already used). This is
the fork-lineage path the TODO(sub-agents) markers anticipated.
- Depth: a merge-extensible AgentOptions.subagentDepth (0 top-level, parent+1 for
a child); the depthLimit capability refuses a spawn past request.maxDepth.
Tests: real-loop unit tests for both backends (mock MODEL only, real loop +
invariants), a multi-subagent test (one parent drives a fork AND a spawn child
then keeps working), and a with-key e2e (a real parent delegates via the
`subagent` tool to a real child that writes a file on disk — world-verified).
100% per-file coverage. The coding-agent demo wires the spawn backend + tool.
Snapshot coverage of nested agents is deferred to a stacked follow-up
(TODO(subagent-snapshots)): dsh-llm-replay is a single global positional cursor
that cannot route calls to a parent vs. a child on one context. Recorded in the
RFC's deferrals and a new AGENTS.md rule: designing a subsystem must design its
test infrastructure END TO END up front, verifying the snapshot/e2e harness can
express the new shape — a gap this plan hit.
Introduce the `packages/subagent/` group and the abstract subagent seam — an
agent delegating to a child agent — as a named-provider registry (`ctx.subagents`),
unlike the single-implementation bash seam, so multiple transports (in-process,
ACP, future A2A) coexist. This first PR lands the interface, a scripted test
backend, and the model-facing tool, validated through the real cordis load path.
- dsh-subagent: SubagentService registry + SubagentProvider/SubagentRun
vocabulary + subagent/start|end events. Start-time capabilities (outputSchema,
depthLimit, toolFilter) are checked pre-start and rejected loud; runtime
capabilities (sendMessage, resume) are optional methods on SubagentRun.
- dsh-subagent-mock (support): scripted provider for keyless, deterministic
tests through the real Loader/export path.
- dsh-tool-subagent: the model-facing `subagent` tool, config-bound to one
provider; synchronous collect with try/finally dispose, signal->cancel
bridging, and non-completed-stop-reason -> isError mapping.
- Proposed RFC documenting the seam, the fork-vs-spawn-as-separate-backends
decision, own-session isolation, synchronous-collect scope, and the deferral
of background/poll/spill to a future unification with bash.
- Wire the new group into tsconfigs, build refs, package hierarchy docs, the
module graph, and the cordis catalog.
RFC: docs/rfc/proposed/feature/2026-06-21-subagent-capability-seam.md
BLOCKER — the published lib/bin.js (stdio + acp) was exercised only via tsx
(demo:* / the src/bin.ts smokes); the built artifact under plain `node` was
unguarded. Root-cause on the BUILT bin:
1. Settle race: boot() returned once loader.create() registered the include
ENTRY, but the include loads its child plugins asynchronously — so boot()
(and main()) resolved while the app plugins (stdin reader, agent loop, ACP
bridge) were still mounting. A CLI with no attached handles yet exits 0
silently, and a load error surfaces as an unhandled rejection AFTER boot.
Fix: `await ctx.loader.await()` after create() — settle the whole tree.
2. Config-path robustness: hand the include the config's ABSOLUTE file:// URL
so resolution never depends on ctx.baseUrl / can never fall back to cwd.
Both bins fixed identically. NOTE: the cordis Loader resolves a config's bare
plugin specifiers via its internal module loader, active only under
`node --expose-internals`; the bin cannot add a node flag itself, so this is
documented in the bin JSDoc + both package READMEs (the demos already comply).
The repo `examples/*/cordis.yml` are tsx-only artifacts (workspace plugins
resolve through the tsconfig paths map, not node_modules), so they are not a
valid plain-node bin target — the smokes use a real-install-shaped temp dir.
Fail loud on a load failure: boot() previously exited 0 SILENTLY when a config
path's directory does not exist — the include plugin fails to IMPORT, the cordis
Loader catches+LOGS it and leaves the entry with no fiber (no rejection), and
`loader.await()` does not rethrow (EntryTree.await uses Promise.allSettled). Fix:
boot() now calls assertEntriesLoaded(ctx) after the tree settles and throws on
any entry with no fiber, so a typo'd config dir exits non-zero with a clear
message. main() also installs an unhandledRejection guard (installFailLoud) that
replaces Node's stack dump with a single labelled stderr line for the
companion case (a missing config FILE in a real dir, whose include-init throw
surfaces as a rejection Node already exits non-zero on). Regression tests added
to both built-bin smokes (missing dir + missing file → non-zero exit + stderr);
verified the missing-dir test fails on the pre-fix bin.
Built-bin smokes (the reviewer's ask): packages/ui/{stdio,acp}-agent/tests/
built-bin.e2e.ts run the REAL lib/bin.js under `node` (NOT tsx) in a temp
consumer dir, asserting the stdio echo round-trip / the acp initialize response
+ stdout purity, plus the fail-loud cases above. They build-gate (skip if lib/
absent) and run in a new ci.yml step after the build.
Issue 2 — packages/README.md + docs/architecture.md said "plugins depend on
interfaces, never on the concrete loop", but dsh-agent-core imports the concrete
dsh-agent-loop. Scope the rule to EXTENSION plugins and carve out the sanctioned
COMPOSITION/bundle exception (dsh-agent-core composes the concrete spine); note
it in the implemented RFC too.
Issue 3 — examples/acp-agent/tests/acp.snapshot.ts fixture-guard claimed
no-model scenarios need no session.jsonl, but runScenario() always boots
llm-replay with the session.jsonl path and loadReplayScript() throws when it is
absent. Require session.jsonl for ALL scenarios (no-model ones ship a
header-only fixture) and rewrite the comment to match reality.
Implements docs/rfc/.../2026-06-20-extract-example-app-packages.md. Each
example was thick — a hand-rolled start.ts, an infra preamble, nested
base.yml/base-core.yml/acp-tail.yml includes, and a coupled front-door
cluster enforced only by prose. This moves the composition into packages so
each example is a thin leaf cordis.yml: pick the swappable backends, load one
app package.
New packages:
- @deepseek-ai/dsh-agent-core (packages/core/agent-core): one bundle plugin
that loads the providerless/executor-less/UI-less spine (timer + llm +
sessions + system-prompt + tools + agents + invariants + tool-bash +
agent-loop) via ctx.plugin(...) inside apply(), and forwards agent-loop's
`agents` list as its own Config (export const Config = AgentLoop.Config,
default []).
- @deepseek-ai/dsh-stdio-agent (packages/ui/stdio-agent): terminal chat APP —
agent-core + console logger + readline UI + a pre-created `main` agent, with
a bin. The demo:echo/coding front door.
- @deepseek-ai/dsh-acp-agent (packages/ui/acp-agent): ACP server APP —
agent-core + JSONL persistence + the acp bridge, NO stdout logger, with a
bin. The stdout-purity footgun is structurally unreachable from the leaf.
Amendment to the RFC: hmr stays a LEAF cordis.yml entry, not baked into
dsh-stdio-agent. hmr is a Loader-only dev plugin (throws without
--expose-internals; the in-process test tier can't even import its decorator
form), so a package statically importing it could never carry the per-file
coverage gate. Unlike the console logger, a stray hmr is not a stdout-purity
footgun, so leaving it at the leaf costs no safety. With hmr out, all three new
packages carry in-process unit specs at 100%.
Boot glue (Loader tail, .env load, snapshot-mode selection, stdin-dispose
lifecycle) moves into each app's bin; start.ts and base.yml/base-core.yml/
acp-tail.yml are deleted. Each app package gets a keyless real-load-path test
that boots through its bin + the cordis Loader (guarding the unwrapExports
export-shape bug class, postmortem 0001). ACP snapshot replay stays green
against the existing committed goldens (pure boot restructuring). RFC moved
proposed->implemented with the amendment recorded; package/example/architecture
docs and the module graph updated.
Adding packages/util/brand/ created a new top-level packages/util/ group that
the hierarchy/dependency docs never enumerated. Document it:
- Add packages/util/README.md, the group README (low-level zero-dependency
utilities shared across groups; lists dsh-brand).
- packages/README.md: add the util/ group to the group table, dsh-brand to the
package table, and dsh-brand to the dependency graph. Correct the now-false
"no harness deps" claims — dsh-llm and dsh-bash both depend on dsh-brand
(verified dsh-bash imports Branded from dsh-brand, not dsh-llm; dsh-session
and dsh-agent depend on it too).
- Root AGENTS.md Repository Layout: add the util/ group with brand/.
Align the implemented branded-ids RFC with what shipped: Branded lives in
@deepseek-ai/dsh-brand (packages/util/brand/), and dsh-bash depends only on
that utility package instead of dsh-llm. Fix the BashTaskId import source, the
illustrative snippet, and the opening policy reference (now dsh-brand).
Add a README to each group dir (core/llm/bash/session-persistence/ui/
support) stating its role and product-vs-support classification, and
rewrite packages/README.md around the hierarchy (group table, grouped
"what goes where", removed the package-hierarchy FIXME).
Move the package-hierarchy RFC to implemented/architecture/ and rewrite
it to describe what shipped (placement rationale, the paths-wildcard and
publint dedup, the two new guardrail gates). Fold the remaining
tsconfig.build.json references dedup into the discover-package-inventory
proposal and fix its cross-link.
Update AGENTS.md: regrouped repo-layout map, depth-2 globs, the new
verify-package-paths gate in the doc-sync listing, and a note that we
lean toward stricter lint in the agentic-coding era (machine-caught
errors and a consistent foundation outweigh the one-time cost).
Add a second axis to every RFC — its class (feature, bug-fix,
simplification, architecture, process, testing) — encoded in the path
as docs/rfc/{lifecycle}/{class}/file.md. The folder is the label, so
the closed set is enforced by structure rather than a parsed field.
Two new doc-sync gates back it:
- verify-rfc-classification: every RFC sits in a valid class folder and
the README index lists it under the matching lifecycle→class heading.
- verify-doc-refs: every docs/*.md path cited in a packages|examples TS
comment resolves — closes a drift class verify-md-links can't see, and
catches the four comment refs this reorg moved.
The README gains a Classification section explaining the taxonomy and
per-class index sub-sections. A self-referential process RFC records why
the scheme is path-encoded and gated.
Logic that lived under examples/ was outside the per-file 100% coverage
gate (examples/ are not workspaces) and, in the stdio-UI case, duplicated
across two examples. Move it into packages/ so it is gated and de-duped.
- packages/ui-stdio (new): unify the two diverged stdio-chat.ts copies into
one @deepseek-ai/dsh-ui-stdio plugin (welcome/agent Config). A test-only
I/O seam (createStdioChat(ctx, config, runtime)) keeps process streams out
of the serializable config and makes every render/EOF/disposal branch
unit-testable. Per-file 100%. echo/coding cordis.yml now load the package;
both src/stdio-chat.ts deleted.
- packages/llm-replay (new): move examples/acp-agent/src/llm-replay.ts (+ its
spec) here so its derive/parse/replay branches fall under the coverage gate.
cordis.snapshot.yml + README rewired to the package name; added apply/env
/assertNever/abort tests to reach per-file 100%.
- examples/{echo,coding}-agent: keyless Loader-path e2e smokes that boot the
real cordis.yml (no key) — the guard a hand-mounted unit test cannot be for
the unwrapExports/export-shape class (postmortem 0001). examples/AGENTS.md
codifies the keyless+with-key smoke convention (keyless-by-nature exception
for echo-agent).
- AGENTS.md: a scoped, removal-triggered pre-release stance (foundation over
blast radius). packages/README.md: new rows + a FIXME to later regroup ALL
packages into a hierarchy. Wiring: tsconfig paths/refs, publint, knip,
module-graph.
Verified: typecheck, lint, test:coverage (887 tests, 100%), build, hygiene,
doc-sync, test:snapshot (10), test:e2e (6 keyless pass, with-key self-skip).
Rename the concrete Agent class to make its ReAct-style reasoning loop
explicit in the name. Package name, default-export plugin (`AgentLoop`),
and the `ctx.agentLoop` service key are unchanged.
Collapse docs/adr/ and docs/rfc/ into a single docs/rfc/ with proposed/,
implemented/, and rejected/ subfolders. Every file is renamed to
yyyy-mm-dd-topic-title.md, where the date is when the topic was first
proposed (from git history). ADRs and RFCs that covered exactly the same
topic are merged (property-based testing, session persistence); the
umbrella RFC 005 stays split across its three implemented decisions, and
RFC 006's deferred part-3 (API extractor reports) splits into its own
proposed RFC. All cross-references become machine-checkable relative
links instead of bare "ADR NNNN" / "RFC NNN" prose.
Add a verify-md-links doc-sync gate (scripts/verify-md-links.ts) that
checks every relative Markdown cross-link resolves, wired into doc-sync
alongside verify-md-wrap. This makes the reorganization self-verifying:
the same change that rewrote ~forty inter-doc links adds the check that
proves none dangle. Document the cross-link convention in a new
docs/AGENTS.md and record the gate as an implemented RFC.
doc-sync, typecheck, lint, and the full test suite (667) all pass.
Implements the RFC 010 MVP: a new `@deepseek-ai/dsh-acp` package bridges the
harness agent to the Agent Client Protocol (JSON-RPC 2.0 over newline-delimited
stdio), so Zed and other ACP editors can drive the coding agent — streaming
render, tool-call display, and resumable sessions via `session/load`.
- packages/acp: AgentSideConnection wiring; initialize/newSession/loadSession/
prompt/cancel; a total TurnEndReason→StopReason codec; settle-once with a
fallback chain (agent/turn-end → logged turn/end → idle); single-session
guard; cwd-must-equal-launch-dir validation; load replays from the persisted
event log (assistant/chunk→agent_message_chunk, tool/call/result→tool_call*).
- agent: add Agent.whenIdle() quiescence signal to the interface; LoopAgent
implements it (resolves on the first running→idle/disposed transition). The
bridge awaits it on disposal so teardown reaches quiescence, not just abort.
- examples: extract the shared provider/tool core into examples/base.yml;
coding-agent nest-includes it; new examples/acp-agent serves the agent over
ACP with JSONL persistence and no stdout logger (stdout is the protocol).
- Permission gate deferred (TODO(rfc010-permission-gate)): tools run with the
executor's full authority; only the Agent→sessionId ownership seam is laid
down. Cancel is best-effort for a not-yet-started queued turn
(TODO(rfc010-cancel-prestep)). RFC 010 stays `proposed`.
- Docs: package README + Zed snippet; client-driver cookbook section; root and
packages layout/commands; RFC 010 implementation-status note.
48 bridge tests + whenIdle coverage; 100% per-file coverage; e2e boots the
example as a subprocess and verifies a written file on disk (key-gated, with a
no-key stdout-purity check).
The `yarn doc-sync` gate (doc-typecheck + verify-event-taxonomy) and the
@deepseek-ai/dsh-invariants package both exist now, but the instruction docs
never caught up and the gate's markdown scope (README.md, docs/**/*.md,
packages/*/README.md) does not cover AGENTS.md / packages/AGENTS.md, so they
drifted silently.
- AGENTS.md: add invariants/ to the Repository Layout; add doc-typecheck /
verify-event-taxonomy / doc-sync to Commands; rewrite the false "CI has no
doc-sync gate" sentence to describe the gate's actual coverage and what
remains outside it (AGENTS.md, packages/README.md, prose drift).
- packages/AGENTS.md: fix the same stale "no doc-sync gate" line.
- packages/README.md: add dsh-invariants to the dependency graph and the
package table.
Verification: `yarn doc-sync` green; `grep -rn "no doc-sync gate"` returns
nothing; the three command names + dsh-invariants are present.
- AGENTS.md Commands: fix typecheck/build descriptions; add lint, lint:fix,
test:coverage, knip, publint, hygiene (were undocumented).
- Drop the bare `yarn demo` for explicit `demo:echo` + `demo:coding`; update
README, examples READMEs (and document coding-agent in examples/README).
- New cookbook guide: adding-a-vendored-package.md (the missing "add" half of
vendor/README's update-only procedure).
- architecture.md: add a table-of-contents and extract the Extension cookbook
to docs/cookbook/extension-cookbook.md (link-preserving); drop the completed
"restructure this document" TODO.
- ADR 0009 (capability seams) + 0010 (twin LLM adapters), and a "when to write
an ADR" standard in adr/README.
- Add a committed dsh-code-review skill under .agents/skills, exposed to Claude
Code via a tracked .claude/skills symlink (gitignore carve-out).
Hard line breaks mid-paragraph make docs harder to edit and diff — a
one-word change reflows and re-diffs the whole paragraph. Reflow all
tracked non-vendor Markdown (plus vendor/AGENTS.md) so each prose
paragraph is a single line; soft-wrapping is the editor's job. Fenced
code, tables, and list structure are preserved (wrapped list items fold
to one line per bullet). Documents the convention in AGENTS.md.
Docs: per-folder README.md for packages/ (family overview + one per
package: service, events, API, extension points, TODOs), examples/,
and examples/echo-agent/; folder-level AGENTS.md (+ CLAUDE.md
symlinks) for packages/ and vendor/; module-level doc comments in
every packages/*/src file; richer JSDoc on all exported API
(event side effects, disposal contracts, error behavior). Root
AGENTS.md gains a "Type Safety and Documentation" policy section:
the codebase aims to be very type-safe and well documented; type
gymnastics are acceptable in core packages when they improve
plugin-author DX; verbose docs are fine as long as they stay strictly
in sync with the code.
Type safety: removed the upstream-inherited "noImplicitAny": false
from tsconfig.base.json — packages/* now compile under full strict
mode; vendor/loader and vendor/include set it locally (vendor/cordis
already did). Eliminated every `: any` / `as any` from packages and
examples (catch clauses use unknown + a CodedError narrowing type;
event data access uses discriminated-union narrowing).
Typed tool schemas: new @deepseek-ai/dsh-tools schema DSL —
SchemaSpec with per-property `required: true` booleans, type-level
InferArgs<S>, a runtime SchemaSpec → JSON Schema converter, and
defineTool() so first-party tools get typed execute(args) with zero
casts (raw JSON Schema still accepted for MCP interop; chosen over
schemastery because it targets JSON Schema generation directly).
echo-tool and all test tools migrated; +7 tests.
