The seed-boundary change made fork-child replay route correctly but shipped
with no recorded fork scenario — the seedLength slice was exercised only by
llm-replay unit tests and a persistence round-trip, never by the full-transcript
snapshot tier. Add two recorded scenarios that drive a real fork child through
it:
- subagent-fork: parent completes a turn, then forks one child (child fixture
carries a non-zero seedLength, the boundary the replay slice consumes).
- subagent-mixed: parent completes a turn, then delegates once via spawn
(seedLength 0) and once via fork (non-zero seedLength) in one transcript —
the first scenario to drive two subagent backends at once, exercising both
branches of the slice.
Both need a completed turn-1 so the fork seed is a non-empty completed-turn
prefix (a turn-1 fork seeds empty = spawn, which would not exercise the slice).
Removing the slice turns both scenarios red (the fork child receives the
parent's recorded chunks), proving the guard bites.
ACP (out-of-process) subagent replay remains a different shape, still tracked
as TODO(acp-subagent-replay).
A fork subagent seeds its child session with a prefix of the parent's log, and
that seed becomes the child's persisted log — so a fork child's .jsonl begins
with the PARENT's events, including the parent's assistant/chunk events. The
snapshot replay harness derived a child's script from its whole log, which would
replay the parent's recorded responses as the child's model calls. Spawn-only
scenarios never hit it, but a fork snapshot would mis-route silently.
Record the seed boundary and skip the inherited prefix at replay:
- SessionHeader gains an optional `seedLength` (how many leading events were
inherited via a seed), threaded through CreateSessionOptions/CreateAgentOptions
meta and stamped by the fork backend (= seeded-prefix length; absent for spawn).
It is EXPLICIT, never inferred from seed.length: a resume seeds the whole stored
log, so the resume path passes the persisted boundary back.
- Both persistence backends round-trip it: JSONL header line, SQLite seed_length
column. The SQLite table change bumps SCHEMA_VERSION 2->3; per the pre-release
stance the backend rejects an older user_version on open with NO migration.
- llm-replay's parseSessionHeader reads seedLength and loadSessionScripts derives
a child script from events AFTER the boundary. seedLength is 0 for spawn, so
spawn replay is byte-for-byte unchanged.
Closes the routing-correctness gap the per-session snapshot replay RFC under-
stated; a recorded fork scenario remains a future addition but now derives
correctly. RFC: docs/rfc/implemented/testing/2026-06-22-fork-child-replay-seed-boundary.md.
Regression coverage: a fork child fixture whose seeded prefix carries a parent
chunk (derived script must exclude it, proven red without the slice); a seedLength
persistence round-trip through the shared coordinator contract (both backends);
the fork backend stamping it; resume preserving it from the persisted header.
The acp-agent cordis configs loaded the fork backend but bound only one
dsh-tool-subagent (to spawn), so the comment's claim that a multi-child scenario
could exercise both transports was false — fork was loaded but unreachable by
the model. Register a second dsh-tool-subagent bound to fork with a distinct
toolName (subagent_fork), matching the coding-agent demo, in both cordis.yml
(record/demo) and cordis.snapshot.yml (replay). Snapshot goldens are unchanged
(the transcript does not capture the available-tool list).
Two findings on the ACP backend:
Blocking: cancel() only sent session/cancel, so a child that ignores the notify
or wedges the prompt left result hung forever — the model-facing tool awaits
result before its finally disposes, so the parent cancellation hung and the
child stayed alive, violating the SubagentRun.cancel() contract (result settles
aborted). The result path now races the ACP drive against a cancelSettled
promise that requestCancel resolves, so result settles aborted the instant a
cancel is requested, regardless of the child. dispose() still kills+reaps the
process. New MOCK_IGNORE_CANCEL mock mode (receives cancel, never resolves the
prompt, never exits) drives a regression proven to hang without the race.
Nit: the drive-path catch was an empty broad catch that discarded the error
(AGENTS.md forbids). Because cancellation is now handled by the race arm, a
rejection reaching the catch is always a genuine child-level error — bind it,
flatten to error, and surface the original via a new AcpRunSpec.onError sink
that the provider wires to ctx.logger.warn, so a real fault is preserved.
addEventListener('abort') does not fire for a signal already aborted before the
listener is added, so a parent step cancelled before the subagent tool ran
would never reach the child — the tool leaned on each provider re-checking
request.signal itself, leaving the bridge's own claim incomplete for any
provider that relies on run.cancel(). Re-check exec.signal.aborted right after
registering and cancel explicitly. Regression test uses a spy provider that
only reacts to cancel() (never inspects the signal); proven to hang without the
fix (result never settles) and settle aborted with it.
Adds the @deepseek-ai/dsh-compact interface package: the abstract
CompactService (ctx.compact) with compactIfNeeded / compactRegion, the
compact/* session-event types via SessionEventMap declaration merging, and the
capability-seam RFC. Wires the package into the three root tsconfigs and the
cordis catalog. A backend implementation lands separately.
Master's #36 moved declaration output to lib/types (and types/exports/files
point there). The merge applied that to all pre-existing packages, but the
subagent backends introduced on this stack (subagent-inprocess, subagent-spawn,
subagent-fork) still used the old lib/ layout. Bring them onto the new
convention and add them to the single typecheck tsconfig.json references.
The shared run driver lived inside dsh-subagent-spawn, so the spawn package
carried fork-aware seeding logic and dsh-subagent-fork depended backward on
dsh-subagent-spawn — the two in-process backends were not independent.
Move the driver (startInProcessRun, depthOf, SubagentDepthError,
InProcessRunOptions) into a new pure-library package
@deepseek-ai/dsh-subagent-inprocess that registers nothing. spawn and fork now
both depend only on that driver and neither knows about the other; spawn no
longer re-exports it and fork no longer imports from spawn.
Also wire BOTH backends in examples/coding-agent/cordis.yml (config-only): load
dsh-subagent-spawn + dsh-subagent-fork + two dsh-tool-subagent instances with
distinct toolNames (subagent → spawn, subagent_fork → fork), demonstrating that
exposing multiple transports needs no code change.
Two round-3 findings:
(A) The EOF-quiesce window reused the 3000ms SIGTERM grace, the SAME value as
dsh-bash-local's own SIGTERM->SIGKILL grace. The child acp-agent's EOF teardown
disposes its loop, which stops child-owned bash -- and a SIGTERM-trapping bash
grandchild can hold that for up to ~3s before its own SIGKILL, then the child
still owes a final flush. With both graces equal, the parent's SIGTERM fired
exactly as the child reached its own SIGKILL+flush, cutting it off. Split the
EOF grace into its own knob (disposeEofGraceMs, default 6000ms) that exceeds a
single signal-grace of nested-teardown headroom. The child is an arbitrary ACP
agent, so the value is a standalone generous default, NOT derived from any
child's internals. Tier-1 test now uses a flush that outlasts the SIGTERM grace
but fits the EOF grace, so it lands only because the EOF tier honors its own
wider window (proven RED when tier 1 reuses the small SIGTERM grace).
(B) The middle-tier (SIGTERM) test only asserted dispose returned in time, so
an EOF->SIGKILL ladder with the rung removed would still pass. The mock's
MOCK_IGNORE_EOF mode now installs a SIGTERM handler that touches an observable
marker before exiting; SIGKILL is uncatchable, so removing the SIGTERM rung
leaves the marker absent (proven RED). The test asserts the marker exists.
dispose() ended stdin and sent SIGTERM in the same tick, so the child's
EOF-driven quiesce had no window to run. The real acp-agent has no SIGTERM
handler in a normal session — it flushes persistence and stops child-owned
work via the server bridge's connection-close path (conn.closed → per-agent
dispose → final session/flush), driven by stdin EOF, NOT by a signal. A prompt
response can resolve from a turn/end before that post-turn flush lands, so the
child still owes durable work when dispose runs; a same-tick default SIGTERM
terminated it mid-flush, orphaning child-owned bash and dropping the flush.
dispose now waits for the child's natural exit after stdin EOF first, then
escalates SIGTERM (grace), then SIGKILL — a three-tier ladder. Add an
`exitsWithin` helper for the bounded waits.
Regression coverage: a new mock mode (MOCK_FLUSH_ON_EOF) flushes a marker
asynchronously on EOF then self-exits; the tier-1 test asserts the marker
lands (proven RED on the same-tick-SIGTERM ordering — child killed mid-flush).
MOCK_IGNORE_EOF covers the middle tier (ignores EOF, dies on default SIGTERM);
the existing MOCK_TRAP_SIGTERM test covers the SIGKILL tier.
Two lifecycle findings from the review:
- A (blocker): dispose() could hang forever. It only sent SIGTERM and awaited
exit, with no escalation — a child that traps SIGTERM (or our acp-agent if it
doesn't quiesce on stdin EOF) would wedge dispose, stranding tool-subagent's
finally cleanup and orphaning child-owned work (e.g. bash subprocesses). dispose
now: ends stdin (graceful ACP close so the child can flush + exit), SIGTERM,
then escalates to SIGKILL if it doesn't exit within a grace period
(DEFAULT_DISPOSE_GRACE_MS, injectable via spec.disposeGraceMs), awaiting the
certain exit. Mirrors the bash executor's bounded teardown. Regression test
drives a SIGTERM-trapping mock subprocess and asserts dispose returns promptly
— proven to hang (red) without the escalation.
- B: an already-aborted request still spawned the configured binary. startAcpRun
now returns an inert already-aborted run BEFORE spawning, so a pre-cancelled
request launches nothing. Test points the command at `touch <sentinel>` and
asserts the sentinel never appears.
The dispose regression test exposed (via systematic-debugging) that the child
must signal trap-armed readiness before the test cancels — a bare timeout raced
the trap install and the default SIGTERM handler killed the child, making the
guard a no-op. The mock now touches its ready file once the trap is in place and
the test waits on that condition. The `cancelled` flag moved onto a holder object
so TS control-flow doesn't narrow the catch-time read to always-false.
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.
Reconcile the session-surface feature with master's package reorg and
simplifications:
- Adopt master's folded usage (assistant/message.usage; standalone `usage`
event dropped) and re-attach surface metadata (surfaceOp/sourceEventSeqs).
- Add surface opts to master's new max-tokens assistant/message append.
- Port surface columns onto the coordinator-refactored SQLite backend at its
new path; drop the dead v1->v2 migration (bump-and-reject, no migration per
pre-release policy).
- Move the session-surface RFC into implemented/architecture/ and refresh its
stale body (no migration, SESSION_FORMAT_VERSION=0, renamed package paths).
- Update the core-data-structures catalog SessionEvent blocks for the two new
surface fields; regenerate the cordis catalog.
- Re-harvest ACP snapshot fixtures (keyless replay) to carry surface metadata.
The createdAt+recordedId child sort comment over-claimed "tie-safe". Codex
flagged that a same-millisecond sibling tie would be broken by random session
id, which does not recover first-call order. In the current synchronous cut that
tie is unreachable — the subagent tool awaits one child's result and disposes it
before the parent starts the next, so siblings' createdAt values are strictly
ordered and match first-call order. Restate the comment to that real invariant
(at both the replay sort and the harvest sort), note that the id tiebreak only
makes a degenerate collision deterministic, and flag the concurrent-subagent cut
that would need a real first-call ordinal with XXX(concurrent-subagents). The RFC
records the same limitation. Comment/doc only — no behavior change.
The snapshot tier was built single-session: dsh-llm-replay served calls from
one global positional cursor, and the harness harvested one session log. A
subagent runs as a second agent with its own session, so a parent→child
scenario could neither replay deterministically nor harvest the child's log.
This resolves the TODO(subagent-snapshots) deferral from the subagent RFC.
- Stamp the calling session id onto the model request: GenerateOptions.sessionId
(typed Branded<'SessionId'> to avoid the dsh-llm↔dsh-session cycle), set by the
agent loop from agent.session.id. Adapters ignore it; an llm/stream listener
routes by it.
- Key replay per session: dsh-llm-replay loads the parent log plus one per child
(childFiles / $DSH_SNAPSHOT_CHILD_FILES), derives a script per recorded session,
and binds each live (freshly-random) session to a recorded script by first-call
order — parent first (earliest createdAt, first to stream). Keys by WHO calls,
so it survives a future concurrent/backgrounded subagent; a global cursor would
not. An unrecorded extra session fails loud.
- Harvest every log: the harness collects all .jsonl across cwd buckets, ordered
primary-first (top-level, then children by createdAt), and RunResult exposes the
plural sessionLogs. The spec writes each back on record (session.jsonl +
session.<n>.jsonl) and diffs each against its fixture on replay.
- Wire the subagent seam + spawn + fork + tool into the acp-agent example (both
cordis configs) and add two nested scenarios recorded against the real API:
subagent-spawn (parent + 1 child) and subagent-multi (parent + 2 children, 3
sessions). Both replay keyless in the default gate.
A new RFC documents the design (docs/rfc/implemented/testing/). Single-session
replay is unchanged (a call with no sessionId is one anonymous primary session).
TODO follow-up: a dedicated branded-ids package could own the SessionId brand and
dissolve the cross-package cycle note; out of scope for this testing PR.
A request signal aborted BEFORE the run starts never fires an `abort` event
(`addEventListener` only fires on the transition), so the backend-level bridge
missed it and ran the child to `completed`. The driver now checks
`request.signal?.aborted` at the top of the result path and settles `aborted`
without running the child. Regression test proven red on the pre-fix code.
Also refresh two stale RFC prose blocks the round-1 fix left behind: the
subagent RFC's Problem statement (cited the removed `TODO(sub-agents)` markers
and claimed nothing existed yet) and the unify-id RFC's fork/spawn risk bullet
(described the seam as "explicitly deferred" via `AgentLoop.create`'s old TODO),
now pointing at the realized seam.
Tianyi Cui
Hypatia May
Yichen Jiang
Dudu-0223
imccyu